Treat '\f' and '\v' as whitespace

Summary: Recognize form feed (`\f`) and vertical tab (`\v`) as whitespace characters when `allow_json5_experimental` is enabled.

Reviewed By: ilvokhin

Differential Revision: D93462431

fbshipit-source-id: 11b515073b08007f9771b66b4274017ce86a0a1f

Author: Mizuchi

third-party/folly/src/folly/json/json.cpp

@@ -431,6 +431,11 @@ struct Input {
           index++;
           continue;
         }
+        if (opts_.allow_json5_experimental &&
+            (range_[index] == '\f' || range_[index] == '\v')) {
+          index++;
+          continue;
+        }
       }
       break;
     }

third-party/folly/src/folly/json/test/Json5Test.cpp

@@ -84,6 +84,7 @@ constexpr auto kPassedTests = {
     "src/misc/npm-package.json",
     "src/misc/npm-package.json5",
     "src/misc/readme-example.json5",
+    "src/misc/valid-whitespace.json5",
     // Objects - single-quoted keys
     "src/objects/single-quoted-key.json5",
     // New lines
@@ -169,8 +170,6 @@ constexpr auto kPassedTests = {
 };
 
 constexpr auto kFailedTests = {
-    // Misc
-    "src/misc/valid-whitespace.json5",
     // Numbers
     "src/numbers/negative-noctal.js",
     "src/numbers/negative-octal.txt",

third-party/folly/src/folly/json/test/JsonTest.cpp

@@ -1358,3 +1358,37 @@ TEST(Json5, MinMaxHexNumbers) {
   EXPECT_EQ(parseJson(maxDoublePlusOne, numberAsString), maxDoublePlusOne);
   EXPECT_EQ(parseJson(minDoubleMinusOne, numberAsString), minDoubleMinusOne);
 }
+
+TEST(Json5, FormFeedWhitespace) {
+  // Form feed (\f = 0x0c) as whitespace
+  EXPECT_EQ(fromJson5("{\f\"a\":\ftrue\f}")["a"], true);
+  EXPECT_EQ(fromJson5("[\f1\f,\f2\f]")[0], 1);
+  EXPECT_EQ(fromJson5("\f42\f"), 42);
+
+  // Vertical tab (\v = 0x0b) as whitespace
+  EXPECT_EQ(fromJson5("{\v\"a\":\vtrue\v}")["a"], true);
+  EXPECT_EQ(fromJson5("\v42\v"), 42);
+
+  // Mixed with other whitespace
+  EXPECT_EQ(fromJson5("{ \f\v\t\n\"a\" : true }")["a"], true);
+
+  // Vertical tab and form feed between array elements
+  auto arr = fromJson5("[\v1\v,\f2\f,\v3\v]");
+  EXPECT_EQ(arr[0], 1);
+  EXPECT_EQ(arr[1], 2);
+  EXPECT_EQ(arr[2], 3);
+
+  // Form feed between object key-value pairs
+  auto obj = fromJson5("{\"a\":\f1\f,\f\"b\":\f2}");
+  EXPECT_EQ(obj["a"], 1);
+  EXPECT_EQ(obj["b"], 2);
+
+  // Vertical tab before/after string values
+  EXPECT_EQ(fromJson5("\v\"hello\"\v"), "hello");
+
+  // Form feed only (no value) should fail
+  EXPECT_THROW(fromJson5("\f"), std::exception);
+
+  // Without json5 flag, form feed should fail
+  EXPECT_THROW(parseJson("\f42"), std::exception);
+}