Prioritize smaller subschemas when unrolling properties (#1264)

Signed-off-by: Juan Cruz Viotti <[email protected]>

src/jsonschema/default_compiler_draft4.h

@@ -423,10 +423,15 @@ auto compiler_draft4_applicator_properties_conditional_annotation(
     }
   }
 
-  // To guarantee order
+  // In many cases, `properties` have some subschemas that are small
+  // and some subschemas that are large. To attempt to improve performance,
+  // we prefer to evaluate smaller subschemas first, in the hope of failing
+  // earlier without spending a lot of time on other subschemas
   std::sort(properties.begin(), properties.end(),
             [](const auto &left, const auto &right) {
-              return left.first < right.first;
+              return (left.second.size() == right.second.size())
+                         ? (left.first < right.first)
+                         : (left.second.size() < right.second.size());
             });
 
   // There are two ways to compile `properties` depending on whether

test/evaluator/evaluator_draft4_test.cc

@@ -1200,6 +1200,110 @@ TEST(JSONSchema_evaluator_draft4, properties_6) {
                                "against the single defined property subschema");
 }
 
+TEST(JSONSchema_evaluator_draft4, properties_7) {
+  const sourcemeta::jsontoolkit::JSON schema{
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema#",
+    "properties": {
+      "foo": { "type": "string", "pattern": "^a" },
+      "bar": { "type": "integer" }
+    }
+  })JSON")};
+
+  const auto compiled_schema{sourcemeta::jsontoolkit::compile(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver,
+      sourcemeta::jsontoolkit::default_schema_compiler)};
+
+  const sourcemeta::jsontoolkit::JSON instance{
+      sourcemeta::jsontoolkit::parse("{ \"bar\": 2, \"foo\": \"abc\" }")};
+
+  EVALUATE_WITH_TRACE_FAST_SUCCESS(compiled_schema, instance, 4);
+
+  EVALUATE_TRACE_PRE(0, LogicalAnd, "/properties", "#/properties", "");
+
+  // Note we evaluate "bar" before "foo" because the number of instructions
+  // in "bar" is less
+  EVALUATE_TRACE_PRE(1, AssertionPropertyTypeStrict, "/properties/bar/type",
+                     "#/properties/bar/type", "/bar");
+  EVALUATE_TRACE_PRE(2, AssertionTypeStrict, "/properties/foo/type",
+                     "#/properties/foo/type", "/foo");
+  EVALUATE_TRACE_PRE(3, AssertionRegex, "/properties/foo/pattern",
+                     "#/properties/foo/pattern", "/foo");
+
+  EVALUATE_TRACE_POST_SUCCESS(0, AssertionPropertyTypeStrict,
+                              "/properties/bar/type", "#/properties/bar/type",
+                              "/bar");
+  EVALUATE_TRACE_POST_SUCCESS(1, AssertionTypeStrict, "/properties/foo/type",
+                              "#/properties/foo/type", "/foo");
+  EVALUATE_TRACE_POST_SUCCESS(2, AssertionRegex, "/properties/foo/pattern",
+                              "#/properties/foo/pattern", "/foo");
+  EVALUATE_TRACE_POST_SUCCESS(3, LogicalAnd, "/properties", "#/properties", "");
+
+  EVALUATE_TRACE_POST_DESCRIBE(instance, 0,
+                               "The value was expected to be of type integer");
+  EVALUATE_TRACE_POST_DESCRIBE(instance, 1,
+                               "The value was expected to be of type string");
+  EVALUATE_TRACE_POST_DESCRIBE(instance, 2,
+                               "The string value \"abc\" was expected to match "
+                               "the regular expression \"^a\"");
+  EVALUATE_TRACE_POST_DESCRIBE(instance, 3,
+                               "The object value was expected to validate "
+                               "against the defined properties subschemas");
+}
+
+TEST(JSONSchema_evaluator_draft4, properties_8) {
+  const sourcemeta::jsontoolkit::JSON schema{
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema#",
+    "properties": {
+      "bar": { "type": "string", "pattern": "^a" },
+      "foo": { "type": "integer" }
+    }
+  })JSON")};
+
+  const auto compiled_schema{sourcemeta::jsontoolkit::compile(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver,
+      sourcemeta::jsontoolkit::default_schema_compiler)};
+
+  const sourcemeta::jsontoolkit::JSON instance{
+      sourcemeta::jsontoolkit::parse("{ \"foo\": 2, \"bar\": \"abc\" }")};
+
+  EVALUATE_WITH_TRACE_FAST_SUCCESS(compiled_schema, instance, 4);
+
+  EVALUATE_TRACE_PRE(0, LogicalAnd, "/properties", "#/properties", "");
+
+  // Note we evaluate "foo" before "bar" because the number of instructions
+  // in "foo" is less
+  EVALUATE_TRACE_PRE(1, AssertionPropertyTypeStrict, "/properties/foo/type",
+                     "#/properties/foo/type", "/foo");
+  EVALUATE_TRACE_PRE(2, AssertionTypeStrict, "/properties/bar/type",
+                     "#/properties/bar/type", "/bar");
+  EVALUATE_TRACE_PRE(3, AssertionRegex, "/properties/bar/pattern",
+                     "#/properties/bar/pattern", "/bar");
+
+  EVALUATE_TRACE_POST_SUCCESS(0, AssertionPropertyTypeStrict,
+                              "/properties/foo/type", "#/properties/foo/type",
+                              "/foo");
+  EVALUATE_TRACE_POST_SUCCESS(1, AssertionTypeStrict, "/properties/bar/type",
+                              "#/properties/bar/type", "/bar");
+  EVALUATE_TRACE_POST_SUCCESS(2, AssertionRegex, "/properties/bar/pattern",
+                              "#/properties/bar/pattern", "/bar");
+  EVALUATE_TRACE_POST_SUCCESS(3, LogicalAnd, "/properties", "#/properties", "");
+
+  EVALUATE_TRACE_POST_DESCRIBE(instance, 0,
+                               "The value was expected to be of type integer");
+  EVALUATE_TRACE_POST_DESCRIBE(instance, 1,
+                               "The value was expected to be of type string");
+  EVALUATE_TRACE_POST_DESCRIBE(instance, 2,
+                               "The string value \"abc\" was expected to match "
+                               "the regular expression \"^a\"");
+  EVALUATE_TRACE_POST_DESCRIBE(instance, 3,
+                               "The object value was expected to validate "
+                               "against the defined properties subschemas");
+}
+
 TEST(JSONSchema_evaluator_draft4, pattern_1) {
   const sourcemeta::jsontoolkit::JSON schema{
       sourcemeta::jsontoolkit::parse(R"JSON({