Enable flatbuffer to initialize Parser from bfbs (#4283) (#5077)

* Enable flatbuffer to initialize Parser from bfbs (#4283)

Now its possible to generate json data from bfbs data type and flatbuffers data
and visa versa.

* add deserialize functionality in parser from bfbs
* add small usage sample

* Fix build break

* Merge branch 'pr/1' into fix-issue4283

* Fix buildbreak

* Build monster_test.bfbs with --bfbs-builtins

Attribute flexbuffer has be included in bfbs. Only with this attribute test
will run. By initialization a parser by a bfbs the attribute has to be known
for this filed. monsterdata_test.golden has a flexbuffer field so parse would
fail.

* Fix generate_code.sh

* Revert automatic indent changes by IDE

* Auto detect size prefixed binary schema files

* Use identifier (bfbs) to detect schema files

include/flatbuffers/flatc.h

@@ -80,6 +80,9 @@ class FlatCompiler {
                  const std::string &contents,
                  std::vector<const char *> &include_directories) const;
 
+  void LoadBinarySchema(Parser &parser, const std::string &filename,
+                        const std::string &contents);
+
   void Warn(const std::string &warn, bool show_exe_name = true) const;
 
   void Error(const std::string &err, bool usage = true,

include/flatbuffers/idl.h

@@ -153,6 +153,8 @@ struct Type {
 
   Offset<reflection::Type> Serialize(FlatBufferBuilder *builder) const;
 
+  bool Deserialize(const Parser &parser, const reflection::Type *type);
+
   BaseType base_type;
   BaseType element;       // only set if t == BASE_TYPE_VECTOR
   StructDef *struct_def;  // only set if t or element == BASE_TYPE_STRUCT
@@ -235,6 +237,9 @@ struct Definition {
       flatbuffers::Vector<flatbuffers::Offset<reflection::KeyValue>>>
   SerializeAttributes(FlatBufferBuilder *builder, const Parser &parser) const;
 
+  bool DeserializeAttributes(Parser &parser,
+                             const Vector<Offset<reflection::KeyValue>> *attrs);
+
   std::string name;
   std::string file;
   std::vector<std::string> doc_comment;
@@ -261,6 +266,8 @@ struct FieldDef : public Definition {
   Offset<reflection::Field> Serialize(FlatBufferBuilder *builder, uint16_t id,
                                       const Parser &parser) const;
 
+  bool Deserialize(Parser &parser, const reflection::Field *field);
+
   Value value;
   bool deprecated;  // Field is allowed to be present in old data, but can't be.
                     // written in new data nor accessed in new code.
@@ -291,6 +298,8 @@ struct StructDef : public Definition {
   Offset<reflection::Object> Serialize(FlatBufferBuilder *builder,
                                        const Parser &parser) const;
 
+  bool Deserialize(Parser &parser, const reflection::Object *object);
+
   SymbolTable<FieldDef> fields;
 
   bool fixed;       // If it's struct, not a table.
@@ -317,9 +326,12 @@ inline size_t InlineAlignment(const Type &type) {
 
 struct EnumVal {
   EnumVal(const std::string &_name, int64_t _val) : name(_name), value(_val) {}
+  EnumVal(){};
 
   Offset<reflection::EnumVal> Serialize(FlatBufferBuilder *builder, const Parser &parser) const;
 
+  bool Deserialize(const Parser &parser, const reflection::EnumVal *val);
+
   std::string name;
   std::vector<std::string> doc_comment;
   int64_t value;
@@ -340,6 +352,8 @@ struct EnumDef : public Definition {
 
   Offset<reflection::Enum> Serialize(FlatBufferBuilder *builder, const Parser &parser) const;
 
+  bool Deserialize(Parser &parser, const reflection::Enum *values);
+
   SymbolTable<EnumVal> vals;
   bool is_union;
   // Type is a union which uses type aliases where at least one type is
@@ -358,11 +372,14 @@ inline bool EqualByName(const Type &a, const Type &b) {
 struct RPCCall : public Definition {
   Offset<reflection::RPCCall> Serialize(FlatBufferBuilder *builder, const Parser &parser) const;
 
+  bool Deserialize(Parser &parser, const reflection::RPCCall *call);
+
   StructDef *request, *response;
 };
 
 struct ServiceDef : public Definition {
   Offset<reflection::Service> Serialize(FlatBufferBuilder *builder, const Parser &parser) const;
+  bool Deserialize(Parser &parser, const reflection::Service *service);
 
   SymbolTable<RPCCall> calls;
 };
@@ -647,6 +664,15 @@ class Parser : public ParserState {
   // See reflection/reflection.fbs
   void Serialize();
 
+  // Deserialize a schema buffer
+  bool Deserialize(const uint8_t *buf, const size_t size);
+
+  // Fills internal structure as if the schema passed had been loaded by parsing
+  // with Parse except that included filenames will not be populated.
+  bool Deserialize(const reflection::Schema* schema);
+
+  Type* DeserializeType(const reflection::Type* type);
+  
   // Checks that the schema represented by this parser is a safe evolution
   // of the schema provided. Returns non-empty error on any problems.
   std::string ConformTo(const Parser &base);
@@ -661,6 +687,8 @@ class Parser : public ParserState {
 
   StructDef *LookupStruct(const std::string &id) const;
 
+  std::string UnqualifiedName(std::string fullQualifiedName);
+
  private:
   void Message(const std::string &msg);
   void Warning(const std::string &msg);