dependants-parser

dependants-parser

Utility to recursively fetch dependant modules by parsing require syntaxes targeting a specified local module using a given a root directory and an import expression regex.

The problem

While writing a custom watch-build tool I needed some quick and easy way to figure out which modules depended on the file that changed would be emitted to in order to avoid re-compiling every file in the codebase at every change.

This tool is easily extensible to work with most pre-processors & syntaxes as long as their import command can be expressed with a regular expression and the modules are located relatively to the target file.

By now Stylus and CommonJS regexes are available by default in this module.

Install

npm install dependants-parser

Test

Test with Mocha by running

npm test

Simple usage

Considering the following tree:

.
├── index.js
└── stylus
    ├── root.styl
    └── target.styl

stylus/root.styl:

@import 'target.styl'

index.js:

var dependants = require('dependants-tree');

var out = dependants.findSync(
	'stylus/target.styl',		// Target dependency
	'stylus',					// Modules root
	dependants.patterns.stylus	// Import expression regex
	);

console.log(out);
// [ 'abs/path/to/stylus/root.styl' ]

Exports

.findSync(filepath, root, importRegex, [ match ])

Returns an array containing absolute paths of all modules that depend on filepath found in root, given an import expression syntax.

• filepath (String) - Path to target module. This needs to be the real filename.
• root - (String) Directory to recursively scan for dependants.
• importRegex - (RegExp|Object) Import syntax expression. Used to parse out a file's dependency. You can also pass an object containing the keys 'exp' (RegExp) and 'offset' (number) of the result module string
• [ match ] - (RegExp) Filename match expression. Use to filter files to scan.

.patterns

Contains simple ready-to-use regexes for local import syntaxes

• .stylus - @import 'module' Stylus syntax pattern
• .commonjs - require('module') CommonJS syntax pattern
• .jade - include module | extend module Jade syntax pattern

Contribute

It would be great to provide import syntaxes for other languages / pre-processors (LESS, SASS, SCSS, Jade, Handlebars) this module could be used for.

Please feel free to drop a pull request if you're using this module with a custom expressions or improving the current ones / writing more tests.

Regexes are tested in test/regexes.js.