[wasm][debugger] Support multidimensional indexing of object scheme

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -387,12 +387,14 @@ private static async Task<IList<JObject>> ResolveElementAccess(ExpressionSyntaxR
  {
  var values = new List<JObject>();
  JObject index = null;
+ List<JObject> nestedIndexers = new();
  IEnumerable<ElementAccessExpressionSyntax> elementAccesses = replacer.elementAccess;
  foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
  {
- index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, index, replacer.variableDefinitions, token);
+ index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, nestedIndexers, replacer.variableDefinitions, token);
  if (index == null)
  throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
+ nestedIndexers.Add(index);
  }
  values.Add(index);
  return values;

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -366,7 +366,12 @@ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject
  }
  }
 
- public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess, Dictionary<string, JObject> memberAccessValues, JObject indexObject, List<VariableDefinition> variableDefinitions, CancellationToken token)
+ public async Task<JObject> Resolve(
+ ElementAccessExpressionSyntax elementAccess,
+ Dictionary<string, JObject> memberAccessValues,
+ List<JObject> nestedIndexObject,
+ List<VariableDefinition> variableDefinitions,
+ CancellationToken token)
  {
  try
  {
@@ -376,12 +381,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
 
  if (rootObject == null)
  {
- // it might be a jagged array where indexObject should be treated as a new rootObject
- rootObject = indexObject;
- indexObject = null;
+ // it might be a jagged array where the previously added nestedIndexObject should be treated as a new rootObject
+ rootObject = nestedIndexObject.LastOrDefault();
+ if (rootObject != null)
+ nestedIndexObject.RemoveAt(nestedIndexObject.Count - 1);
  }
 
- ElementIndexInfo elementIdxInfo = await GetElementIndexInfo();
+ ElementIndexInfo elementIdxInfo = await GetElementIndexInfo(nestedIndexObject);
  if (elementIdxInfo is null)
  return null;
 
@@ -394,6 +400,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  if (!DotnetObjectId.TryParse(rootObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
  throw new InvalidOperationException($"Cannot apply indexing with [] to a primitive object of type '{type}'");
 
+ bool isMultidimensional = elementIdxInfo.DimensionsCount != 1;
  switch (objectId.Scheme)
  {
  case "valuetype": //can be an inlined array
@@ -407,7 +414,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  }
  case "array":
  rootObject["value"] = await context.SdbAgent.GetArrayValues(objectId.Value, token);
- if (!elementIdxInfo.IsMultidimensional)
+ if (!isMultidimensional)
  {
  int.TryParse(elementIdxInfo.ElementIdxStr, out elementIdx);
  return (JObject)rootObject["value"][elementIdx]["value"];
@@ -417,18 +424,16 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  return (JObject)(((JArray)rootObject["value"]).FirstOrDefault(x => x["name"].Value<string>() == elementIdxInfo.ElementIdxStr)["value"]);
  }
  case "object":
- if (elementIdxInfo.IsMultidimensional)
- throw new InvalidOperationException($"Cannot apply indexing with [,] to an object of type '{type}'");
  // ToDo: try to use the get_Item for string as well
- if (type == "string")
+ if (!isMultidimensional && type == "string")
  {
  var eaExpressionFormatted = elementAccessStrExpression.Replace('.', '_'); // instance_str
  variableDefinitions.Add(new (eaExpressionFormatted, rootObject, ExpressionEvaluator.ConvertJSToCSharpLocalVariableAssignment(eaExpressionFormatted, rootObject)));
  var eaFormatted = elementAccessStr.Replace('.', '_'); // instance_str[1]
  var variableDef = await ExpressionEvaluator.GetVariableDefinitions(this, variableDefinitions, invokeToStringInObject: false, token);
  return await ExpressionEvaluator.EvaluateSimpleExpression(this, eaFormatted, elementAccessStr, variableDef, logger, token);
  }
- if (indexObject is null && elementIdxInfo.IndexingExpression is null)
+ if (elementIdxInfo.Indexers is null || elementIdxInfo.Indexers.Count == 0)
  throw new InternalErrorException($"Unable to write index parameter to invoke the method in the runtime.");
 
  var typeIds = await context.SdbAgent.GetTypeIdsForObject(objectId.Value, true, token);
@@ -441,15 +446,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  {
  MethodInfoWithDebugInformation methodInfo = await context.SdbAgent.GetMethodInfo(methodIds[i], token);
  ParameterInfo[] paramInfo = methodInfo.GetParametersInfo();
- if (paramInfo.Length == 1)
+ if (paramInfo.Length == elementIdxInfo.DimensionsCount)
  {
  try
  {
- if (indexObject != null && !CheckParametersCompatibility(paramInfo[0].TypeCode, indexObject))
+ if (!CheckParametersCompatibility(paramInfo, elementIdxInfo.Indexers))
  continue;
- ArraySegment<byte> buffer = indexObject is null ?
- await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression, elementIdxInfo.ElementIdxStr) :
- await WriteJObjectAsIndex(objectId, indexObject, elementIdxInfo.ElementIdxStr, paramInfo[0].TypeCode);
+ ArraySegment<byte> buffer = await WriteIndexObjectAsIndices(objectId, elementIdxInfo.Indexers, paramInfo);
  JObject getItemRetObj = await context.SdbAgent.InvokeMethod(buffer, methodIds[i], token);
  return (JObject)getItemRetObj["value"];
  }
@@ -470,31 +473,32 @@ await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression,
  throw new ReturnAsErrorException($"Unable to evaluate element access '{elementAccess}': {ex.Message}", ex.GetType().Name);
  }
 
- async Task<ElementIndexInfo> GetElementIndexInfo()
+ async Task<ElementIndexInfo> GetElementIndexInfo(List<JObject> nestedIndexers)
  {
- // e.g. x[a[0]], x[a[b[1]]] etc.
- if (indexObject is not null)
- return new ElementIndexInfo(ElementIdxStr: indexObject["value"].ToString() );
-
  if (elementAccess.ArgumentList is null)
  return null;
 
- StringBuilder elementIdxStr = new StringBuilder();
- var multiDimensionalArray = false;
+ int dimCnt = elementAccess.ArgumentList.Arguments.Count;
  LiteralExpressionSyntax indexingExpression = null;
- for (int i = 0; i < elementAccess.ArgumentList.Arguments.Count; i++)
+ StringBuilder elementIdxStr = new StringBuilder();
+ List<object> indexers = new();
+ // nesting should be resolved in reverse order
+ int nestedIndexersCnt = nestedIndexers.Count - 1;
+ for (int i = 0; i < dimCnt; i++)
  {
+ JObject indexObject;
  var arg = elementAccess.ArgumentList.Arguments[i];
  if (i != 0)
  {
  elementIdxStr.Append(", ");
- multiDimensionalArray = true;
  }
  // e.g. x[1]
  if (arg.Expression is LiteralExpressionSyntax)
  {
  indexingExpression = arg.Expression as LiteralExpressionSyntax;
- elementIdxStr.Append(indexingExpression.ToString());
+ string expression = indexingExpression.ToString();
+ elementIdxStr.Append(expression);
+ indexers.Add(indexingExpression);
  }
 
  // e.g. x[a] or x[a.b]
@@ -508,6 +512,18 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  // x[a]
  indexObject ??= await Resolve(argParm.Identifier.Text, token);
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
+ }
+ // nested indexing, e.g. x[a[0]], x[a[b[1]]], x[a[0], b[1]]
+ else if (arg.Expression is ElementAccessExpressionSyntax)
+ {
+ if (nestedIndexers == null || nestedIndexersCnt < 0)
+ throw new InvalidOperationException($"Cannot resolve nested indexing");
+ JObject nestedIndexObject = nestedIndexers[nestedIndexersCnt];
+ nestedIndexers.RemoveAt(nestedIndexersCnt);
+ elementIdxStr.Append(nestedIndexObject["value"].ToString());
+ indexers.Add(nestedIndexObject);
+ nestedIndexersCnt--;
  }
  // indexing with expressions, e.g. x[a + 1]
  else
@@ -519,36 +535,57 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  if (idxType != "number")
  throw new InvalidOperationException($"Cannot index with an object of type '{idxType}'");
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
  }
  }
  return new ElementIndexInfo(
+ DimensionsCount: dimCnt,
  ElementIdxStr: elementIdxStr.ToString(),
- IsMultidimensional: multiDimensionalArray,
- IndexingExpression: indexingExpression);
+ Indexers: indexers);
  }
 
- async Task<ArraySegment<byte>> WriteJObjectAsIndex(DotnetObjectId rootObjId, JObject indexObject, string elementIdxStr, ElementType? expectedType)
+ async Task<ArraySegment<byte>> WriteIndexObjectAsIndices(DotnetObjectId rootObjId, List<object> indexObjects, ParameterInfo[] paramInfo)
  {
  using var writer = new MonoBinaryWriter();
  writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteJsonValue(indexObject, context.SdbAgent, expectedType, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
+ writer.Write(indexObjects.Count); // number of method args
+ foreach ((ParameterInfo pi, object indexObject) in paramInfo.Zip(indexObjects))
+ {
+ if (indexObject is JObject indexJObject)
+ {
+ // indexed by an identifier name syntax
+ if (!await writer.WriteJsonValue(indexJObject, context.SdbAgent, pi.TypeCode, token))
+ throw new InternalErrorException($"Parsing index of type {indexJObject["type"].Value<string>()} to write it into the buffer failed.");
+ }
+ else if (indexObject is LiteralExpressionSyntax expression)
+ {
+ // indexed by a literal expression syntax
+ if (!await writer.WriteConst(expression, context.SdbAgent, token))
+ throw new InternalErrorException($"Parsing literal expression index = {expression} to write it into the buffer failed.");
+ }
+ else
+ {
+ throw new InternalErrorException($"Unexpected index type.");
+ }
+ }
  return writer.GetParameterBuffer();
  }
+ }
 
- async Task<ArraySegment<byte>> WriteLiteralExpressionAsIndex(DotnetObjectId rootObjId, LiteralExpressionSyntax indexingExpression, string elementIdxStr)
+ private static bool CheckParametersCompatibility(ParameterInfo[] paramInfos, List<object> indexObjects)
+ {
+ if (paramInfos.Length != indexObjects.Count)
+ return false;
+ foreach ((ParameterInfo paramInfo, object indexObj) in paramInfos.Zip(indexObjects))
  {
- using var writer = new MonoBinaryWriter();
- writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteConst(indexingExpression, context.SdbAgent, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
- return writer.GetParameterBuffer();
+ // shouldn't we check LiteralExpressionSyntax for compatibility as well?
+ if (indexObj is JObject indexJObj && !CheckParameterCompatibility(paramInfo.TypeCode, indexJObj))
+ return false;
  }
+ return true;
  }
 
- private static bool CheckParametersCompatibility(ElementType? paramTypeCode, JObject value)
+ private static bool CheckParameterCompatibility(ElementType? paramTypeCode, JObject value)
  {
  if (!paramTypeCode.HasValue)
  return true;
@@ -871,7 +908,8 @@ public JObject TryGetEvaluationResult(string id)
 
  private sealed record ElementIndexInfo(
  string ElementIdxStr,
- bool IsMultidimensional = false,
- LiteralExpressionSyntax IndexingExpression = null);
+ // keeps JObjects and LiteralExpressionSyntaxes:
+ List<object> Indexers,
+ int DimensionsCount = 1);
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrame2Tests.cs

@@ -745,5 +745,24 @@ await EvaluateOnCallFrameAndCheck(id,
  // ("mc.valueTypeEnum.HasFlag(SampleEnum.no)", TBool(true)) // ToDo: https://github.com/dotnet/runtime/issues/92262
  );
  });
+
+ [Fact]
+ public async Task EvaluateObjectIndexingMultidimensional() => await CheckInspectLocalsAtBreakpointSite(
+ "DebuggerTests.EvaluateLocalsWithIndexingTests", "EvaluateLocals", 12, "DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals",
+ "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.EvaluateLocalsWithIndexingTests:EvaluateLocals'); })",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ await EvaluateOnCallFrameAndCheck(id,
+ ("f[j, aDouble]", TNumber("3.34")), //only IdentifierNameSyntaxes
+ ("f[1, aDouble]", TNumber("3.34")), //IdentifierNameSyntax with LiteralExpressionSyntax
+ ("f[aChar, \"&\", longString]", TString("9-&-longString")),
+ ("f[f.numArray[j], aDouble]", TNumber("4.34")), //ElementAccessExpressionSyntax
+ ("f[f.numArray[j], f.numArray[0]]", TNumber("3")), //multiple ElementAccessExpressionSyntaxes
+ ("f[f.numArray[f.numList[0]], f.numArray[i]]", TNumber("3")),
+ ("f[f.numArray[f.numList[0]], f.numArray[f.numArray[i]]]", TNumber("4"))
+ ); 
+ });
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -585,7 +585,7 @@ public async Task EvaluateIndexingNegative() => await CheckInspectLocalsAtBreakp
  Assert.Equal("Unable to evaluate element access 'f.idx0[2]': Cannot apply indexing with [] to a primitive object of type 'number'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  (_, res) = await EvaluateOnCallFrame(id, "f[1]", expect_ok: false );
  Assert.Equal( "Unable to evaluate element access 'f[1]': Cannot apply indexing with [] to an object of type 'DebuggerTests.EvaluateLocalsWithIndexingTests.TestEvaluate'", res.Error["result"]?["description"]?.Value<string>());
@@ -724,7 +724,7 @@ public async Task EvaluateIndexingByExpressionNegative() => await CheckInspectLo
  Assert.Equal("Unable to evaluate element access 'f.numList[\"a\" + 1]': Cannot index with an object of type 'string'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  });
 
@@ -861,7 +861,9 @@ await EvaluateOnCallFrameAndCheck(id,
  ("f.textArrayOfArrays[f.idx1][f.idx1]", TString("2")),
  ("f.textListOfLists[1][1]", TString("2")),
  ("f.textListOfLists[j][j]", TString("2")),
- ("f.textListOfLists[f.idx1][f.idx1]", TString("2")));
+ ("f.textListOfLists[f.idx1][f.idx1]", TString("2")),
+ ("f.numArrayOfArrays[f.numArray[f.numList[1]]][f.numList[0]]", TNumber(2))
+ );
 
  });
 

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -387,12 +387,14 @@ private static async Task<IList<JObject>> ResolveElementAccess(ExpressionSyntaxR
  {
  var values = new List<JObject>();
  JObject index = null;
+ List<JObject> nestedIndexers = new();
  IEnumerable<ElementAccessExpressionSyntax> elementAccesses = replacer.elementAccess;
  foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
  {
- index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, index, replacer.variableDefinitions, token);
+ index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, nestedIndexers, replacer.variableDefinitions, token);
  if (index == null)
  throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
+ nestedIndexers.Add(index);
  }
  values.Add(index);
  return values;

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -366,7 +366,12 @@ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject
  }
  }
 
- public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess, Dictionary<string, JObject> memberAccessValues, JObject indexObject, List<VariableDefinition> variableDefinitions, CancellationToken token)
+ public async Task<JObject> Resolve(
+ ElementAccessExpressionSyntax elementAccess,
+ Dictionary<string, JObject> memberAccessValues,
+ List<JObject> nestedIndexObject,
+ List<VariableDefinition> variableDefinitions,
+ CancellationToken token)
  {
  try
  {
@@ -376,12 +381,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
 
  if (rootObject == null)
  {
- // it might be a jagged array where indexObject should be treated as a new rootObject
- rootObject = indexObject;
- indexObject = null;
+ // it might be a jagged array where the previously added nestedIndexObject should be treated as a new rootObject
+ rootObject = nestedIndexObject.LastOrDefault();
+ if (rootObject != null)
+ nestedIndexObject.RemoveAt(nestedIndexObject.Count - 1);
  }
 
- ElementIndexInfo elementIdxInfo = await GetElementIndexInfo();
+ ElementIndexInfo elementIdxInfo = await GetElementIndexInfo(nestedIndexObject);
  if (elementIdxInfo is null)
  return null;
 
@@ -394,6 +400,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  if (!DotnetObjectId.TryParse(rootObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
  throw new InvalidOperationException($"Cannot apply indexing with [] to a primitive object of type '{type}'");
 
+ bool isMultidimensional = elementIdxInfo.DimensionsCount != 1;
  switch (objectId.Scheme)
  {
  case "valuetype": //can be an inlined array
@@ -407,7 +414,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  }
  case "array":
  rootObject["value"] = await context.SdbAgent.GetArrayValues(objectId.Value, token);
- if (!elementIdxInfo.IsMultidimensional)
+ if (!isMultidimensional)
  {
  int.TryParse(elementIdxInfo.ElementIdxStr, out elementIdx);
  return (JObject)rootObject["value"][elementIdx]["value"];
@@ -417,18 +424,16 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  return (JObject)(((JArray)rootObject["value"]).FirstOrDefault(x => x["name"].Value<string>() == elementIdxInfo.ElementIdxStr)["value"]);
  }
  case "object":
- if (elementIdxInfo.IsMultidimensional)
- throw new InvalidOperationException($"Cannot apply indexing with [,] to an object of type '{type}'");
  // ToDo: try to use the get_Item for string as well
- if (type == "string")
+ if (!isMultidimensional && type == "string")
  {
  var eaExpressionFormatted = elementAccessStrExpression.Replace('.', '_'); // instance_str
  variableDefinitions.Add(new (eaExpressionFormatted, rootObject, ExpressionEvaluator.ConvertJSToCSharpLocalVariableAssignment(eaExpressionFormatted, rootObject)));
  var eaFormatted = elementAccessStr.Replace('.', '_'); // instance_str[1]
  var variableDef = await ExpressionEvaluator.GetVariableDefinitions(this, variableDefinitions, invokeToStringInObject: false, token);
  return await ExpressionEvaluator.EvaluateSimpleExpression(this, eaFormatted, elementAccessStr, variableDef, logger, token);
  }
- if (indexObject is null && elementIdxInfo.IndexingExpression is null)
+ if (elementIdxInfo.Indexers is null || elementIdxInfo.Indexers.Count == 0)
  throw new InternalErrorException($"Unable to write index parameter to invoke the method in the runtime.");
 
  var typeIds = await context.SdbAgent.GetTypeIdsForObject(objectId.Value, true, token);
@@ -441,15 +446,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  {
  MethodInfoWithDebugInformation methodInfo = await context.SdbAgent.GetMethodInfo(methodIds[i], token);
  ParameterInfo[] paramInfo = methodInfo.GetParametersInfo();
- if (paramInfo.Length == 1)
+ if (paramInfo.Length == elementIdxInfo.DimensionsCount)
  {
  try
  {
- if (indexObject != null && !CheckParametersCompatibility(paramInfo[0].TypeCode, indexObject))
+ if (!CheckParametersCompatibility(paramInfo, elementIdxInfo.Indexers))
  continue;
- ArraySegment<byte> buffer = indexObject is null ?
- await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression, elementIdxInfo.ElementIdxStr) :
- await WriteJObjectAsIndex(objectId, indexObject, elementIdxInfo.ElementIdxStr, paramInfo[0].TypeCode);
+ ArraySegment<byte> buffer = await WriteIndexObjectAsIndices(objectId, elementIdxInfo.Indexers, paramInfo);
  JObject getItemRetObj = await context.SdbAgent.InvokeMethod(buffer, methodIds[i], token);
  return (JObject)getItemRetObj["value"];
  }
@@ -470,31 +473,32 @@ await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression,
  throw new ReturnAsErrorException($"Unable to evaluate element access '{elementAccess}': {ex.Message}", ex.GetType().Name);
  }
 
- async Task<ElementIndexInfo> GetElementIndexInfo()
+ async Task<ElementIndexInfo> GetElementIndexInfo(List<JObject> nestedIndexers)
  {
- // e.g. x[a[0]], x[a[b[1]]] etc.
- if (indexObject is not null)
- return new ElementIndexInfo(ElementIdxStr: indexObject["value"].ToString() );
-
  if (elementAccess.ArgumentList is null)
  return null;
 
- StringBuilder elementIdxStr = new StringBuilder();
- var multiDimensionalArray = false;
+ int dimCnt = elementAccess.ArgumentList.Arguments.Count;
  LiteralExpressionSyntax indexingExpression = null;
- for (int i = 0; i < elementAccess.ArgumentList.Arguments.Count; i++)
+ StringBuilder elementIdxStr = new StringBuilder();
+ List<object> indexers = new();
+ // nesting should be resolved in reverse order
+ int nestedIndexersCnt = nestedIndexers.Count - 1;
+ for (int i = 0; i < dimCnt; i++)
  {
+ JObject indexObject;
  var arg = elementAccess.ArgumentList.Arguments[i];
  if (i != 0)
  {
  elementIdxStr.Append(", ");
- multiDimensionalArray = true;
  }
  // e.g. x[1]
  if (arg.Expression is LiteralExpressionSyntax)
  {
  indexingExpression = arg.Expression as LiteralExpressionSyntax;
- elementIdxStr.Append(indexingExpression.ToString());
+ string expression = indexingExpression.ToString();
+ elementIdxStr.Append(expression);
+ indexers.Add(indexingExpression);
  }
 
  // e.g. x[a] or x[a.b]
@@ -508,6 +512,18 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  // x[a]
  indexObject ??= await Resolve(argParm.Identifier.Text, token);
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
+ }
+ // nested indexing, e.g. x[a[0]], x[a[b[1]]], x[a[0], b[1]]
+ else if (arg.Expression is ElementAccessExpressionSyntax)
+ {
+ if (nestedIndexers == null || nestedIndexersCnt < 0)
+ throw new InvalidOperationException($"Cannot resolve nested indexing");
+ JObject nestedIndexObject = nestedIndexers[nestedIndexersCnt];
+ nestedIndexers.RemoveAt(nestedIndexersCnt);
+ elementIdxStr.Append(nestedIndexObject["value"].ToString());
+ indexers.Add(nestedIndexObject);
+ nestedIndexersCnt--;
  }
  // indexing with expressions, e.g. x[a + 1]
  else
@@ -519,36 +535,57 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  if (idxType != "number")
  throw new InvalidOperationException($"Cannot index with an object of type '{idxType}'");
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
  }
  }
  return new ElementIndexInfo(
+ DimensionsCount: dimCnt,
  ElementIdxStr: elementIdxStr.ToString(),
- IsMultidimensional: multiDimensionalArray,
- IndexingExpression: indexingExpression);
+ Indexers: indexers);
  }
 
- async Task<ArraySegment<byte>> WriteJObjectAsIndex(DotnetObjectId rootObjId, JObject indexObject, string elementIdxStr, ElementType? expectedType)
+ async Task<ArraySegment<byte>> WriteIndexObjectAsIndices(DotnetObjectId rootObjId, List<object> indexObjects, ParameterInfo[] paramInfo)
  {
  using var writer = new MonoBinaryWriter();
  writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteJsonValue(indexObject, context.SdbAgent, expectedType, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
+ writer.Write(indexObjects.Count); // number of method args
+ foreach ((ParameterInfo pi, object indexObject) in paramInfo.Zip(indexObjects))
+ {
+ if (indexObject is JObject indexJObject)
+ {
+ // indexed by an identifier name syntax
+ if (!await writer.WriteJsonValue(indexJObject, context.SdbAgent, pi.TypeCode, token))
+ throw new InternalErrorException($"Parsing index of type {indexJObject["type"].Value<string>()} to write it into the buffer failed.");
+ }
+ else if (indexObject is LiteralExpressionSyntax expression)
+ {
+ // indexed by a literal expression syntax
+ if (!await writer.WriteConst(expression, context.SdbAgent, token))
+ throw new InternalErrorException($"Parsing literal expression index = {expression} to write it into the buffer failed.");
+ }
+ else
+ {
+ throw new InternalErrorException($"Unexpected index type.");
+ }
+ }
  return writer.GetParameterBuffer();
  }
+ }
 
- async Task<ArraySegment<byte>> WriteLiteralExpressionAsIndex(DotnetObjectId rootObjId, LiteralExpressionSyntax indexingExpression, string elementIdxStr)
+ private static bool CheckParametersCompatibility(ParameterInfo[] paramInfos, List<object> indexObjects)
+ {
+ if (paramInfos.Length != indexObjects.Count)
+ return false;
+ foreach ((ParameterInfo paramInfo, object indexObj) in paramInfos.Zip(indexObjects))
  {
- using var writer = new MonoBinaryWriter();
- writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteConst(indexingExpression, context.SdbAgent, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
- return writer.GetParameterBuffer();
+ // shouldn't we check LiteralExpressionSyntax for compatibility as well?
+ if (indexObj is JObject indexJObj && !CheckParameterCompatibility(paramInfo.TypeCode, indexJObj))
+ return false;
  }
+ return true;
  }
 
- private static bool CheckParametersCompatibility(ElementType? paramTypeCode, JObject value)
+ private static bool CheckParameterCompatibility(ElementType? paramTypeCode, JObject value)
  {
  if (!paramTypeCode.HasValue)
  return true;
@@ -871,7 +908,8 @@ public JObject TryGetEvaluationResult(string id)
 
  private sealed record ElementIndexInfo(
  string ElementIdxStr,
- bool IsMultidimensional = false,
- LiteralExpressionSyntax IndexingExpression = null);
+ // keeps JObjects and LiteralExpressionSyntaxes:
+ List<object> Indexers,
+ int DimensionsCount = 1);
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrame2Tests.cs

@@ -745,5 +745,24 @@ await EvaluateOnCallFrameAndCheck(id,
  // ("mc.valueTypeEnum.HasFlag(SampleEnum.no)", TBool(true)) // ToDo: https://github.com/dotnet/runtime/issues/92262
  );
  });
+
+ [Fact]
+ public async Task EvaluateObjectIndexingMultidimensional() => await CheckInspectLocalsAtBreakpointSite(
+ "DebuggerTests.EvaluateLocalsWithIndexingTests", "EvaluateLocals", 12, "DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals",
+ "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.EvaluateLocalsWithIndexingTests:EvaluateLocals'); })",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ await EvaluateOnCallFrameAndCheck(id,
+ ("f[j, aDouble]", TNumber("3.34")), //only IdentifierNameSyntaxes
+ ("f[1, aDouble]", TNumber("3.34")), //IdentifierNameSyntax with LiteralExpressionSyntax
+ ("f[aChar, \"&\", longString]", TString("9-&-longString")),
+ ("f[f.numArray[j], aDouble]", TNumber("4.34")), //ElementAccessExpressionSyntax
+ ("f[f.numArray[j], f.numArray[0]]", TNumber("3")), //multiple ElementAccessExpressionSyntaxes
+ ("f[f.numArray[f.numList[0]], f.numArray[i]]", TNumber("3")),
+ ("f[f.numArray[f.numList[0]], f.numArray[f.numArray[i]]]", TNumber("4"))
+ ); 
+ });
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -585,7 +585,7 @@ public async Task EvaluateIndexingNegative() => await CheckInspectLocalsAtBreakp
  Assert.Equal("Unable to evaluate element access 'f.idx0[2]': Cannot apply indexing with [] to a primitive object of type 'number'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  (_, res) = await EvaluateOnCallFrame(id, "f[1]", expect_ok: false );
  Assert.Equal( "Unable to evaluate element access 'f[1]': Cannot apply indexing with [] to an object of type 'DebuggerTests.EvaluateLocalsWithIndexingTests.TestEvaluate'", res.Error["result"]?["description"]?.Value<string>());
@@ -724,7 +724,7 @@ public async Task EvaluateIndexingByExpressionNegative() => await CheckInspectLo
  Assert.Equal("Unable to evaluate element access 'f.numList[\"a\" + 1]': Cannot index with an object of type 'string'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  });
 
@@ -861,7 +861,9 @@ await EvaluateOnCallFrameAndCheck(id,
  ("f.textArrayOfArrays[f.idx1][f.idx1]", TString("2")),
  ("f.textListOfLists[1][1]", TString("2")),
  ("f.textListOfLists[j][j]", TString("2")),
- ("f.textListOfLists[f.idx1][f.idx1]", TString("2")));
+ ("f.textListOfLists[f.idx1][f.idx1]", TString("2")),
+ ("f.numArrayOfArrays[f.numArray[f.numList[1]]][f.numList[0]]", TNumber(2))
+ );
 
  });
 

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -387,12 +387,14 @@ private static async Task<IList<JObject>> ResolveElementAccess(ExpressionSyntaxR
  {
  var values = new List<JObject>();
  JObject index = null;
+ List<JObject> nestedIndexers = new();
  IEnumerable<ElementAccessExpressionSyntax> elementAccesses = replacer.elementAccess;
  foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
  {
- index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, index, replacer.variableDefinitions, token);
+ index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, nestedIndexers, replacer.variableDefinitions, token);
  if (index == null)
  throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
+ nestedIndexers.Add(index);
  }
  values.Add(index);
  return values;

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -366,7 +366,12 @@ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject
  }
  }
 
- public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess, Dictionary<string, JObject> memberAccessValues, JObject indexObject, List<VariableDefinition> variableDefinitions, CancellationToken token)
+ public async Task<JObject> Resolve(
+ ElementAccessExpressionSyntax elementAccess,
+ Dictionary<string, JObject> memberAccessValues,
+ List<JObject> nestedIndexObject,
+ List<VariableDefinition> variableDefinitions,
+ CancellationToken token)
  {
  try
  {
@@ -376,12 +381,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
 
  if (rootObject == null)
  {
- // it might be a jagged array where indexObject should be treated as a new rootObject
- rootObject = indexObject;
- indexObject = null;
+ // it might be a jagged array where the previously added nestedIndexObject should be treated as a new rootObject
+ rootObject = nestedIndexObject.LastOrDefault();
+ if (rootObject != null)
+ nestedIndexObject.RemoveAt(nestedIndexObject.Count - 1);
  }
 
- ElementIndexInfo elementIdxInfo = await GetElementIndexInfo();
+ ElementIndexInfo elementIdxInfo = await GetElementIndexInfo(nestedIndexObject);
  if (elementIdxInfo is null)
  return null;
 
@@ -394,6 +400,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  if (!DotnetObjectId.TryParse(rootObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
  throw new InvalidOperationException($"Cannot apply indexing with [] to a primitive object of type '{type}'");
 
+ bool isMultidimensional = elementIdxInfo.DimensionsCount != 1;
  switch (objectId.Scheme)
  {
  case "valuetype": //can be an inlined array
@@ -407,7 +414,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  }
  case "array":
  rootObject["value"] = await context.SdbAgent.GetArrayValues(objectId.Value, token);
- if (!elementIdxInfo.IsMultidimensional)
+ if (!isMultidimensional)
  {
  int.TryParse(elementIdxInfo.ElementIdxStr, out elementIdx);
  return (JObject)rootObject["value"][elementIdx]["value"];
@@ -417,18 +424,16 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  return (JObject)(((JArray)rootObject["value"]).FirstOrDefault(x => x["name"].Value<string>() == elementIdxInfo.ElementIdxStr)["value"]);
  }
  case "object":
- if (elementIdxInfo.IsMultidimensional)
- throw new InvalidOperationException($"Cannot apply indexing with [,] to an object of type '{type}'");
  // ToDo: try to use the get_Item for string as well
- if (type == "string")
+ if (!isMultidimensional && type == "string")
  {
  var eaExpressionFormatted = elementAccessStrExpression.Replace('.', '_'); // instance_str
  variableDefinitions.Add(new (eaExpressionFormatted, rootObject, ExpressionEvaluator.ConvertJSToCSharpLocalVariableAssignment(eaExpressionFormatted, rootObject)));
  var eaFormatted = elementAccessStr.Replace('.', '_'); // instance_str[1]
  var variableDef = await ExpressionEvaluator.GetVariableDefinitions(this, variableDefinitions, invokeToStringInObject: false, token);
  return await ExpressionEvaluator.EvaluateSimpleExpression(this, eaFormatted, elementAccessStr, variableDef, logger, token);
  }
- if (indexObject is null && elementIdxInfo.IndexingExpression is null)
+ if (elementIdxInfo.Indexers is null || elementIdxInfo.Indexers.Count == 0)
  throw new InternalErrorException($"Unable to write index parameter to invoke the method in the runtime.");
 
  var typeIds = await context.SdbAgent.GetTypeIdsForObject(objectId.Value, true, token);
@@ -441,15 +446,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  {
  MethodInfoWithDebugInformation methodInfo = await context.SdbAgent.GetMethodInfo(methodIds[i], token);
  ParameterInfo[] paramInfo = methodInfo.GetParametersInfo();
- if (paramInfo.Length == 1)
+ if (paramInfo.Length == elementIdxInfo.DimensionsCount)
  {
  try
  {
- if (indexObject != null && !CheckParametersCompatibility(paramInfo[0].TypeCode, indexObject))
+ if (!CheckParametersCompatibility(paramInfo, elementIdxInfo.Indexers))
  continue;
- ArraySegment<byte> buffer = indexObject is null ?
- await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression, elementIdxInfo.ElementIdxStr) :
- await WriteJObjectAsIndex(objectId, indexObject, elementIdxInfo.ElementIdxStr, paramInfo[0].TypeCode);
+ ArraySegment<byte> buffer = await WriteIndexObjectAsIndices(objectId, elementIdxInfo.Indexers, paramInfo);
  JObject getItemRetObj = await context.SdbAgent.InvokeMethod(buffer, methodIds[i], token);
  return (JObject)getItemRetObj["value"];
  }
@@ -470,31 +473,32 @@ await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression,
  throw new ReturnAsErrorException($"Unable to evaluate element access '{elementAccess}': {ex.Message}", ex.GetType().Name);
  }
 
- async Task<ElementIndexInfo> GetElementIndexInfo()
+ async Task<ElementIndexInfo> GetElementIndexInfo(List<JObject> nestedIndexers)
  {
- // e.g. x[a[0]], x[a[b[1]]] etc.
- if (indexObject is not null)
- return new ElementIndexInfo(ElementIdxStr: indexObject["value"].ToString() );
-
  if (elementAccess.ArgumentList is null)
  return null;
 
- StringBuilder elementIdxStr = new StringBuilder();
- var multiDimensionalArray = false;
+ int dimCnt = elementAccess.ArgumentList.Arguments.Count;
  LiteralExpressionSyntax indexingExpression = null;
- for (int i = 0; i < elementAccess.ArgumentList.Arguments.Count; i++)
+ StringBuilder elementIdxStr = new StringBuilder();
+ List<object> indexers = new();
+ // nesting should be resolved in reverse order
+ int nestedIndexersCnt = nestedIndexers.Count - 1;
+ for (int i = 0; i < dimCnt; i++)
  {
+ JObject indexObject;
  var arg = elementAccess.ArgumentList.Arguments[i];
  if (i != 0)
  {
  elementIdxStr.Append(", ");
- multiDimensionalArray = true;
  }
  // e.g. x[1]
  if (arg.Expression is LiteralExpressionSyntax)
  {
  indexingExpression = arg.Expression as LiteralExpressionSyntax;
- elementIdxStr.Append(indexingExpression.ToString());
+ string expression = indexingExpression.ToString();
+ elementIdxStr.Append(expression);
+ indexers.Add(indexingExpression);
  }
 
  // e.g. x[a] or x[a.b]
@@ -508,6 +512,18 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  // x[a]
  indexObject ??= await Resolve(argParm.Identifier.Text, token);
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
+ }
+ // nested indexing, e.g. x[a[0]], x[a[b[1]]], x[a[0], b[1]]
+ else if (arg.Expression is ElementAccessExpressionSyntax)
+ {
+ if (nestedIndexers == null || nestedIndexersCnt < 0)
+ throw new InvalidOperationException($"Cannot resolve nested indexing");
+ JObject nestedIndexObject = nestedIndexers[nestedIndexersCnt];
+ nestedIndexers.RemoveAt(nestedIndexersCnt);
+ elementIdxStr.Append(nestedIndexObject["value"].ToString());
+ indexers.Add(nestedIndexObject);
+ nestedIndexersCnt--;
  }
  // indexing with expressions, e.g. x[a + 1]
  else
@@ -519,36 +535,57 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  if (idxType != "number")
  throw new InvalidOperationException($"Cannot index with an object of type '{idxType}'");
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
  }
  }
  return new ElementIndexInfo(
+ DimensionsCount: dimCnt,
  ElementIdxStr: elementIdxStr.ToString(),
- IsMultidimensional: multiDimensionalArray,
- IndexingExpression: indexingExpression);
+ Indexers: indexers);
  }
 
- async Task<ArraySegment<byte>> WriteJObjectAsIndex(DotnetObjectId rootObjId, JObject indexObject, string elementIdxStr, ElementType? expectedType)
+ async Task<ArraySegment<byte>> WriteIndexObjectAsIndices(DotnetObjectId rootObjId, List<object> indexObjects, ParameterInfo[] paramInfo)
  {
  using var writer = new MonoBinaryWriter();
  writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteJsonValue(indexObject, context.SdbAgent, expectedType, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
+ writer.Write(indexObjects.Count); // number of method args
+ foreach ((ParameterInfo pi, object indexObject) in paramInfo.Zip(indexObjects))
+ {
+ if (indexObject is JObject indexJObject)
+ {
+ // indexed by an identifier name syntax
+ if (!await writer.WriteJsonValue(indexJObject, context.SdbAgent, pi.TypeCode, token))
+ throw new InternalErrorException($"Parsing index of type {indexJObject["type"].Value<string>()} to write it into the buffer failed.");
+ }
+ else if (indexObject is LiteralExpressionSyntax expression)
+ {
+ // indexed by a literal expression syntax
+ if (!await writer.WriteConst(expression, context.SdbAgent, token))
+ throw new InternalErrorException($"Parsing literal expression index = {expression} to write it into the buffer failed.");
+ }
+ else
+ {
+ throw new InternalErrorException($"Unexpected index type.");
+ }
+ }
  return writer.GetParameterBuffer();
  }
+ }
 
- async Task<ArraySegment<byte>> WriteLiteralExpressionAsIndex(DotnetObjectId rootObjId, LiteralExpressionSyntax indexingExpression, string elementIdxStr)
+ private static bool CheckParametersCompatibility(ParameterInfo[] paramInfos, List<object> indexObjects)
+ {
+ if (paramInfos.Length != indexObjects.Count)
+ return false;
+ foreach ((ParameterInfo paramInfo, object indexObj) in paramInfos.Zip(indexObjects))
  {
- using var writer = new MonoBinaryWriter();
- writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteConst(indexingExpression, context.SdbAgent, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
- return writer.GetParameterBuffer();
+ // shouldn't we check LiteralExpressionSyntax for compatibility as well?
+ if (indexObj is JObject indexJObj && !CheckParameterCompatibility(paramInfo.TypeCode, indexJObj))
+ return false;
  }
+ return true;
  }
 
- private static bool CheckParametersCompatibility(ElementType? paramTypeCode, JObject value)
+ private static bool CheckParameterCompatibility(ElementType? paramTypeCode, JObject value)
  {
  if (!paramTypeCode.HasValue)
  return true;
@@ -871,7 +908,8 @@ public JObject TryGetEvaluationResult(string id)
 
  private sealed record ElementIndexInfo(
  string ElementIdxStr,
- bool IsMultidimensional = false,
- LiteralExpressionSyntax IndexingExpression = null);
+ // keeps JObjects and LiteralExpressionSyntaxes:
+ List<object> Indexers,
+ int DimensionsCount = 1);
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrame2Tests.cs

@@ -745,5 +745,24 @@ await EvaluateOnCallFrameAndCheck(id,
  // ("mc.valueTypeEnum.HasFlag(SampleEnum.no)", TBool(true)) // ToDo: https://github.com/dotnet/runtime/issues/92262
  );
  });
+
+ [Fact]
+ public async Task EvaluateObjectIndexingMultidimensional() => await CheckInspectLocalsAtBreakpointSite(
+ "DebuggerTests.EvaluateLocalsWithIndexingTests", "EvaluateLocals", 12, "DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals",
+ "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.EvaluateLocalsWithIndexingTests:EvaluateLocals'); })",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ await EvaluateOnCallFrameAndCheck(id,
+ ("f[j, aDouble]", TNumber("3.34")), //only IdentifierNameSyntaxes
+ ("f[1, aDouble]", TNumber("3.34")), //IdentifierNameSyntax with LiteralExpressionSyntax
+ ("f[aChar, \"&\", longString]", TString("9-&-longString")),
+ ("f[f.numArray[j], aDouble]", TNumber("4.34")), //ElementAccessExpressionSyntax
+ ("f[f.numArray[j], f.numArray[0]]", TNumber("3")), //multiple ElementAccessExpressionSyntaxes
+ ("f[f.numArray[f.numList[0]], f.numArray[i]]", TNumber("3")),
+ ("f[f.numArray[f.numList[0]], f.numArray[f.numArray[i]]]", TNumber("4"))
+ ); 
+ });
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -585,7 +585,7 @@ public async Task EvaluateIndexingNegative() => await CheckInspectLocalsAtBreakp
  Assert.Equal("Unable to evaluate element access 'f.idx0[2]': Cannot apply indexing with [] to a primitive object of type 'number'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  (_, res) = await EvaluateOnCallFrame(id, "f[1]", expect_ok: false );
  Assert.Equal( "Unable to evaluate element access 'f[1]': Cannot apply indexing with [] to an object of type 'DebuggerTests.EvaluateLocalsWithIndexingTests.TestEvaluate'", res.Error["result"]?["description"]?.Value<string>());
@@ -724,7 +724,7 @@ public async Task EvaluateIndexingByExpressionNegative() => await CheckInspectLo
  Assert.Equal("Unable to evaluate element access 'f.numList[\"a\" + 1]': Cannot index with an object of type 'string'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  });
 
@@ -861,7 +861,9 @@ await EvaluateOnCallFrameAndCheck(id,
  ("f.textArrayOfArrays[f.idx1][f.idx1]", TString("2")),
  ("f.textListOfLists[1][1]", TString("2")),
  ("f.textListOfLists[j][j]", TString("2")),
- ("f.textListOfLists[f.idx1][f.idx1]", TString("2")));
+ ("f.textListOfLists[f.idx1][f.idx1]", TString("2")),
+ ("f.numArrayOfArrays[f.numArray[f.numList[1]]][f.numList[0]]", TNumber(2))
+ );
 
  });
 

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -387,12 +387,14 @@ private static async Task<IList<JObject>> ResolveElementAccess(ExpressionSyntaxR
  {
  var values = new List<JObject>();
  JObject index = null;
+ List<JObject> nestedIndexers = new();
  IEnumerable<ElementAccessExpressionSyntax> elementAccesses = replacer.elementAccess;
  foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
  {
- index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, index, replacer.variableDefinitions, token);
+ index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, nestedIndexers, replacer.variableDefinitions, token);
  if (index == null)
  throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
+ nestedIndexers.Add(index);
  }
  values.Add(index);
  return values;

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -366,7 +366,12 @@ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject
  }
  }
 
- public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess, Dictionary<string, JObject> memberAccessValues, JObject indexObject, List<VariableDefinition> variableDefinitions, CancellationToken token)
+ public async Task<JObject> Resolve(
+ ElementAccessExpressionSyntax elementAccess,
+ Dictionary<string, JObject> memberAccessValues,
+ List<JObject> nestedIndexObject,
+ List<VariableDefinition> variableDefinitions,
+ CancellationToken token)
  {
  try
  {
@@ -376,12 +381,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
 
  if (rootObject == null)
  {
- // it might be a jagged array where indexObject should be treated as a new rootObject
- rootObject = indexObject;
- indexObject = null;
+ // it might be a jagged array where the previously added nestedIndexObject should be treated as a new rootObject
+ rootObject = nestedIndexObject.LastOrDefault();
+ if (rootObject != null)
+ nestedIndexObject.RemoveAt(nestedIndexObject.Count - 1);
  }
 
- ElementIndexInfo elementIdxInfo = await GetElementIndexInfo();
+ ElementIndexInfo elementIdxInfo = await GetElementIndexInfo(nestedIndexObject);
  if (elementIdxInfo is null)
  return null;
 
@@ -394,6 +400,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  if (!DotnetObjectId.TryParse(rootObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
  throw new InvalidOperationException($"Cannot apply indexing with [] to a primitive object of type '{type}'");
 
+ bool isMultidimensional = elementIdxInfo.DimensionsCount != 1;
  switch (objectId.Scheme)
  {
  case "valuetype": //can be an inlined array
@@ -407,7 +414,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  }
  case "array":
  rootObject["value"] = await context.SdbAgent.GetArrayValues(objectId.Value, token);
- if (!elementIdxInfo.IsMultidimensional)
+ if (!isMultidimensional)
  {
  int.TryParse(elementIdxInfo.ElementIdxStr, out elementIdx);
  return (JObject)rootObject["value"][elementIdx]["value"];
@@ -417,18 +424,16 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  return (JObject)(((JArray)rootObject["value"]).FirstOrDefault(x => x["name"].Value<string>() == elementIdxInfo.ElementIdxStr)["value"]);
  }
  case "object":
- if (elementIdxInfo.IsMultidimensional)
- throw new InvalidOperationException($"Cannot apply indexing with [,] to an object of type '{type}'");
  // ToDo: try to use the get_Item for string as well
- if (type == "string")
+ if (!isMultidimensional && type == "string")
  {
  var eaExpressionFormatted = elementAccessStrExpression.Replace('.', '_'); // instance_str
  variableDefinitions.Add(new (eaExpressionFormatted, rootObject, ExpressionEvaluator.ConvertJSToCSharpLocalVariableAssignment(eaExpressionFormatted, rootObject)));
  var eaFormatted = elementAccessStr.Replace('.', '_'); // instance_str[1]
  var variableDef = await ExpressionEvaluator.GetVariableDefinitions(this, variableDefinitions, invokeToStringInObject: false, token);
  return await ExpressionEvaluator.EvaluateSimpleExpression(this, eaFormatted, elementAccessStr, variableDef, logger, token);
  }
- if (indexObject is null && elementIdxInfo.IndexingExpression is null)
+ if (elementIdxInfo.Indexers is null || elementIdxInfo.Indexers.Count == 0)
  throw new InternalErrorException($"Unable to write index parameter to invoke the method in the runtime.");
 
  var typeIds = await context.SdbAgent.GetTypeIdsForObject(objectId.Value, true, token);
@@ -441,15 +446,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  {
  MethodInfoWithDebugInformation methodInfo = await context.SdbAgent.GetMethodInfo(methodIds[i], token);
  ParameterInfo[] paramInfo = methodInfo.GetParametersInfo();
- if (paramInfo.Length == 1)
+ if (paramInfo.Length == elementIdxInfo.DimensionsCount)
  {
  try
  {
- if (indexObject != null && !CheckParametersCompatibility(paramInfo[0].TypeCode, indexObject))
+ if (!CheckParametersCompatibility(paramInfo, elementIdxInfo.Indexers))
  continue;
- ArraySegment<byte> buffer = indexObject is null ?
- await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression, elementIdxInfo.ElementIdxStr) :
- await WriteJObjectAsIndex(objectId, indexObject, elementIdxInfo.ElementIdxStr, paramInfo[0].TypeCode);
+ ArraySegment<byte> buffer = await WriteIndexObjectAsIndices(objectId, elementIdxInfo.Indexers, paramInfo);
  JObject getItemRetObj = await context.SdbAgent.InvokeMethod(buffer, methodIds[i], token);
  return (JObject)getItemRetObj["value"];
  }
@@ -470,31 +473,32 @@ await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression,
  throw new ReturnAsErrorException($"Unable to evaluate element access '{elementAccess}': {ex.Message}", ex.GetType().Name);
  }
 
- async Task<ElementIndexInfo> GetElementIndexInfo()
+ async Task<ElementIndexInfo> GetElementIndexInfo(List<JObject> nestedIndexers)
  {
- // e.g. x[a[0]], x[a[b[1]]] etc.
- if (indexObject is not null)
- return new ElementIndexInfo(ElementIdxStr: indexObject["value"].ToString() );
-
  if (elementAccess.ArgumentList is null)
  return null;
 
- StringBuilder elementIdxStr = new StringBuilder();
- var multiDimensionalArray = false;
+ int dimCnt = elementAccess.ArgumentList.Arguments.Count;
  LiteralExpressionSyntax indexingExpression = null;
- for (int i = 0; i < elementAccess.ArgumentList.Arguments.Count; i++)
+ StringBuilder elementIdxStr = new StringBuilder();
+ List<object> indexers = new();
+ // nesting should be resolved in reverse order
+ int nestedIndexersCnt = nestedIndexers.Count - 1;
+ for (int i = 0; i < dimCnt; i++)
  {
+ JObject indexObject;
  var arg = elementAccess.ArgumentList.Arguments[i];
  if (i != 0)
  {
  elementIdxStr.Append(", ");
- multiDimensionalArray = true;
  }
  // e.g. x[1]
  if (arg.Expression is LiteralExpressionSyntax)
  {
  indexingExpression = arg.Expression as LiteralExpressionSyntax;
- elementIdxStr.Append(indexingExpression.ToString());
+ string expression = indexingExpression.ToString();
+ elementIdxStr.Append(expression);
+ indexers.Add(indexingExpression);
  }
 
  // e.g. x[a] or x[a.b]
@@ -508,6 +512,18 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  // x[a]
  indexObject ??= await Resolve(argParm.Identifier.Text, token);
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
+ }
+ // nested indexing, e.g. x[a[0]], x[a[b[1]]], x[a[0], b[1]]
+ else if (arg.Expression is ElementAccessExpressionSyntax)
+ {
+ if (nestedIndexers == null || nestedIndexersCnt < 0)
+ throw new InvalidOperationException($"Cannot resolve nested indexing");
+ JObject nestedIndexObject = nestedIndexers[nestedIndexersCnt];
+ nestedIndexers.RemoveAt(nestedIndexersCnt);
+ elementIdxStr.Append(nestedIndexObject["value"].ToString());
+ indexers.Add(nestedIndexObject);
+ nestedIndexersCnt--;
  }
  // indexing with expressions, e.g. x[a + 1]
  else
@@ -519,36 +535,57 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  if (idxType != "number")
  throw new InvalidOperationException($"Cannot index with an object of type '{idxType}'");
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
  }
  }
  return new ElementIndexInfo(
+ DimensionsCount: dimCnt,
  ElementIdxStr: elementIdxStr.ToString(),
- IsMultidimensional: multiDimensionalArray,
- IndexingExpression: indexingExpression);
+ Indexers: indexers);
  }
 
- async Task<ArraySegment<byte>> WriteJObjectAsIndex(DotnetObjectId rootObjId, JObject indexObject, string elementIdxStr, ElementType? expectedType)
+ async Task<ArraySegment<byte>> WriteIndexObjectAsIndices(DotnetObjectId rootObjId, List<object> indexObjects, ParameterInfo[] paramInfo)
  {
  using var writer = new MonoBinaryWriter();
  writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteJsonValue(indexObject, context.SdbAgent, expectedType, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
+ writer.Write(indexObjects.Count); // number of method args
+ foreach ((ParameterInfo pi, object indexObject) in paramInfo.Zip(indexObjects))
+ {
+ if (indexObject is JObject indexJObject)
+ {
+ // indexed by an identifier name syntax
+ if (!await writer.WriteJsonValue(indexJObject, context.SdbAgent, pi.TypeCode, token))
+ throw new InternalErrorException($"Parsing index of type {indexJObject["type"].Value<string>()} to write it into the buffer failed.");
+ }
+ else if (indexObject is LiteralExpressionSyntax expression)
+ {
+ // indexed by a literal expression syntax
+ if (!await writer.WriteConst(expression, context.SdbAgent, token))
+ throw new InternalErrorException($"Parsing literal expression index = {expression} to write it into the buffer failed.");
+ }
+ else
+ {
+ throw new InternalErrorException($"Unexpected index type.");
+ }
+ }
  return writer.GetParameterBuffer();
  }
+ }
 
- async Task<ArraySegment<byte>> WriteLiteralExpressionAsIndex(DotnetObjectId rootObjId, LiteralExpressionSyntax indexingExpression, string elementIdxStr)
+ private static bool CheckParametersCompatibility(ParameterInfo[] paramInfos, List<object> indexObjects)
+ {
+ if (paramInfos.Length != indexObjects.Count)
+ return false;
+ foreach ((ParameterInfo paramInfo, object indexObj) in paramInfos.Zip(indexObjects))
  {
- using var writer = new MonoBinaryWriter();
- writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteConst(indexingExpression, context.SdbAgent, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
- return writer.GetParameterBuffer();
+ // shouldn't we check LiteralExpressionSyntax for compatibility as well?
+ if (indexObj is JObject indexJObj && !CheckParameterCompatibility(paramInfo.TypeCode, indexJObj))
+ return false;
  }
+ return true;
  }
 
- private static bool CheckParametersCompatibility(ElementType? paramTypeCode, JObject value)
+ private static bool CheckParameterCompatibility(ElementType? paramTypeCode, JObject value)
  {
  if (!paramTypeCode.HasValue)
  return true;
@@ -871,7 +908,8 @@ public JObject TryGetEvaluationResult(string id)
 
  private sealed record ElementIndexInfo(
  string ElementIdxStr,
- bool IsMultidimensional = false,
- LiteralExpressionSyntax IndexingExpression = null);
+ // keeps JObjects and LiteralExpressionSyntaxes:
+ List<object> Indexers,
+ int DimensionsCount = 1);
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrame2Tests.cs

@@ -745,5 +745,24 @@ await EvaluateOnCallFrameAndCheck(id,
  // ("mc.valueTypeEnum.HasFlag(SampleEnum.no)", TBool(true)) // ToDo: https://github.com/dotnet/runtime/issues/92262
  );
  });
+
+ [Fact]
+ public async Task EvaluateObjectIndexingMultidimensional() => await CheckInspectLocalsAtBreakpointSite(
+ "DebuggerTests.EvaluateLocalsWithIndexingTests", "EvaluateLocals", 12, "DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals",
+ "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.EvaluateLocalsWithIndexingTests:EvaluateLocals'); })",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ await EvaluateOnCallFrameAndCheck(id,
+ ("f[j, aDouble]", TNumber("3.34")), //only IdentifierNameSyntaxes
+ ("f[1, aDouble]", TNumber("3.34")), //IdentifierNameSyntax with LiteralExpressionSyntax
+ ("f[aChar, \"&\", longString]", TString("9-&-longString")),
+ ("f[f.numArray[j], aDouble]", TNumber("4.34")), //ElementAccessExpressionSyntax
+ ("f[f.numArray[j], f.numArray[0]]", TNumber("3")), //multiple ElementAccessExpressionSyntaxes
+ ("f[f.numArray[f.numList[0]], f.numArray[i]]", TNumber("3")),
+ ("f[f.numArray[f.numList[0]], f.numArray[f.numArray[i]]]", TNumber("4"))
+ ); 
+ });
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -585,7 +585,7 @@ public async Task EvaluateIndexingNegative() => await CheckInspectLocalsAtBreakp
  Assert.Equal("Unable to evaluate element access 'f.idx0[2]': Cannot apply indexing with [] to a primitive object of type 'number'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  (_, res) = await EvaluateOnCallFrame(id, "f[1]", expect_ok: false );
  Assert.Equal( "Unable to evaluate element access 'f[1]': Cannot apply indexing with [] to an object of type 'DebuggerTests.EvaluateLocalsWithIndexingTests.TestEvaluate'", res.Error["result"]?["description"]?.Value<string>());
@@ -724,7 +724,7 @@ public async Task EvaluateIndexingByExpressionNegative() => await CheckInspectLo
  Assert.Equal("Unable to evaluate element access 'f.numList[\"a\" + 1]': Cannot index with an object of type 'string'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  });
 
@@ -861,7 +861,9 @@ await EvaluateOnCallFrameAndCheck(id,
  ("f.textArrayOfArrays[f.idx1][f.idx1]", TString("2")),
  ("f.textListOfLists[1][1]", TString("2")),
  ("f.textListOfLists[j][j]", TString("2")),
- ("f.textListOfLists[f.idx1][f.idx1]", TString("2")));
+ ("f.textListOfLists[f.idx1][f.idx1]", TString("2")),
+ ("f.numArrayOfArrays[f.numArray[f.numList[1]]][f.numList[0]]", TNumber(2))
+ );
 
  });
 

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -387,12 +387,14 @@ private static async Task<IList<JObject>> ResolveElementAccess(ExpressionSyntaxR
  {
  var values = new List<JObject>();
  JObject index = null;
+ List<JObject> nestedIndexers = new();
  IEnumerable<ElementAccessExpressionSyntax> elementAccesses = replacer.elementAccess;
  foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
  {
- index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, index, replacer.variableDefinitions, token);
+ index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, nestedIndexers, replacer.variableDefinitions, token);
  if (index == null)
  throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
+ nestedIndexers.Add(index);
  }
  values.Add(index);
  return values;

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -366,7 +366,12 @@ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject
  }
  }
 
- public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess, Dictionary<string, JObject> memberAccessValues, JObject indexObject, List<VariableDefinition> variableDefinitions, CancellationToken token)
+ public async Task<JObject> Resolve(
+ ElementAccessExpressionSyntax elementAccess,
+ Dictionary<string, JObject> memberAccessValues,
+ List<JObject> nestedIndexObject,
+ List<VariableDefinition> variableDefinitions,
+ CancellationToken token)
  {
  try
  {
@@ -376,12 +381,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
 
  if (rootObject == null)
  {
- // it might be a jagged array where indexObject should be treated as a new rootObject
- rootObject = indexObject;
- indexObject = null;
+ // it might be a jagged array where the previously added nestedIndexObject should be treated as a new rootObject
+ rootObject = nestedIndexObject.LastOrDefault();
+ if (rootObject != null)
+ nestedIndexObject.RemoveAt(nestedIndexObject.Count - 1);
  }
 
- ElementIndexInfo elementIdxInfo = await GetElementIndexInfo();
+ ElementIndexInfo elementIdxInfo = await GetElementIndexInfo(nestedIndexObject);
  if (elementIdxInfo is null)
  return null;
 
@@ -394,6 +400,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  if (!DotnetObjectId.TryParse(rootObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
  throw new InvalidOperationException($"Cannot apply indexing with [] to a primitive object of type '{type}'");
 
+ bool isMultidimensional = elementIdxInfo.DimensionsCount != 1;
  switch (objectId.Scheme)
  {
  case "valuetype": //can be an inlined array
@@ -407,7 +414,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  }
  case "array":
  rootObject["value"] = await context.SdbAgent.GetArrayValues(objectId.Value, token);
- if (!elementIdxInfo.IsMultidimensional)
+ if (!isMultidimensional)
  {
  int.TryParse(elementIdxInfo.ElementIdxStr, out elementIdx);
  return (JObject)rootObject["value"][elementIdx]["value"];
@@ -417,18 +424,16 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  return (JObject)(((JArray)rootObject["value"]).FirstOrDefault(x => x["name"].Value<string>() == elementIdxInfo.ElementIdxStr)["value"]);
  }
  case "object":
- if (elementIdxInfo.IsMultidimensional)
- throw new InvalidOperationException($"Cannot apply indexing with [,] to an object of type '{type}'");
  // ToDo: try to use the get_Item for string as well
- if (type == "string")
+ if (!isMultidimensional && type == "string")
  {
  var eaExpressionFormatted = elementAccessStrExpression.Replace('.', '_'); // instance_str
  variableDefinitions.Add(new (eaExpressionFormatted, rootObject, ExpressionEvaluator.ConvertJSToCSharpLocalVariableAssignment(eaExpressionFormatted, rootObject)));
  var eaFormatted = elementAccessStr.Replace('.', '_'); // instance_str[1]
  var variableDef = await ExpressionEvaluator.GetVariableDefinitions(this, variableDefinitions, invokeToStringInObject: false, token);
  return await ExpressionEvaluator.EvaluateSimpleExpression(this, eaFormatted, elementAccessStr, variableDef, logger, token);
  }
- if (indexObject is null && elementIdxInfo.IndexingExpression is null)
+ if (elementIdxInfo.Indexers is null || elementIdxInfo.Indexers.Count == 0)
  throw new InternalErrorException($"Unable to write index parameter to invoke the method in the runtime.");
 
  var typeIds = await context.SdbAgent.GetTypeIdsForObject(objectId.Value, true, token);
@@ -441,15 +446,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  {
  MethodInfoWithDebugInformation methodInfo = await context.SdbAgent.GetMethodInfo(methodIds[i], token);
  ParameterInfo[] paramInfo = methodInfo.GetParametersInfo();
- if (paramInfo.Length == 1)
+ if (paramInfo.Length == elementIdxInfo.DimensionsCount)
  {
  try
  {
- if (indexObject != null && !CheckParametersCompatibility(paramInfo[0].TypeCode, indexObject))
+ if (!CheckParametersCompatibility(paramInfo, elementIdxInfo.Indexers))
  continue;
- ArraySegment<byte> buffer = indexObject is null ?
- await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression, elementIdxInfo.ElementIdxStr) :
- await WriteJObjectAsIndex(objectId, indexObject, elementIdxInfo.ElementIdxStr, paramInfo[0].TypeCode);
+ ArraySegment<byte> buffer = await WriteIndexObjectAsIndices(objectId, elementIdxInfo.Indexers, paramInfo);
  JObject getItemRetObj = await context.SdbAgent.InvokeMethod(buffer, methodIds[i], token);
  return (JObject)getItemRetObj["value"];
  }
@@ -470,31 +473,32 @@ await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression,
  throw new ReturnAsErrorException($"Unable to evaluate element access '{elementAccess}': {ex.Message}", ex.GetType().Name);
  }
 
- async Task<ElementIndexInfo> GetElementIndexInfo()
+ async Task<ElementIndexInfo> GetElementIndexInfo(List<JObject> nestedIndexers)
  {
- // e.g. x[a[0]], x[a[b[1]]] etc.
- if (indexObject is not null)
- return new ElementIndexInfo(ElementIdxStr: indexObject["value"].ToString() );
-
  if (elementAccess.ArgumentList is null)
  return null;
 
- StringBuilder elementIdxStr = new StringBuilder();
- var multiDimensionalArray = false;
+ int dimCnt = elementAccess.ArgumentList.Arguments.Count;
  LiteralExpressionSyntax indexingExpression = null;
- for (int i = 0; i < elementAccess.ArgumentList.Arguments.Count; i++)
+ StringBuilder elementIdxStr = new StringBuilder();
+ List<object> indexers = new();
+ // nesting should be resolved in reverse order
+ int nestedIndexersCnt = nestedIndexers.Count - 1;
+ for (int i = 0; i < dimCnt; i++)
  {
+ JObject indexObject;
  var arg = elementAccess.ArgumentList.Arguments[i];
  if (i != 0)
  {
  elementIdxStr.Append(", ");
- multiDimensionalArray = true;
  }
  // e.g. x[1]
  if (arg.Expression is LiteralExpressionSyntax)
  {
  indexingExpression = arg.Expression as LiteralExpressionSyntax;
- elementIdxStr.Append(indexingExpression.ToString());
+ string expression = indexingExpression.ToString();
+ elementIdxStr.Append(expression);
+ indexers.Add(indexingExpression);
  }
 
  // e.g. x[a] or x[a.b]
@@ -508,6 +512,18 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  // x[a]
  indexObject ??= await Resolve(argParm.Identifier.Text, token);
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
+ }
+ // nested indexing, e.g. x[a[0]], x[a[b[1]]], x[a[0], b[1]]
+ else if (arg.Expression is ElementAccessExpressionSyntax)
+ {
+ if (nestedIndexers == null || nestedIndexersCnt < 0)
+ throw new InvalidOperationException($"Cannot resolve nested indexing");
+ JObject nestedIndexObject = nestedIndexers[nestedIndexersCnt];
+ nestedIndexers.RemoveAt(nestedIndexersCnt);
+ elementIdxStr.Append(nestedIndexObject["value"].ToString());
+ indexers.Add(nestedIndexObject);
+ nestedIndexersCnt--;
  }
  // indexing with expressions, e.g. x[a + 1]
  else
@@ -519,36 +535,57 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  if (idxType != "number")
  throw new InvalidOperationException($"Cannot index with an object of type '{idxType}'");
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
  }
  }
  return new ElementIndexInfo(
+ DimensionsCount: dimCnt,
  ElementIdxStr: elementIdxStr.ToString(),
- IsMultidimensional: multiDimensionalArray,
- IndexingExpression: indexingExpression);
+ Indexers: indexers);
  }
 
- async Task<ArraySegment<byte>> WriteJObjectAsIndex(DotnetObjectId rootObjId, JObject indexObject, string elementIdxStr, ElementType? expectedType)
+ async Task<ArraySegment<byte>> WriteIndexObjectAsIndices(DotnetObjectId rootObjId, List<object> indexObjects, ParameterInfo[] paramInfo)
  {
  using var writer = new MonoBinaryWriter();
  writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteJsonValue(indexObject, context.SdbAgent, expectedType, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
+ writer.Write(indexObjects.Count); // number of method args
+ foreach ((ParameterInfo pi, object indexObject) in paramInfo.Zip(indexObjects))
+ {
+ if (indexObject is JObject indexJObject)
+ {
+ // indexed by an identifier name syntax
+ if (!await writer.WriteJsonValue(indexJObject, context.SdbAgent, pi.TypeCode, token))
+ throw new InternalErrorException($"Parsing index of type {indexJObject["type"].Value<string>()} to write it into the buffer failed.");
+ }
+ else if (indexObject is LiteralExpressionSyntax expression)
+ {
+ // indexed by a literal expression syntax
+ if (!await writer.WriteConst(expression, context.SdbAgent, token))
+ throw new InternalErrorException($"Parsing literal expression index = {expression} to write it into the buffer failed.");
+ }
+ else
+ {
+ throw new InternalErrorException($"Unexpected index type.");
+ }
+ }
  return writer.GetParameterBuffer();
  }
+ }
 
- async Task<ArraySegment<byte>> WriteLiteralExpressionAsIndex(DotnetObjectId rootObjId, LiteralExpressionSyntax indexingExpression, string elementIdxStr)
+ private static bool CheckParametersCompatibility(ParameterInfo[] paramInfos, List<object> indexObjects)
+ {
+ if (paramInfos.Length != indexObjects.Count)
+ return false;
+ foreach ((ParameterInfo paramInfo, object indexObj) in paramInfos.Zip(indexObjects))
  {
- using var writer = new MonoBinaryWriter();
- writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteConst(indexingExpression, context.SdbAgent, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
- return writer.GetParameterBuffer();
+ // shouldn't we check LiteralExpressionSyntax for compatibility as well?
+ if (indexObj is JObject indexJObj && !CheckParameterCompatibility(paramInfo.TypeCode, indexJObj))
+ return false;
  }
+ return true;
  }
 
- private static bool CheckParametersCompatibility(ElementType? paramTypeCode, JObject value)
+ private static bool CheckParameterCompatibility(ElementType? paramTypeCode, JObject value)
  {
  if (!paramTypeCode.HasValue)
  return true;
@@ -871,7 +908,8 @@ public JObject TryGetEvaluationResult(string id)
 
  private sealed record ElementIndexInfo(
  string ElementIdxStr,
- bool IsMultidimensional = false,
- LiteralExpressionSyntax IndexingExpression = null);
+ // keeps JObjects and LiteralExpressionSyntaxes:
+ List<object> Indexers,
+ int DimensionsCount = 1);
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrame2Tests.cs

@@ -745,5 +745,24 @@ await EvaluateOnCallFrameAndCheck(id,
  // ("mc.valueTypeEnum.HasFlag(SampleEnum.no)", TBool(true)) // ToDo: https://github.com/dotnet/runtime/issues/92262
  );
  });
+
+ [Fact]
+ public async Task EvaluateObjectIndexingMultidimensional() => await CheckInspectLocalsAtBreakpointSite(
+ "DebuggerTests.EvaluateLocalsWithIndexingTests", "EvaluateLocals", 12, "DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals",
+ "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.EvaluateLocalsWithIndexingTests:EvaluateLocals'); })",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ await EvaluateOnCallFrameAndCheck(id,
+ ("f[j, aDouble]", TNumber("3.34")), //only IdentifierNameSyntaxes
+ ("f[1, aDouble]", TNumber("3.34")), //IdentifierNameSyntax with LiteralExpressionSyntax
+ ("f[aChar, \"&\", longString]", TString("9-&-longString")),
+ ("f[f.numArray[j], aDouble]", TNumber("4.34")), //ElementAccessExpressionSyntax
+ ("f[f.numArray[j], f.numArray[0]]", TNumber("3")), //multiple ElementAccessExpressionSyntaxes
+ ("f[f.numArray[f.numList[0]], f.numArray[i]]", TNumber("3")),
+ ("f[f.numArray[f.numList[0]], f.numArray[f.numArray[i]]]", TNumber("4"))
+ ); 
+ });
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -585,7 +585,7 @@ public async Task EvaluateIndexingNegative() => await CheckInspectLocalsAtBreakp
  Assert.Equal("Unable to evaluate element access 'f.idx0[2]': Cannot apply indexing with [] to a primitive object of type 'number'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  (_, res) = await EvaluateOnCallFrame(id, "f[1]", expect_ok: false );
  Assert.Equal( "Unable to evaluate element access 'f[1]': Cannot apply indexing with [] to an object of type 'DebuggerTests.EvaluateLocalsWithIndexingTests.TestEvaluate'", res.Error["result"]?["description"]?.Value<string>());
@@ -724,7 +724,7 @@ public async Task EvaluateIndexingByExpressionNegative() => await CheckInspectLo
  Assert.Equal("Unable to evaluate element access 'f.numList[\"a\" + 1]': Cannot index with an object of type 'string'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  });
 
@@ -861,7 +861,9 @@ await EvaluateOnCallFrameAndCheck(id,
  ("f.textArrayOfArrays[f.idx1][f.idx1]", TString("2")),
  ("f.textListOfLists[1][1]", TString("2")),
  ("f.textListOfLists[j][j]", TString("2")),
- ("f.textListOfLists[f.idx1][f.idx1]", TString("2")));
+ ("f.textListOfLists[f.idx1][f.idx1]", TString("2")),
+ ("f.numArrayOfArrays[f.numArray[f.numList[1]]][f.numList[0]]", TNumber(2))
+ );
 
  });
 

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -387,12 +387,14 @@ private static async Task<IList<JObject>> ResolveElementAccess(ExpressionSyntaxR
  {
  var values = new List<JObject>();
  JObject index = null;
+ List<JObject> nestedIndexers = new();
  IEnumerable<ElementAccessExpressionSyntax> elementAccesses = replacer.elementAccess;
  foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
  {
- index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, index, replacer.variableDefinitions, token);
+ index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, nestedIndexers, replacer.variableDefinitions, token);
  if (index == null)
  throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
+ nestedIndexers.Add(index);
  }
  values.Add(index);
  return values;

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -366,7 +366,12 @@ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject
  }
  }
 
- public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess, Dictionary<string, JObject> memberAccessValues, JObject indexObject, List<VariableDefinition> variableDefinitions, CancellationToken token)
+ public async Task<JObject> Resolve(
+ ElementAccessExpressionSyntax elementAccess,
+ Dictionary<string, JObject> memberAccessValues,
+ List<JObject> nestedIndexObject,
+ List<VariableDefinition> variableDefinitions,
+ CancellationToken token)
  {
  try
  {
@@ -376,12 +381,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
 
  if (rootObject == null)
  {
- // it might be a jagged array where indexObject should be treated as a new rootObject
- rootObject = indexObject;
- indexObject = null;
+ // it might be a jagged array where the previously added nestedIndexObject should be treated as a new rootObject
+ rootObject = nestedIndexObject.LastOrDefault();
+ if (rootObject != null)
+ nestedIndexObject.RemoveAt(nestedIndexObject.Count - 1);
  }
 
- ElementIndexInfo elementIdxInfo = await GetElementIndexInfo();
+ ElementIndexInfo elementIdxInfo = await GetElementIndexInfo(nestedIndexObject);
  if (elementIdxInfo is null)
  return null;
 
@@ -394,6 +400,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  if (!DotnetObjectId.TryParse(rootObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
  throw new InvalidOperationException($"Cannot apply indexing with [] to a primitive object of type '{type}'");
 
+ bool isMultidimensional = elementIdxInfo.DimensionsCount != 1;
  switch (objectId.Scheme)
  {
  case "valuetype": //can be an inlined array
@@ -407,7 +414,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  }
  case "array":
  rootObject["value"] = await context.SdbAgent.GetArrayValues(objectId.Value, token);
- if (!elementIdxInfo.IsMultidimensional)
+ if (!isMultidimensional)
  {
  int.TryParse(elementIdxInfo.ElementIdxStr, out elementIdx);
  return (JObject)rootObject["value"][elementIdx]["value"];
@@ -417,18 +424,16 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  return (JObject)(((JArray)rootObject["value"]).FirstOrDefault(x => x["name"].Value<string>() == elementIdxInfo.ElementIdxStr)["value"]);
  }
  case "object":
- if (elementIdxInfo.IsMultidimensional)
- throw new InvalidOperationException($"Cannot apply indexing with [,] to an object of type '{type}'");
  // ToDo: try to use the get_Item for string as well
- if (type == "string")
+ if (!isMultidimensional && type == "string")
  {
  var eaExpressionFormatted = elementAccessStrExpression.Replace('.', '_'); // instance_str
  variableDefinitions.Add(new (eaExpressionFormatted, rootObject, ExpressionEvaluator.ConvertJSToCSharpLocalVariableAssignment(eaExpressionFormatted, rootObject)));
  var eaFormatted = elementAccessStr.Replace('.', '_'); // instance_str[1]
  var variableDef = await ExpressionEvaluator.GetVariableDefinitions(this, variableDefinitions, invokeToStringInObject: false, token);
  return await ExpressionEvaluator.EvaluateSimpleExpression(this, eaFormatted, elementAccessStr, variableDef, logger, token);
  }
- if (indexObject is null && elementIdxInfo.IndexingExpression is null)
+ if (elementIdxInfo.Indexers is null || elementIdxInfo.Indexers.Count == 0)
  throw new InternalErrorException($"Unable to write index parameter to invoke the method in the runtime.");
 
  var typeIds = await context.SdbAgent.GetTypeIdsForObject(objectId.Value, true, token);
@@ -441,15 +446,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  {
  MethodInfoWithDebugInformation methodInfo = await context.SdbAgent.GetMethodInfo(methodIds[i], token);
  ParameterInfo[] paramInfo = methodInfo.GetParametersInfo();
- if (paramInfo.Length == 1)
+ if (paramInfo.Length == elementIdxInfo.DimensionsCount)
  {
  try
  {
- if (indexObject != null && !CheckParametersCompatibility(paramInfo[0].TypeCode, indexObject))
+ if (!CheckParametersCompatibility(paramInfo, elementIdxInfo.Indexers))
  continue;
- ArraySegment<byte> buffer = indexObject is null ?
- await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression, elementIdxInfo.ElementIdxStr) :
- await WriteJObjectAsIndex(objectId, indexObject, elementIdxInfo.ElementIdxStr, paramInfo[0].TypeCode);
+ ArraySegment<byte> buffer = await WriteIndexObjectAsIndices(objectId, elementIdxInfo.Indexers, paramInfo);
  JObject getItemRetObj = await context.SdbAgent.InvokeMethod(buffer, methodIds[i], token);
  return (JObject)getItemRetObj["value"];
  }
@@ -470,31 +473,32 @@ await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression,
  throw new ReturnAsErrorException($"Unable to evaluate element access '{elementAccess}': {ex.Message}", ex.GetType().Name);
  }
 
- async Task<ElementIndexInfo> GetElementIndexInfo()
+ async Task<ElementIndexInfo> GetElementIndexInfo(List<JObject> nestedIndexers)
  {
- // e.g. x[a[0]], x[a[b[1]]] etc.
- if (indexObject is not null)
- return new ElementIndexInfo(ElementIdxStr: indexObject["value"].ToString() );
-
  if (elementAccess.ArgumentList is null)
  return null;
 
- StringBuilder elementIdxStr = new StringBuilder();
- var multiDimensionalArray = false;
+ int dimCnt = elementAccess.ArgumentList.Arguments.Count;
  LiteralExpressionSyntax indexingExpression = null;
- for (int i = 0; i < elementAccess.ArgumentList.Arguments.Count; i++)
+ StringBuilder elementIdxStr = new StringBuilder();
+ List<object> indexers = new();
+ // nesting should be resolved in reverse order
+ int nestedIndexersCnt = nestedIndexers.Count - 1;
+ for (int i = 0; i < dimCnt; i++)
  {
+ JObject indexObject;
  var arg = elementAccess.ArgumentList.Arguments[i];
  if (i != 0)
  {
  elementIdxStr.Append(", ");
- multiDimensionalArray = true;
  }
  // e.g. x[1]
  if (arg.Expression is LiteralExpressionSyntax)
  {
  indexingExpression = arg.Expression as LiteralExpressionSyntax;
- elementIdxStr.Append(indexingExpression.ToString());
+ string expression = indexingExpression.ToString();
+ elementIdxStr.Append(expression);
+ indexers.Add(indexingExpression);
  }
 
  // e.g. x[a] or x[a.b]
@@ -508,6 +512,18 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  // x[a]
  indexObject ??= await Resolve(argParm.Identifier.Text, token);
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
+ }
+ // nested indexing, e.g. x[a[0]], x[a[b[1]]], x[a[0], b[1]]
+ else if (arg.Expression is ElementAccessExpressionSyntax)
+ {
+ if (nestedIndexers == null || nestedIndexersCnt < 0)
+ throw new InvalidOperationException($"Cannot resolve nested indexing");
+ JObject nestedIndexObject = nestedIndexers[nestedIndexersCnt];
+ nestedIndexers.RemoveAt(nestedIndexersCnt);
+ elementIdxStr.Append(nestedIndexObject["value"].ToString());
+ indexers.Add(nestedIndexObject);
+ nestedIndexersCnt--;
  }
  // indexing with expressions, e.g. x[a + 1]
  else
@@ -519,36 +535,57 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  if (idxType != "number")
  throw new InvalidOperationException($"Cannot index with an object of type '{idxType}'");
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
  }
  }
  return new ElementIndexInfo(
+ DimensionsCount: dimCnt,
  ElementIdxStr: elementIdxStr.ToString(),
- IsMultidimensional: multiDimensionalArray,
- IndexingExpression: indexingExpression);
+ Indexers: indexers);
  }
 
- async Task<ArraySegment<byte>> WriteJObjectAsIndex(DotnetObjectId rootObjId, JObject indexObject, string elementIdxStr, ElementType? expectedType)
+ async Task<ArraySegment<byte>> WriteIndexObjectAsIndices(DotnetObjectId rootObjId, List<object> indexObjects, ParameterInfo[] paramInfo)
  {
  using var writer = new MonoBinaryWriter();
  writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteJsonValue(indexObject, context.SdbAgent, expectedType, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
+ writer.Write(indexObjects.Count); // number of method args
+ foreach ((ParameterInfo pi, object indexObject) in paramInfo.Zip(indexObjects))
+ {
+ if (indexObject is JObject indexJObject)
+ {
+ // indexed by an identifier name syntax
+ if (!await writer.WriteJsonValue(indexJObject, context.SdbAgent, pi.TypeCode, token))
+ throw new InternalErrorException($"Parsing index of type {indexJObject["type"].Value<string>()} to write it into the buffer failed.");
+ }
+ else if (indexObject is LiteralExpressionSyntax expression)
+ {
+ // indexed by a literal expression syntax
+ if (!await writer.WriteConst(expression, context.SdbAgent, token))
+ throw new InternalErrorException($"Parsing literal expression index = {expression} to write it into the buffer failed.");
+ }
+ else
+ {
+ throw new InternalErrorException($"Unexpected index type.");
+ }
+ }
  return writer.GetParameterBuffer();
  }
+ }
 
- async Task<ArraySegment<byte>> WriteLiteralExpressionAsIndex(DotnetObjectId rootObjId, LiteralExpressionSyntax indexingExpression, string elementIdxStr)
+ private static bool CheckParametersCompatibility(ParameterInfo[] paramInfos, List<object> indexObjects)
+ {
+ if (paramInfos.Length != indexObjects.Count)
+ return false;
+ foreach ((ParameterInfo paramInfo, object indexObj) in paramInfos.Zip(indexObjects))
  {
- using var writer = new MonoBinaryWriter();
- writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteConst(indexingExpression, context.SdbAgent, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
- return writer.GetParameterBuffer();
+ // shouldn't we check LiteralExpressionSyntax for compatibility as well?
+ if (indexObj is JObject indexJObj && !CheckParameterCompatibility(paramInfo.TypeCode, indexJObj))
+ return false;
  }
+ return true;
  }
 
- private static bool CheckParametersCompatibility(ElementType? paramTypeCode, JObject value)
+ private static bool CheckParameterCompatibility(ElementType? paramTypeCode, JObject value)
  {
  if (!paramTypeCode.HasValue)
  return true;
@@ -871,7 +908,8 @@ public JObject TryGetEvaluationResult(string id)
 
  private sealed record ElementIndexInfo(
  string ElementIdxStr,
- bool IsMultidimensional = false,
- LiteralExpressionSyntax IndexingExpression = null);
+ // keeps JObjects and LiteralExpressionSyntaxes:
+ List<object> Indexers,
+ int DimensionsCount = 1);
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrame2Tests.cs

@@ -745,5 +745,24 @@ await EvaluateOnCallFrameAndCheck(id,
  // ("mc.valueTypeEnum.HasFlag(SampleEnum.no)", TBool(true)) // ToDo: https://github.com/dotnet/runtime/issues/92262
  );
  });
+
+ [Fact]
+ public async Task EvaluateObjectIndexingMultidimensional() => await CheckInspectLocalsAtBreakpointSite(
+ "DebuggerTests.EvaluateLocalsWithIndexingTests", "EvaluateLocals", 12, "DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals",
+ "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.EvaluateLocalsWithIndexingTests:EvaluateLocals'); })",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ await EvaluateOnCallFrameAndCheck(id,
+ ("f[j, aDouble]", TNumber("3.34")), //only IdentifierNameSyntaxes
+ ("f[1, aDouble]", TNumber("3.34")), //IdentifierNameSyntax with LiteralExpressionSyntax
+ ("f[aChar, \"&\", longString]", TString("9-&-longString")),
+ ("f[f.numArray[j], aDouble]", TNumber("4.34")), //ElementAccessExpressionSyntax
+ ("f[f.numArray[j], f.numArray[0]]", TNumber("3")), //multiple ElementAccessExpressionSyntaxes
+ ("f[f.numArray[f.numList[0]], f.numArray[i]]", TNumber("3")),
+ ("f[f.numArray[f.numList[0]], f.numArray[f.numArray[i]]]", TNumber("4"))
+ ); 
+ });
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -585,7 +585,7 @@ public async Task EvaluateIndexingNegative() => await CheckInspectLocalsAtBreakp
  Assert.Equal("Unable to evaluate element access 'f.idx0[2]': Cannot apply indexing with [] to a primitive object of type 'number'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  (_, res) = await EvaluateOnCallFrame(id, "f[1]", expect_ok: false );
  Assert.Equal( "Unable to evaluate element access 'f[1]': Cannot apply indexing with [] to an object of type 'DebuggerTests.EvaluateLocalsWithIndexingTests.TestEvaluate'", res.Error["result"]?["description"]?.Value<string>());
@@ -724,7 +724,7 @@ public async Task EvaluateIndexingByExpressionNegative() => await CheckInspectLo
  Assert.Equal("Unable to evaluate element access 'f.numList[\"a\" + 1]': Cannot index with an object of type 'string'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  });
 
@@ -861,7 +861,9 @@ await EvaluateOnCallFrameAndCheck(id,
  ("f.textArrayOfArrays[f.idx1][f.idx1]", TString("2")),
  ("f.textListOfLists[1][1]", TString("2")),
  ("f.textListOfLists[j][j]", TString("2")),
- ("f.textListOfLists[f.idx1][f.idx1]", TString("2")));
+ ("f.textListOfLists[f.idx1][f.idx1]", TString("2")),
+ ("f.numArrayOfArrays[f.numArray[f.numList[1]]][f.numList[0]]", TNumber(2))
+ );
 
  });
 

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -387,12 +387,14 @@ private static async Task<IList<JObject>> ResolveElementAccess(ExpressionSyntaxR
  {
  var values = new List<JObject>();
  JObject index = null;
+ List<JObject> nestedIndexers = new();
  IEnumerable<ElementAccessExpressionSyntax> elementAccesses = replacer.elementAccess;
  foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
  {
- index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, index, replacer.variableDefinitions, token);
+ index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, nestedIndexers, replacer.variableDefinitions, token);
  if (index == null)
  throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
+ nestedIndexers.Add(index);
  }
  values.Add(index);
  return values;

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -366,7 +366,12 @@ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject
  }
  }
 
- public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess, Dictionary<string, JObject> memberAccessValues, JObject indexObject, List<VariableDefinition> variableDefinitions, CancellationToken token)
+ public async Task<JObject> Resolve(
+ ElementAccessExpressionSyntax elementAccess,
+ Dictionary<string, JObject> memberAccessValues,
+ List<JObject> nestedIndexObject,
+ List<VariableDefinition> variableDefinitions,
+ CancellationToken token)
  {
  try
  {
@@ -376,12 +381,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
 
  if (rootObject == null)
  {
- // it might be a jagged array where indexObject should be treated as a new rootObject
- rootObject = indexObject;
- indexObject = null;
+ // it might be a jagged array where the previously added nestedIndexObject should be treated as a new rootObject
+ rootObject = nestedIndexObject.LastOrDefault();
+ if (rootObject != null)
+ nestedIndexObject.RemoveAt(nestedIndexObject.Count - 1);
  }
 
- ElementIndexInfo elementIdxInfo = await GetElementIndexInfo();
+ ElementIndexInfo elementIdxInfo = await GetElementIndexInfo(nestedIndexObject);
  if (elementIdxInfo is null)
  return null;
 
@@ -394,6 +400,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  if (!DotnetObjectId.TryParse(rootObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
  throw new InvalidOperationException($"Cannot apply indexing with [] to a primitive object of type '{type}'");
 
+ bool isMultidimensional = elementIdxInfo.DimensionsCount != 1;
  switch (objectId.Scheme)
  {
  case "valuetype": //can be an inlined array
@@ -407,7 +414,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  }
  case "array":
  rootObject["value"] = await context.SdbAgent.GetArrayValues(objectId.Value, token);
- if (!elementIdxInfo.IsMultidimensional)
+ if (!isMultidimensional)
  {
  int.TryParse(elementIdxInfo.ElementIdxStr, out elementIdx);
  return (JObject)rootObject["value"][elementIdx]["value"];
@@ -417,18 +424,16 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  return (JObject)(((JArray)rootObject["value"]).FirstOrDefault(x => x["name"].Value<string>() == elementIdxInfo.ElementIdxStr)["value"]);
  }
  case "object":
- if (elementIdxInfo.IsMultidimensional)
- throw new InvalidOperationException($"Cannot apply indexing with [,] to an object of type '{type}'");
  // ToDo: try to use the get_Item for string as well
- if (type == "string")
+ if (!isMultidimensional && type == "string")
  {
  var eaExpressionFormatted = elementAccessStrExpression.Replace('.', '_'); // instance_str
  variableDefinitions.Add(new (eaExpressionFormatted, rootObject, ExpressionEvaluator.ConvertJSToCSharpLocalVariableAssignment(eaExpressionFormatted, rootObject)));
  var eaFormatted = elementAccessStr.Replace('.', '_'); // instance_str[1]
  var variableDef = await ExpressionEvaluator.GetVariableDefinitions(this, variableDefinitions, invokeToStringInObject: false, token);
  return await ExpressionEvaluator.EvaluateSimpleExpression(this, eaFormatted, elementAccessStr, variableDef, logger, token);
  }
- if (indexObject is null && elementIdxInfo.IndexingExpression is null)
+ if (elementIdxInfo.Indexers is null || elementIdxInfo.Indexers.Count == 0)
  throw new InternalErrorException($"Unable to write index parameter to invoke the method in the runtime.");
 
  var typeIds = await context.SdbAgent.GetTypeIdsForObject(objectId.Value, true, token);
@@ -441,15 +446,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  {
  MethodInfoWithDebugInformation methodInfo = await context.SdbAgent.GetMethodInfo(methodIds[i], token);
  ParameterInfo[] paramInfo = methodInfo.GetParametersInfo();
- if (paramInfo.Length == 1)
+ if (paramInfo.Length == elementIdxInfo.DimensionsCount)
  {
  try
  {
- if (indexObject != null && !CheckParametersCompatibility(paramInfo[0].TypeCode, indexObject))
+ if (!CheckParametersCompatibility(paramInfo, elementIdxInfo.Indexers))
  continue;
- ArraySegment<byte> buffer = indexObject is null ?
- await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression, elementIdxInfo.ElementIdxStr) :
- await WriteJObjectAsIndex(objectId, indexObject, elementIdxInfo.ElementIdxStr, paramInfo[0].TypeCode);
+ ArraySegment<byte> buffer = await WriteIndexObjectAsIndices(objectId, elementIdxInfo.Indexers, paramInfo);
  JObject getItemRetObj = await context.SdbAgent.InvokeMethod(buffer, methodIds[i], token);
  return (JObject)getItemRetObj["value"];
  }
@@ -470,31 +473,32 @@ await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression,
  throw new ReturnAsErrorException($"Unable to evaluate element access '{elementAccess}': {ex.Message}", ex.GetType().Name);
  }
 
- async Task<ElementIndexInfo> GetElementIndexInfo()
+ async Task<ElementIndexInfo> GetElementIndexInfo(List<JObject> nestedIndexers)
  {
- // e.g. x[a[0]], x[a[b[1]]] etc.
- if (indexObject is not null)
- return new ElementIndexInfo(ElementIdxStr: indexObject["value"].ToString() );
-
  if (elementAccess.ArgumentList is null)
  return null;
 
- StringBuilder elementIdxStr = new StringBuilder();
- var multiDimensionalArray = false;
+ int dimCnt = elementAccess.ArgumentList.Arguments.Count;
  LiteralExpressionSyntax indexingExpression = null;
- for (int i = 0; i < elementAccess.ArgumentList.Arguments.Count; i++)
+ StringBuilder elementIdxStr = new StringBuilder();
+ List<object> indexers = new();
+ // nesting should be resolved in reverse order
+ int nestedIndexersCnt = nestedIndexers.Count - 1;
+ for (int i = 0; i < dimCnt; i++)
  {
+ JObject indexObject;
  var arg = elementAccess.ArgumentList.Arguments[i];
  if (i != 0)
  {
  elementIdxStr.Append(", ");
- multiDimensionalArray = true;
  }
  // e.g. x[1]
  if (arg.Expression is LiteralExpressionSyntax)
  {
  indexingExpression = arg.Expression as LiteralExpressionSyntax;
- elementIdxStr.Append(indexingExpression.ToString());
+ string expression = indexingExpression.ToString();
+ elementIdxStr.Append(expression);
+ indexers.Add(indexingExpression);
  }
 
  // e.g. x[a] or x[a.b]
@@ -508,6 +512,18 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  // x[a]
  indexObject ??= await Resolve(argParm.Identifier.Text, token);
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
+ }
+ // nested indexing, e.g. x[a[0]], x[a[b[1]]], x[a[0], b[1]]
+ else if (arg.Expression is ElementAccessExpressionSyntax)
+ {
+ if (nestedIndexers == null || nestedIndexersCnt < 0)
+ throw new InvalidOperationException($"Cannot resolve nested indexing");
+ JObject nestedIndexObject = nestedIndexers[nestedIndexersCnt];
+ nestedIndexers.RemoveAt(nestedIndexersCnt);
+ elementIdxStr.Append(nestedIndexObject["value"].ToString());
+ indexers.Add(nestedIndexObject);
+ nestedIndexersCnt--;
  }
  // indexing with expressions, e.g. x[a + 1]
  else
@@ -519,36 +535,57 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  if (idxType != "number")
  throw new InvalidOperationException($"Cannot index with an object of type '{idxType}'");
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
  }
  }
  return new ElementIndexInfo(
+ DimensionsCount: dimCnt,
  ElementIdxStr: elementIdxStr.ToString(),
- IsMultidimensional: multiDimensionalArray,
- IndexingExpression: indexingExpression);
+ Indexers: indexers);
  }
 
- async Task<ArraySegment<byte>> WriteJObjectAsIndex(DotnetObjectId rootObjId, JObject indexObject, string elementIdxStr, ElementType? expectedType)
+ async Task<ArraySegment<byte>> WriteIndexObjectAsIndices(DotnetObjectId rootObjId, List<object> indexObjects, ParameterInfo[] paramInfo)
  {
  using var writer = new MonoBinaryWriter();
  writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteJsonValue(indexObject, context.SdbAgent, expectedType, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
+ writer.Write(indexObjects.Count); // number of method args
+ foreach ((ParameterInfo pi, object indexObject) in paramInfo.Zip(indexObjects))
+ {
+ if (indexObject is JObject indexJObject)
+ {
+ // indexed by an identifier name syntax
+ if (!await writer.WriteJsonValue(indexJObject, context.SdbAgent, pi.TypeCode, token))
+ throw new InternalErrorException($"Parsing index of type {indexJObject["type"].Value<string>()} to write it into the buffer failed.");
+ }
+ else if (indexObject is LiteralExpressionSyntax expression)
+ {
+ // indexed by a literal expression syntax
+ if (!await writer.WriteConst(expression, context.SdbAgent, token))
+ throw new InternalErrorException($"Parsing literal expression index = {expression} to write it into the buffer failed.");
+ }
+ else
+ {
+ throw new InternalErrorException($"Unexpected index type.");
+ }
+ }
  return writer.GetParameterBuffer();
  }
+ }
 
- async Task<ArraySegment<byte>> WriteLiteralExpressionAsIndex(DotnetObjectId rootObjId, LiteralExpressionSyntax indexingExpression, string elementIdxStr)
+ private static bool CheckParametersCompatibility(ParameterInfo[] paramInfos, List<object> indexObjects)
+ {
+ if (paramInfos.Length != indexObjects.Count)
+ return false;
+ foreach ((ParameterInfo paramInfo, object indexObj) in paramInfos.Zip(indexObjects))
  {
- using var writer = new MonoBinaryWriter();
- writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteConst(indexingExpression, context.SdbAgent, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
- return writer.GetParameterBuffer();
+ // shouldn't we check LiteralExpressionSyntax for compatibility as well?
+ if (indexObj is JObject indexJObj && !CheckParameterCompatibility(paramInfo.TypeCode, indexJObj))
+ return false;
  }
+ return true;
  }
 
- private static bool CheckParametersCompatibility(ElementType? paramTypeCode, JObject value)
+ private static bool CheckParameterCompatibility(ElementType? paramTypeCode, JObject value)
  {
  if (!paramTypeCode.HasValue)
  return true;
@@ -871,7 +908,8 @@ public JObject TryGetEvaluationResult(string id)
 
  private sealed record ElementIndexInfo(
  string ElementIdxStr,
- bool IsMultidimensional = false,
- LiteralExpressionSyntax IndexingExpression = null);
+ // keeps JObjects and LiteralExpressionSyntaxes:
+ List<object> Indexers,
+ int DimensionsCount = 1);
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrame2Tests.cs

@@ -745,5 +745,24 @@ await EvaluateOnCallFrameAndCheck(id,
  // ("mc.valueTypeEnum.HasFlag(SampleEnum.no)", TBool(true)) // ToDo: https://github.com/dotnet/runtime/issues/92262
  );
  });
+
+ [Fact]
+ public async Task EvaluateObjectIndexingMultidimensional() => await CheckInspectLocalsAtBreakpointSite(
+ "DebuggerTests.EvaluateLocalsWithIndexingTests", "EvaluateLocals", 12, "DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals",
+ "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.EvaluateLocalsWithIndexingTests:EvaluateLocals'); })",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ await EvaluateOnCallFrameAndCheck(id,
+ ("f[j, aDouble]", TNumber("3.34")), //only IdentifierNameSyntaxes
+ ("f[1, aDouble]", TNumber("3.34")), //IdentifierNameSyntax with LiteralExpressionSyntax
+ ("f[aChar, \"&\", longString]", TString("9-&-longString")),
+ ("f[f.numArray[j], aDouble]", TNumber("4.34")), //ElementAccessExpressionSyntax
+ ("f[f.numArray[j], f.numArray[0]]", TNumber("3")), //multiple ElementAccessExpressionSyntaxes
+ ("f[f.numArray[f.numList[0]], f.numArray[i]]", TNumber("3")),
+ ("f[f.numArray[f.numList[0]], f.numArray[f.numArray[i]]]", TNumber("4"))
+ ); 
+ });
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -585,7 +585,7 @@ public async Task EvaluateIndexingNegative() => await CheckInspectLocalsAtBreakp
  Assert.Equal("Unable to evaluate element access 'f.idx0[2]': Cannot apply indexing with [] to a primitive object of type 'number'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  (_, res) = await EvaluateOnCallFrame(id, "f[1]", expect_ok: false );
  Assert.Equal( "Unable to evaluate element access 'f[1]': Cannot apply indexing with [] to an object of type 'DebuggerTests.EvaluateLocalsWithIndexingTests.TestEvaluate'", res.Error["result"]?["description"]?.Value<string>());
@@ -724,7 +724,7 @@ public async Task EvaluateIndexingByExpressionNegative() => await CheckInspectLo
  Assert.Equal("Unable to evaluate element access 'f.numList[\"a\" + 1]': Cannot index with an object of type 'string'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  });
 
@@ -861,7 +861,9 @@ await EvaluateOnCallFrameAndCheck(id,
  ("f.textArrayOfArrays[f.idx1][f.idx1]", TString("2")),
  ("f.textListOfLists[1][1]", TString("2")),
  ("f.textListOfLists[j][j]", TString("2")),
- ("f.textListOfLists[f.idx1][f.idx1]", TString("2")));
+ ("f.textListOfLists[f.idx1][f.idx1]", TString("2")),
+ ("f.numArrayOfArrays[f.numArray[f.numList[1]]][f.numList[0]]", TNumber(2))
+ );
 
  });
 

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -387,12 +387,14 @@ private static async Task<IList<JObject>> ResolveElementAccess(ExpressionSyntaxR
  {
  var values = new List<JObject>();
  JObject index = null;
+ List<JObject> nestedIndexers = new();
  IEnumerable<ElementAccessExpressionSyntax> elementAccesses = replacer.elementAccess;
  foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
  {
- index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, index, replacer.variableDefinitions, token);
+ index = await resolver.Resolve(elementAccess, replacer.memberAccessValues, nestedIndexers, replacer.variableDefinitions, token);
  if (index == null)
  throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
+ nestedIndexers.Add(index);
  }
  values.Add(index);
  return values;

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -366,7 +366,12 @@ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject
  }
  }
 
- public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess, Dictionary<string, JObject> memberAccessValues, JObject indexObject, List<VariableDefinition> variableDefinitions, CancellationToken token)
+ public async Task<JObject> Resolve(
+ ElementAccessExpressionSyntax elementAccess,
+ Dictionary<string, JObject> memberAccessValues,
+ List<JObject> nestedIndexObject,
+ List<VariableDefinition> variableDefinitions,
+ CancellationToken token)
  {
  try
  {
@@ -376,12 +381,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
 
  if (rootObject == null)
  {
- // it might be a jagged array where indexObject should be treated as a new rootObject
- rootObject = indexObject;
- indexObject = null;
+ // it might be a jagged array where the previously added nestedIndexObject should be treated as a new rootObject
+ rootObject = nestedIndexObject.LastOrDefault();
+ if (rootObject != null)
+ nestedIndexObject.RemoveAt(nestedIndexObject.Count - 1);
  }
 
- ElementIndexInfo elementIdxInfo = await GetElementIndexInfo();
+ ElementIndexInfo elementIdxInfo = await GetElementIndexInfo(nestedIndexObject);
  if (elementIdxInfo is null)
  return null;
 
@@ -394,6 +400,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  if (!DotnetObjectId.TryParse(rootObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
  throw new InvalidOperationException($"Cannot apply indexing with [] to a primitive object of type '{type}'");
 
+ bool isMultidimensional = elementIdxInfo.DimensionsCount != 1;
  switch (objectId.Scheme)
  {
  case "valuetype": //can be an inlined array
@@ -407,7 +414,7 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  }
  case "array":
  rootObject["value"] = await context.SdbAgent.GetArrayValues(objectId.Value, token);
- if (!elementIdxInfo.IsMultidimensional)
+ if (!isMultidimensional)
  {
  int.TryParse(elementIdxInfo.ElementIdxStr, out elementIdx);
  return (JObject)rootObject["value"][elementIdx]["value"];
@@ -417,18 +424,16 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  return (JObject)(((JArray)rootObject["value"]).FirstOrDefault(x => x["name"].Value<string>() == elementIdxInfo.ElementIdxStr)["value"]);
  }
  case "object":
- if (elementIdxInfo.IsMultidimensional)
- throw new InvalidOperationException($"Cannot apply indexing with [,] to an object of type '{type}'");
  // ToDo: try to use the get_Item for string as well
- if (type == "string")
+ if (!isMultidimensional && type == "string")
  {
  var eaExpressionFormatted = elementAccessStrExpression.Replace('.', '_'); // instance_str
  variableDefinitions.Add(new (eaExpressionFormatted, rootObject, ExpressionEvaluator.ConvertJSToCSharpLocalVariableAssignment(eaExpressionFormatted, rootObject)));
  var eaFormatted = elementAccessStr.Replace('.', '_'); // instance_str[1]
  var variableDef = await ExpressionEvaluator.GetVariableDefinitions(this, variableDefinitions, invokeToStringInObject: false, token);
  return await ExpressionEvaluator.EvaluateSimpleExpression(this, eaFormatted, elementAccessStr, variableDef, logger, token);
  }
- if (indexObject is null && elementIdxInfo.IndexingExpression is null)
+ if (elementIdxInfo.Indexers is null || elementIdxInfo.Indexers.Count == 0)
  throw new InternalErrorException($"Unable to write index parameter to invoke the method in the runtime.");
 
  var typeIds = await context.SdbAgent.GetTypeIdsForObject(objectId.Value, true, token);
@@ -441,15 +446,13 @@ public async Task<JObject> Resolve(ElementAccessExpressionSyntax elementAccess,
  {
  MethodInfoWithDebugInformation methodInfo = await context.SdbAgent.GetMethodInfo(methodIds[i], token);
  ParameterInfo[] paramInfo = methodInfo.GetParametersInfo();
- if (paramInfo.Length == 1)
+ if (paramInfo.Length == elementIdxInfo.DimensionsCount)
  {
  try
  {
- if (indexObject != null && !CheckParametersCompatibility(paramInfo[0].TypeCode, indexObject))
+ if (!CheckParametersCompatibility(paramInfo, elementIdxInfo.Indexers))
  continue;
- ArraySegment<byte> buffer = indexObject is null ?
- await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression, elementIdxInfo.ElementIdxStr) :
- await WriteJObjectAsIndex(objectId, indexObject, elementIdxInfo.ElementIdxStr, paramInfo[0].TypeCode);
+ ArraySegment<byte> buffer = await WriteIndexObjectAsIndices(objectId, elementIdxInfo.Indexers, paramInfo);
  JObject getItemRetObj = await context.SdbAgent.InvokeMethod(buffer, methodIds[i], token);
  return (JObject)getItemRetObj["value"];
  }
@@ -470,31 +473,32 @@ await WriteLiteralExpressionAsIndex(objectId, elementIdxInfo.IndexingExpression,
  throw new ReturnAsErrorException($"Unable to evaluate element access '{elementAccess}': {ex.Message}", ex.GetType().Name);
  }
 
- async Task<ElementIndexInfo> GetElementIndexInfo()
+ async Task<ElementIndexInfo> GetElementIndexInfo(List<JObject> nestedIndexers)
  {
- // e.g. x[a[0]], x[a[b[1]]] etc.
- if (indexObject is not null)
- return new ElementIndexInfo(ElementIdxStr: indexObject["value"].ToString() );
-
  if (elementAccess.ArgumentList is null)
  return null;
 
- StringBuilder elementIdxStr = new StringBuilder();
- var multiDimensionalArray = false;
+ int dimCnt = elementAccess.ArgumentList.Arguments.Count;
  LiteralExpressionSyntax indexingExpression = null;
- for (int i = 0; i < elementAccess.ArgumentList.Arguments.Count; i++)
+ StringBuilder elementIdxStr = new StringBuilder();
+ List<object> indexers = new();
+ // nesting should be resolved in reverse order
+ int nestedIndexersCnt = nestedIndexers.Count - 1;
+ for (int i = 0; i < dimCnt; i++)
  {
+ JObject indexObject;
  var arg = elementAccess.ArgumentList.Arguments[i];
  if (i != 0)
  {
  elementIdxStr.Append(", ");
- multiDimensionalArray = true;
  }
  // e.g. x[1]
  if (arg.Expression is LiteralExpressionSyntax)
  {
  indexingExpression = arg.Expression as LiteralExpressionSyntax;
- elementIdxStr.Append(indexingExpression.ToString());
+ string expression = indexingExpression.ToString();
+ elementIdxStr.Append(expression);
+ indexers.Add(indexingExpression);
  }
 
  // e.g. x[a] or x[a.b]
@@ -508,6 +512,18 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  // x[a]
  indexObject ??= await Resolve(argParm.Identifier.Text, token);
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
+ }
+ // nested indexing, e.g. x[a[0]], x[a[b[1]]], x[a[0], b[1]]
+ else if (arg.Expression is ElementAccessExpressionSyntax)
+ {
+ if (nestedIndexers == null || nestedIndexersCnt < 0)
+ throw new InvalidOperationException($"Cannot resolve nested indexing");
+ JObject nestedIndexObject = nestedIndexers[nestedIndexersCnt];
+ nestedIndexers.RemoveAt(nestedIndexersCnt);
+ elementIdxStr.Append(nestedIndexObject["value"].ToString());
+ indexers.Add(nestedIndexObject);
+ nestedIndexersCnt--;
  }
  // indexing with expressions, e.g. x[a + 1]
  else
@@ -519,36 +535,57 @@ async Task<ElementIndexInfo> GetElementIndexInfo()
  if (idxType != "number")
  throw new InvalidOperationException($"Cannot index with an object of type '{idxType}'");
  elementIdxStr.Append(indexObject["value"].ToString());
+ indexers.Add(indexObject);
  }
  }
  return new ElementIndexInfo(
+ DimensionsCount: dimCnt,
  ElementIdxStr: elementIdxStr.ToString(),
- IsMultidimensional: multiDimensionalArray,
- IndexingExpression: indexingExpression);
+ Indexers: indexers);
  }
 
- async Task<ArraySegment<byte>> WriteJObjectAsIndex(DotnetObjectId rootObjId, JObject indexObject, string elementIdxStr, ElementType? expectedType)
+ async Task<ArraySegment<byte>> WriteIndexObjectAsIndices(DotnetObjectId rootObjId, List<object> indexObjects, ParameterInfo[] paramInfo)
  {
  using var writer = new MonoBinaryWriter();
  writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteJsonValue(indexObject, context.SdbAgent, expectedType, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
+ writer.Write(indexObjects.Count); // number of method args
+ foreach ((ParameterInfo pi, object indexObject) in paramInfo.Zip(indexObjects))
+ {
+ if (indexObject is JObject indexJObject)
+ {
+ // indexed by an identifier name syntax
+ if (!await writer.WriteJsonValue(indexJObject, context.SdbAgent, pi.TypeCode, token))
+ throw new InternalErrorException($"Parsing index of type {indexJObject["type"].Value<string>()} to write it into the buffer failed.");
+ }
+ else if (indexObject is LiteralExpressionSyntax expression)
+ {
+ // indexed by a literal expression syntax
+ if (!await writer.WriteConst(expression, context.SdbAgent, token))
+ throw new InternalErrorException($"Parsing literal expression index = {expression} to write it into the buffer failed.");
+ }
+ else
+ {
+ throw new InternalErrorException($"Unexpected index type.");
+ }
+ }
  return writer.GetParameterBuffer();
  }
+ }
 
- async Task<ArraySegment<byte>> WriteLiteralExpressionAsIndex(DotnetObjectId rootObjId, LiteralExpressionSyntax indexingExpression, string elementIdxStr)
+ private static bool CheckParametersCompatibility(ParameterInfo[] paramInfos, List<object> indexObjects)
+ {
+ if (paramInfos.Length != indexObjects.Count)
+ return false;
+ foreach ((ParameterInfo paramInfo, object indexObj) in paramInfos.Zip(indexObjects))
  {
- using var writer = new MonoBinaryWriter();
- writer.WriteObj(rootObjId, context.SdbAgent);
- writer.Write(1); // number of method args
- if (!await writer.WriteConst(indexingExpression, context.SdbAgent, token))
- throw new InternalErrorException($"Parsing index of type {indexObject["type"].Value<string>()} to write it into the buffer failed.");
- return writer.GetParameterBuffer();
+ // shouldn't we check LiteralExpressionSyntax for compatibility as well?
+ if (indexObj is JObject indexJObj && !CheckParameterCompatibility(paramInfo.TypeCode, indexJObj))
+ return false;
  }
+ return true;
  }
 
- private static bool CheckParametersCompatibility(ElementType? paramTypeCode, JObject value)
+ private static bool CheckParameterCompatibility(ElementType? paramTypeCode, JObject value)
  {
  if (!paramTypeCode.HasValue)
  return true;
@@ -871,7 +908,8 @@ public JObject TryGetEvaluationResult(string id)
 
  private sealed record ElementIndexInfo(
  string ElementIdxStr,
- bool IsMultidimensional = false,
- LiteralExpressionSyntax IndexingExpression = null);
+ // keeps JObjects and LiteralExpressionSyntaxes:
+ List<object> Indexers,
+ int DimensionsCount = 1);
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrame2Tests.cs

@@ -745,5 +745,24 @@ await EvaluateOnCallFrameAndCheck(id,
  // ("mc.valueTypeEnum.HasFlag(SampleEnum.no)", TBool(true)) // ToDo: https://github.com/dotnet/runtime/issues/92262
  );
  });
+
+ [Fact]
+ public async Task EvaluateObjectIndexingMultidimensional() => await CheckInspectLocalsAtBreakpointSite(
+ "DebuggerTests.EvaluateLocalsWithIndexingTests", "EvaluateLocals", 12, "DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals",
+ "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.EvaluateLocalsWithIndexingTests:EvaluateLocals'); })",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ await EvaluateOnCallFrameAndCheck(id,
+ ("f[j, aDouble]", TNumber("3.34")), //only IdentifierNameSyntaxes
+ ("f[1, aDouble]", TNumber("3.34")), //IdentifierNameSyntax with LiteralExpressionSyntax
+ ("f[aChar, \"&\", longString]", TString("9-&-longString")),
+ ("f[f.numArray[j], aDouble]", TNumber("4.34")), //ElementAccessExpressionSyntax
+ ("f[f.numArray[j], f.numArray[0]]", TNumber("3")), //multiple ElementAccessExpressionSyntaxes
+ ("f[f.numArray[f.numList[0]], f.numArray[i]]", TNumber("3")),
+ ("f[f.numArray[f.numList[0]], f.numArray[f.numArray[i]]]", TNumber("4"))
+ ); 
+ });
  }
 }

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -585,7 +585,7 @@ public async Task EvaluateIndexingNegative() => await CheckInspectLocalsAtBreakp
  Assert.Equal("Unable to evaluate element access 'f.idx0[2]': Cannot apply indexing with [] to a primitive object of type 'number'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  (_, res) = await EvaluateOnCallFrame(id, "f[1]", expect_ok: false );
  Assert.Equal( "Unable to evaluate element access 'f[1]': Cannot apply indexing with [] to an object of type 'DebuggerTests.EvaluateLocalsWithIndexingTests.TestEvaluate'", res.Error["result"]?["description"]?.Value<string>());
@@ -724,7 +724,7 @@ public async Task EvaluateIndexingByExpressionNegative() => await CheckInspectLo
  Assert.Equal("Unable to evaluate element access 'f.numList[\"a\" + 1]': Cannot index with an object of type 'string'", res.Error["result"]?["description"]?.Value<string>());
  var exceptionDetailsStack = res.Error["exceptionDetails"]?["stackTrace"]?["callFrames"]?[0];
  Assert.Equal("DebuggerTests.EvaluateLocalsWithIndexingTests.EvaluateLocals", exceptionDetailsStack?["functionName"]?.Value<string>());
- Assert.Equal(560, exceptionDetailsStack?["lineNumber"]?.Value<int>());
+ Assert.Equal(562, exceptionDetailsStack?["lineNumber"]?.Value<int>());
  Assert.Equal(12, exceptionDetailsStack?["columnNumber"]?.Value<int>());
  });
 
@@ -861,7 +861,9 @@ await EvaluateOnCallFrameAndCheck(id,
  ("f.textArrayOfArrays[f.idx1][f.idx1]", TString("2")),
  ("f.textListOfLists[1][1]", TString("2")),
  ("f.textListOfLists[j][j]", TString("2")),
- ("f.textListOfLists[f.idx1][f.idx1]", TString("2")));
+ ("f.textListOfLists[f.idx1][f.idx1]", TString("2")),
+ ("f.numArrayOfArrays[f.numArray[f.numList[1]]][f.numList[0]]", TNumber(2))
+ );
 
  });