Add ConstantFoldingOptions

optimizer/src/main/java/dev/cel/optimizer/optimizers/BUILD.bazel

@@ -14,6 +14,7 @@ java_library(
     tags = [
     ],
     deps = [
+        "//:auto_value",
         "//bundle:cel",
         "//common",
         "//common:compiler_common",

optimizer/src/main/java/dev/cel/optimizer/optimizers/ConstantFoldingOptimizer.java

@@ -16,6 +16,7 @@
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.MoreCollectors.onlyElement;
 
+import com.google.auto.value.AutoValue;
 import com.google.common.collect.ImmutableList;
 import dev.cel.bundle.Cel;
 import dev.cel.common.CelAbstractSyntaxTree;
@@ -47,9 +48,22 @@
  * calls and select statements with their evaluated result.
  */
 public final class ConstantFoldingOptimizer implements CelAstOptimizer {
-  private static final int MAX_ITERATION_COUNT = 400;
+  private static final ConstantFoldingOptimizer INSTANCE =
+      new ConstantFoldingOptimizer(ConstantFoldingOptions.newBuilder().build());
 
-  public static final ConstantFoldingOptimizer INSTANCE = new ConstantFoldingOptimizer();
+  /** Returns a default instance of constant folding optimizer with preconfigured defaults. */
+  public static ConstantFoldingOptimizer getInstance() {
+    return INSTANCE;
+  }
+
+  /**
+   * Returns a new instance of constant folding optimizer configured with the provided {@link
+   * ConstantFoldingOptions}.
+   */
+  public static ConstantFoldingOptimizer newInstance(
+      ConstantFoldingOptions constantFoldingOptions) {
+    return new ConstantFoldingOptimizer(constantFoldingOptions);
+  }
 
   // Use optional.of and optional.none as sentinel function names for folding optional calls.
   // TODO: Leverage CelValue representation of Optionals instead when available.
@@ -58,6 +72,7 @@ public final class ConstantFoldingOptimizer implements CelAstOptimizer {
   private static final CelExpr OPTIONAL_NONE_EXPR =
       CelExpr.ofCallExpr(0, Optional.empty(), OPTIONAL_NONE_FUNCTION, ImmutableList.of());
 
+  private final ConstantFoldingOptions constantFoldingOptions;
   private final MutableAst mutableAst;
 
   @Override
@@ -67,7 +82,7 @@ public CelAbstractSyntaxTree optimize(CelNavigableAst navigableAst, Cel cel)
     int iterCount = 0;
     while (true) {
       iterCount++;
-      if (iterCount == MAX_ITERATION_COUNT) {
+      if (iterCount >= constantFoldingOptions.maxIterationLimit()) {
         throw new IllegalStateException("Max iteration count reached.");
       }
       Optional<CelExpr> foldableExpr =
@@ -553,7 +568,37 @@ private CelAbstractSyntaxTree pruneOptionalStructElements(
     return ast;
   }
 
-  private ConstantFoldingOptimizer() {
-    this.mutableAst = MutableAst.newInstance(MAX_ITERATION_COUNT);
+  /** Options to configure how Constant Folding behave. */
+  @AutoValue
+  public abstract static class ConstantFoldingOptions {
+    public abstract int maxIterationLimit();
+
+    /** Builder for configuring the {@link ConstantFoldingOptions}. */
+    @AutoValue.Builder
+    public abstract static class Builder {
+
+      /**
+       * Limit the number of iteration while performing constant folding. An exception is thrown if
+       * the iteration count exceeds the set value.
+       */
+      public abstract Builder maxIterationLimit(int value);
+
+      public abstract ConstantFoldingOptions build();
+
+      Builder() {}
+    }
+
+    /** Returns a new options builder with recommended defaults pre-configured. */
+    public static Builder newBuilder() {
+      return new AutoValue_ConstantFoldingOptimizer_ConstantFoldingOptions.Builder()
+          .maxIterationLimit(400);
+    }
+
+    ConstantFoldingOptions() {}
+  }
+
+  private ConstantFoldingOptimizer(ConstantFoldingOptions constantFoldingOptions) {
+    this.constantFoldingOptions = constantFoldingOptions;
+    this.mutableAst = MutableAst.newInstance(constantFoldingOptions.maxIterationLimit());
   }
 }

optimizer/src/test/java/dev/cel/optimizer/optimizers/ConstantFoldingOptimizerTest.java

@@ -30,6 +30,7 @@
 import dev.cel.optimizer.CelOptimizationException;
 import dev.cel.optimizer.CelOptimizer;
 import dev.cel.optimizer.CelOptimizerFactory;
+import dev.cel.optimizer.optimizers.ConstantFoldingOptimizer.ConstantFoldingOptions;
 import dev.cel.parser.CelStandardMacro;
 import dev.cel.parser.CelUnparser;
 import dev.cel.parser.CelUnparserFactory;
@@ -53,7 +54,7 @@ public class ConstantFoldingOptimizerTest {
 
   private static final CelOptimizer CEL_OPTIMIZER =
       CelOptimizerFactory.standardCelOptimizerBuilder(CEL)
-          .addAstOptimizers(ConstantFoldingOptimizer.INSTANCE)
+          .addAstOptimizers(ConstantFoldingOptimizer.getInstance())
           .build();
 
   private static final CelUnparser CEL_UNPARSER = CelUnparserFactory.newUnparser();
@@ -211,7 +212,7 @@ public void constantFold_macros_macroCallMetadataPopulated(String source, String
             .build();
     CelOptimizer celOptimizer =
         CelOptimizerFactory.standardCelOptimizerBuilder(cel)
-            .addAstOptimizers(ConstantFoldingOptimizer.INSTANCE)
+            .addAstOptimizers(ConstantFoldingOptimizer.getInstance())
             .build();
     CelAbstractSyntaxTree ast = cel.compile(source).getAst();
 
@@ -253,7 +254,7 @@ public void constantFold_macros_withoutMacroCallMetadata(String source) throws E
             .build();
     CelOptimizer celOptimizer =
         CelOptimizerFactory.standardCelOptimizerBuilder(cel)
-            .addAstOptimizers(ConstantFoldingOptimizer.INSTANCE)
+            .addAstOptimizers(ConstantFoldingOptimizer.getInstance())
             .build();
     CelAbstractSyntaxTree ast = cel.compile(source).getAst();
 
@@ -299,7 +300,7 @@ public void constantFold_withMacroCallPopulated_comprehensionsAreReplacedWithNot
             .build();
     CelOptimizer celOptimizer =
         CelOptimizerFactory.standardCelOptimizerBuilder(cel)
-            .addAstOptimizers(ConstantFoldingOptimizer.INSTANCE)
+            .addAstOptimizers(ConstantFoldingOptimizer.getInstance())
             .build();
     CelAbstractSyntaxTree ast =
         cel.compile("[1, 1 + 1, 1 + 1+ 1].map(i, i).filter(j, j % 2 == x)").getAst();
@@ -384,17 +385,19 @@ public void constantFold_astProducesConsistentlyNumberedIds() throws Exception {
   public void iterationLimitReached_throws() throws Exception {
     StringBuilder sb = new StringBuilder();
     sb.append("0");
-    for (int i = 1; i < 400; i++) {
+    for (int i = 1; i < 200; i++) {
       sb.append(" + ").append(i);
-    } // 0 + 1 + 2 + 3 + ... 400
+    } // 0 + 1 + 2 + 3 + ... 200
     Cel cel =
         CelFactory.standardCelBuilder()
-            .setOptions(CelOptions.current().maxParseRecursionDepth(400).build())
+            .setOptions(CelOptions.current().maxParseRecursionDepth(200).build())
             .build();
     CelAbstractSyntaxTree ast = cel.compile(sb.toString()).getAst();
     CelOptimizer optimizer =
         CelOptimizerFactory.standardCelOptimizerBuilder(cel)
-            .addAstOptimizers(ConstantFoldingOptimizer.INSTANCE)
+            .addAstOptimizers(
+                ConstantFoldingOptimizer.newInstance(
+                    ConstantFoldingOptions.newBuilder().maxIterationLimit(200).build()))
             .build();
 
     CelOptimizationException e =

optimizer/src/test/java/dev/cel/optimizer/optimizers/SubexpressionOptimizerTest.java

@@ -616,7 +616,7 @@ public void cse_applyConstFoldingAfter() throws Exception {
             .addAstOptimizers(
                 SubexpressionOptimizer.newInstance(
                     SubexpressionOptimizerOptions.newBuilder().populateMacroCalls(true).build()),
-                ConstantFoldingOptimizer.INSTANCE)
+                ConstantFoldingOptimizer.getInstance())
             .build();
 
     CelAbstractSyntaxTree optimizedAst = optimizer.optimize(ast);