Internal changes

policy/src/main/java/dev/cel/policy/BUILD.bazel

@@ -167,7 +167,9 @@ java_library(
     ],
     deps = [
         ":policy",
+        "//:auto_value",
         "//common/formats:parser_context",
+        "//policy:source",
     ],
 )
 

policy/src/main/java/dev/cel/policy/CelPolicyYamlParser.java

@@ -94,11 +94,17 @@ private CelPolicy parseYaml() throws CelPolicyValidationException {
     }
 
     @Override
-    public CelPolicy parsePolicy(PolicyParserContext<Node> ctx, Node node) {
-      CelPolicy.Builder policyBuilder = CelPolicy.newBuilder();
+    public NewPolicyMetadata newPolicy(Node node) {
       long id = ctx.collectMetadata(node);
-      if (!assertYamlType(ctx, id, node, YamlNodeType.MAP)) {
-        return policyBuilder.setPolicySource(policySource).build();
+      return NewPolicyMetadata.create(policySource, id);
+    }
+
+    @Override
+    public CelPolicy parsePolicy(PolicyParserContext<Node> ctx, Node node) {
+      NewPolicyMetadata newPolicyMetadata = newPolicy(node);
+      CelPolicy.Builder policyBuilder = newPolicyMetadata.policyBuilder();
+      if (!assertYamlType(ctx, newPolicyMetadata.id(), node, YamlNodeType.MAP)) {
+        return policyBuilder.build();
       }
 
       MappingNode rootNode = (MappingNode) node;

policy/src/main/java/dev/cel/policy/PolicyParserContext.java

@@ -14,6 +14,7 @@
 
 package dev.cel.policy;
 
+import com.google.auto.value.AutoValue;
 import dev.cel.common.formats.ParserContext;
 import dev.cel.policy.CelPolicy.Match;
 import dev.cel.policy.CelPolicy.Rule;
@@ -24,6 +25,25 @@
  * for {@link CelPolicy}.
  */
 public interface PolicyParserContext<T> extends ParserContext<T> {
+
+  /**
+   * Wrapper for a new instance of {@link CelPolicy.Builder} and the associated node ID. The
+   * CelPolicy builder also has a policy source set by the parser.
+   */
+  @AutoValue
+  abstract class NewPolicyMetadata {
+    public abstract CelPolicy.Builder policyBuilder();
+
+    public abstract long id();
+
+    static NewPolicyMetadata create(CelPolicySource source, long id) {
+      return new AutoValue_PolicyParserContext_NewPolicyMetadata(
+          CelPolicy.newBuilder().setPolicySource(source), id);
+    }
+  }
+
+  NewPolicyMetadata newPolicy(T node);
+
   CelPolicy parsePolicy(PolicyParserContext<T> ctx, T node);
 
   Rule parseRule(PolicyParserContext<T> ctx, CelPolicy.Builder policyBuilder, T node);