trejs

Javascript implementation of approximate regular expressions using webasm of the C-library tre.

It's a crude solution, feel free to improve.

src/libtre.so

libtre.so Is a webasm-compiled shared object for libtre. You can probably use the one in this repo, as webasm should be cross-platform. You can, however, also create it by specifying emcc as the compiler and follow the normal tre build instructions. I.e.:

# clone git repo as needed
# git clone https://github.com/laurikari/tre
cd tre # move into repo

./utils/autogen.sh

CC=emcc ./configure
CC=emcc make

The object file should be in lib/.libs/libre.so.

header files

If you want to rebuild, e.g. against a newer version of tre, make sure to include all header files in local_includes from the tre git-repo.

c++ code (trejs.cpp)

This is a wrapper around tre that outputs json, either with an error message {"error": "some error"}, and empty list [] if no matches or [{"start": ..., "end": ..., "value": "..."}, ...] with the hierarchy of the entire match and all the capture groups, as per tre_regexec docs.

This file is (also) alread build into webasm as trejs.js and trejs.wasm. However, you can (re)compile it as you wish as per:

MCC_DEBUG=1 emcc -O1 -sASSERTIONS=1 -s WASM=1 -s EXPORTED_RUNTIME_METHODS='["cwrap"]' -I . libtre.so trejs.cpp -o trejs.js

wrapper js (tre.js)

This code returns a hierarchy of the capture groups, e.g.

findall("(([0-9]{1,3})[a-z]\.){<2} ([0-9]{1,3} [0-9]{3}[A-Z]\.){<2}", "1zc. 234 3zAD.  1zc. 234 3zAD.")

Results in this hierarchy:

[{
    "start":0,
    "end":14,
    "value":"1zc. 234 3zAD.",
    "children": [
        {"start":0,
            "end":4,
            "value":"1zc.",
            "children":[
            {"start":0,
                "end":2,
                "value":"1z"}
            ]},
            {"start":5,
            "end":14,
            "value":"234 3zAD.  1zc"}
    ]}, {
    "start":16,
    "end":30,
    "value":"1zc. 234 3zAD.",
    "children":[
        {"start":16,
            "end":20,
            "value":"1zc. 2",
            "children":[
            {"start":16,
                "end":18,
                "value":"1zc."}
            ]},
            {"start":21,
            "end":30,
            "value":"234 3zAD.",}
    ]
}]

webpack / react:

The fallbacks for fs, crypto and path need to be disabled in webpack.config.js, to avoid errors (I'm usure why). Furthermore, a .webasm needs to be added for adding the webassembly as a (binary) asset. The latter doesn't seem to work for me, so I included trejs.wasm as a static file to the path in module.exports.entry.output.path of webpack.config.js.

module.exports = {
    //...
    module: {
        rules: [
            //...
            {
                test: /\.wasm$/,
                type: "asset/inline",
            },
        ]
      },
  //...
  resolve: {
      ///...
      fallback: {
        fs: false,
        crypto: false,
        path: false
    },
  },
};

I added trejs.js and tre.js to a place in the webapp javascript source, from which I can import findall, e.g. in the regex folder:

import findall from ".regex/tre";