PLY Protobuf

[Protocol Buffers] 0 lexer & parser written in Python for [PLY] 1.

With this library you can create and process parse trees of a Protocol Buffers files with Python. For example usage see demo.py.

My use case: automated refactoring of .proto files.

• Benefit of this project is support for easy refactoring of the protocol buffers files. From the parse result one can simply determine position of a particular lexical unit in the source text and replace it.
• The visitor pattern is used for processing a parse tree.

Dependency

• This project has only one dependency, [PLY] 1.
• ply/ subdirectory is present in this repo for demonstration purposes and completeness only. If you intend to use this project, prefer better original [PLY] 1 repository which is up-to-date.

Contributions

• There may be bugs although it works for me for quite complicated protocol buffers files. If you find a bug, please feel free to submit a pull request or file an issue.

Bugs

• Oneof is not implemented yet.

Demo 1

• demo.py
• The first demo file shows simple parsing of the example protocol buffer message. It produces a parse tree of this simple examples.

Demo 2 - Protocol Buffers file refactoring.

• prefixize.py
• Main use-case is rename refactoring of entities in Protocol Buffers.
• [Protocol Buffers Objetive C compiler] 5 does not prefix entities and this may conflict with some objects in the project. This script renames all entties in protobuf file by prefixing them wth specified string. Also identifiers with conflicting names can be renamed if specified by parameter (e.g., hash, description). Result of this refactoring can be then used with objeciveC protoc without conflicts.

Acknowledgement

This work was inspired by:

• [plyj] 2, Java lexer & parser for PLY.
• [pyparsing] 3, Protocol Buffers parsing example.
• [PLYTalk] 4, nice tutorial for PLY I used.

Disclaimer

• This project was created because I needed it for myself and I didn't find Protocol Buffers parser for PLY. It is my first PLY / parser generator project and the first version was created in couple hours so it is not polished code.
• There already exist Protocol Buffer parsing variant as [pyparsing] 3 example, but my previous scripts used PLY for parsing Java so I chosen to stay with PLY and to create Protocol Buffer variant for PLY. I like the output I can get from PLY (e.g., line, character position in the input text) so I can automatically process input files - e.g., refactoring.
• API for this project is not guaranteed to remain stable. In particular I mean model generated from .proto files. Initial model may be considered suboptimal and changed at some point. This project is intended to serve as an inspiration or a starting point. You will probably adapt it for your own needs.