cel-expr · copybara-service · Feb 12, 2026 · Feb 12, 2026 · cel-expr · copybara-service
diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java b/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java
@@ -29,6 +29,30 @@ public interface CelPolicyParserBuilder<T> {
  @CanIgnoreReturnValue
  CelPolicyParserBuilder<T> addTagVisitor(TagVisitor<T> tagVisitor);
 
+ /**
+ * Configures the parser to allow for key-value pairs to declare a variable name and expression.
+ *
+ * <p>For example:
+ *
+ * <pre>{@code
+ * variables:
+ * - foo: bar
+ * - baz: qux
+ * }</pre>
+ *
+ * <p>This is in contrast to the default behavior, which requires the following syntax:
+ *
+ * <pre>{@code
+ * variables:
+ * - name: foo
+ * expression: bar
+ * - name: baz
+ * expression: qux
+ * }</pre>
+ */
+ @CanIgnoreReturnValue
+ CelPolicyParserBuilder<T> enableSimpleVariables(boolean enable);
+
  /** Builds a new instance of {@link CelPolicyParser}. */
  @CheckReturnValue
  CelPolicyParser build();

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java b/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java
@@ -49,6 +49,7 @@ final class CelPolicyYamlParser implements CelPolicyParser {
  Variable.newBuilder().setExpression(ERROR_VALUE).setName(ERROR_VALUE).build();
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
 
  @Override
  public CelPolicy parse(String policySource) throws CelPolicyValidationException {
@@ -58,13 +59,15 @@ public CelPolicy parse(String policySource) throws CelPolicyValidationException
  @Override
  public CelPolicy parse(String policySource, String description)
  throws CelPolicyValidationException {
- ParserImpl parser = new ParserImpl(tagVisitor, policySource, description);
+ ParserImpl parser =
+ new ParserImpl(tagVisitor, enableSimpleVariables, policySource, description);
  return parser.parseYaml();
  }
 
  private static class ParserImpl implements PolicyParserContext<Node> {
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
  private final CelPolicySource policySource;
  private final ParserContext<Node> ctx;
 
@@ -336,9 +339,45 @@ public CelPolicy.Variable parseVariable(
  if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
  return ERROR_VARIABLE;
  }
+
  MappingNode variableMap = (MappingNode) node;
  Variable.Builder builder = Variable.newBuilder();
 
+ if (enableSimpleVariables) {
+ return parseVariableInline(ctx, id, variableMap, builder);
+ }
+ return parseVariableObject(ctx, policyBuilder, id, variableMap, builder);
+ }
+
+ private Variable parseVariableInline(
+ PolicyParserContext<Node> ctx, long id, MappingNode variableMap, Variable.Builder builder) {
+ int iterations = 0;
+ for (NodeTuple nodeTuple : variableMap.getValue()) {
+ Node keyNode = nodeTuple.getKeyNode();
+ long keyId = ctx.collectMetadata(keyNode);
+ builder
+ .setName(ctx.newValueString(keyNode))
+ .setExpression(ctx.newValueString(nodeTuple.getValueNode()));
+ iterations++;
+
+ if (iterations > 1) {
+ ctx.reportError(keyId, "Only one variable may be defined inline");
+ }
+ }
+
+ if (!assertRequiredFields(ctx, id, builder.getMissingRequiredFieldNames())) {
+ return ERROR_VARIABLE;
+ }
+
+ return builder.build();
+ }
+
+ private Variable parseVariableObject(
+ PolicyParserContext<Node> ctx,
+ CelPolicy.Builder policyBuilder,
+ long id,
+ MappingNode variableMap,
+ Variable.Builder builder) {
  for (NodeTuple nodeTuple : variableMap.getValue()) {
  Node keyNode = nodeTuple.getKeyNode();
  long keyId = ctx.collectMetadata(keyNode);
@@ -370,8 +409,13 @@ public CelPolicy.Variable parseVariable(
  return builder.build();
  }
 
- private ParserImpl(TagVisitor<Node> tagVisitor, String source, String description) {
+ private ParserImpl(
+ TagVisitor<Node> tagVisitor,
+ boolean enableSimpleVariables,
+ String source,
+ String description) {
  this.tagVisitor = tagVisitor;
+ this.enableSimpleVariables = enableSimpleVariables;
  this.policySource =
  CelPolicySource.newBuilder(CelCodePointArray.fromString(source))
  .setDescription(description)
@@ -413,9 +457,11 @@ public ValueString newValueString(Node node) {
  static final class Builder implements CelPolicyParserBuilder<Node> {
 
  private TagVisitor<Node> tagVisitor;
+ private boolean enableSimpleVariables;
 
  private Builder() {
  this.tagVisitor = new TagVisitor<Node>() {};
+ this.enableSimpleVariables = false;
  }
 
  @Override
@@ -424,17 +470,24 @@ public CelPolicyParserBuilder<Node> addTagVisitor(TagVisitor<Node> tagVisitor) {
  return this;
  }
 
+ @Override
+ public CelPolicyParserBuilder<Node> enableSimpleVariables(boolean enable) {
+ this.enableSimpleVariables = enable;
+ return this;
+ }
+
  @Override
  public CelPolicyParser build() {
- return new CelPolicyYamlParser(tagVisitor);
+ return new CelPolicyYamlParser(tagVisitor, enableSimpleVariables);
  }
  }
 
- static Builder newBuilder() {
- return new Builder();
+ static CelPolicyParserBuilder<Node> newBuilder() {
+ return new Builder().enableSimpleVariables(false);
  }
 
- private CelPolicyYamlParser(TagVisitor<Node> tagVisitor) {
+ private CelPolicyYamlParser(TagVisitor<Node> tagVisitor, boolean enableSimpleVariables) {
  this.tagVisitor = checkNotNull(tagVisitor);
+ this.enableSimpleVariables = enableSimpleVariables;
  }
 }
diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java
@@ -302,6 +302,29 @@ public void evaluateYamlPolicy_lateBoundFunction() throws Exception {
  assertThat(evalResult).isEqualTo("foo" + exampleValue);
  }
 
+ @Test
+ public void evaluateYamlPolicy_withSimpleVariable() throws Exception {
+ Cel cel = newCel();
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " - second: 'false'\n"
+ + " match:\n"
+ + " - output: 'variables.first && variables.second'";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+ CelPolicy policy = parser.parse(policySource);
+
+ CelAbstractSyntaxTree compiledPolicyAst =
+ CelPolicyCompilerFactory.newPolicyCompiler(cel).build().compile(policy);
+
+ boolean evalResult = (boolean) cel.createProgram(compiledPolicyAst).eval();
+
+ assertThat(evalResult).isFalse();
+ }
+
  private static final class EvaluablePolicyTestData {
  private final TestYamlPolicy yamlPolicy;
  private final PolicyTestCase testCase;

diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java
@@ -148,6 +148,30 @@ public void parseYamlPolicy_withImports() throws Exception {
  .inOrder();
  }
 
+ @Test
+ public void parseYamlPolicy_withSimpleVariable_multipleInlinedVariables() {
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " second: 'false'\n"
+ + " match:\n"
+ + " - condition: 'variables.my_var'\n"
+ + " output: 'true'\n";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+
+ CelPolicyValidationException e =
+ assertThrows(CelPolicyValidationException.class, () -> parser.parse(policySource));
+ assertThat(e)
+ .hasMessageThat()
+ .contains(
+ "ERROR: <input>:5:7: Only one variable may be defined inline\n"
+ + " | second: 'false'\n"
+ + " | ......^");
+ }
+
  @Test
  public void parseYamlPolicy_errors(@TestParameter PolicyParseErrorTestCase testCase) {
  CelPolicyValidationException e =

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java b/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java
@@ -29,6 +29,30 @@ public interface CelPolicyParserBuilder<T> {
  @CanIgnoreReturnValue
  CelPolicyParserBuilder<T> addTagVisitor(TagVisitor<T> tagVisitor);
 
+ /**
+ * Configures the parser to allow for key-value pairs to declare a variable name and expression.
+ *
+ * <p>For example:
+ *
+ * <pre>{@code
+ * variables:
+ * - foo: bar
+ * - baz: qux
+ * }</pre>
+ *
+ * <p>This is in contrast to the default behavior, which requires the following syntax:
+ *
+ * <pre>{@code
+ * variables:
+ * - name: foo
+ * expression: bar
+ * - name: baz
+ * expression: qux
+ * }</pre>
+ */
+ @CanIgnoreReturnValue
+ CelPolicyParserBuilder<T> enableSimpleVariables(boolean enable);
+
  /** Builds a new instance of {@link CelPolicyParser}. */
  @CheckReturnValue
  CelPolicyParser build();

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java b/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java
@@ -49,6 +49,7 @@ final class CelPolicyYamlParser implements CelPolicyParser {
  Variable.newBuilder().setExpression(ERROR_VALUE).setName(ERROR_VALUE).build();
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
 
  @Override
  public CelPolicy parse(String policySource) throws CelPolicyValidationException {
@@ -58,13 +59,15 @@ public CelPolicy parse(String policySource) throws CelPolicyValidationException
  @Override
  public CelPolicy parse(String policySource, String description)
  throws CelPolicyValidationException {
- ParserImpl parser = new ParserImpl(tagVisitor, policySource, description);
+ ParserImpl parser =
+ new ParserImpl(tagVisitor, enableSimpleVariables, policySource, description);
  return parser.parseYaml();
  }
 
  private static class ParserImpl implements PolicyParserContext<Node> {
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
  private final CelPolicySource policySource;
  private final ParserContext<Node> ctx;
 
@@ -336,9 +339,45 @@ public CelPolicy.Variable parseVariable(
  if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
  return ERROR_VARIABLE;
  }
+
  MappingNode variableMap = (MappingNode) node;
  Variable.Builder builder = Variable.newBuilder();
 
+ if (enableSimpleVariables) {
+ return parseVariableInline(ctx, id, variableMap, builder);
+ }
+ return parseVariableObject(ctx, policyBuilder, id, variableMap, builder);
+ }
+
+ private Variable parseVariableInline(
+ PolicyParserContext<Node> ctx, long id, MappingNode variableMap, Variable.Builder builder) {
+ int iterations = 0;
+ for (NodeTuple nodeTuple : variableMap.getValue()) {
+ Node keyNode = nodeTuple.getKeyNode();
+ long keyId = ctx.collectMetadata(keyNode);
+ builder
+ .setName(ctx.newValueString(keyNode))
+ .setExpression(ctx.newValueString(nodeTuple.getValueNode()));
+ iterations++;
+
+ if (iterations > 1) {
+ ctx.reportError(keyId, "Only one variable may be defined inline");
+ }
+ }
+
+ if (!assertRequiredFields(ctx, id, builder.getMissingRequiredFieldNames())) {
+ return ERROR_VARIABLE;
+ }
+
+ return builder.build();
+ }
+
+ private Variable parseVariableObject(
+ PolicyParserContext<Node> ctx,
+ CelPolicy.Builder policyBuilder,
+ long id,
+ MappingNode variableMap,
+ Variable.Builder builder) {
  for (NodeTuple nodeTuple : variableMap.getValue()) {
  Node keyNode = nodeTuple.getKeyNode();
  long keyId = ctx.collectMetadata(keyNode);
@@ -370,8 +409,13 @@ public CelPolicy.Variable parseVariable(
  return builder.build();
  }
 
- private ParserImpl(TagVisitor<Node> tagVisitor, String source, String description) {
+ private ParserImpl(
+ TagVisitor<Node> tagVisitor,
+ boolean enableSimpleVariables,
+ String source,
+ String description) {
  this.tagVisitor = tagVisitor;
+ this.enableSimpleVariables = enableSimpleVariables;
  this.policySource =
  CelPolicySource.newBuilder(CelCodePointArray.fromString(source))
  .setDescription(description)
@@ -413,9 +457,11 @@ public ValueString newValueString(Node node) {
  static final class Builder implements CelPolicyParserBuilder<Node> {
 
  private TagVisitor<Node> tagVisitor;
+ private boolean enableSimpleVariables;
 
  private Builder() {
  this.tagVisitor = new TagVisitor<Node>() {};
+ this.enableSimpleVariables = false;
  }
 
  @Override
@@ -424,17 +470,24 @@ public CelPolicyParserBuilder<Node> addTagVisitor(TagVisitor<Node> tagVisitor) {
  return this;
  }
 
+ @Override
+ public CelPolicyParserBuilder<Node> enableSimpleVariables(boolean enable) {
+ this.enableSimpleVariables = enable;
+ return this;
+ }
+
  @Override
  public CelPolicyParser build() {
- return new CelPolicyYamlParser(tagVisitor);
+ return new CelPolicyYamlParser(tagVisitor, enableSimpleVariables);
  }
  }
 
- static Builder newBuilder() {
- return new Builder();
+ static CelPolicyParserBuilder<Node> newBuilder() {
+ return new Builder().enableSimpleVariables(false);
  }
 
- private CelPolicyYamlParser(TagVisitor<Node> tagVisitor) {
+ private CelPolicyYamlParser(TagVisitor<Node> tagVisitor, boolean enableSimpleVariables) {
  this.tagVisitor = checkNotNull(tagVisitor);
+ this.enableSimpleVariables = enableSimpleVariables;
  }
 }
diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java
@@ -302,6 +302,29 @@ public void evaluateYamlPolicy_lateBoundFunction() throws Exception {
  assertThat(evalResult).isEqualTo("foo" + exampleValue);
  }
 
+ @Test
+ public void evaluateYamlPolicy_withSimpleVariable() throws Exception {
+ Cel cel = newCel();
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " - second: 'false'\n"
+ + " match:\n"
+ + " - output: 'variables.first && variables.second'";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+ CelPolicy policy = parser.parse(policySource);
+
+ CelAbstractSyntaxTree compiledPolicyAst =
+ CelPolicyCompilerFactory.newPolicyCompiler(cel).build().compile(policy);
+
+ boolean evalResult = (boolean) cel.createProgram(compiledPolicyAst).eval();
+
+ assertThat(evalResult).isFalse();
+ }
+
  private static final class EvaluablePolicyTestData {
  private final TestYamlPolicy yamlPolicy;
  private final PolicyTestCase testCase;

diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java
@@ -148,6 +148,30 @@ public void parseYamlPolicy_withImports() throws Exception {
  .inOrder();
  }
 
+ @Test
+ public void parseYamlPolicy_withSimpleVariable_multipleInlinedVariables() {
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " second: 'false'\n"
+ + " match:\n"
+ + " - condition: 'variables.my_var'\n"
+ + " output: 'true'\n";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+
+ CelPolicyValidationException e =
+ assertThrows(CelPolicyValidationException.class, () -> parser.parse(policySource));
+ assertThat(e)
+ .hasMessageThat()
+ .contains(
+ "ERROR: <input>:5:7: Only one variable may be defined inline\n"
+ + " | second: 'false'\n"
+ + " | ......^");
+ }
+
  @Test
  public void parseYamlPolicy_errors(@TestParameter PolicyParseErrorTestCase testCase) {
  CelPolicyValidationException e =

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java b/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java
@@ -29,6 +29,30 @@ public interface CelPolicyParserBuilder<T> {
  @CanIgnoreReturnValue
  CelPolicyParserBuilder<T> addTagVisitor(TagVisitor<T> tagVisitor);
 
+ /**
+ * Configures the parser to allow for key-value pairs to declare a variable name and expression.
+ *
+ * <p>For example:
+ *
+ * <pre>{@code
+ * variables:
+ * - foo: bar
+ * - baz: qux
+ * }</pre>
+ *
+ * <p>This is in contrast to the default behavior, which requires the following syntax:
+ *
+ * <pre>{@code
+ * variables:
+ * - name: foo
+ * expression: bar
+ * - name: baz
+ * expression: qux
+ * }</pre>
+ */
+ @CanIgnoreReturnValue
+ CelPolicyParserBuilder<T> enableSimpleVariables(boolean enable);
+
  /** Builds a new instance of {@link CelPolicyParser}. */
  @CheckReturnValue
  CelPolicyParser build();

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java b/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java
@@ -49,6 +49,7 @@ final class CelPolicyYamlParser implements CelPolicyParser {
  Variable.newBuilder().setExpression(ERROR_VALUE).setName(ERROR_VALUE).build();
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
 
  @Override
  public CelPolicy parse(String policySource) throws CelPolicyValidationException {
@@ -58,13 +59,15 @@ public CelPolicy parse(String policySource) throws CelPolicyValidationException
  @Override
  public CelPolicy parse(String policySource, String description)
  throws CelPolicyValidationException {
- ParserImpl parser = new ParserImpl(tagVisitor, policySource, description);
+ ParserImpl parser =
+ new ParserImpl(tagVisitor, enableSimpleVariables, policySource, description);
  return parser.parseYaml();
  }
 
  private static class ParserImpl implements PolicyParserContext<Node> {
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
  private final CelPolicySource policySource;
  private final ParserContext<Node> ctx;
 
@@ -336,9 +339,45 @@ public CelPolicy.Variable parseVariable(
  if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
  return ERROR_VARIABLE;
  }
+
  MappingNode variableMap = (MappingNode) node;
  Variable.Builder builder = Variable.newBuilder();
 
+ if (enableSimpleVariables) {
+ return parseVariableInline(ctx, id, variableMap, builder);
+ }
+ return parseVariableObject(ctx, policyBuilder, id, variableMap, builder);
+ }
+
+ private Variable parseVariableInline(
+ PolicyParserContext<Node> ctx, long id, MappingNode variableMap, Variable.Builder builder) {
+ int iterations = 0;
+ for (NodeTuple nodeTuple : variableMap.getValue()) {
+ Node keyNode = nodeTuple.getKeyNode();
+ long keyId = ctx.collectMetadata(keyNode);
+ builder
+ .setName(ctx.newValueString(keyNode))
+ .setExpression(ctx.newValueString(nodeTuple.getValueNode()));
+ iterations++;
+
+ if (iterations > 1) {
+ ctx.reportError(keyId, "Only one variable may be defined inline");
+ }
+ }
+
+ if (!assertRequiredFields(ctx, id, builder.getMissingRequiredFieldNames())) {
+ return ERROR_VARIABLE;
+ }
+
+ return builder.build();
+ }
+
+ private Variable parseVariableObject(
+ PolicyParserContext<Node> ctx,
+ CelPolicy.Builder policyBuilder,
+ long id,
+ MappingNode variableMap,
+ Variable.Builder builder) {
  for (NodeTuple nodeTuple : variableMap.getValue()) {
  Node keyNode = nodeTuple.getKeyNode();
  long keyId = ctx.collectMetadata(keyNode);
@@ -370,8 +409,13 @@ public CelPolicy.Variable parseVariable(
  return builder.build();
  }
 
- private ParserImpl(TagVisitor<Node> tagVisitor, String source, String description) {
+ private ParserImpl(
+ TagVisitor<Node> tagVisitor,
+ boolean enableSimpleVariables,
+ String source,
+ String description) {
  this.tagVisitor = tagVisitor;
+ this.enableSimpleVariables = enableSimpleVariables;
  this.policySource =
  CelPolicySource.newBuilder(CelCodePointArray.fromString(source))
  .setDescription(description)
@@ -413,9 +457,11 @@ public ValueString newValueString(Node node) {
  static final class Builder implements CelPolicyParserBuilder<Node> {
 
  private TagVisitor<Node> tagVisitor;
+ private boolean enableSimpleVariables;
 
  private Builder() {
  this.tagVisitor = new TagVisitor<Node>() {};
+ this.enableSimpleVariables = false;
  }
 
  @Override
@@ -424,17 +470,24 @@ public CelPolicyParserBuilder<Node> addTagVisitor(TagVisitor<Node> tagVisitor) {
  return this;
  }
 
+ @Override
+ public CelPolicyParserBuilder<Node> enableSimpleVariables(boolean enable) {
+ this.enableSimpleVariables = enable;
+ return this;
+ }
+
  @Override
  public CelPolicyParser build() {
- return new CelPolicyYamlParser(tagVisitor);
+ return new CelPolicyYamlParser(tagVisitor, enableSimpleVariables);
  }
  }
 
- static Builder newBuilder() {
- return new Builder();
+ static CelPolicyParserBuilder<Node> newBuilder() {
+ return new Builder().enableSimpleVariables(false);
  }
 
- private CelPolicyYamlParser(TagVisitor<Node> tagVisitor) {
+ private CelPolicyYamlParser(TagVisitor<Node> tagVisitor, boolean enableSimpleVariables) {
  this.tagVisitor = checkNotNull(tagVisitor);
+ this.enableSimpleVariables = enableSimpleVariables;
  }
 }
diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java
@@ -302,6 +302,29 @@ public void evaluateYamlPolicy_lateBoundFunction() throws Exception {
  assertThat(evalResult).isEqualTo("foo" + exampleValue);
  }
 
+ @Test
+ public void evaluateYamlPolicy_withSimpleVariable() throws Exception {
+ Cel cel = newCel();
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " - second: 'false'\n"
+ + " match:\n"
+ + " - output: 'variables.first && variables.second'";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+ CelPolicy policy = parser.parse(policySource);
+
+ CelAbstractSyntaxTree compiledPolicyAst =
+ CelPolicyCompilerFactory.newPolicyCompiler(cel).build().compile(policy);
+
+ boolean evalResult = (boolean) cel.createProgram(compiledPolicyAst).eval();
+
+ assertThat(evalResult).isFalse();
+ }
+
  private static final class EvaluablePolicyTestData {
  private final TestYamlPolicy yamlPolicy;
  private final PolicyTestCase testCase;

diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java
@@ -148,6 +148,30 @@ public void parseYamlPolicy_withImports() throws Exception {
  .inOrder();
  }
 
+ @Test
+ public void parseYamlPolicy_withSimpleVariable_multipleInlinedVariables() {
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " second: 'false'\n"
+ + " match:\n"
+ + " - condition: 'variables.my_var'\n"
+ + " output: 'true'\n";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+
+ CelPolicyValidationException e =
+ assertThrows(CelPolicyValidationException.class, () -> parser.parse(policySource));
+ assertThat(e)
+ .hasMessageThat()
+ .contains(
+ "ERROR: <input>:5:7: Only one variable may be defined inline\n"
+ + " | second: 'false'\n"
+ + " | ......^");
+ }
+
  @Test
  public void parseYamlPolicy_errors(@TestParameter PolicyParseErrorTestCase testCase) {
  CelPolicyValidationException e =

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java b/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java
@@ -29,6 +29,30 @@ public interface CelPolicyParserBuilder<T> {
  @CanIgnoreReturnValue
  CelPolicyParserBuilder<T> addTagVisitor(TagVisitor<T> tagVisitor);
 
+ /**
+ * Configures the parser to allow for key-value pairs to declare a variable name and expression.
+ *
+ * <p>For example:
+ *
+ * <pre>{@code
+ * variables:
+ * - foo: bar
+ * - baz: qux
+ * }</pre>
+ *
+ * <p>This is in contrast to the default behavior, which requires the following syntax:
+ *
+ * <pre>{@code
+ * variables:
+ * - name: foo
+ * expression: bar
+ * - name: baz
+ * expression: qux
+ * }</pre>
+ */
+ @CanIgnoreReturnValue
+ CelPolicyParserBuilder<T> enableSimpleVariables(boolean enable);
+
  /** Builds a new instance of {@link CelPolicyParser}. */
  @CheckReturnValue
  CelPolicyParser build();

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java b/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java
@@ -49,6 +49,7 @@ final class CelPolicyYamlParser implements CelPolicyParser {
  Variable.newBuilder().setExpression(ERROR_VALUE).setName(ERROR_VALUE).build();
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
 
  @Override
  public CelPolicy parse(String policySource) throws CelPolicyValidationException {
@@ -58,13 +59,15 @@ public CelPolicy parse(String policySource) throws CelPolicyValidationException
  @Override
  public CelPolicy parse(String policySource, String description)
  throws CelPolicyValidationException {
- ParserImpl parser = new ParserImpl(tagVisitor, policySource, description);
+ ParserImpl parser =
+ new ParserImpl(tagVisitor, enableSimpleVariables, policySource, description);
  return parser.parseYaml();
  }
 
  private static class ParserImpl implements PolicyParserContext<Node> {
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
  private final CelPolicySource policySource;
  private final ParserContext<Node> ctx;
 
@@ -336,9 +339,45 @@ public CelPolicy.Variable parseVariable(
  if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
  return ERROR_VARIABLE;
  }
+
  MappingNode variableMap = (MappingNode) node;
  Variable.Builder builder = Variable.newBuilder();
 
+ if (enableSimpleVariables) {
+ return parseVariableInline(ctx, id, variableMap, builder);
+ }
+ return parseVariableObject(ctx, policyBuilder, id, variableMap, builder);
+ }
+
+ private Variable parseVariableInline(
+ PolicyParserContext<Node> ctx, long id, MappingNode variableMap, Variable.Builder builder) {
+ int iterations = 0;
+ for (NodeTuple nodeTuple : variableMap.getValue()) {
+ Node keyNode = nodeTuple.getKeyNode();
+ long keyId = ctx.collectMetadata(keyNode);
+ builder
+ .setName(ctx.newValueString(keyNode))
+ .setExpression(ctx.newValueString(nodeTuple.getValueNode()));
+ iterations++;
+
+ if (iterations > 1) {
+ ctx.reportError(keyId, "Only one variable may be defined inline");
+ }
+ }
+
+ if (!assertRequiredFields(ctx, id, builder.getMissingRequiredFieldNames())) {
+ return ERROR_VARIABLE;
+ }
+
+ return builder.build();
+ }
+
+ private Variable parseVariableObject(
+ PolicyParserContext<Node> ctx,
+ CelPolicy.Builder policyBuilder,
+ long id,
+ MappingNode variableMap,
+ Variable.Builder builder) {
  for (NodeTuple nodeTuple : variableMap.getValue()) {
  Node keyNode = nodeTuple.getKeyNode();
  long keyId = ctx.collectMetadata(keyNode);
@@ -370,8 +409,13 @@ public CelPolicy.Variable parseVariable(
  return builder.build();
  }
 
- private ParserImpl(TagVisitor<Node> tagVisitor, String source, String description) {
+ private ParserImpl(
+ TagVisitor<Node> tagVisitor,
+ boolean enableSimpleVariables,
+ String source,
+ String description) {
  this.tagVisitor = tagVisitor;
+ this.enableSimpleVariables = enableSimpleVariables;
  this.policySource =
  CelPolicySource.newBuilder(CelCodePointArray.fromString(source))
  .setDescription(description)
@@ -413,9 +457,11 @@ public ValueString newValueString(Node node) {
  static final class Builder implements CelPolicyParserBuilder<Node> {
 
  private TagVisitor<Node> tagVisitor;
+ private boolean enableSimpleVariables;
 
  private Builder() {
  this.tagVisitor = new TagVisitor<Node>() {};
+ this.enableSimpleVariables = false;
  }
 
  @Override
@@ -424,17 +470,24 @@ public CelPolicyParserBuilder<Node> addTagVisitor(TagVisitor<Node> tagVisitor) {
  return this;
  }
 
+ @Override
+ public CelPolicyParserBuilder<Node> enableSimpleVariables(boolean enable) {
+ this.enableSimpleVariables = enable;
+ return this;
+ }
+
  @Override
  public CelPolicyParser build() {
- return new CelPolicyYamlParser(tagVisitor);
+ return new CelPolicyYamlParser(tagVisitor, enableSimpleVariables);
  }
  }
 
- static Builder newBuilder() {
- return new Builder();
+ static CelPolicyParserBuilder<Node> newBuilder() {
+ return new Builder().enableSimpleVariables(false);
  }
 
- private CelPolicyYamlParser(TagVisitor<Node> tagVisitor) {
+ private CelPolicyYamlParser(TagVisitor<Node> tagVisitor, boolean enableSimpleVariables) {
  this.tagVisitor = checkNotNull(tagVisitor);
+ this.enableSimpleVariables = enableSimpleVariables;
  }
 }
diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java
@@ -302,6 +302,29 @@ public void evaluateYamlPolicy_lateBoundFunction() throws Exception {
  assertThat(evalResult).isEqualTo("foo" + exampleValue);
  }
 
+ @Test
+ public void evaluateYamlPolicy_withSimpleVariable() throws Exception {
+ Cel cel = newCel();
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " - second: 'false'\n"
+ + " match:\n"
+ + " - output: 'variables.first && variables.second'";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+ CelPolicy policy = parser.parse(policySource);
+
+ CelAbstractSyntaxTree compiledPolicyAst =
+ CelPolicyCompilerFactory.newPolicyCompiler(cel).build().compile(policy);
+
+ boolean evalResult = (boolean) cel.createProgram(compiledPolicyAst).eval();
+
+ assertThat(evalResult).isFalse();
+ }
+
  private static final class EvaluablePolicyTestData {
  private final TestYamlPolicy yamlPolicy;
  private final PolicyTestCase testCase;

diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java
@@ -148,6 +148,30 @@ public void parseYamlPolicy_withImports() throws Exception {
  .inOrder();
  }
 
+ @Test
+ public void parseYamlPolicy_withSimpleVariable_multipleInlinedVariables() {
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " second: 'false'\n"
+ + " match:\n"
+ + " - condition: 'variables.my_var'\n"
+ + " output: 'true'\n";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+
+ CelPolicyValidationException e =
+ assertThrows(CelPolicyValidationException.class, () -> parser.parse(policySource));
+ assertThat(e)
+ .hasMessageThat()
+ .contains(
+ "ERROR: <input>:5:7: Only one variable may be defined inline\n"
+ + " | second: 'false'\n"
+ + " | ......^");
+ }
+
  @Test
  public void parseYamlPolicy_errors(@TestParameter PolicyParseErrorTestCase testCase) {
  CelPolicyValidationException e =

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java b/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java
@@ -29,6 +29,30 @@ public interface CelPolicyParserBuilder<T> {
  @CanIgnoreReturnValue
  CelPolicyParserBuilder<T> addTagVisitor(TagVisitor<T> tagVisitor);
 
+ /**
+ * Configures the parser to allow for key-value pairs to declare a variable name and expression.
+ *
+ * <p>For example:
+ *
+ * <pre>{@code
+ * variables:
+ * - foo: bar
+ * - baz: qux
+ * }</pre>
+ *
+ * <p>This is in contrast to the default behavior, which requires the following syntax:
+ *
+ * <pre>{@code
+ * variables:
+ * - name: foo
+ * expression: bar
+ * - name: baz
+ * expression: qux
+ * }</pre>
+ */
+ @CanIgnoreReturnValue
+ CelPolicyParserBuilder<T> enableSimpleVariables(boolean enable);
+
  /** Builds a new instance of {@link CelPolicyParser}. */
  @CheckReturnValue
  CelPolicyParser build();

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java b/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java
@@ -49,6 +49,7 @@ final class CelPolicyYamlParser implements CelPolicyParser {
  Variable.newBuilder().setExpression(ERROR_VALUE).setName(ERROR_VALUE).build();
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
 
  @Override
  public CelPolicy parse(String policySource) throws CelPolicyValidationException {
@@ -58,13 +59,15 @@ public CelPolicy parse(String policySource) throws CelPolicyValidationException
  @Override
  public CelPolicy parse(String policySource, String description)
  throws CelPolicyValidationException {
- ParserImpl parser = new ParserImpl(tagVisitor, policySource, description);
+ ParserImpl parser =
+ new ParserImpl(tagVisitor, enableSimpleVariables, policySource, description);
  return parser.parseYaml();
  }
 
  private static class ParserImpl implements PolicyParserContext<Node> {
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
  private final CelPolicySource policySource;
  private final ParserContext<Node> ctx;
 
@@ -336,9 +339,45 @@ public CelPolicy.Variable parseVariable(
  if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
  return ERROR_VARIABLE;
  }
+
  MappingNode variableMap = (MappingNode) node;
  Variable.Builder builder = Variable.newBuilder();
 
+ if (enableSimpleVariables) {
+ return parseVariableInline(ctx, id, variableMap, builder);
+ }
+ return parseVariableObject(ctx, policyBuilder, id, variableMap, builder);
+ }
+
+ private Variable parseVariableInline(
+ PolicyParserContext<Node> ctx, long id, MappingNode variableMap, Variable.Builder builder) {
+ int iterations = 0;
+ for (NodeTuple nodeTuple : variableMap.getValue()) {
+ Node keyNode = nodeTuple.getKeyNode();
+ long keyId = ctx.collectMetadata(keyNode);
+ builder
+ .setName(ctx.newValueString(keyNode))
+ .setExpression(ctx.newValueString(nodeTuple.getValueNode()));
+ iterations++;
+
+ if (iterations > 1) {
+ ctx.reportError(keyId, "Only one variable may be defined inline");
+ }
+ }
+
+ if (!assertRequiredFields(ctx, id, builder.getMissingRequiredFieldNames())) {
+ return ERROR_VARIABLE;
+ }
+
+ return builder.build();
+ }
+
+ private Variable parseVariableObject(
+ PolicyParserContext<Node> ctx,
+ CelPolicy.Builder policyBuilder,
+ long id,
+ MappingNode variableMap,
+ Variable.Builder builder) {
  for (NodeTuple nodeTuple : variableMap.getValue()) {
  Node keyNode = nodeTuple.getKeyNode();
  long keyId = ctx.collectMetadata(keyNode);
@@ -370,8 +409,13 @@ public CelPolicy.Variable parseVariable(
  return builder.build();
  }
 
- private ParserImpl(TagVisitor<Node> tagVisitor, String source, String description) {
+ private ParserImpl(
+ TagVisitor<Node> tagVisitor,
+ boolean enableSimpleVariables,
+ String source,
+ String description) {
  this.tagVisitor = tagVisitor;
+ this.enableSimpleVariables = enableSimpleVariables;
  this.policySource =
  CelPolicySource.newBuilder(CelCodePointArray.fromString(source))
  .setDescription(description)
@@ -413,9 +457,11 @@ public ValueString newValueString(Node node) {
  static final class Builder implements CelPolicyParserBuilder<Node> {
 
  private TagVisitor<Node> tagVisitor;
+ private boolean enableSimpleVariables;
 
  private Builder() {
  this.tagVisitor = new TagVisitor<Node>() {};
+ this.enableSimpleVariables = false;
  }
 
  @Override
@@ -424,17 +470,24 @@ public CelPolicyParserBuilder<Node> addTagVisitor(TagVisitor<Node> tagVisitor) {
  return this;
  }
 
+ @Override
+ public CelPolicyParserBuilder<Node> enableSimpleVariables(boolean enable) {
+ this.enableSimpleVariables = enable;
+ return this;
+ }
+
  @Override
  public CelPolicyParser build() {
- return new CelPolicyYamlParser(tagVisitor);
+ return new CelPolicyYamlParser(tagVisitor, enableSimpleVariables);
  }
  }
 
- static Builder newBuilder() {
- return new Builder();
+ static CelPolicyParserBuilder<Node> newBuilder() {
+ return new Builder().enableSimpleVariables(false);
  }
 
- private CelPolicyYamlParser(TagVisitor<Node> tagVisitor) {
+ private CelPolicyYamlParser(TagVisitor<Node> tagVisitor, boolean enableSimpleVariables) {
  this.tagVisitor = checkNotNull(tagVisitor);
+ this.enableSimpleVariables = enableSimpleVariables;
  }
 }
diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java
@@ -302,6 +302,29 @@ public void evaluateYamlPolicy_lateBoundFunction() throws Exception {
  assertThat(evalResult).isEqualTo("foo" + exampleValue);
  }
 
+ @Test
+ public void evaluateYamlPolicy_withSimpleVariable() throws Exception {
+ Cel cel = newCel();
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " - second: 'false'\n"
+ + " match:\n"
+ + " - output: 'variables.first && variables.second'";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+ CelPolicy policy = parser.parse(policySource);
+
+ CelAbstractSyntaxTree compiledPolicyAst =
+ CelPolicyCompilerFactory.newPolicyCompiler(cel).build().compile(policy);
+
+ boolean evalResult = (boolean) cel.createProgram(compiledPolicyAst).eval();
+
+ assertThat(evalResult).isFalse();
+ }
+
  private static final class EvaluablePolicyTestData {
  private final TestYamlPolicy yamlPolicy;
  private final PolicyTestCase testCase;

diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java
@@ -148,6 +148,30 @@ public void parseYamlPolicy_withImports() throws Exception {
  .inOrder();
  }
 
+ @Test
+ public void parseYamlPolicy_withSimpleVariable_multipleInlinedVariables() {
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " second: 'false'\n"
+ + " match:\n"
+ + " - condition: 'variables.my_var'\n"
+ + " output: 'true'\n";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+
+ CelPolicyValidationException e =
+ assertThrows(CelPolicyValidationException.class, () -> parser.parse(policySource));
+ assertThat(e)
+ .hasMessageThat()
+ .contains(
+ "ERROR: <input>:5:7: Only one variable may be defined inline\n"
+ + " | second: 'false'\n"
+ + " | ......^");
+ }
+
  @Test
  public void parseYamlPolicy_errors(@TestParameter PolicyParseErrorTestCase testCase) {
  CelPolicyValidationException e =

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java b/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java
@@ -29,6 +29,30 @@ public interface CelPolicyParserBuilder<T> {
  @CanIgnoreReturnValue
  CelPolicyParserBuilder<T> addTagVisitor(TagVisitor<T> tagVisitor);
 
+ /**
+ * Configures the parser to allow for key-value pairs to declare a variable name and expression.
+ *
+ * <p>For example:
+ *
+ * <pre>{@code
+ * variables:
+ * - foo: bar
+ * - baz: qux
+ * }</pre>
+ *
+ * <p>This is in contrast to the default behavior, which requires the following syntax:
+ *
+ * <pre>{@code
+ * variables:
+ * - name: foo
+ * expression: bar
+ * - name: baz
+ * expression: qux
+ * }</pre>
+ */
+ @CanIgnoreReturnValue
+ CelPolicyParserBuilder<T> enableSimpleVariables(boolean enable);
+
  /** Builds a new instance of {@link CelPolicyParser}. */
  @CheckReturnValue
  CelPolicyParser build();

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java b/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java
@@ -49,6 +49,7 @@ final class CelPolicyYamlParser implements CelPolicyParser {
  Variable.newBuilder().setExpression(ERROR_VALUE).setName(ERROR_VALUE).build();
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
 
  @Override
  public CelPolicy parse(String policySource) throws CelPolicyValidationException {
@@ -58,13 +59,15 @@ public CelPolicy parse(String policySource) throws CelPolicyValidationException
  @Override
  public CelPolicy parse(String policySource, String description)
  throws CelPolicyValidationException {
- ParserImpl parser = new ParserImpl(tagVisitor, policySource, description);
+ ParserImpl parser =
+ new ParserImpl(tagVisitor, enableSimpleVariables, policySource, description);
  return parser.parseYaml();
  }
 
  private static class ParserImpl implements PolicyParserContext<Node> {
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
  private final CelPolicySource policySource;
  private final ParserContext<Node> ctx;
 
@@ -336,9 +339,45 @@ public CelPolicy.Variable parseVariable(
  if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
  return ERROR_VARIABLE;
  }
+
  MappingNode variableMap = (MappingNode) node;
  Variable.Builder builder = Variable.newBuilder();
 
+ if (enableSimpleVariables) {
+ return parseVariableInline(ctx, id, variableMap, builder);
+ }
+ return parseVariableObject(ctx, policyBuilder, id, variableMap, builder);
+ }
+
+ private Variable parseVariableInline(
+ PolicyParserContext<Node> ctx, long id, MappingNode variableMap, Variable.Builder builder) {
+ int iterations = 0;
+ for (NodeTuple nodeTuple : variableMap.getValue()) {
+ Node keyNode = nodeTuple.getKeyNode();
+ long keyId = ctx.collectMetadata(keyNode);
+ builder
+ .setName(ctx.newValueString(keyNode))
+ .setExpression(ctx.newValueString(nodeTuple.getValueNode()));
+ iterations++;
+
+ if (iterations > 1) {
+ ctx.reportError(keyId, "Only one variable may be defined inline");
+ }
+ }
+
+ if (!assertRequiredFields(ctx, id, builder.getMissingRequiredFieldNames())) {
+ return ERROR_VARIABLE;
+ }
+
+ return builder.build();
+ }
+
+ private Variable parseVariableObject(
+ PolicyParserContext<Node> ctx,
+ CelPolicy.Builder policyBuilder,
+ long id,
+ MappingNode variableMap,
+ Variable.Builder builder) {
  for (NodeTuple nodeTuple : variableMap.getValue()) {
  Node keyNode = nodeTuple.getKeyNode();
  long keyId = ctx.collectMetadata(keyNode);
@@ -370,8 +409,13 @@ public CelPolicy.Variable parseVariable(
  return builder.build();
  }
 
- private ParserImpl(TagVisitor<Node> tagVisitor, String source, String description) {
+ private ParserImpl(
+ TagVisitor<Node> tagVisitor,
+ boolean enableSimpleVariables,
+ String source,
+ String description) {
  this.tagVisitor = tagVisitor;
+ this.enableSimpleVariables = enableSimpleVariables;
  this.policySource =
  CelPolicySource.newBuilder(CelCodePointArray.fromString(source))
  .setDescription(description)
@@ -413,9 +457,11 @@ public ValueString newValueString(Node node) {
  static final class Builder implements CelPolicyParserBuilder<Node> {
 
  private TagVisitor<Node> tagVisitor;
+ private boolean enableSimpleVariables;
 
  private Builder() {
  this.tagVisitor = new TagVisitor<Node>() {};
+ this.enableSimpleVariables = false;
  }
 
  @Override
@@ -424,17 +470,24 @@ public CelPolicyParserBuilder<Node> addTagVisitor(TagVisitor<Node> tagVisitor) {
  return this;
  }
 
+ @Override
+ public CelPolicyParserBuilder<Node> enableSimpleVariables(boolean enable) {
+ this.enableSimpleVariables = enable;
+ return this;
+ }
+
  @Override
  public CelPolicyParser build() {
- return new CelPolicyYamlParser(tagVisitor);
+ return new CelPolicyYamlParser(tagVisitor, enableSimpleVariables);
  }
  }
 
- static Builder newBuilder() {
- return new Builder();
+ static CelPolicyParserBuilder<Node> newBuilder() {
+ return new Builder().enableSimpleVariables(false);
  }
 
- private CelPolicyYamlParser(TagVisitor<Node> tagVisitor) {
+ private CelPolicyYamlParser(TagVisitor<Node> tagVisitor, boolean enableSimpleVariables) {
  this.tagVisitor = checkNotNull(tagVisitor);
+ this.enableSimpleVariables = enableSimpleVariables;
  }
 }
diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java
@@ -302,6 +302,29 @@ public void evaluateYamlPolicy_lateBoundFunction() throws Exception {
  assertThat(evalResult).isEqualTo("foo" + exampleValue);
  }
 
+ @Test
+ public void evaluateYamlPolicy_withSimpleVariable() throws Exception {
+ Cel cel = newCel();
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " - second: 'false'\n"
+ + " match:\n"
+ + " - output: 'variables.first && variables.second'";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+ CelPolicy policy = parser.parse(policySource);
+
+ CelAbstractSyntaxTree compiledPolicyAst =
+ CelPolicyCompilerFactory.newPolicyCompiler(cel).build().compile(policy);
+
+ boolean evalResult = (boolean) cel.createProgram(compiledPolicyAst).eval();
+
+ assertThat(evalResult).isFalse();
+ }
+
  private static final class EvaluablePolicyTestData {
  private final TestYamlPolicy yamlPolicy;
  private final PolicyTestCase testCase;

diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java
@@ -148,6 +148,30 @@ public void parseYamlPolicy_withImports() throws Exception {
  .inOrder();
  }
 
+ @Test
+ public void parseYamlPolicy_withSimpleVariable_multipleInlinedVariables() {
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " second: 'false'\n"
+ + " match:\n"
+ + " - condition: 'variables.my_var'\n"
+ + " output: 'true'\n";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+
+ CelPolicyValidationException e =
+ assertThrows(CelPolicyValidationException.class, () -> parser.parse(policySource));
+ assertThat(e)
+ .hasMessageThat()
+ .contains(
+ "ERROR: <input>:5:7: Only one variable may be defined inline\n"
+ + " | second: 'false'\n"
+ + " | ......^");
+ }
+
  @Test
  public void parseYamlPolicy_errors(@TestParameter PolicyParseErrorTestCase testCase) {
  CelPolicyValidationException e =

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java b/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java
@@ -29,6 +29,30 @@ public interface CelPolicyParserBuilder<T> {
  @CanIgnoreReturnValue
  CelPolicyParserBuilder<T> addTagVisitor(TagVisitor<T> tagVisitor);
 
+ /**
+ * Configures the parser to allow for key-value pairs to declare a variable name and expression.
+ *
+ * <p>For example:
+ *
+ * <pre>{@code
+ * variables:
+ * - foo: bar
+ * - baz: qux
+ * }</pre>
+ *
+ * <p>This is in contrast to the default behavior, which requires the following syntax:
+ *
+ * <pre>{@code
+ * variables:
+ * - name: foo
+ * expression: bar
+ * - name: baz
+ * expression: qux
+ * }</pre>
+ */
+ @CanIgnoreReturnValue
+ CelPolicyParserBuilder<T> enableSimpleVariables(boolean enable);
+
  /** Builds a new instance of {@link CelPolicyParser}. */
  @CheckReturnValue
  CelPolicyParser build();

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java b/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java
@@ -49,6 +49,7 @@ final class CelPolicyYamlParser implements CelPolicyParser {
  Variable.newBuilder().setExpression(ERROR_VALUE).setName(ERROR_VALUE).build();
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
 
  @Override
  public CelPolicy parse(String policySource) throws CelPolicyValidationException {
@@ -58,13 +59,15 @@ public CelPolicy parse(String policySource) throws CelPolicyValidationException
  @Override
  public CelPolicy parse(String policySource, String description)
  throws CelPolicyValidationException {
- ParserImpl parser = new ParserImpl(tagVisitor, policySource, description);
+ ParserImpl parser =
+ new ParserImpl(tagVisitor, enableSimpleVariables, policySource, description);
  return parser.parseYaml();
  }
 
  private static class ParserImpl implements PolicyParserContext<Node> {
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
  private final CelPolicySource policySource;
  private final ParserContext<Node> ctx;
 
@@ -336,9 +339,45 @@ public CelPolicy.Variable parseVariable(
  if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
  return ERROR_VARIABLE;
  }
+
  MappingNode variableMap = (MappingNode) node;
  Variable.Builder builder = Variable.newBuilder();
 
+ if (enableSimpleVariables) {
+ return parseVariableInline(ctx, id, variableMap, builder);
+ }
+ return parseVariableObject(ctx, policyBuilder, id, variableMap, builder);
+ }
+
+ private Variable parseVariableInline(
+ PolicyParserContext<Node> ctx, long id, MappingNode variableMap, Variable.Builder builder) {
+ int iterations = 0;
+ for (NodeTuple nodeTuple : variableMap.getValue()) {
+ Node keyNode = nodeTuple.getKeyNode();
+ long keyId = ctx.collectMetadata(keyNode);
+ builder
+ .setName(ctx.newValueString(keyNode))
+ .setExpression(ctx.newValueString(nodeTuple.getValueNode()));
+ iterations++;
+
+ if (iterations > 1) {
+ ctx.reportError(keyId, "Only one variable may be defined inline");
+ }
+ }
+
+ if (!assertRequiredFields(ctx, id, builder.getMissingRequiredFieldNames())) {
+ return ERROR_VARIABLE;
+ }
+
+ return builder.build();
+ }
+
+ private Variable parseVariableObject(
+ PolicyParserContext<Node> ctx,
+ CelPolicy.Builder policyBuilder,
+ long id,
+ MappingNode variableMap,
+ Variable.Builder builder) {
  for (NodeTuple nodeTuple : variableMap.getValue()) {
  Node keyNode = nodeTuple.getKeyNode();
  long keyId = ctx.collectMetadata(keyNode);
@@ -370,8 +409,13 @@ public CelPolicy.Variable parseVariable(
  return builder.build();
  }
 
- private ParserImpl(TagVisitor<Node> tagVisitor, String source, String description) {
+ private ParserImpl(
+ TagVisitor<Node> tagVisitor,
+ boolean enableSimpleVariables,
+ String source,
+ String description) {
  this.tagVisitor = tagVisitor;
+ this.enableSimpleVariables = enableSimpleVariables;
  this.policySource =
  CelPolicySource.newBuilder(CelCodePointArray.fromString(source))
  .setDescription(description)
@@ -413,9 +457,11 @@ public ValueString newValueString(Node node) {
  static final class Builder implements CelPolicyParserBuilder<Node> {
 
  private TagVisitor<Node> tagVisitor;
+ private boolean enableSimpleVariables;
 
  private Builder() {
  this.tagVisitor = new TagVisitor<Node>() {};
+ this.enableSimpleVariables = false;
  }
 
  @Override
@@ -424,17 +470,24 @@ public CelPolicyParserBuilder<Node> addTagVisitor(TagVisitor<Node> tagVisitor) {
  return this;
  }
 
+ @Override
+ public CelPolicyParserBuilder<Node> enableSimpleVariables(boolean enable) {
+ this.enableSimpleVariables = enable;
+ return this;
+ }
+
  @Override
  public CelPolicyParser build() {
- return new CelPolicyYamlParser(tagVisitor);
+ return new CelPolicyYamlParser(tagVisitor, enableSimpleVariables);
  }
  }
 
- static Builder newBuilder() {
- return new Builder();
+ static CelPolicyParserBuilder<Node> newBuilder() {
+ return new Builder().enableSimpleVariables(false);
  }
 
- private CelPolicyYamlParser(TagVisitor<Node> tagVisitor) {
+ private CelPolicyYamlParser(TagVisitor<Node> tagVisitor, boolean enableSimpleVariables) {
  this.tagVisitor = checkNotNull(tagVisitor);
+ this.enableSimpleVariables = enableSimpleVariables;
  }
 }
diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java
@@ -302,6 +302,29 @@ public void evaluateYamlPolicy_lateBoundFunction() throws Exception {
  assertThat(evalResult).isEqualTo("foo" + exampleValue);
  }
 
+ @Test
+ public void evaluateYamlPolicy_withSimpleVariable() throws Exception {
+ Cel cel = newCel();
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " - second: 'false'\n"
+ + " match:\n"
+ + " - output: 'variables.first && variables.second'";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+ CelPolicy policy = parser.parse(policySource);
+
+ CelAbstractSyntaxTree compiledPolicyAst =
+ CelPolicyCompilerFactory.newPolicyCompiler(cel).build().compile(policy);
+
+ boolean evalResult = (boolean) cel.createProgram(compiledPolicyAst).eval();
+
+ assertThat(evalResult).isFalse();
+ }
+
  private static final class EvaluablePolicyTestData {
  private final TestYamlPolicy yamlPolicy;
  private final PolicyTestCase testCase;

diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java
@@ -148,6 +148,30 @@ public void parseYamlPolicy_withImports() throws Exception {
  .inOrder();
  }
 
+ @Test
+ public void parseYamlPolicy_withSimpleVariable_multipleInlinedVariables() {
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " second: 'false'\n"
+ + " match:\n"
+ + " - condition: 'variables.my_var'\n"
+ + " output: 'true'\n";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+
+ CelPolicyValidationException e =
+ assertThrows(CelPolicyValidationException.class, () -> parser.parse(policySource));
+ assertThat(e)
+ .hasMessageThat()
+ .contains(
+ "ERROR: <input>:5:7: Only one variable may be defined inline\n"
+ + " | second: 'false'\n"
+ + " | ......^");
+ }
+
  @Test
  public void parseYamlPolicy_errors(@TestParameter PolicyParseErrorTestCase testCase) {
  CelPolicyValidationException e =

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java b/policy/src/main/java/dev/cel/policy/CelPolicyParserBuilder.java
@@ -29,6 +29,30 @@ public interface CelPolicyParserBuilder<T> {
  @CanIgnoreReturnValue
  CelPolicyParserBuilder<T> addTagVisitor(TagVisitor<T> tagVisitor);
 
+ /**
+ * Configures the parser to allow for key-value pairs to declare a variable name and expression.
+ *
+ * <p>For example:
+ *
+ * <pre>{@code
+ * variables:
+ * - foo: bar
+ * - baz: qux
+ * }</pre>
+ *
+ * <p>This is in contrast to the default behavior, which requires the following syntax:
+ *
+ * <pre>{@code
+ * variables:
+ * - name: foo
+ * expression: bar
+ * - name: baz
+ * expression: qux
+ * }</pre>
+ */
+ @CanIgnoreReturnValue
+ CelPolicyParserBuilder<T> enableSimpleVariables(boolean enable);
+
  /** Builds a new instance of {@link CelPolicyParser}. */
  @CheckReturnValue
  CelPolicyParser build();

diff --git a/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java b/policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java
@@ -49,6 +49,7 @@ final class CelPolicyYamlParser implements CelPolicyParser {
  Variable.newBuilder().setExpression(ERROR_VALUE).setName(ERROR_VALUE).build();
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
 
  @Override
  public CelPolicy parse(String policySource) throws CelPolicyValidationException {
@@ -58,13 +59,15 @@ public CelPolicy parse(String policySource) throws CelPolicyValidationException
  @Override
  public CelPolicy parse(String policySource, String description)
  throws CelPolicyValidationException {
- ParserImpl parser = new ParserImpl(tagVisitor, policySource, description);
+ ParserImpl parser =
+ new ParserImpl(tagVisitor, enableSimpleVariables, policySource, description);
  return parser.parseYaml();
  }
 
  private static class ParserImpl implements PolicyParserContext<Node> {
 
  private final TagVisitor<Node> tagVisitor;
+ private final boolean enableSimpleVariables;
  private final CelPolicySource policySource;
  private final ParserContext<Node> ctx;
 
@@ -336,9 +339,45 @@ public CelPolicy.Variable parseVariable(
  if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
  return ERROR_VARIABLE;
  }
+
  MappingNode variableMap = (MappingNode) node;
  Variable.Builder builder = Variable.newBuilder();
 
+ if (enableSimpleVariables) {
+ return parseVariableInline(ctx, id, variableMap, builder);
+ }
+ return parseVariableObject(ctx, policyBuilder, id, variableMap, builder);
+ }
+
+ private Variable parseVariableInline(
+ PolicyParserContext<Node> ctx, long id, MappingNode variableMap, Variable.Builder builder) {
+ int iterations = 0;
+ for (NodeTuple nodeTuple : variableMap.getValue()) {
+ Node keyNode = nodeTuple.getKeyNode();
+ long keyId = ctx.collectMetadata(keyNode);
+ builder
+ .setName(ctx.newValueString(keyNode))
+ .setExpression(ctx.newValueString(nodeTuple.getValueNode()));
+ iterations++;
+
+ if (iterations > 1) {
+ ctx.reportError(keyId, "Only one variable may be defined inline");
+ }
+ }
+
+ if (!assertRequiredFields(ctx, id, builder.getMissingRequiredFieldNames())) {
+ return ERROR_VARIABLE;
+ }
+
+ return builder.build();
+ }
+
+ private Variable parseVariableObject(
+ PolicyParserContext<Node> ctx,
+ CelPolicy.Builder policyBuilder,
+ long id,
+ MappingNode variableMap,
+ Variable.Builder builder) {
  for (NodeTuple nodeTuple : variableMap.getValue()) {
  Node keyNode = nodeTuple.getKeyNode();
  long keyId = ctx.collectMetadata(keyNode);
@@ -370,8 +409,13 @@ public CelPolicy.Variable parseVariable(
  return builder.build();
  }
 
- private ParserImpl(TagVisitor<Node> tagVisitor, String source, String description) {
+ private ParserImpl(
+ TagVisitor<Node> tagVisitor,
+ boolean enableSimpleVariables,
+ String source,
+ String description) {
  this.tagVisitor = tagVisitor;
+ this.enableSimpleVariables = enableSimpleVariables;
  this.policySource =
  CelPolicySource.newBuilder(CelCodePointArray.fromString(source))
  .setDescription(description)
@@ -413,9 +457,11 @@ public ValueString newValueString(Node node) {
  static final class Builder implements CelPolicyParserBuilder<Node> {
 
  private TagVisitor<Node> tagVisitor;
+ private boolean enableSimpleVariables;
 
  private Builder() {
  this.tagVisitor = new TagVisitor<Node>() {};
+ this.enableSimpleVariables = false;
  }
 
  @Override
@@ -424,17 +470,24 @@ public CelPolicyParserBuilder<Node> addTagVisitor(TagVisitor<Node> tagVisitor) {
  return this;
  }
 
+ @Override
+ public CelPolicyParserBuilder<Node> enableSimpleVariables(boolean enable) {
+ this.enableSimpleVariables = enable;
+ return this;
+ }
+
  @Override
  public CelPolicyParser build() {
- return new CelPolicyYamlParser(tagVisitor);
+ return new CelPolicyYamlParser(tagVisitor, enableSimpleVariables);
  }
  }
 
- static Builder newBuilder() {
- return new Builder();
+ static CelPolicyParserBuilder<Node> newBuilder() {
+ return new Builder().enableSimpleVariables(false);
  }
 
- private CelPolicyYamlParser(TagVisitor<Node> tagVisitor) {
+ private CelPolicyYamlParser(TagVisitor<Node> tagVisitor, boolean enableSimpleVariables) {
  this.tagVisitor = checkNotNull(tagVisitor);
+ this.enableSimpleVariables = enableSimpleVariables;
  }
 }
diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyCompilerImplTest.java
@@ -302,6 +302,29 @@ public void evaluateYamlPolicy_lateBoundFunction() throws Exception {
  assertThat(evalResult).isEqualTo("foo" + exampleValue);
  }
 
+ @Test
+ public void evaluateYamlPolicy_withSimpleVariable() throws Exception {
+ Cel cel = newCel();
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " - second: 'false'\n"
+ + " match:\n"
+ + " - output: 'variables.first && variables.second'";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+ CelPolicy policy = parser.parse(policySource);
+
+ CelAbstractSyntaxTree compiledPolicyAst =
+ CelPolicyCompilerFactory.newPolicyCompiler(cel).build().compile(policy);
+
+ boolean evalResult = (boolean) cel.createProgram(compiledPolicyAst).eval();
+
+ assertThat(evalResult).isFalse();
+ }
+
  private static final class EvaluablePolicyTestData {
  private final TestYamlPolicy yamlPolicy;
  private final PolicyTestCase testCase;

diff --git a/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java b/policy/src/test/java/dev/cel/policy/CelPolicyYamlParserTest.java
@@ -148,6 +148,30 @@ public void parseYamlPolicy_withImports() throws Exception {
  .inOrder();
  }
 
+ @Test
+ public void parseYamlPolicy_withSimpleVariable_multipleInlinedVariables() {
+ String policySource =
+ "name: shorthand_variables_policy\n"
+ + "rule:\n"
+ + " variables:\n"
+ + " - first: 'true'\n"
+ + " second: 'false'\n"
+ + " match:\n"
+ + " - condition: 'variables.my_var'\n"
+ + " output: 'true'\n";
+ CelPolicyParser parser =
+ CelPolicyParserFactory.newYamlParserBuilder().enableSimpleVariables(true).build();
+
+ CelPolicyValidationException e =
+ assertThrows(CelPolicyValidationException.class, () -> parser.parse(policySource));
+ assertThat(e)
+ .hasMessageThat()
+ .contains(
+ "ERROR: <input>:5:7: Only one variable may be defined inline\n"
+ + " | second: 'false'\n"
+ + " | ......^");
+ }
+
  @Test
  public void parseYamlPolicy_errors(@TestParameter PolicyParseErrorTestCase testCase) {
  CelPolicyValidationException e =