Add default NaN/Inf to C#, Java, Python (#5107)

* Add default NaN/Inf to C#, Java, Python

* Python NaN/Inf test added

* Remove MSVC2010/13 dependent code

4 files changed, 133 insertions, 58 deletions

diff --git a/src/code_generators.cpp b/src/code_generators.cpp
index b78b5ca1..3b10db7f 100644
--- a/src/code_generators.cpp
+++ b/src/code_generators.cpp
@@ -188,6 +188,94 @@ std::string FloatConstantGenerator::GenFloatConstant(
   };
 }
 
+TypedFloatConstantGenerator::TypedFloatConstantGenerator(
+    const char *double_prefix, const char *single_prefix,
+    const char *nan_number, const char *pos_inf_number,
+    const char *neg_inf_number)
+    : double_prefix_(double_prefix),
+      single_prefix_(single_prefix),
+      nan_number_(nan_number),
+      pos_inf_number_(pos_inf_number),
+      neg_inf_number_(neg_inf_number) {}
+
+std::string TypedFloatConstantGenerator::MakeNaN(
+    const std::string &prefix) const {
+  return prefix + nan_number_;
+}
+std::string TypedFloatConstantGenerator::MakeInf(
+    bool neg, const std::string &prefix) const {
+  if (neg)
+    return !neg_inf_number_.empty() ? (prefix + neg_inf_number_)
+                                    : ("-" + prefix + pos_inf_number_);
+  else
+    return prefix + pos_inf_number_;
+}
+
+std::string TypedFloatConstantGenerator::Value(double v,
+                                               const std::string &src) const {
+  (void)v;
+  return src;
+}
+
+std::string TypedFloatConstantGenerator::Inf(double v) const {
+  return MakeInf(v < 0, double_prefix_);
+}
+
+std::string TypedFloatConstantGenerator::NaN(double v) const {
+  (void)v;
+  return MakeNaN(double_prefix_);
+}
+
+std::string TypedFloatConstantGenerator::Value(float v,
+                                               const std::string &src) const {
+  (void)v;
+  return src + "f";
+}
+
+std::string TypedFloatConstantGenerator::Inf(float v) const {
+  return MakeInf(v < 0, single_prefix_);
+}
+
+std::string TypedFloatConstantGenerator::NaN(float v) const {
+  (void)v;
+  return MakeNaN(single_prefix_);
+}
+
+SimpleFloatConstantGenerator::SimpleFloatConstantGenerator(
+    const char *nan_number, const char *pos_inf_number,
+    const char *neg_inf_number)
+    : nan_number_(nan_number),
+      pos_inf_number_(pos_inf_number),
+      neg_inf_number_(neg_inf_number) {}
+
+std::string SimpleFloatConstantGenerator::Value(double v,
+                                                const std::string &src) const {
+  (void)v;
+  return src;
+}
+
+std::string SimpleFloatConstantGenerator::Inf(double v) const {
+  return (v < 0) ? neg_inf_number_ : pos_inf_number_;
+}
+
+std::string SimpleFloatConstantGenerator::NaN(double v) const {
+  (void)v;
+  return nan_number_;
+}
+
+std::string SimpleFloatConstantGenerator::Value(float v,
+                                                const std::string &src) const {
+  return this->Value(static_cast<double>(v), src);
+}
+
+std::string SimpleFloatConstantGenerator::Inf(float v) const {
+  return this->Inf(static_cast<double>(v));
+}
+
+std::string SimpleFloatConstantGenerator::NaN(float v) const {
+  return this->NaN(static_cast<double>(v));
+}
+
 }  // namespace flatbuffers
 
 #if defined(_MSC_VER)
diff --git a/src/idl_gen_cpp.cpp b/src/idl_gen_cpp.cpp
index 06896d9c..9884081a 100644
--- a/src/idl_gen_cpp.cpp
+++ b/src/idl_gen_cpp.cpp
@@ -34,50 +34,15 @@ static std::string GeneratedFileName(const std::string &path,
 }
 
 namespace cpp {
-class CppFloatConstantGenerator : public FloatConstantGenerator {
- protected:
-  std::string Value(double v,
-                    const std::string &src) const FLATBUFFERS_OVERRIDE {
-    (void)v;
-    return src;
-  };
-
-  std::string Value(float v,
-                    const std::string &src) const FLATBUFFERS_OVERRIDE {
-    (void)v;
-    return src + "f";
-  }
-
-  std::string NaN(double v) const FLATBUFFERS_OVERRIDE {
-    (void)v;
-    return "std::numeric_limits<double>::quiet_NaN()";
-  }
-  std::string NaN(float v) const FLATBUFFERS_OVERRIDE {
-    (void)v;
-    return "std::numeric_limits<float>::quiet_NaN()";
-  }
-
-  std::string Inf(double v) const FLATBUFFERS_OVERRIDE {
-    if(v < 0)
-      return "-std::numeric_limits<double>::infinity()";
-    else
-      return "std::numeric_limits<double>::infinity()";
-  }
-
-  std::string Inf(float v) const FLATBUFFERS_OVERRIDE {
-    if (v < 0)
-      return "-std::numeric_limits<float>::infinity()";
-    else
-      return "std::numeric_limits<float>::infinity()";
-  }
-};
-
 class CppGenerator : public BaseGenerator {
  public:
   CppGenerator(const Parser &parser, const std::string &path,
                const std::string &file_name)
       : BaseGenerator(parser, path, file_name, "", "::"),
-        cur_name_space_(nullptr) {
+        cur_name_space_(nullptr),
+        float_const_gen_("std::numeric_limits<double>::",
+                         "std::numeric_limits<float>::", "quiet_NaN()",
+                         "infinity()") {
     static const char * const keywords[] = {
                                "alignas",
                                "alignof",
@@ -2785,7 +2750,7 @@ class CppGenerator : public BaseGenerator {
     cur_name_space_ = ns;
   }
 
-  const CppFloatConstantGenerator float_const_gen_;
+  const TypedFloatConstantGenerator float_const_gen_;
 };
 
 }  // namespace cpp
diff --git a/src/idl_gen_general.cpp b/src/idl_gen_general.cpp
index 66984da0..7c34ee28 100644
--- a/src/idl_gen_general.cpp
+++ b/src/idl_gen_general.cpp
@@ -58,9 +58,16 @@ struct LanguageParameters {
   std::string class_annotation;
   std::string generated_type_annotation;
   CommentConfig comment_config;
+  const FloatConstantGenerator *float_gen;
 };
 
 const LanguageParameters &GetLangParams(IDLOptions::Language lang) {
+  static TypedFloatConstantGenerator CSharpFloatGen(
+      "Double.", "Single.", "NaN", "PositiveInfinity", "NegativeInfinity");
+
+  static TypedFloatConstantGenerator JavaFloatGen(
+      "Double.", "Float.", "NaN", "POSITIVE_INFINITY", "NEGATIVE_INFINITY");
+
   static const LanguageParameters language_parameters[] = {
     {
         IDLOptions::kJava,
@@ -95,6 +102,7 @@ const LanguageParameters &GetLangParams(IDLOptions::Language lang) {
             " *",
             " */",
         },
+        &JavaFloatGen
     },
     {
         IDLOptions::kCSharp,
@@ -128,6 +136,7 @@ const LanguageParameters &GetLangParams(IDLOptions::Language lang) {
             "///",
             nullptr,
         },
+        &CSharpFloatGen
     },
   };
 
@@ -429,7 +438,8 @@ class GeneralGenerator : public BaseGenerator {
     return SourceCastBasic(type, true);
   }
 
-  std::string GenEnumDefaultValue(const Value &value) const {
+  std::string GenEnumDefaultValue(const FieldDef &field) const {
+    auto& value = field.value;
     auto enum_def = value.type.enum_def;
     auto vec = enum_def->vals.vec;
     auto default_value = StringToInt(value.constant.c_str());
@@ -446,19 +456,19 @@ class GeneralGenerator : public BaseGenerator {
     return result;
   }
 
-  std::string GenDefaultValue(const Value &value, bool enableLangOverrides) const {
+  std::string GenDefaultValue(const FieldDef &field, bool enableLangOverrides) const {
+    auto& value = field.value;
     if (enableLangOverrides) {
       // handles both enum case and vector of enum case
       if (lang_.language == IDLOptions::kCSharp &&
           value.type.enum_def != nullptr &&
           value.type.base_type != BASE_TYPE_UNION) {
-        return GenEnumDefaultValue(value);
+        return GenEnumDefaultValue(field);
       }
     }
 
     auto longSuffix = lang_.language == IDLOptions::kJava ? "L" : "";
     switch (value.type.base_type) {
-      case BASE_TYPE_FLOAT: return value.constant + "f";
       case BASE_TYPE_BOOL: return value.constant == "0" ? "false" : "true";
       case BASE_TYPE_ULONG: {
         if (lang_.language != IDLOptions::kJava) return value.constant;
@@ -468,16 +478,21 @@ class GeneralGenerator : public BaseGenerator {
       }
       case BASE_TYPE_UINT:
       case BASE_TYPE_LONG: return value.constant + longSuffix;
-      default: return value.constant;
+      default:
+        if(IsFloat(value.type.base_type))
+          return lang_.float_gen->GenFloatConstant(field);
+        else
+          return value.constant;
     }
   }
 
-  std::string GenDefaultValue(const Value &value) const {
-    return GenDefaultValue(value, true);
+  std::string GenDefaultValue(const FieldDef &field) const {
+    return GenDefaultValue(field, true);
   }
 
-  std::string GenDefaultValueBasic(const Value &value,
+  std::string GenDefaultValueBasic(const FieldDef &field,
                                    bool enableLangOverrides) const {
+    auto& value = field.value;
     if (!IsScalar(value.type.base_type)) {
       if (enableLangOverrides) {
         if (lang_.language == IDLOptions::kCSharp) {
@@ -493,11 +508,11 @@ class GeneralGenerator : public BaseGenerator {
       }
       return "0";
     }
-    return GenDefaultValue(value, enableLangOverrides);
+    return GenDefaultValue(field, enableLangOverrides);
   }
 
-  std::string GenDefaultValueBasic(const Value &value) const {
-    return GenDefaultValueBasic(value, true);
+  std::string GenDefaultValueBasic(const FieldDef &field) const {
+    return GenDefaultValueBasic(field, true);
   }
 
   void GenEnum(EnumDef &enum_def, std::string *code_ptr) const {
@@ -956,7 +971,7 @@ class GeneralGenerator : public BaseGenerator {
           code += offset_prefix + getter;
           code += "(o + " + lang_.accessor_prefix + "bb_pos)" + dest_mask;
           code += " : " + default_cast;
-          code += GenDefaultValue(field.value);
+          code += GenDefaultValue(field);
         }
       } else {
         switch (field.value.type.base_type) {
@@ -1278,7 +1293,7 @@ class GeneralGenerator : public BaseGenerator {
           // supply all arguments, and thus won't compile when fields are added.
           if (lang_.language != IDLOptions::kJava) {
             code += " = ";
-            code += GenDefaultValueBasic(field.value);
+            code += GenDefaultValueBasic(field);
           }
         }
         code += ") {\n    builder.";
@@ -1338,7 +1353,7 @@ class GeneralGenerator : public BaseGenerator {
         code += ", ";
         if (lang_.language == IDLOptions::kJava)
           code += SourceCastBasic(field.value.type);
-        code += GenDefaultValue(field.value, false);
+        code += GenDefaultValue(field, false);
         code += "); }\n";
         if (field.value.type.base_type == BASE_TYPE_VECTOR) {
           auto vector_type = field.value.type.VectorType();
diff --git a/src/idl_gen_python.cpp b/src/idl_gen_python.cpp
index 11491c00..fbb0805c 100644
--- a/src/idl_gen_python.cpp
+++ b/src/idl_gen_python.cpp
@@ -36,7 +36,8 @@ class PythonGenerator : public BaseGenerator {
   PythonGenerator(const Parser &parser, const std::string &path,
                   const std::string &file_name)
       : BaseGenerator(parser, path, file_name, "" /* not used */,
-                      "" /* not used */){
+                      "" /* not used */),
+        float_const_gen_("float('nan')", "float('inf')", "float('-inf')") {
     static const char * const keywords[] = {
       "False",
       "None",
@@ -191,7 +192,7 @@ class PythonGenerator : public BaseGenerator {
     code += "(self):";
     code += OffsetPrefix(field);
     getter += "o + self._tab.Pos)";
-    auto is_bool = field.value.type.base_type == BASE_TYPE_BOOL;
+    auto is_bool = IsBool(field.value.type.base_type);
     if (is_bool) {
       getter = "bool(" + getter + ")";
     }
@@ -200,7 +201,9 @@ class PythonGenerator : public BaseGenerator {
     if (is_bool) {
       default_value = field.value.constant == "0" ? "False" : "True";
     } else {
-      default_value = field.value.constant;
+      default_value = IsFloat(field.value.type.base_type)
+                          ? float_const_gen_.GenFloatConstant(field)
+                          : field.value.constant;
     }
     code += Indent + Indent + "return " + default_value + "\n\n";
   }
@@ -452,7 +455,10 @@ class PythonGenerator : public BaseGenerator {
     } else {
       code += MakeCamel(NormalizedName(field), false);
     }
-    code += ", " + field.value.constant;
+    code += ", ";
+    code += IsFloat(field.value.type.base_type)
+                ? float_const_gen_.GenFloatConstant(field)
+                : field.value.constant;
     code += ")\n";
   }
 
@@ -715,6 +721,7 @@ class PythonGenerator : public BaseGenerator {
   }
  private:
   std::unordered_set<std::string> keywords_;
+  const SimpleFloatConstantGenerator float_const_gen_;
 };
 
 }  // namespace python