Refactor languages to use CodeGenerator interface. (#7797)

* Refactor to use CodeGenerator interface.

- Move code to its own header file to be included in flatc_main.cpp
- Refactor code to use CodeGenerator interface for all languages

* Format all files

* remove lua code generator since it doesn't support bfbs generator

* Update CMakeLists file with new idl_gen_*.cpp and idl_gen_*.h files

* Add idl_gen_swift header file

* Add idl_gen_swift header file and update bazel file

* Remove CodeGenerator interface for idl_gen_text.*. Remove comments and extern declaration

* Reorder header and implementation files in CMakeLists.txt

* Add idl_gen_* header files to implementation files

* Update CMakeLists and remove unused import

Co-authored-by: Derek Bailey <derekbailey@google.com>

src/idl_gen_python.cpp

@@ -16,6 +16,8 @@
 
 // independent from idl_parser, since this code is not needed for most clients
 
+#include "idl_gen_python.h"
+
 #include <cctype>
 #include <set>
 #include <string>
@@ -1912,4 +1914,50 @@ bool GeneratePython(const Parser &parser, const std::string &path,
   return generator.generate();
 }
 
+namespace {
+
+class PythonCodeGenerator : public CodeGenerator {
+ public:
+  Status GenerateCode(const Parser &parser, const std::string &path,
+                      const std::string &filename) override {
+    if (!GeneratePython(parser, path, filename)) { return Status::ERROR; }
+    return Status::OK;
+  }
+
+  Status GenerateCode(const uint8_t *buffer, int64_t length) override {
+    (void)buffer;
+    (void)length;
+    return Status::NOT_IMPLEMENTED;
+  }
+
+  Status GenerateMakeRule(const Parser &parser, const std::string &path,
+                          const std::string &filename,
+                          std::string &output) override {
+    (void)parser;
+    (void)path;
+    (void)filename;
+    (void)output;
+    return Status::NOT_IMPLEMENTED;
+  }
+
+  Status GenerateGrpcCode(const Parser &parser, const std::string &path,
+                          const std::string &filename) override {
+    if (!GeneratePythonGRPC(parser, path, filename)) { return Status::ERROR; }
+    return Status::OK;
+  }
+
+  bool IsSchemaOnly() const override { return true; }
+
+  bool SupportsBfbsGeneration() const override { return false; }
+
+  IDLOptions::Language Language() const override { return IDLOptions::kPython; }
+
+  std::string LanguageName() const override { return "Python"; }
+};
+}  // namespace
+
+std::unique_ptr<CodeGenerator> NewPythonCodeGenerator() {
+  return std::unique_ptr<PythonCodeGenerator>(new PythonCodeGenerator());
+}
+
 }  // namespace flatbuffers