Rust Tree-sitter
The Rust binding to Tree-sitter has been moved to the main Tree-sitter repo.
Rust bindings to the Tree-sitter parsing library.
Basic Usage
First, create a parser:
use tree_sitter::{Parser, Language};
// ...
let mut parser = Parser::new();Then assign a language to the parser. Tree-sitter languages consist of generated C code. To use them from rust, you must declare them as extern "C" functions and invoke them with unsafe:
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:
let source_code = "fn test() {}";
let tree = parser.parse_str(source_code, None);
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:
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_str(new_source_code, Some(&tree));Text Input
The source code to parse can be provided either as a string or as a function that returns text encoded as either UTF8 or UTF16:
// 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_utf8(&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))))"
);