73 lines
2.1 KiB
Markdown
73 lines
2.1 KiB
Markdown
# Using buffers
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> Here is some information on creating gulp plugin that manipulates buffers.
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[Writing a Plugin](README.md) > Using buffers
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## Using buffers
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If your plugin is relying on a buffer based library, you will probably choose to base your plugin around file.contents as a buffer. Let's implement a plugin prepending some text to files:
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```js
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var through = require('through2');
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var gutil = require('gulp-util');
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var PluginError = gutil.PluginError;
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// Consts
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const PLUGIN_NAME = 'gulp-prefixer';
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// Plugin level function (dealing with files)
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function gulpPrefixer(prefixText) {
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if (!prefixText) {
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throw new PluginError(PLUGIN_NAME, "Missing prefix text!");
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}
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prefixText = new Buffer(prefixText); // allocate ahead of time
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// Creating a stream through which each file will pass
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var stream = through.obj(function (file, enc, callback) {
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if (file.isNull()) {
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this.push(file); // Do nothing if no contents
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return callback();
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}
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if (file.isBuffer()) {
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file.contents = Buffer.concat([prefixText, file.contents]);
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this.push(file);
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return callback();
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}
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if (file.isStream()) {
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this.emit('error', new PluginError(PLUGIN_NAME, 'Streams are not supported!'));
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return callback();
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}
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});
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// returning the file stream
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return stream;
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};
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// Exporting the plugin main function
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module.exports = gulpPrefixer;
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```
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The above plugin can be used like this:
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```js
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var gulp = require('gulp');
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var gulpPrefixer = require('gulp-prefixer');
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gulp.src('files/**/*.js')
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.pipe(gulpPrefixer('prepended string'))
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.pipe(gulp.dest('/modified-files/'));
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```
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## Handling streams
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Unfortunately, the above plugin will error when using gulp.src in non-buffered (streaming) mode. You should support streams too if possible. See [Dealing with streams](dealing-with-streams.md) for more information.
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## Some plugins based on buffers
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* [gulp-coffee](https://github.com/wearefractal/gulp-coffee)
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* [gulp-svgmin](https://github.com/ben-eb/gulp-svgmin)
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* [gulp-marked](https://github.com/lmtm/gulp-marked)
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* [gulp-svg2ttf](https://github.com/nfroidure/gulp-svg2ttf)
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