Implement structured field and rule paths for violations (#213)

Implements the changes needed to pass conformance after
bufbuild/protovalidate#265.

This is basically a straight port of what is done in
bufbuild/protovalidate-go#154, owing to the
similarities between protovalidate-go and protovalidate-java.
Unfortunately this means it inherits some of the trickier maneuvers
needed to weave the right data into the right places. This version is
also not as efficient as a result of differences between Go and Java
protobufs, but effort was made to try to prevent big regressions in the
case of successful validation.

Some of this is probably not as pretty as it could be. I'm open to
improvements if there are any obvious things (I am certainly not a Java
expert after all) but if possible I'd like to defer anything that would
require major rethinking to down the road. (Happy to add TODOs for
those, though.)

DO NOT MERGE until the following is done:
- [x] bufbuild/protovalidate#265 is merged
- [x] Dependencies updated to stable version release (waiting on manage
module push)

gradle.properties

@@ -1,5 +1,5 @@
 # Version of buf.build/bufbuild/protovalidate to use.
-protovalidate.version = v0.8.2
+protovalidate.version = v0.9.0
 
 # Arguments to the protovalidate-conformance CLI
 protovalidate.conformance.args = --strict --strict_message --strict_error

src/main/java/build/buf/protovalidate/Validator.java

@@ -17,6 +17,7 @@
 import build.buf.protovalidate.exceptions.CompilationException;
 import build.buf.protovalidate.exceptions.ValidationException;
 import build.buf.protovalidate.internal.celext.ValidateLibrary;
+import build.buf.protovalidate.internal.errors.FieldPathUtils;
 import build.buf.protovalidate.internal.evaluator.Evaluator;
 import build.buf.protovalidate.internal.evaluator.EvaluatorBuilder;
 import build.buf.protovalidate.internal.evaluator.MessageValue;
@@ -74,7 +75,11 @@ public ValidationResult validate(Message msg) throws ValidationException {
     }
     Descriptor descriptor = msg.getDescriptorForType();
     Evaluator evaluator = evaluatorBuilder.load(descriptor);
-    return evaluator.evaluate(new MessageValue(msg), failFast);
+    ValidationResult result = evaluator.evaluate(new MessageValue(msg), failFast);
+    if (result.isSuccess()) {
+      return result;
+    }
+    return new ValidationResult(FieldPathUtils.calculateFieldPathStrings(result.getViolations()));
   }
 
   /**

src/main/java/build/buf/protovalidate/internal/constraints/ConstraintCache.java

@@ -16,11 +16,13 @@
 
 import build.buf.protovalidate.Config;
 import build.buf.protovalidate.exceptions.CompilationException;
+import build.buf.protovalidate.internal.errors.FieldPathUtils;
 import build.buf.protovalidate.internal.expression.AstExpression;
 import build.buf.protovalidate.internal.expression.CompiledProgram;
 import build.buf.protovalidate.internal.expression.Expression;
 import build.buf.protovalidate.internal.expression.Variable;
 import build.buf.validate.FieldConstraints;
+import build.buf.validate.FieldPath;
 import build.buf.validate.ValidateProto;
 import com.google.protobuf.DescriptorProtos;
 import com.google.protobuf.Descriptors;
@@ -52,10 +54,12 @@ public class ConstraintCache {
   private static class CelRule {
     public final AstExpression astExpression;
     public final FieldDescriptor field;
+    public final FieldPath rulePath;
 
-    public CelRule(AstExpression astExpression, FieldDescriptor field) {
+    public CelRule(AstExpression astExpression, FieldDescriptor field, FieldPath rulePath) {
       this.astExpression = astExpression;
       this.field = field;
+      this.rulePath = rulePath;
     }
   }
 
@@ -119,16 +123,17 @@ public ConstraintCache(Env env, Config config) {
   public List<CompiledProgram> compile(
       FieldDescriptor fieldDescriptor, FieldConstraints fieldConstraints, boolean forItems)
       throws CompilationException {
-    Message message = resolveConstraints(fieldDescriptor, fieldConstraints, forItems);
-    if (message == null) {
+    ResolvedConstraint resolved = resolveConstraints(fieldDescriptor, fieldConstraints, forItems);
+    if (resolved == null) {
       // Message null means there were no constraints resolved.
       return Collections.emptyList();
     }
+    Message message = resolved.message;
     List<CelRule> completeProgramList = new ArrayList<>();
     for (Map.Entry<FieldDescriptor, Object> entry : message.getAllFields().entrySet()) {
       FieldDescriptor constraintFieldDesc = entry.getKey();
       List<CelRule> programList =
-          compileRule(fieldDescriptor, forItems, constraintFieldDesc, message);
+          compileRule(fieldDescriptor, forItems, resolved.setOneof, constraintFieldDesc, message);
       if (programList == null) continue;
       completeProgramList.addAll(programList);
     }
@@ -152,11 +157,14 @@ public List<CompiledProgram> compile(
         }
         Ast residual = ruleEnv.residualAst(rule.astExpression.ast, evalResult.getEvalDetails());
         programs.add(
-            new CompiledProgram(ruleEnv.program(residual, globals), rule.astExpression.source));
+            new CompiledProgram(
+                ruleEnv.program(residual, globals), rule.astExpression.source, rule.rulePath));
       } catch (Exception e) {
         programs.add(
             new CompiledProgram(
-                ruleEnv.program(rule.astExpression.ast, globals), rule.astExpression.source));
+                ruleEnv.program(rule.astExpression.ast, globals),
+                rule.astExpression.source,
+                rule.rulePath));
       }
     }
     return Collections.unmodifiableList(programs);
@@ -165,6 +173,7 @@ public List<CompiledProgram> compile(
   private @Nullable List<CelRule> compileRule(
       FieldDescriptor fieldDescriptor,
       boolean forItems,
+      FieldDescriptor setOneof,
       FieldDescriptor constraintFieldDesc,
       Message message)
       throws CompilationException {
@@ -178,8 +187,14 @@ public List<CompiledProgram> compile(
     celRules = new ArrayList<>(expressions.size());
     Env ruleEnv = getRuleEnv(fieldDescriptor, message, constraintFieldDesc, forItems);
     for (Expression expression : expressions) {
+      FieldPath rulePath =
+          FieldPath.newBuilder()
+              .addElements(FieldPathUtils.fieldPathElement(setOneof))
+              .addElements(FieldPathUtils.fieldPathElement(constraintFieldDesc))
+              .build();
       celRules.add(
-          new CelRule(AstExpression.newAstExpression(ruleEnv, expression), constraintFieldDesc));
+          new CelRule(
+              AstExpression.newAstExpression(ruleEnv, expression), constraintFieldDesc, rulePath));
     }
     descriptorMap.put(constraintFieldDesc, celRules);
     return celRules;
@@ -246,13 +261,23 @@ private Env getRuleEnv(
                 Variable.RULE_NAME, DescriptorMappings.getCELType(constraintFieldDesc, false))));
   }
 
+  private static class ResolvedConstraint {
+    final Message message;
+    final FieldDescriptor setOneof;
+
+    ResolvedConstraint(Message message, FieldDescriptor setOneof) {
+      this.message = message;
+      this.setOneof = setOneof;
+    }
+  }
+
   /**
    * Extracts the standard constraints for the specified field. An exception is thrown if the wrong
    * constraints are applied to a field (typically if there is a type-mismatch). Null is returned if
    * there are no standard constraints to apply to this field.
    */
   @Nullable
-  private Message resolveConstraints(
+  private ResolvedConstraint resolveConstraints(
       FieldDescriptor fieldDescriptor, FieldConstraints fieldConstraints, boolean forItems)
       throws CompilationException {
     // Get the oneof field descriptor from the field constraints.
@@ -313,6 +338,6 @@ private Message resolveConstraints(
     if (!allowUnknownFields && !typeConstraints.getUnknownFields().isEmpty()) {
       throw new CompilationException("unrecognized field constraints");
     }
-    return typeConstraints;
+    return new ResolvedConstraint(typeConstraints, oneofFieldDescriptor);
   }
 }