From 69b329fc87e7a10f84a0bd012e74e3af7549526d Mon Sep 17 00:00:00 2001
From: Vladimir Glavnyy <31897320+vglavnyy@users.noreply.github.com>
Date: Tue, 16 Mar 2021 01:44:42 +0700
Subject: [PATCH] [flexbuffers, json] Parse `nan` and `inf` (#6512)

---
 include/flatbuffers/idl.h |  2 ++
 src/idl_parser.cpp        | 24 ++++++++++++++++++++++++
 tests/test.cpp            | 26 ++++++++++++++++++++++++++
 3 files changed, 52 insertions(+)

diff --git a/include/flatbuffers/idl.h b/include/flatbuffers/idl.h
index d9ef95b..ab77893 100644
--- a/include/flatbuffers/idl.h
+++ b/include/flatbuffers/idl.h
@@ -956,6 +956,8 @@ class Parser : public ParserState {
   FLATBUFFERS_CHECKED_ERROR ParseProtoCurliesOrIdent();
   FLATBUFFERS_CHECKED_ERROR ParseTypeFromProtoType(Type *type);
   FLATBUFFERS_CHECKED_ERROR SkipAnyJsonValue();
+  FLATBUFFERS_CHECKED_ERROR ParseFlexBufferNumericConstant(
+      flexbuffers::Builder *builder);
   FLATBUFFERS_CHECKED_ERROR ParseFlexBufferValue(flexbuffers::Builder *builder);
   FLATBUFFERS_CHECKED_ERROR StartParseFile(const char *source,
                                            const char *source_filename);
diff --git a/src/idl_parser.cpp b/src/idl_parser.cpp
index 6faee4d..f20b6f9 100644
--- a/src/idl_parser.cpp
+++ b/src/idl_parser.cpp
@@ -3009,6 +3009,15 @@ CheckedError Parser::SkipAnyJsonValue() {
   return NoError();
 }
 
+CheckedError Parser::ParseFlexBufferNumericConstant(
+    flexbuffers::Builder *builder) {
+  double d;
+  if (!StringToNumber(attribute_.c_str(), &d))
+    return Error("unexpected floating-point constant: " + attribute_);
+  builder->Double(d);
+  return NoError();
+}
+
 CheckedError Parser::ParseFlexBufferValue(flexbuffers::Builder *builder) {
   ParseDepthGuard depth_guard(this);
   ECHECK(depth_guard.Check());
@@ -3056,6 +3065,18 @@ CheckedError Parser::ParseFlexBufferValue(flexbuffers::Builder *builder) {
       EXPECT(kTokenFloatConstant);
       break;
     }
+    case '-':
+    case '+': {
+      // `[-+]?(nan|inf|infinity)`, see ParseSingleValue().
+      const auto sign = static_cast<char>(token_);
+      NEXT();
+      if (token_ != kTokenIdentifier)
+        return Error("floating-point constant expected");
+      attribute_.insert(0, 1, sign);
+      ECHECK(ParseFlexBufferNumericConstant(builder));
+      NEXT();
+      break;
+    }
     default:
       if (IsIdent("true")) {
         builder->Bool(true);
@@ -3066,6 +3087,9 @@ CheckedError Parser::ParseFlexBufferValue(flexbuffers::Builder *builder) {
       } else if (IsIdent("null")) {
         builder->Null();
         NEXT();
+      } else if (IsIdent("inf") || IsIdent("infinity") || IsIdent("nan")) {
+        ECHECK(ParseFlexBufferNumericConstant(builder));
+        NEXT();
       } else
         return TokenError();
   }
diff --git a/tests/test.cpp b/tests/test.cpp
index ffd293d..87568c2 100644
--- a/tests/test.cpp
+++ b/tests/test.cpp
@@ -3020,6 +3020,31 @@ void FlexBuffersTest() {
   TEST_EQ(slb.GetSize(), 664);
 }
 
+void FlexBuffersFloatingPointTest() {
+#if defined(FLATBUFFERS_HAS_NEW_STRTOD) && (FLATBUFFERS_HAS_NEW_STRTOD > 0)
+  flexbuffers::Builder slb(512,
+                           flexbuffers::BUILDER_FLAG_SHARE_KEYS_AND_STRINGS);
+  // Parse floating-point values from JSON:
+  flatbuffers::Parser parser;
+  slb.Clear();
+  auto jsontest =
+      "{ a: [1.0, nan, inf, infinity, -inf, +inf, -infinity, 8.0] }";
+  TEST_EQ(parser.ParseFlexBuffer(jsontest, nullptr, &slb), true);
+  auto jroot = flexbuffers::GetRoot(slb.GetBuffer());
+  auto jmap = jroot.AsMap();
+  auto jvec = jmap["a"].AsVector();
+  TEST_EQ(8, jvec.size());
+  TEST_EQ(1.0, jvec[0].AsDouble());
+  TEST_ASSERT(is_quiet_nan(jvec[1].AsDouble()));
+  TEST_EQ(infinity_d, jvec[2].AsDouble());
+  TEST_EQ(infinity_d, jvec[3].AsDouble());
+  TEST_EQ(-infinity_d, jvec[4].AsDouble());
+  TEST_EQ(+infinity_d, jvec[5].AsDouble());
+  TEST_EQ(-infinity_d, jvec[6].AsDouble());
+  TEST_EQ(8.0, jvec[7].AsDouble());
+#endif
+}
+
 void FlexBuffersDeprecatedTest() {
   // FlexBuffers as originally designed had a flaw involving the
   // FBT_VECTOR_STRING datatype, and this test documents/tests the fix for it.
@@ -3909,6 +3934,7 @@ int FlatBufferTests() {
   FieldIdentifierTest();
   StringVectorDefaultsTest();
   ParseIncorrectMonsterJsonTest();
+  FlexBuffersFloatingPointTest();
   return 0;
 }
 
-- 
2.7.4