broccoli-filter


Helper base class for Broccoli plugins that map input files into output files
one-to-one.

API

``js
class Filter {
/**
* Abstract base-class for filtering purposes.
*
* Enforces that it is invoked on an instance of a class which prototypically
* inherits from Filter, and which is not itself Filter.
*/
constructor(inputNode: BroccoliNode, options: FilterOptions): Filter;

/**
* Abstract method processString: must be implemented on subclasses of
* Filter.
*
* The return value is written as the contents of the output file
*/
abstract processString(contents: string, relativePath: string): string;

/**
* Virtual method getDestFilePath: determine whether the source file should
* be processed, and optionally rename the output file when processing occurs.
*
* Return null to pass the file through without processing. Return
* relativePath to process the file with processString. Return a
* different path to process the file with processString and rename it.
*
* By default, if the options passed into the Filter constructor contain a
* property extensions, and targetExtension is supplied, the first matching
* extension in the list is replaced with the targetExtension option's value.
*/
virtual getDestFilePath(relativePath: string): string;
}
`

$3

* extensions: An array of file extensions to process, e.g. ['md', 'markdown'].
* targetExtension: The file extension of the corresponding output files, e.g.
'html'.
* inputEncoding: The character encoding used for reading input files to be
processed (default: 'utf8'). For binary files, pass null to receive a
Buffer object in processString.
* outputEncoding: The character encoding used for writing output files after
processing (default: 'utf8'). For binary files, pass null and return a
Buffer object from processString.
* name, annotation: Same as
broccoli-plugin;
see there.

All options except name and annotation can also be set on the prototype
instead of being passed into the constructor.

$3

`js
var Filter = require('broccoli-filter');

Awk.prototype = Object.create(Filter.prototype);
Awk.prototype.constructor = Awk;
function Awk(inputNode, search, replace, options) {
options = options || {};
Filter.call(this, inputNode, {
annotation: options.annotation
});
this.search = search;
this.replace = replace;
}

Awk.prototype.extensions = ['txt'];
Awk.prototype.targetExtension = 'txt';

Awk.prototype.processString = function(content, relativePath) {
return content.replace(this.search, this.replace);
};
`

In Brocfile.js, use your new Awk plugin like so:

`
var node = new Awk('docs', 'ES6', 'ECMAScript 2015');

module.exports = node;
`

FAQ

$3

You must now call the base class constructor. For example:

`js
// broccoli-filter 0.1.x:
function MyPlugin(inputTree) {
this.inputTree = inputTree;
}

// broccoli-filter 1.x:
function MyPlugin(inputNode) {
Filter.call(this, inputNode);
}
`

Note that "node" is simply new terminology for "tree".

$3

**Can this help with compilers that are almost 1:1, like a minifier that takes
a .js and .js.map file and outputs a .js and .js.map file?**

Not at the moment. We don't know yet how to implement this and still have the
API look beautiful. Such cases complicate the caching logic, as we have to make
sure to rebuild a file if either the .js or the .js.map` file changes.

For now, your best bet is the
broccoli-multifilter
plugin base class.