https://github.com/langston-barrett/mogglo

Multi-language AST-based code search and rewriting tool that supports embedding Lua code in patterns
https://github.com/langston-barrett/mogglo

ast code-search codemod lua refactoring semantic-search tree-sitter

Last synced: 21 days ago
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Multi-language AST-based code search and rewriting tool that supports embedding Lua code in patterns

• Host: GitHub
• URL: https://github.com/langston-barrett/mogglo
• Owner: langston-barrett
• License: mit
• Created: 2023-03-26T16:31:14.000Z (almost 2 years ago)
• Default Branch: main
• Last Pushed: 2024-07-08T01:54:35.000Z (7 months ago)
• Last Synced: 2025-01-01T03:09:51.378Z (28 days ago)
• Topics: ast, code-search, codemod, lua, refactoring, semantic-search, tree-sitter
• Language: Rust
• Homepage: https://langston-barrett.github.io/mogglo/
• Size: 1.25 MB
• Stars: 29
• Watchers: 2
• Forks: 1
• Open Issues: 14
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# Mogglo

Mogglo is a multi-language AST-based code search and rewriting tool. Mogglo

supports embedding [Lua][lua] code in search patterns and replacements.

Mogglo focuses on the following goals:

- *Minimal setup*: Mogglo will work right away on any codebase in a

  supported language.

- *Many languages*: 12 and counting!

- *High-quality grammars*: Mogglo is based on [tree-sitter][tree-sitter]

  grammars.

- *Lua*: Mogglo exposes a rich API to embedded Lua snippets.

[lua]: https://www.lua.org/

[tree-sitter]: https://tree-sitter.github.io/tree-sitter/

## Introduction

The following examples give a taste of Mogglo. Here's how to find pointless

assignments of an expression to itself:

```sh

mogglo-rust --detail 'let $x = $x;' ./**/*.rs

```

Lua code is wrapped in braces. Lua can recursively match patterns with `rec`.

Here's a pattern to detect out-of-bounds array accesses:

```sh

mogglo-rust 'while $i <= $buf.len() { ${{ rec("$buf.get($i)") }} }' ./**/*.rs

```

Here's how to [unroll][unroll] a simple loop:

```sh

mogglo-rust \

  'for $i in 0..$h { $b; }' \

  --where 'h_num = tonumber(h); return h_num ~= nil and h_num % 4 == 0' \

  --replace 'for $i in 0..${{ string.format("%.0f", h / 4) }} { $b; $b; $b; $b; }' \

  ./*/**.rs

```

This transformation demonstrates the power of using Lua: it can't be done with

regular expression substitutions and would be very difficult with other codemod

tools.

See [the documentation][doc] for more details!

[doc]: https://langston-barrett.github.io/mogglo/

[cargo]: https://doc.rust-lang.org/cargo/

[crates-io]: https://crates.io/

[releases]: https://github.com/langston-barrett/mogglo/releases

[rustup]: https://rustup.rs/

[unroll]: https://en.wikipedia.org/wiki/Loop_unrolling