Add shorthands for retrieving CelExpr variants or its default instance.

This is useful to avoid having to check for the underlying kind before accessing its properties. Example: expr.getKind().equals(Kind.CALL) && expr.call().function().equals("foo") We can instead write: expr.callOrDefault().function().equals("foo") PiperOrigin-RevId: 559821213
google · Aug 24, 2023 · 1fa54c9 · 1fa54c9
1 parent 5567748
commit 1fa54c9
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Showing 8 changed files with 282 additions and 4 deletions.
diff --git a/common/src/main/java/dev/cel/common/ast/CelConstant.java b/common/src/main/java/dev/cel/common/ast/CelConstant.java
@@ -15,6 +15,7 @@
 package dev.cel.common.ast;
 
 import com.google.auto.value.AutoOneOf;
+import com.google.auto.value.AutoValue;
 import com.google.common.primitives.UnsignedLong;
 import com.google.errorprone.annotations.Immutable;
 import com.google.protobuf.ByteString;
@@ -34,6 +35,7 @@
 public abstract class CelConstant {
   /** Represents the type of the Constant */
   public enum Kind {
+    NOT_SET,
     NULL_VALUE,
     BOOLEAN_VALUE,
     INT64_VALUE,
@@ -55,6 +57,18 @@ public enum Kind {
 
   public abstract Kind getKind();
 
+  /**
+   * An unset constant.
+   *
+   * <p>As the name implies, this constant does nothing. This is used to represent a default
+   * instance of CelConstant.
+   */
+  @AutoValue
+  @Immutable
+  public abstract static class CelConstantNotSet {}
+
+  public abstract CelConstantNotSet notSet();
+
   public abstract NullValue nullValue();
 
   public abstract boolean booleanValue();
@@ -81,6 +95,10 @@ public enum Kind {
   @Deprecated
   public abstract Duration durationValue();
 
+  public static CelConstant ofNotSet() {
+    return AutoOneOf_CelConstant.notSet(new AutoValue_CelConstant_CelConstantNotSet());
+  }
+
   public static CelConstant ofValue(NullValue value) {
     return AutoOneOf_CelConstant.nullValue(value);
   }

diff --git a/common/src/main/java/dev/cel/common/ast/CelExpr.java b/common/src/main/java/dev/cel/common/ast/CelExpr.java
@@ -23,6 +23,7 @@
 import com.google.errorprone.annotations.CheckReturnValue;
 import com.google.errorprone.annotations.Immutable;
 import dev.cel.common.annotations.Internal;
+import dev.cel.common.ast.CelExpr.ExprKind.Kind;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -50,42 +51,167 @@
 @Immutable
 public abstract class CelExpr {
 
+  /**
+   * Required. An id assigned to this node by the parser which is unique in a given expression tree.
+   * This is used to associate type information and other attributes to a node in the parse tree.
+   */
   public abstract long id();
 
+  /** Represents the variant of the expression. */
   public abstract ExprKind exprKind();
 
+  /**
+   * Gets the underlying constant expression.
+   *
+   * @throws UnsupportedOperationException if expression is not {@link Kind#CONSTANT}.
+   */
   public CelConstant constant() {
     return exprKind().constant();
   }
 
+  /**
+   * Gets the underlying identifier expression.
+   *
+   * @throws UnsupportedOperationException if expression is not {@link Kind#IDENT}.
+   */
   public CelIdent ident() {
     return exprKind().ident();
   }
 
+  /**
+   * Gets the underlying select expression.
+   *
+   * @throws UnsupportedOperationException if expression is not {@link Kind#SELECT}.
+   */
   public CelSelect select() {
     return exprKind().select();
   }
 
+  /**
+   * Gets the underlying call expression.
+   *
+   * @throws UnsupportedOperationException if expression is not {@link Kind#CALL}.
+   */
   public CelCall call() {
     return exprKind().call();
   }
 
+  /**
+   * Gets the underlying createList expression.
+   *
+   * @throws UnsupportedOperationException if expression is not {@link Kind#CREATE_LIST}.
+   */
   public CelCreateList createList() {
     return exprKind().createList();
   }
 
+  /**
+   * Gets the underlying createStruct expression.
+   *
+   * @throws UnsupportedOperationException if expression is not {@link Kind#CREATE_STRUCT}.
+   */
   public CelCreateStruct createStruct() {
     return exprKind().createStruct();
   }
 
+  /**
+   * Gets the underlying createMap expression.
+   *
+   * @throws UnsupportedOperationException if expression is not {@link Kind#createMap}.
+   */
   public CelCreateMap createMap() {
     return exprKind().createMap();
   }
 
+  /**
+   * Gets the underlying comprehension expression.
+   *
+   * @throws UnsupportedOperationException if expression is not {@link Kind#COMPREHENSION}.
+   */
   public CelComprehension comprehension() {
     return exprKind().comprehension();
   }
 
+  /**
+   * Gets the underlying constant expression or a default instance of one if expression is not
+   * {@link Kind#CONSTANT}.
+   */
+  public CelConstant constantOrDefault() {
+    return exprKind().getKind().equals(ExprKind.Kind.CONSTANT)
+        ? exprKind().constant()
+        : CelConstant.ofNotSet();
+  }
+
+  /**
+   * Gets the underlying identifier expression or a default instance of one if expression is not
+   * {@link Kind#IDENT}.
+   */
+  public CelIdent identOrDefault() {
+    return exprKind().getKind().equals(ExprKind.Kind.IDENT)
+        ? exprKind().ident()
+        : CelIdent.newBuilder().build();
+  }
+
+  /**
+   * Gets the underlying select expression or a default instance of one if expression is not {@link
+   * Kind#SELECT}.
+   */
+  public CelSelect selectOrDefault() {
+    return exprKind().getKind().equals(ExprKind.Kind.SELECT)
+        ? exprKind().select()
+        : CelSelect.newBuilder().build();
+  }
+
+  /**
+   * Gets the underlying call expression or a default instance of one if expression is not {@link
+   * Kind#CALL}.
+   */
+  public CelCall callOrDefault() {
+    return exprKind().getKind().equals(ExprKind.Kind.CALL)
+        ? exprKind().call()
+        : CelCall.newBuilder().build();
+  }
+
+  /**
+   * Gets the underlying createList expression or a default instance of one if expression is not
+   * {@link Kind#CREATE_LIST}.
+   */
+  public CelCreateList createListOrDefault() {
+    return exprKind().getKind().equals(ExprKind.Kind.CREATE_LIST)
+        ? exprKind().createList()
+        : CelCreateList.newBuilder().build();
+  }
+
+  /**
+   * Gets the underlying createStruct expression or a default instance of one if expression is not
+   * {@link Kind#CREATE_STRUCT}.
+   */
+  public CelCreateStruct createStructOrDefault() {
+    return exprKind().getKind().equals(ExprKind.Kind.CREATE_STRUCT)
+        ? exprKind().createStruct()
+        : CelCreateStruct.newBuilder().build();
+  }
+
+  /**
+   * Gets the underlying createMap expression or a default instance of one if expression is not
+   * {@link Kind#CREATE_MAP}.
+   */
+  public CelCreateMap createMapOrDefault() {
+    return exprKind().getKind().equals(ExprKind.Kind.CREATE_MAP)
+        ? exprKind().createMap()
+        : CelCreateMap.newBuilder().build();
+  }
+
+  /**
+   * Gets the underlying comprehension expression or a default instance of one if expression is not
+   * {@link Kind#COMPREHENSION}.
+   */
+  public CelComprehension comprehensionOrDefault() {
+    return exprKind().getKind().equals(ExprKind.Kind.COMPREHENSION)
+        ? exprKind().comprehension()
+        : CelComprehension.newBuilder().build();
+  }
+
   /** Builder for CelExpr. */
   @AutoValue.Builder
   public abstract static class Builder {
@@ -212,7 +338,7 @@ public abstract static class Builder {
     public abstract Builder toBuilder();
 
     public static Builder newBuilder() {
-      return new AutoValue_CelExpr_CelIdent.Builder();
+      return new AutoValue_CelExpr_CelIdent.Builder().setName("");
     }
   }
 
@@ -261,7 +387,10 @@ public abstract static class Builder {
     public abstract Builder toBuilder();
 
     public static Builder newBuilder() {
-      return new AutoValue_CelExpr_CelSelect.Builder().setTestOnly(false);
+      return new AutoValue_CelExpr_CelSelect.Builder()
+          .setField("")
+          .setOperand(CelExpr.newBuilder().build())
+          .setTestOnly(false);
     }
   }
 
@@ -345,7 +474,7 @@ public Builder toBuilder() {
     }
 
     public static Builder newBuilder() {
-      return new AutoValue_CelExpr_CelCall.Builder();
+      return new AutoValue_CelExpr_CelCall.Builder().setFunction("");
     }
   }
 
@@ -761,7 +890,14 @@ public abstract static class Builder {
     public abstract Builder toBuilder();
 
     public static Builder newBuilder() {
-      return new AutoValue_CelExpr_CelComprehension.Builder();
+      return new AutoValue_CelExpr_CelComprehension.Builder()
+          .setIterVar("")
+          .setIterRange(CelExpr.newBuilder().build())
+          .setAccuVar("")
+          .setAccuInit(CelExpr.newBuilder().build())
+          .setLoopCondition(CelExpr.newBuilder().build())
+          .setLoopStep(CelExpr.newBuilder().build())
+          .setResult(CelExpr.newBuilder().build());
     }
   }
 

diff --git a/common/src/main/java/dev/cel/common/ast/CelExprConverter.java b/common/src/main/java/dev/cel/common/ast/CelExprConverter.java
@@ -174,6 +174,8 @@ public static CelReference exprReferenceToCelReference(Reference reference) {
    */
   public static CelConstant exprConstantToCelConstant(Constant constExpr) {
     switch (constExpr.getConstantKindCase()) {
+      case CONSTANTKIND_NOT_SET:
+        return CelConstant.ofNotSet();
       case NULL_VALUE:
         return CelConstant.ofValue(constExpr.getNullValue());
       case BOOL_VALUE:
@@ -243,6 +245,8 @@ private static Expr.Builder newExprBuilder(CelExpr expr) {
    */
   public static Constant celConstantToExprConstant(CelConstant celConstant) {
     switch (celConstant.getKind()) {
+      case NOT_SET:
+        return Constant.getDefaultInstance();
       case NULL_VALUE:
         return Constant.newBuilder().setNullValue(celConstant.nullValue()).build();
       case BOOLEAN_VALUE:

diff --git a/common/src/main/java/dev/cel/common/ast/CelExprV1Alpha1Converter.java b/common/src/main/java/dev/cel/common/ast/CelExprV1Alpha1Converter.java
@@ -174,6 +174,8 @@ public static CelReference exprReferenceToCelReference(Reference reference) {
    */
   public static CelConstant exprConstantToCelConstant(Constant constExpr) {
     switch (constExpr.getConstantKindCase()) {
+      case CONSTANTKIND_NOT_SET:
+        return CelConstant.ofNotSet();
       case NULL_VALUE:
         return CelConstant.ofValue(constExpr.getNullValue());
       case BOOL_VALUE:
@@ -243,6 +245,8 @@ private static Expr.Builder newExprBuilder(CelExpr expr) {
    */
   public static Constant celConstantToExprConstant(CelConstant celConstant) {
     switch (celConstant.getKind()) {
+      case NOT_SET:
+        return Constant.getDefaultInstance();
       case NULL_VALUE:
         return Constant.newBuilder().setNullValue(celConstant.nullValue()).build();
       case BOOLEAN_VALUE:

diff --git a/common/src/test/java/dev/cel/common/ast/CelConstantTest.java b/common/src/test/java/dev/cel/common/ast/CelConstantTest.java
@@ -137,6 +137,14 @@ public void constructTimestampValue() {
         .isEqualTo(Timestamp.newBuilder().setSeconds(100L).build());
   }
 
+  @Test
+  public void constructNotSetConstant() {
+    CelConstant constant = CelConstant.ofNotSet();
+
+    assertThat(constant).isNotNull();
+    assertThat(constant.getKind()).isEqualTo(Kind.NOT_SET);
+  }
+
   private enum CelConstantTestCase {
     NULL(CelConstant.ofValue(NullValue.NULL_VALUE)),
     BOOLEAN(CelConstant.ofValue(true)),

diff --git a/common/src/test/java/dev/cel/common/ast/CelExprConverterTest.java b/common/src/test/java/dev/cel/common/ast/CelExprConverterTest.java
@@ -41,6 +41,9 @@
 @RunWith(TestParameterInjector.class)
 public class CelExprConverterTest {
   private enum ConstantTestCase {
+    NOT_SET(
+        Expr.newBuilder().setId(1).setConstExpr(Constant.getDefaultInstance()).build(),
+        CelExpr.ofConstantExpr(1, CelConstant.ofNotSet())),
     NULL(
         Expr.newBuilder()
             .setId(1)