@daiyam/regexp
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RegExp parser/formatter/visitor/transformer
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[@daiyam/regexp](https://github.com/daiyam/node-regexp)
======================================================================
[](./LICENSE)
[](https://www.npmjs.com/package/@daiyam/regexp)
With `@daiyam/regexp`, you can parse a regular expression to get an AST. Then you can visit, transform or/and translate the ast. When you have finished your edits, you can stringify the AST to get a string to create a `RegExp`.
Getting Started
---------------
With [node](http://nodejs.org) previously installed:
npm install @daiyam/regexp
```typescript
import { escape, parse, stringify, translate, visit, Flavor, Token, TokenType } from '@daiyam/regexp'
function listCaptureGroups(regex: string): Token[] {
const ast = parse(regex);
const groups: Token[] = [];
visit(ast.body, {
[TokenType.CAPTURE_GROUP](token) {
groups.push(token);
}
});
return groups;
}
function toES2018(source: string): RegExp {
return new RegExp(translate(source, Flavor.ES2018));
}
```
Syntax
------
The library is supporting ES2018 syntax and some elements of PCRE2 syntax.
| Characters / constructs | Corresponding article |
| ---------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| `\`, `.`, `\cX`, `\d`, `\D`, `\f`, `\n`, `\r`, `\s`, `\S`, `\t`, `\v`, `\w`, `\W`, `\0`, `\xhh`, `\uhhhh`, `\uhhhhh`, `[\b]` | [Character classes (MDN)](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Character_Classes) |
| `^`, `$`, `x(?=y)`, `x(?!y)`, `(?<=y)x`, `(? Token
with `interface Token`, parse the `value` to generate an AST tree.
### stringify(tokens?: Token | Token[] | RegExp) => string
generate a string based on the given AST tokens.
### visit(tokens?: Token | Token[], callback?: { [TokenType: string]: Visitor } | Visitor) => void
with `type Visitor = (token: Token) => void`, call the `callback` when iterating the given AST tokens
### transform(tokens?: Token | Token[], callback?: { [TokenType: string]: Transformer } | Transformer) => void
with `type Transformer = (token: Token, parent: Token | null, key: string | null, index: number | null) => void`, call the `callback` when iterating the given AST tokens.
The `this` context of the `callback` with have the following functions:
- `this.remove() => void`: remove the current token
- `this.replace(token: string | Token | Token[], transform?: boolean) => void`: replace the current token with the given token(s). If `transform` is true, then the new token(s) are going to be transformed.
- `this.transform(tokens: Token | Token[], parent?: Token, key?: string) => void`: run the tranformation on the given token(s).
### translate(value: string | RegExp | Token | Token[], target: Flavor, toString?: boolean = true) => string | Token | Token[]
translate a regex for the `target` regexp language.
```typescript
function toES2018(source: string): RegExp {
return new RegExp(translate(source, Flavor.ES2018));
}
```
| Supported Flavors |
| ----------------- |
| `ES2018` |
### escape(value: string) => string
escape the RegExp special characters from the `value`.
### isRegExp(value: any) => boolean
determine if the `value` is a RexExp or not.
License
-------
Copyright © 2021 Baptiste Augrain
Licensed under the [MIT license](http://www.opensource.org/licenses/mit-license.php).