More bug fixes

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

Author: jviotti

src/alterschema/common/double_negation_elimination.h

@@ -44,6 +44,16 @@ class DoubleNegationElimination final : public SchemaTransformRule {
   auto transform(JSON &schema, const Result &) const -> void override {
     auto inner{schema.at("not").at("not")};
     schema.erase("not");
+
+    while (inner.is_object() && inner.size() == 1 && inner.defines("not") &&
+           inner.at("not").is_object() && inner.at("not").size() == 1 &&
+           inner.at("not").defines("not") &&
+           !(inner.at("not").at("not").is_boolean() &&
+             !inner.at("not").at("not").to_boolean())) {
+      auto next{inner.at("not").at("not")};
+      inner = std::move(next);
+    }
+
     if (inner.is_object()) {
       schema.merge(inner.as_object());
     }
@@ -53,7 +63,10 @@ class DoubleNegationElimination final : public SchemaTransformRule {
                                  const Pointer &target,
                                  const Pointer &current) const
       -> Pointer override {
-    const Pointer old_prefix{current.concat({"not", "not"})};
+    auto old_prefix{current.concat({"not", "not"})};
+    while (target.starts_with(old_prefix.concat({"not", "not"}))) {
+      old_prefix = old_prefix.concat({"not", "not"});
+    }
     if (!target.starts_with(old_prefix)) {
       return target;
     }

test/alterschema/alterschema_lint_draft7_test.cc

@@ -4420,3 +4420,39 @@ TEST(AlterSchema_lint_draft7, triple_negation_to_single) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(AlterSchema_lint_draft7, quadruple_negation_to_identity) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "not": { "not": { "not": { "not": { "type": "string" } } } }
+  })JSON");
+
+  LINT_AND_FIX(document, result, traces);
+
+  EXPECT_FALSE(result.first);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "string"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_draft7, quintuple_negation_to_single) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "not": { "not": { "not": { "not": { "not": { "type": "string" } } } } }
+  })JSON");
+
+  LINT_AND_FIX(document, result, traces);
+
+  EXPECT_FALSE(result.first);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "not": { "type": "string" }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}