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55 lines
1.3 KiB
55 lines
1.3 KiB
3 years ago
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var util = require('util');
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var PassThrough = require('readable-stream/passthrough');
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module.exports = {
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Readable: Readable,
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Writable: Writable
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};
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util.inherits(Readable, PassThrough);
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util.inherits(Writable, PassThrough);
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// Patch the given method of instance so that the callback
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// is executed once, before the actual method is called the
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// first time.
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function beforeFirstCall(instance, method, callback) {
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instance[method] = function() {
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delete instance[method];
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callback.apply(this, arguments);
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return this[method].apply(this, arguments);
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};
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}
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function Readable(fn, options) {
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if (!(this instanceof Readable))
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return new Readable(fn, options);
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PassThrough.call(this, options);
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beforeFirstCall(this, '_read', function() {
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var source = fn.call(this, options);
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var emit = this.emit.bind(this, 'error');
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source.on('error', emit);
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source.pipe(this);
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});
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this.emit('readable');
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}
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function Writable(fn, options) {
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if (!(this instanceof Writable))
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return new Writable(fn, options);
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PassThrough.call(this, options);
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beforeFirstCall(this, '_write', function() {
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var destination = fn.call(this, options);
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var emit = this.emit.bind(this, 'error');
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destination.on('error', emit);
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this.pipe(destination);
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});
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this.emit('writable');
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}
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