diff options
Diffstat (limited to 'node_modules/lazystream/lib')
-rw-r--r-- | node_modules/lazystream/lib/lazystream.js | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/node_modules/lazystream/lib/lazystream.js b/node_modules/lazystream/lib/lazystream.js new file mode 100644 index 000000000..d9f617096 --- /dev/null +++ b/node_modules/lazystream/lib/lazystream.js @@ -0,0 +1,54 @@ +var util = require('util'); +var PassThrough = require('readable-stream/passthrough'); + +module.exports = { + Readable: Readable, + Writable: Writable +}; + +util.inherits(Readable, PassThrough); +util.inherits(Writable, PassThrough); + +// Patch the given method of instance so that the callback +// is executed once, before the actual method is called the +// first time. +function beforeFirstCall(instance, method, callback) { + instance[method] = function() { + delete instance[method]; + callback.apply(this, arguments); + return this[method].apply(this, arguments); + }; +} + +function Readable(fn, options) { + if (!(this instanceof Readable)) + return new Readable(fn, options); + + PassThrough.call(this, options); + + beforeFirstCall(this, '_read', function() { + var source = fn.call(this, options); + var emit = this.emit.bind(this, 'error'); + source.on('error', emit); + source.pipe(this); + }); + + this.emit('readable'); +} + +function Writable(fn, options) { + if (!(this instanceof Writable)) + return new Writable(fn, options); + + PassThrough.call(this, options); + + beforeFirstCall(this, '_write', function() { + var destination = fn.call(this, options); + var emit = this.emit.bind(this, 'error'); + destination.on('error', emit); + this.pipe(destination); + }); + + this.emit('writable'); +} + |