syntax-parser is a parser using pure javascript, so it can both run in browser and nodejs.
syntax-parser supports:
createLexer
can help you create a lexer.
import { createLexer } from 'syntax-parser';
const myLexer = createLexer([
{
type: 'whitespace',
regexes: [/^(\s+)/],
ignore: true
},
{
type: 'word',
regexes: [/^([a-zA-Z0-9]+)/]
},
{
type: 'operator',
regexes: [/^(\+)/]
}
]);
myLexer('a + b');
// [
// { "type": "word", "value": "a", "position": [0, 1] },
// { "type": "operator", "value": "+", "position": [2, 3] },
// { "type": "word", "value": "b", "position": [4, 5] }
// ]
type
Token
type name, you can use any value here, and you will use it in the parser stage.
regexes
Regexes that use to be matched for each Token
type.
ignore
The matching Token
will not be added to the Token
result queue.
In general, whitespace can be ignored in syntax parsing.
createParser
can help you create a parser. Parser requires a lexer.
import { createParser, chain, matchTokenType, many } from 'syntax-parser';
const root = () => chain(addExpr)(ast => ast[0]);
const addExpr = () =>
chain(matchTokenType('word'), many(addPlus))(ast => ({
left: ast[0].value,
operator: ast[1] && ast[1][0].operator,
right: ast[1] && ast[1][0].term
}));
const addPlus = () =>
chain('+', root)(ast => ({
operator: ast[0].value,
term: ast[1]
}));
const myParser = createParser(
root, // Root grammar.
myLexer // Created in lexer example.
);
myParser('a + b');
// ast:
// [{
// "left": "a",
// "operator": "+",
// "right": {
// "left": "b",
// "operator": null,
// "right": null
// }
// }]
Basic grammatical element, support four parameters:
String means match token:
chain('select', 'table'); // Match 'select table'
Array means 'or':
chain('select', ['table', 'chart']); // Match both 'select table' and 'select chart'
matchTokenType
allow you match Token
type defined in lexer.
chain('select', matchTokenType('word')); // Match 'select [any word!]'
It's easy to call another chain function:
const a = () => chain('select', b);
const b = () => chain('table');
Just as literal meaning:
const a = () => chain('select', optional('table')); // Match both 'select' and 'select table'
const b = () => chain('select', many(',', matchTokenType('word'))); // Match both 'select' and 'select a' and 'select a, b' .. and so on.
optional
many
can also usechain
as parameter.many(chain(..))
The last callback allow partial redefin of local ast:
chain('select', 'table')(
ast => ast[0] // return 'select'
);
npm test
If you want to see this demo, run this command:
npm run docs
Then select demo Monaco Editor
.
此处可能存在不合适展示的内容,页面不予展示。您可通过相关编辑功能自查并修改。
如您确认内容无涉及 不当用语 / 纯广告导流 / 暴力 / 低俗色情 / 侵权 / 盗版 / 虚假 / 无价值内容或违法国家有关法律法规的内容,可点击提交进行申诉,我们将尽快为您处理。