618 releases (5 major breaking)
new 5.0.0 | Nov 6, 2024 |
---|---|
4.0.0 | Nov 1, 2024 |
3.0.1 | Oct 31, 2024 |
2.0.0 | Oct 29, 2024 |
0.5.4 | Nov 26, 2018 |
#279 in Parser implementations
241,184 downloads per month
Used in 304 crates
(107 directly)
2.5MB
70K
SLoC
EcmaScript/TypeScript parser for the rust programming language.
Features
Heavily tested
Passes almost all tests from tc39/test262.
Error reporting
error: 'implements', 'interface', 'let', 'package', 'private', 'protected', 'public', 'static', or 'yield' cannot be used as an identifier in strict mode
--> invalid.js:3:10
|
3 | function yield() {
| ^^^^^
Error recovery
The parser can recover from some parsing errors. For example, parser returns
Ok(Module)
for the code below, while emitting error to handler.
const CONST = 9000 % 2;
const enum D {
// Comma is required, but parser can recover because of the newline.
d = 10
g = CONST
}
Example (lexer)
See lexer.rs
in examples directory.
Example (parser)
#[macro_use]
extern crate swc_common;
extern crate swc_ecma_parser;
use swc_common::sync::Lrc;
use swc_common::{
errors::{ColorConfig, Handler},
FileName, FilePathMapping, SourceMap,
};
use swc_ecma_parser::{lexer::Lexer, Parser, StringInput, Syntax};
fn main() {
let cm: Lrc<SourceMap> = Default::default();
let handler =
Handler::with_tty_emitter(ColorConfig::Auto, true, false,
Some(cm.clone()));
// Real usage
// let fm = cm
// .load_file(Path::new("test.js"))
// .expect("failed to load test.js");
let fm = cm.new_source_file(
FileName::Custom("test.js".into()).into(),
"function foo() {}".into(),
);
let lexer = Lexer::new(
// We want to parse ecmascript
Syntax::Es(Default::default()),
// EsVersion defaults to es5
Default::default(),
StringInput::from(&*fm),
None,
);
let mut parser = Parser::new_from(lexer);
for e in parser.take_errors() {
e.into_diagnostic(&handler).emit();
}
let _module = parser
.parse_module()
.map_err(|mut e| {
// Unrecoverable fatal error occurred
e.into_diagnostic(&handler).emit()
})
.expect("failed to parser module");
}
Cargo features
typescript
Enables typescript parser.
verify
Verify more errors, using swc_ecma_visit
.
Known issues
Null character after \
Because [String] of rust should only contain valid utf-8 characters while javascript allows non-utf8 characters, the parser stores invalid utf8 characters in escaped form.
As a result, swc needs a way to distinguish invalid-utf8 code points and
input specified by the user. The parser stores a null character right after
\\
for non-utf8 code points. Note that other parts of swc is aware of this
fact.
Note that this can be changed at anytime with a breaking change.
Dependencies
~7–15MB
~175K SLoC