Add getOrUpdate helper

src/compiler/binder.ts

@@ -326,7 +326,7 @@ namespace ts {
  // Otherwise, we'll be merging into a compatible existing symbol (for example when
  // you have multiple 'vars' with the same name in the same container). In this case
  // just add this node into the declarations list of the symbol.
- symbol = symbolTable[name] || (symbolTable[name] = createSymbol(SymbolFlags.None, name));
+ symbol = getOrUpdate(symbolTable, name, name => createSymbol(SymbolFlags.None, name));
 
  if (name && (includes & SymbolFlags.Classifiable)) {
  classifiableNames[name] = name;

src/compiler/checker.ts

@@ -518,12 +518,12 @@ namespace ts {
  function getSymbolLinks(symbol: Symbol): SymbolLinks {
  if (symbol.flags & SymbolFlags.Transient) return <TransientSymbol>symbol;
  const id = getSymbolId(symbol);
- return symbolLinks[id] || (symbolLinks[id] = {});
+ return getOrUpdateArray(symbolLinks, id, () => ({}));
  }
 
  function getNodeLinks(node: Node): NodeLinks {
  const nodeId = getNodeId(node);
- return nodeLinks[nodeId] || (nodeLinks[nodeId] = { flags: 0 });
+ return getOrUpdateArray<NodeLinks>(nodeLinks, nodeId, () => ({ flags: 0 }));
  }
 
  function isGlobalSourceFile(node: Node) {
@@ -8351,7 +8351,7 @@ namespace ts {
  // If we have previously computed the control flow type for the reference at
  // this flow loop junction, return the cached type.
  const id = getFlowNodeId(flow);
- const cache = flowLoopCaches[id] || (flowLoopCaches[id] = createMap<Type>());
+ const cache = getOrUpdateArray<Map<Type>>(flowLoopCaches, id, () => createMap<Type>());
  if (!key) {
  key = getFlowCacheKey(reference);
  }

src/compiler/core.ts

@@ -409,6 +409,23 @@ namespace ts {
  return hasOwnProperty.call(map, key) ? map[key] : undefined;
  }
 
+ /**
+ * Gets a property in a Map, or if it doesn't exist, creates and returns it.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdate<T>(map: Map<T>, key: string, makeValue: (key: string) => T) {
+ return map[key] || (map[key] = makeValue(key));
+ }
+
+ /**
+ * Gets a value in an array, or if it doesn't exist, creates and returns it.
+ * It is the caller's responsibility to ensure that `key` is within the bounds of the array.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdateArray<T>(arr: T[], key: number, makeValue: (key: number) => T) {
+ return arr[key] || (arr[key] = makeValue(key));
+ }
+
  /**
  * Gets the owned, enumerable property keys of a map-like.
  *

src/compiler/parser.ts

@@ -1086,7 +1086,7 @@ namespace ts {
 
  function internIdentifier(text: string): string {
  text = escapeIdentifier(text);
- return identifiers[text] || (identifiers[text] = text);
+ return getOrUpdate(identifiers, text, text => text);
  }
 
  // An identifier that starts with two underscores has an extra underscore character prepended to it to avoid issues

src/services/services.ts

@@ -990,7 +990,7 @@ namespace ts {
  }
 
  function getDeclarations(name: string) {
- return result[name] || (result[name] = []);
+ return getOrUpdate(result, name, () => []);
  }
 
  function getDeclarationName(declaration: Declaration) {

src/compiler/binder.ts

@@ -326,7 +326,7 @@ namespace ts {
  // Otherwise, we'll be merging into a compatible existing symbol (for example when
  // you have multiple 'vars' with the same name in the same container). In this case
  // just add this node into the declarations list of the symbol.
- symbol = symbolTable[name] || (symbolTable[name] = createSymbol(SymbolFlags.None, name));
+ symbol = getOrUpdate(symbolTable, name, name => createSymbol(SymbolFlags.None, name));
 
  if (name && (includes & SymbolFlags.Classifiable)) {
  classifiableNames[name] = name;

src/compiler/checker.ts

@@ -518,12 +518,12 @@ namespace ts {
  function getSymbolLinks(symbol: Symbol): SymbolLinks {
  if (symbol.flags & SymbolFlags.Transient) return <TransientSymbol>symbol;
  const id = getSymbolId(symbol);
- return symbolLinks[id] || (symbolLinks[id] = {});
+ return getOrUpdateArray(symbolLinks, id, () => ({}));
  }
 
  function getNodeLinks(node: Node): NodeLinks {
  const nodeId = getNodeId(node);
- return nodeLinks[nodeId] || (nodeLinks[nodeId] = { flags: 0 });
+ return getOrUpdateArray<NodeLinks>(nodeLinks, nodeId, () => ({ flags: 0 }));
  }
 
  function isGlobalSourceFile(node: Node) {
@@ -8351,7 +8351,7 @@ namespace ts {
  // If we have previously computed the control flow type for the reference at
  // this flow loop junction, return the cached type.
  const id = getFlowNodeId(flow);
- const cache = flowLoopCaches[id] || (flowLoopCaches[id] = createMap<Type>());
+ const cache = getOrUpdateArray<Map<Type>>(flowLoopCaches, id, () => createMap<Type>());
  if (!key) {
  key = getFlowCacheKey(reference);
  }

src/compiler/core.ts

@@ -409,6 +409,23 @@ namespace ts {
  return hasOwnProperty.call(map, key) ? map[key] : undefined;
  }
 
+ /**
+ * Gets a property in a Map, or if it doesn't exist, creates and returns it.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdate<T>(map: Map<T>, key: string, makeValue: (key: string) => T) {
+ return map[key] || (map[key] = makeValue(key));
+ }
+
+ /**
+ * Gets a value in an array, or if it doesn't exist, creates and returns it.
+ * It is the caller's responsibility to ensure that `key` is within the bounds of the array.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdateArray<T>(arr: T[], key: number, makeValue: (key: number) => T) {
+ return arr[key] || (arr[key] = makeValue(key));
+ }
+
  /**
  * Gets the owned, enumerable property keys of a map-like.
  *

src/compiler/parser.ts

@@ -1086,7 +1086,7 @@ namespace ts {
 
  function internIdentifier(text: string): string {
  text = escapeIdentifier(text);
- return identifiers[text] || (identifiers[text] = text);
+ return getOrUpdate(identifiers, text, text => text);
  }
 
  // An identifier that starts with two underscores has an extra underscore character prepended to it to avoid issues

src/services/services.ts

@@ -990,7 +990,7 @@ namespace ts {
  }
 
  function getDeclarations(name: string) {
- return result[name] || (result[name] = []);
+ return getOrUpdate(result, name, () => []);
  }
 
  function getDeclarationName(declaration: Declaration) {

src/compiler/binder.ts

@@ -326,7 +326,7 @@ namespace ts {
  // Otherwise, we'll be merging into a compatible existing symbol (for example when
  // you have multiple 'vars' with the same name in the same container). In this case
  // just add this node into the declarations list of the symbol.
- symbol = symbolTable[name] || (symbolTable[name] = createSymbol(SymbolFlags.None, name));
+ symbol = getOrUpdate(symbolTable, name, name => createSymbol(SymbolFlags.None, name));
 
  if (name && (includes & SymbolFlags.Classifiable)) {
  classifiableNames[name] = name;

src/compiler/checker.ts

@@ -518,12 +518,12 @@ namespace ts {
  function getSymbolLinks(symbol: Symbol): SymbolLinks {
  if (symbol.flags & SymbolFlags.Transient) return <TransientSymbol>symbol;
  const id = getSymbolId(symbol);
- return symbolLinks[id] || (symbolLinks[id] = {});
+ return getOrUpdateArray(symbolLinks, id, () => ({}));
  }
 
  function getNodeLinks(node: Node): NodeLinks {
  const nodeId = getNodeId(node);
- return nodeLinks[nodeId] || (nodeLinks[nodeId] = { flags: 0 });
+ return getOrUpdateArray<NodeLinks>(nodeLinks, nodeId, () => ({ flags: 0 }));
  }
 
  function isGlobalSourceFile(node: Node) {
@@ -8351,7 +8351,7 @@ namespace ts {
  // If we have previously computed the control flow type for the reference at
  // this flow loop junction, return the cached type.
  const id = getFlowNodeId(flow);
- const cache = flowLoopCaches[id] || (flowLoopCaches[id] = createMap<Type>());
+ const cache = getOrUpdateArray<Map<Type>>(flowLoopCaches, id, () => createMap<Type>());
  if (!key) {
  key = getFlowCacheKey(reference);
  }

src/compiler/core.ts

@@ -409,6 +409,23 @@ namespace ts {
  return hasOwnProperty.call(map, key) ? map[key] : undefined;
  }
 
+ /**
+ * Gets a property in a Map, or if it doesn't exist, creates and returns it.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdate<T>(map: Map<T>, key: string, makeValue: (key: string) => T) {
+ return map[key] || (map[key] = makeValue(key));
+ }
+
+ /**
+ * Gets a value in an array, or if it doesn't exist, creates and returns it.
+ * It is the caller's responsibility to ensure that `key` is within the bounds of the array.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdateArray<T>(arr: T[], key: number, makeValue: (key: number) => T) {
+ return arr[key] || (arr[key] = makeValue(key));
+ }
+
  /**
  * Gets the owned, enumerable property keys of a map-like.
  *

src/compiler/parser.ts

@@ -1086,7 +1086,7 @@ namespace ts {
 
  function internIdentifier(text: string): string {
  text = escapeIdentifier(text);
- return identifiers[text] || (identifiers[text] = text);
+ return getOrUpdate(identifiers, text, text => text);
  }
 
  // An identifier that starts with two underscores has an extra underscore character prepended to it to avoid issues

src/services/services.ts

@@ -990,7 +990,7 @@ namespace ts {
  }
 
  function getDeclarations(name: string) {
- return result[name] || (result[name] = []);
+ return getOrUpdate(result, name, () => []);
  }
 
  function getDeclarationName(declaration: Declaration) {

src/compiler/binder.ts

@@ -326,7 +326,7 @@ namespace ts {
  // Otherwise, we'll be merging into a compatible existing symbol (for example when
  // you have multiple 'vars' with the same name in the same container). In this case
  // just add this node into the declarations list of the symbol.
- symbol = symbolTable[name] || (symbolTable[name] = createSymbol(SymbolFlags.None, name));
+ symbol = getOrUpdate(symbolTable, name, name => createSymbol(SymbolFlags.None, name));
 
  if (name && (includes & SymbolFlags.Classifiable)) {
  classifiableNames[name] = name;

src/compiler/checker.ts

@@ -518,12 +518,12 @@ namespace ts {
  function getSymbolLinks(symbol: Symbol): SymbolLinks {
  if (symbol.flags & SymbolFlags.Transient) return <TransientSymbol>symbol;
  const id = getSymbolId(symbol);
- return symbolLinks[id] || (symbolLinks[id] = {});
+ return getOrUpdateArray(symbolLinks, id, () => ({}));
  }
 
  function getNodeLinks(node: Node): NodeLinks {
  const nodeId = getNodeId(node);
- return nodeLinks[nodeId] || (nodeLinks[nodeId] = { flags: 0 });
+ return getOrUpdateArray<NodeLinks>(nodeLinks, nodeId, () => ({ flags: 0 }));
  }
 
  function isGlobalSourceFile(node: Node) {
@@ -8351,7 +8351,7 @@ namespace ts {
  // If we have previously computed the control flow type for the reference at
  // this flow loop junction, return the cached type.
  const id = getFlowNodeId(flow);
- const cache = flowLoopCaches[id] || (flowLoopCaches[id] = createMap<Type>());
+ const cache = getOrUpdateArray<Map<Type>>(flowLoopCaches, id, () => createMap<Type>());
  if (!key) {
  key = getFlowCacheKey(reference);
  }

src/compiler/core.ts

@@ -409,6 +409,23 @@ namespace ts {
  return hasOwnProperty.call(map, key) ? map[key] : undefined;
  }
 
+ /**
+ * Gets a property in a Map, or if it doesn't exist, creates and returns it.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdate<T>(map: Map<T>, key: string, makeValue: (key: string) => T) {
+ return map[key] || (map[key] = makeValue(key));
+ }
+
+ /**
+ * Gets a value in an array, or if it doesn't exist, creates and returns it.
+ * It is the caller's responsibility to ensure that `key` is within the bounds of the array.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdateArray<T>(arr: T[], key: number, makeValue: (key: number) => T) {
+ return arr[key] || (arr[key] = makeValue(key));
+ }
+
  /**
  * Gets the owned, enumerable property keys of a map-like.
  *

src/compiler/parser.ts

@@ -1086,7 +1086,7 @@ namespace ts {
 
  function internIdentifier(text: string): string {
  text = escapeIdentifier(text);
- return identifiers[text] || (identifiers[text] = text);
+ return getOrUpdate(identifiers, text, text => text);
  }
 
  // An identifier that starts with two underscores has an extra underscore character prepended to it to avoid issues

src/services/services.ts

@@ -990,7 +990,7 @@ namespace ts {
  }
 
  function getDeclarations(name: string) {
- return result[name] || (result[name] = []);
+ return getOrUpdate(result, name, () => []);
  }
 
  function getDeclarationName(declaration: Declaration) {

src/compiler/binder.ts

@@ -326,7 +326,7 @@ namespace ts {
  // Otherwise, we'll be merging into a compatible existing symbol (for example when
  // you have multiple 'vars' with the same name in the same container). In this case
  // just add this node into the declarations list of the symbol.
- symbol = symbolTable[name] || (symbolTable[name] = createSymbol(SymbolFlags.None, name));
+ symbol = getOrUpdate(symbolTable, name, name => createSymbol(SymbolFlags.None, name));
 
  if (name && (includes & SymbolFlags.Classifiable)) {
  classifiableNames[name] = name;

src/compiler/checker.ts

@@ -518,12 +518,12 @@ namespace ts {
  function getSymbolLinks(symbol: Symbol): SymbolLinks {
  if (symbol.flags & SymbolFlags.Transient) return <TransientSymbol>symbol;
  const id = getSymbolId(symbol);
- return symbolLinks[id] || (symbolLinks[id] = {});
+ return getOrUpdateArray(symbolLinks, id, () => ({}));
  }
 
  function getNodeLinks(node: Node): NodeLinks {
  const nodeId = getNodeId(node);
- return nodeLinks[nodeId] || (nodeLinks[nodeId] = { flags: 0 });
+ return getOrUpdateArray<NodeLinks>(nodeLinks, nodeId, () => ({ flags: 0 }));
  }
 
  function isGlobalSourceFile(node: Node) {
@@ -8351,7 +8351,7 @@ namespace ts {
  // If we have previously computed the control flow type for the reference at
  // this flow loop junction, return the cached type.
  const id = getFlowNodeId(flow);
- const cache = flowLoopCaches[id] || (flowLoopCaches[id] = createMap<Type>());
+ const cache = getOrUpdateArray<Map<Type>>(flowLoopCaches, id, () => createMap<Type>());
  if (!key) {
  key = getFlowCacheKey(reference);
  }

src/compiler/core.ts

@@ -409,6 +409,23 @@ namespace ts {
  return hasOwnProperty.call(map, key) ? map[key] : undefined;
  }
 
+ /**
+ * Gets a property in a Map, or if it doesn't exist, creates and returns it.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdate<T>(map: Map<T>, key: string, makeValue: (key: string) => T) {
+ return map[key] || (map[key] = makeValue(key));
+ }
+
+ /**
+ * Gets a value in an array, or if it doesn't exist, creates and returns it.
+ * It is the caller's responsibility to ensure that `key` is within the bounds of the array.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdateArray<T>(arr: T[], key: number, makeValue: (key: number) => T) {
+ return arr[key] || (arr[key] = makeValue(key));
+ }
+
  /**
  * Gets the owned, enumerable property keys of a map-like.
  *

src/compiler/parser.ts

@@ -1086,7 +1086,7 @@ namespace ts {
 
  function internIdentifier(text: string): string {
  text = escapeIdentifier(text);
- return identifiers[text] || (identifiers[text] = text);
+ return getOrUpdate(identifiers, text, text => text);
  }
 
  // An identifier that starts with two underscores has an extra underscore character prepended to it to avoid issues

src/services/services.ts

@@ -990,7 +990,7 @@ namespace ts {
  }
 
  function getDeclarations(name: string) {
- return result[name] || (result[name] = []);
+ return getOrUpdate(result, name, () => []);
  }
 
  function getDeclarationName(declaration: Declaration) {

src/compiler/binder.ts

@@ -326,7 +326,7 @@ namespace ts {
  // Otherwise, we'll be merging into a compatible existing symbol (for example when
  // you have multiple 'vars' with the same name in the same container). In this case
  // just add this node into the declarations list of the symbol.
- symbol = symbolTable[name] || (symbolTable[name] = createSymbol(SymbolFlags.None, name));
+ symbol = getOrUpdate(symbolTable, name, name => createSymbol(SymbolFlags.None, name));
 
  if (name && (includes & SymbolFlags.Classifiable)) {
  classifiableNames[name] = name;

src/compiler/checker.ts

@@ -518,12 +518,12 @@ namespace ts {
  function getSymbolLinks(symbol: Symbol): SymbolLinks {
  if (symbol.flags & SymbolFlags.Transient) return <TransientSymbol>symbol;
  const id = getSymbolId(symbol);
- return symbolLinks[id] || (symbolLinks[id] = {});
+ return getOrUpdateArray(symbolLinks, id, () => ({}));
  }
 
  function getNodeLinks(node: Node): NodeLinks {
  const nodeId = getNodeId(node);
- return nodeLinks[nodeId] || (nodeLinks[nodeId] = { flags: 0 });
+ return getOrUpdateArray<NodeLinks>(nodeLinks, nodeId, () => ({ flags: 0 }));
  }
 
  function isGlobalSourceFile(node: Node) {
@@ -8351,7 +8351,7 @@ namespace ts {
  // If we have previously computed the control flow type for the reference at
  // this flow loop junction, return the cached type.
  const id = getFlowNodeId(flow);
- const cache = flowLoopCaches[id] || (flowLoopCaches[id] = createMap<Type>());
+ const cache = getOrUpdateArray<Map<Type>>(flowLoopCaches, id, () => createMap<Type>());
  if (!key) {
  key = getFlowCacheKey(reference);
  }

src/compiler/core.ts

@@ -409,6 +409,23 @@ namespace ts {
  return hasOwnProperty.call(map, key) ? map[key] : undefined;
  }
 
+ /**
+ * Gets a property in a Map, or if it doesn't exist, creates and returns it.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdate<T>(map: Map<T>, key: string, makeValue: (key: string) => T) {
+ return map[key] || (map[key] = makeValue(key));
+ }
+
+ /**
+ * Gets a value in an array, or if it doesn't exist, creates and returns it.
+ * It is the caller's responsibility to ensure that `key` is within the bounds of the array.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdateArray<T>(arr: T[], key: number, makeValue: (key: number) => T) {
+ return arr[key] || (arr[key] = makeValue(key));
+ }
+
  /**
  * Gets the owned, enumerable property keys of a map-like.
  *

src/compiler/parser.ts

@@ -1086,7 +1086,7 @@ namespace ts {
 
  function internIdentifier(text: string): string {
  text = escapeIdentifier(text);
- return identifiers[text] || (identifiers[text] = text);
+ return getOrUpdate(identifiers, text, text => text);
  }
 
  // An identifier that starts with two underscores has an extra underscore character prepended to it to avoid issues

src/services/services.ts

@@ -990,7 +990,7 @@ namespace ts {
  }
 
  function getDeclarations(name: string) {
- return result[name] || (result[name] = []);
+ return getOrUpdate(result, name, () => []);
  }
 
  function getDeclarationName(declaration: Declaration) {

src/compiler/binder.ts

@@ -326,7 +326,7 @@ namespace ts {
  // Otherwise, we'll be merging into a compatible existing symbol (for example when
  // you have multiple 'vars' with the same name in the same container). In this case
  // just add this node into the declarations list of the symbol.
- symbol = symbolTable[name] || (symbolTable[name] = createSymbol(SymbolFlags.None, name));
+ symbol = getOrUpdate(symbolTable, name, name => createSymbol(SymbolFlags.None, name));
 
  if (name && (includes & SymbolFlags.Classifiable)) {
  classifiableNames[name] = name;

src/compiler/checker.ts

@@ -518,12 +518,12 @@ namespace ts {
  function getSymbolLinks(symbol: Symbol): SymbolLinks {
  if (symbol.flags & SymbolFlags.Transient) return <TransientSymbol>symbol;
  const id = getSymbolId(symbol);
- return symbolLinks[id] || (symbolLinks[id] = {});
+ return getOrUpdateArray(symbolLinks, id, () => ({}));
  }
 
  function getNodeLinks(node: Node): NodeLinks {
  const nodeId = getNodeId(node);
- return nodeLinks[nodeId] || (nodeLinks[nodeId] = { flags: 0 });
+ return getOrUpdateArray<NodeLinks>(nodeLinks, nodeId, () => ({ flags: 0 }));
  }
 
  function isGlobalSourceFile(node: Node) {
@@ -8351,7 +8351,7 @@ namespace ts {
  // If we have previously computed the control flow type for the reference at
  // this flow loop junction, return the cached type.
  const id = getFlowNodeId(flow);
- const cache = flowLoopCaches[id] || (flowLoopCaches[id] = createMap<Type>());
+ const cache = getOrUpdateArray<Map<Type>>(flowLoopCaches, id, () => createMap<Type>());
  if (!key) {
  key = getFlowCacheKey(reference);
  }

src/compiler/core.ts

@@ -409,6 +409,23 @@ namespace ts {
  return hasOwnProperty.call(map, key) ? map[key] : undefined;
  }
 
+ /**
+ * Gets a property in a Map, or if it doesn't exist, creates and returns it.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdate<T>(map: Map<T>, key: string, makeValue: (key: string) => T) {
+ return map[key] || (map[key] = makeValue(key));
+ }
+
+ /**
+ * Gets a value in an array, or if it doesn't exist, creates and returns it.
+ * It is the caller's responsibility to ensure that `key` is within the bounds of the array.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdateArray<T>(arr: T[], key: number, makeValue: (key: number) => T) {
+ return arr[key] || (arr[key] = makeValue(key));
+ }
+
  /**
  * Gets the owned, enumerable property keys of a map-like.
  *

src/compiler/parser.ts

@@ -1086,7 +1086,7 @@ namespace ts {
 
  function internIdentifier(text: string): string {
  text = escapeIdentifier(text);
- return identifiers[text] || (identifiers[text] = text);
+ return getOrUpdate(identifiers, text, text => text);
  }
 
  // An identifier that starts with two underscores has an extra underscore character prepended to it to avoid issues

src/services/services.ts

@@ -990,7 +990,7 @@ namespace ts {
  }
 
  function getDeclarations(name: string) {
- return result[name] || (result[name] = []);
+ return getOrUpdate(result, name, () => []);
  }
 
  function getDeclarationName(declaration: Declaration) {

src/compiler/binder.ts

@@ -326,7 +326,7 @@ namespace ts {
  // Otherwise, we'll be merging into a compatible existing symbol (for example when
  // you have multiple 'vars' with the same name in the same container). In this case
  // just add this node into the declarations list of the symbol.
- symbol = symbolTable[name] || (symbolTable[name] = createSymbol(SymbolFlags.None, name));
+ symbol = getOrUpdate(symbolTable, name, name => createSymbol(SymbolFlags.None, name));
 
  if (name && (includes & SymbolFlags.Classifiable)) {
  classifiableNames[name] = name;

src/compiler/checker.ts

@@ -518,12 +518,12 @@ namespace ts {
  function getSymbolLinks(symbol: Symbol): SymbolLinks {
  if (symbol.flags & SymbolFlags.Transient) return <TransientSymbol>symbol;
  const id = getSymbolId(symbol);
- return symbolLinks[id] || (symbolLinks[id] = {});
+ return getOrUpdateArray(symbolLinks, id, () => ({}));
  }
 
  function getNodeLinks(node: Node): NodeLinks {
  const nodeId = getNodeId(node);
- return nodeLinks[nodeId] || (nodeLinks[nodeId] = { flags: 0 });
+ return getOrUpdateArray<NodeLinks>(nodeLinks, nodeId, () => ({ flags: 0 }));
  }
 
  function isGlobalSourceFile(node: Node) {
@@ -8351,7 +8351,7 @@ namespace ts {
  // If we have previously computed the control flow type for the reference at
  // this flow loop junction, return the cached type.
  const id = getFlowNodeId(flow);
- const cache = flowLoopCaches[id] || (flowLoopCaches[id] = createMap<Type>());
+ const cache = getOrUpdateArray<Map<Type>>(flowLoopCaches, id, () => createMap<Type>());
  if (!key) {
  key = getFlowCacheKey(reference);
  }

src/compiler/core.ts

@@ -409,6 +409,23 @@ namespace ts {
  return hasOwnProperty.call(map, key) ? map[key] : undefined;
  }
 
+ /**
+ * Gets a property in a Map, or if it doesn't exist, creates and returns it.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdate<T>(map: Map<T>, key: string, makeValue: (key: string) => T) {
+ return map[key] || (map[key] = makeValue(key));
+ }
+
+ /**
+ * Gets a value in an array, or if it doesn't exist, creates and returns it.
+ * It is the caller's responsibility to ensure that `key` is within the bounds of the array.
+ * `makeValue` is also passed the key to avoid creating unnecessary closures.
+ */
+ export function getOrUpdateArray<T>(arr: T[], key: number, makeValue: (key: number) => T) {
+ return arr[key] || (arr[key] = makeValue(key));
+ }
+
  /**
  * Gets the owned, enumerable property keys of a map-like.
  *

src/compiler/parser.ts

@@ -1086,7 +1086,7 @@ namespace ts {
 
  function internIdentifier(text: string): string {
  text = escapeIdentifier(text);
- return identifiers[text] || (identifiers[text] = text);
+ return getOrUpdate(identifiers, text, text => text);
  }
 
  // An identifier that starts with two underscores has an extra underscore character prepended to it to avoid issues

src/services/services.ts

@@ -990,7 +990,7 @@ namespace ts {
  }
 
  function getDeclarations(name: string) {
- return result[name] || (result[name] = []);
+ return getOrUpdate(result, name, () => []);
  }
 
  function getDeclarationName(declaration: Declaration) {