Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://github.com/slevithan/babel-plugin-transform-regex below:

slevithan/babel-plugin-transform-regex: Babel plugin for Regex+

This is a Babel plugin that transpiles tagged Regex+ regex templates into native RegExp literals, enabling syntax for modern, readable regex features (atomic groups, subroutines, insignificant whitespace, comments, etc.) without the need for calling regex at runtime. Although Regex+ is already a lightweight and high-performance library, this takes things further by giving you its developer experience benefits without adding any runtime dependencies and without users paying any runtime cost.

Turns this:

const ipv4 = regex`
  ^ \g<byte> (\.\g<byte>){3} $

  (?(DEFINE)
    (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d)
  )
`;

Into this:

const ipv4 = /^(?:2[0-4]\d|25[0-5]|1\d\d|[1-9]?\d)(?:\.(?:2[0-4]\d|25[0-5]|1\d\d|[1-9]?\d)){3}$/v;

The following call formats are all supported:

• regex`<expression>`
• regex()`<expression>`
• regex('<flags>')`<expression>`
• regex({<options>})`<expression>`

Interpolation into the expression is supported, so long as the interpolated values are:

• Inline string, regexp, or number literals.
• Inline regexes constructed via RegExp or new RegExp with string values.
• Inline patterns, via pattern`…` as a template tag (without interpolation) or pattern(…) as a function call with a string or number literal as the value.

Additional details:

• Wherever strings are allowed, '…', "…", `…`, and String.raw`…` can all be used, so long as they don't include interpolation.

• Tagged regex templates that interpolate variables or other dynamic values are not transformed.
• The specific regex options subclass, plugins, and unicodeSetsPlugin are unsupported. Regexes that use these options are not transformed.
• Calling the regex tag as a function instead of with backticks is not transformed.

The following options are available when running the Babel plugin:

• removeImport — If true, removes any import declarations with module name 'regex'.
• disableUnicodeSets — If true, adds regex option disable: {v: true} to all regexes before transformation.
• headerComment — If given a value, it will be added in a comment at the top of processed output/files.
• optimize (experimental) — If true, attempts to optimize/shorten the regex source generated by regex.
  • Uses an external library (regexp-tree's optimizer) that doesn't support flag-v-only syntax and isn't fully context-aware, so you should check the output.

By default, the regex tag implicitly adds flag v (unicodeSets, supported by Node.js 20 and 2023-era browsers) to generated regexes, but it automatically switches to flag u (while applying v's escaping rules) in environments without native v support. This creates an issue for the Babel plugin, because although it will typically be run in environments that support flag v, the transpiled results may need to run for users in old browsers without native v.

There are several ways to address this:

• Option 1: Leave v enabled and transpile v with a separate Babel plugin.
  • This allows supporting v-only syntax (like nested character classes) in older environments.
  • Use Babel's official plugin @babel/plugin-transform-unicode-sets-regex, which is also included in @babel/preset-env.
• Option 2: Disable v for all transpiled regexes.
  • To do this, set the Babel plugin option disableUnicodeSets: true (see details above).
  • This keeps things simple/clean and avoids a second regex transpilation step.
  • This doesn't support the use of v-only syntax.
• Option 3: Disable v for individual regexes.
  • To do this, use the regex option regex({disable: {v: true}})`…` in your code.
  • This maintains 100% parity between code running with or without the Babel plugin.
  • This doesn't support the use of v-only syntax.

Tip

You can try all of these options in the demo REPL.

Add this plugin and a recent version of Babel (tested with 7.24–7.26) to your project:

npm install --save-dev @babel/core @babel/cli
npm install --save-dev babel-plugin-transform-regex

Run the following command to compile all of your code from the src directory to lib:

./node_modules/.bin/babel src --out-dir lib --plugins=babel-plugin-transform-regex

To make this easier to run, create a config file in the root of your project named babel.config.json, with this content:

{
  "plugins": ["babel-plugin-transform-regex"]
}

If you're using TypeScript, also add plugin @babel/plugin-syntax-typescript. Here's an example of that which additionally sets plugin options:

{
  "plugins": [
    "@babel/plugin-syntax-typescript",
    ["babel-plugin-transform-regex", {
      "removeImport": true,
      "disableUnicodeSets": true,
      "optimize": true
    }]
  ]
}

Then add a script to your package.json to run the build:

"scripts": {
  "build": "babel src --out-dir lib"
}

After that, you can run it via npm run build.

Created by Steven Levithan.

If you want to support this project, I'd love your help by contributing improvements, sharing it with others, or sponsoring ongoing development.

© 2024–present. MIT License.

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4