mirror of https://github.com/jkjoy/sunpeiwen.git
69 lines
1.7 KiB
Markdown
69 lines
1.7 KiB
Markdown
# token-stream
|
|
|
|
Take an array of token and produce a more useful API to give to a parser.
|
|
|
|
[](https://travis-ci.org/pugjs/token-stream)
|
|
[](https://david-dm.org/pugjs/token-stream)
|
|
[](https://www.npmjs.org/package/token-stream)
|
|
|
|
## Installation
|
|
|
|
npm install token-stream
|
|
|
|
## Usage
|
|
|
|
```js
|
|
var TokenStream = require('token-stream');
|
|
|
|
var stream = new TokenStream([
|
|
'a',
|
|
'b',
|
|
'c',
|
|
'd'
|
|
]);
|
|
assert(stream.peek() === 'a');
|
|
assert(stream.lookahead(0) == 'a');
|
|
assert(stream.lookahead(1) == 'b');
|
|
|
|
assert(stream.advance() === 'a');
|
|
assert(stream.peek() === 'b');
|
|
assert(stream.lookahead(0) == 'b');
|
|
assert(stream.lookahead(1) == 'c');
|
|
|
|
stream.defer('z');
|
|
assert(stream.peek() === 'z');
|
|
assert(stream.lookahead(0) == 'z');
|
|
assert(stream.lookahead(1) == 'b');
|
|
assert(stream.advance() === 'z');
|
|
assert(stream.advance() === 'b');
|
|
assert(stream.advance() === 'c');
|
|
assert(stream.advance() === 'd');
|
|
|
|
// an error is thrown if you try and advance beyond the end of the stream
|
|
assert.throws(function () {
|
|
stream.advance();
|
|
});
|
|
```
|
|
|
|
## API
|
|
|
|
### stream.peek()
|
|
|
|
Gets and returns the next item in the stream without advancing the stream's position.
|
|
|
|
### stream.advance()
|
|
|
|
Returns the next item in the stream and advances the stream by one item.
|
|
|
|
### stream.defer(token)
|
|
|
|
Put a token on the start of the stream (useful if you need to back track after calling advance).
|
|
|
|
### stream.lookahead(index)
|
|
|
|
Return the item at `index` position from the start of the stream, but don't advance the stream. `stream.lookahead(0)` is equivalent to `stream.peek()`.
|
|
|
|
## License
|
|
|
|
MIT
|