regex-trigram


regex-trigram-js
================

This project ports some ideas Russ Cox shared on
how Google Code Search works — in
particular the RegexpQuery and related functions —
from Go to JavaScript. Since JavaScript doesn't have an equivalent to Go's regexp/syntax,
use PEG.js to introduce a simplified regular
expression grammar and obtain a parse tree.

The goal is to query trigram indexes from JS clients.

Usage
-----

Include the library.

``javascript
var regex = require('regex-trigram');
`

Parse a regular expression.

`javascript
var re = regex.parse("a[bc]d");
console.log(JSON.stringify(re, null, 2));
`

Which should look like:

`json
{
"type": "concat",
"value": [
{
"type": "literal",
"value": "a"
},
{
"type": "concat",
"value": [
{
"type": "char_class",
"value": "bc"
},
{
"type": "literal",
"value": "d"
}
]
}
]
}
`

Convert the parsed regular expression into a trigram query.

`javascript
var q = regex.query(re);
console.log(JSON.stringify(q, null, 2));
`

Which should look like:

`json
{
"op": "OR",
"trigram": [
"abd",
"acd"
],
"sub": []
}
``