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https://github.com/ehwan/rustylr
GLR, LR(1) LALR(1) parser generator for Rust with custom reduce action
https://github.com/ehwan/rustylr
automata automaton bison code-generation compiler compiler-compiler deterministic-finite-automata dfa glr glr-parser lalr-parser lalr1 lr1 lr1-parser non-deterministic-finite-automaton parser parser-generator rust rust-lang yacc
Last synced: 3 months ago
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GLR, LR(1) LALR(1) parser generator for Rust with custom reduce action
- Host: GitHub
- URL: https://github.com/ehwan/rustylr
- Owner: ehwan
- License: apache-2.0
- Created: 2024-07-13T03:30:16.000Z (7 months ago)
- Default Branch: main
- Last Pushed: 2024-10-26T14:42:38.000Z (3 months ago)
- Last Synced: 2024-10-27T09:04:41.719Z (3 months ago)
- Topics: automata, automaton, bison, code-generation, compiler, compiler-compiler, deterministic-finite-automata, dfa, glr, glr-parser, lalr-parser, lalr1, lr1, lr1-parser, non-deterministic-finite-automaton, parser, parser-generator, rust, rust-lang, yacc
- Language: Rust
- Homepage: https://docs.rs/rusty_lr
- Size: 1.16 MB
- Stars: 9
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE-APACHE
Awesome Lists containing this project
README
# rusty_lr
[](https://crates.io/crates/rusty_lr)
[](https://docs.rs/rusty_lr)
GLR, LR(1) and LALR(1) parser generator for Rust.
Please refer to [docs.rs](https://docs.rs/rusty_lr) for detailed example and documentation.
## Cargo Features
- `build` : Enable buildscript tools.
- `fxhash` : In parser table, replace `std::collections::HashMap` with `FxHashMap` from [`rustc-hash`](https://github.com/rust-lang/rustc-hash).
- `tree` : Enable automatic syntax tree construction.
This feature should be used on debug purpose only, since it will consume much more memory and time.
- `error` : Enable detailed parsing error messages, for `Display` and `Debug` trait.
This feature should be used on debug purpose only, since it will consume much more memory and time.
## Features
- GLR, LR(1) and LALR(1) parser generator
- Multiple paths of parsing with GLR parser
- Provides procedural macros and buildscript tools
- readable error messages, both for parsing and building grammar
- customizable reduce action
- resolving conflicts of ambiguous grammar
- regex patterns partially supported
## Example
```rust
// this define `EParser` struct
// where `E` is the start symbol
lr1! {
%userdata i32; // userdata type
%tokentype char; // token type
%start E; // start symbol
%eof '\0'; // eof token
// token definition
%token zero '0';
%token one '1';
%token two '2';
%token three '3';
%token four '4';
%token five '5';
%token six '6';
%token seven '7';
%token eight '8';
%token nine '9';
%token plus '+';
%token star '*';
%token lparen '(';
%token rparen ')';
%token space ' ';
// conflict resolving
%left [plus star]; // reduce first for token 'plus', 'star'
// context-free grammars
Digit(char): [zero-nine]; // character set '0' to '9'
Number(i32) // type assigned to production rule `Number`
: space* Digit+ space* // regex pattern
{ Digit.into_iter().collect::().parse().unwrap() }; // this will be the value of `Number`
// reduce action written in Rust code
A(f32): A plus a2=A {
*data += 1; // access userdata by `data`
println!( "{:?} {:?} {:?}", A, plus, a2 );
A + a2 // this will be the value of `A`
}
| M
;
M(f32): M star m2=M { M * m2 }
| P
;
P(f32): Number { Number as f32 }
| space* lparen E rparen space* { E }
;
E(f32) : A ;
}
```
```rust
let parser = EParser::new(); // generate `EParser`
let mut context = EContext::new(); // create context
let mut userdata: i32 = 0; // define userdata
let input_sequence = "1 + 2 * ( 3 + 4 )";
// start feeding tokens
for token in input_sequence.chars() {
match context.feed(&parser, token, &mut userdata) {
// ^^^^^ ^^^^^^^^^^^^ userdata passed here as `&mut i32`
// feed token
Ok(_) => {}
Err(e) => {
match e {
EParseError::InvalidTerminal(invalid_terminal) => {
...
}
EParseError::ReduceAction(error_from_reduce_action) => {
...
}
}
println!("{}", e);
// println!( "{}", e.long_message( &parser, &context ) );
return;
}
}
}
context.feed(&parser, '\0', &mut userdata).unwrap(); // feed `eof` token
let res = context.accept(); // get the value of start symbol
println!("{}", res);
println!("userdata: {}", userdata);
```
## Readable error messages (with [codespan](https://github.com/brendanzab/codespan))
- This error message is generated by the buildscript tool, not the procedural macros.
## Visualized syntax tree
- With `tree` feature enabled.
## detailed `ParseError` message
- With `error` feature enabled.
## Syntax
See [SYNTAX.md](SYNTAX.md) for details of grammar-definition syntax.
- [Bootstrap](rusty_lr_parser/src/parser/parser.rs): rusty_lr syntax is written in rusty_lr itself.
## Contribution
- Any contribution is welcome.
- Please feel free to open an issue or pull request.
## License (Since 2.8.0)
Either of
- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
## Other Examples
- [Simple Calculator](examples/calculator_u8/src/parser.rs)
- [lua 5.4 syntax parser](https://github.com/ehwan/lua_rust)