116 lines
3.1 KiB
Markdown
116 lines
3.1 KiB
Markdown
# Rust Tree-sitter
|
|
|
|
[](https://crates.io/crates/tree-sitter)
|
|
|
|
Rust bindings to the [Tree-sitter][] parsing library.
|
|
|
|
### Basic Usage
|
|
|
|
First, create a parser:
|
|
|
|
```rust
|
|
use tree_sitter::{Parser, Language};
|
|
|
|
let mut parser = Parser::new();
|
|
```
|
|
|
|
Tree-sitter languages consist of generated C code. To make sure they're properly compiled and linked, you can create a [build script](https://doc.rust-lang.org/cargo/reference/build-scripts.html) like the following (assuming `tree-sitter-javascript` is in your root directory):
|
|
|
|
```rust
|
|
use std::path::PathBuf;
|
|
|
|
fn main() {
|
|
let dir: PathBuf = ["tree-sitter-javascript", "src"].iter().collect();
|
|
|
|
cc::Build::new()
|
|
.include(&dir)
|
|
.file(dir.join("parser.c"))
|
|
.file(dir.join("scanner.c"))
|
|
.compile("tree-sitter-javascript");
|
|
}
|
|
```
|
|
|
|
Add the `cc` crate to your `Cargo.toml` under `[build-dependencies]`:
|
|
|
|
```toml
|
|
[build-dependencies]
|
|
cc="*"
|
|
```
|
|
|
|
To then use languages from rust, you must declare them as `extern "C"` functions and invoke them with `unsafe`. Then you can assign them to the parser.
|
|
|
|
```rust
|
|
extern "C" { fn tree_sitter_c() -> Language; }
|
|
extern "C" { fn tree_sitter_rust() -> Language; }
|
|
extern "C" { fn tree_sitter_javascript() -> Language; }
|
|
|
|
let language = unsafe { tree_sitter_rust() };
|
|
parser.set_language(language).unwrap();
|
|
```
|
|
|
|
Now you can parse source code:
|
|
|
|
```rust
|
|
let source_code = "fn test() {}";
|
|
let tree = parser.parse(source_code, None).unwrap();
|
|
let root_node = tree.root_node();
|
|
|
|
assert_eq!(root_node.kind(), "source_file");
|
|
assert_eq!(root_node.start_position().column, 0);
|
|
assert_eq!(root_node.end_position().column, 12);
|
|
```
|
|
|
|
### Editing
|
|
|
|
Once you have a syntax tree, you can update it when your source code changes. Passing in the previous edited tree makes `parse` run much more quickly:
|
|
|
|
```rust
|
|
let new_source_code = "fn test(a: u32) {}"
|
|
|
|
tree.edit(InputEdit {
|
|
start_byte: 8,
|
|
old_end_byte: 8,
|
|
new_end_byte: 14,
|
|
start_position: Point::new(0, 8),
|
|
old_end_position: Point::new(0, 8),
|
|
new_end_position: Point::new(0, 14),
|
|
});
|
|
|
|
let new_tree = parser.parse(new_source_code, Some(&tree));
|
|
```
|
|
|
|
### Text Input
|
|
|
|
The source code to parse can be provided either as a string, a slice, a vector, or as a function that returns a slice. The text can be encoded as either UTF8 or UTF16:
|
|
|
|
```rust
|
|
// Store some source code in an array of lines.
|
|
let lines = &[
|
|
"pub fn foo() {",
|
|
" 1",
|
|
"}",
|
|
];
|
|
|
|
// Parse the source code using a custom callback. The callback is called
|
|
// with both a byte offset and a row/column offset.
|
|
let tree = parser.parse_with(&mut |_byte: u32, position: Point| -> &[u8] {
|
|
let row = position.row as usize;
|
|
let column = position.column as usize;
|
|
if row < lines.len() {
|
|
if column < lines[row].as_bytes().len() {
|
|
&lines[row].as_bytes()[column..]
|
|
} else {
|
|
"\n".as_bytes()
|
|
}
|
|
} else {
|
|
&[]
|
|
}
|
|
}, None).unwrap();
|
|
|
|
assert_eq!(
|
|
tree.root_node().to_sexp(),
|
|
"(source_file (function_item (visibility_modifier) (identifier) (parameters) (block (number_literal))))"
|
|
);
|
|
```
|
|
|
|
[tree-sitter]: https://github.com/tree-sitter/tree-sitter
|