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diff --git a/middleware/node_modules/combined-stream/Readme.md b/middleware/node_modules/combined-stream/Readme.md new file mode 100644 index 0000000..9e367b5 --- /dev/null +++ b/middleware/node_modules/combined-stream/Readme.md @@ -0,0 +1,138 @@ +# combined-stream + +A stream that emits multiple other streams one after another. + +**NB** Currently `combined-stream` works with streams version 1 only. There is ongoing effort to switch this library to streams version 2. Any help is welcome. :) Meanwhile you can explore other libraries that provide streams2 support with more or less compatibility with `combined-stream`. + +- [combined-stream2](https://www.npmjs.com/package/combined-stream2): A drop-in streams2-compatible replacement for the combined-stream module. + +- [multistream](https://www.npmjs.com/package/multistream): A stream that emits multiple other streams one after another. + +## Installation + +``` bash +npm install combined-stream +``` + +## Usage + +Here is a simple example that shows how you can use combined-stream to combine +two files into one: + +``` javascript +var CombinedStream = require('combined-stream'); +var fs = require('fs'); + +var combinedStream = CombinedStream.create(); +combinedStream.append(fs.createReadStream('file1.txt')); +combinedStream.append(fs.createReadStream('file2.txt')); + +combinedStream.pipe(fs.createWriteStream('combined.txt')); +``` + +While the example above works great, it will pause all source streams until +they are needed. If you don't want that to happen, you can set `pauseStreams` +to `false`: + +``` javascript +var CombinedStream = require('combined-stream'); +var fs = require('fs'); + +var combinedStream = CombinedStream.create({pauseStreams: false}); +combinedStream.append(fs.createReadStream('file1.txt')); +combinedStream.append(fs.createReadStream('file2.txt')); + +combinedStream.pipe(fs.createWriteStream('combined.txt')); +``` + +However, what if you don't have all the source streams yet, or you don't want +to allocate the resources (file descriptors, memory, etc.) for them right away? +Well, in that case you can simply provide a callback that supplies the stream +by calling a `next()` function: + +``` javascript +var CombinedStream = require('combined-stream'); +var fs = require('fs'); + +var combinedStream = CombinedStream.create(); +combinedStream.append(function(next) { + next(fs.createReadStream('file1.txt')); +}); +combinedStream.append(function(next) { + next(fs.createReadStream('file2.txt')); +}); + +combinedStream.pipe(fs.createWriteStream('combined.txt')); +``` + +## API + +### CombinedStream.create([options]) + +Returns a new combined stream object. Available options are: + +* `maxDataSize` +* `pauseStreams` + +The effect of those options is described below. + +### combinedStream.pauseStreams = `true` + +Whether to apply back pressure to the underlaying streams. If set to `false`, +the underlaying streams will never be paused. If set to `true`, the +underlaying streams will be paused right after being appended, as well as when +`delayedStream.pipe()` wants to throttle. + +### combinedStream.maxDataSize = `2 * 1024 * 1024` + +The maximum amount of bytes (or characters) to buffer for all source streams. +If this value is exceeded, `combinedStream` emits an `'error'` event. + +### combinedStream.dataSize = `0` + +The amount of bytes (or characters) currently buffered by `combinedStream`. + +### combinedStream.append(stream) + +Appends the given `stream` to the combinedStream object. If `pauseStreams` is +set to `true, this stream will also be paused right away. + +`streams` can also be a function that takes one parameter called `next`. `next` +is a function that must be invoked in order to provide the `next` stream, see +example above. + +Regardless of how the `stream` is appended, combined-stream always attaches an +`'error'` listener to it, so you don't have to do that manually. + +Special case: `stream` can also be a String or Buffer. + +### combinedStream.write(data) + +You should not call this, `combinedStream` takes care of piping the appended +streams into itself for you. + +### combinedStream.resume() + +Causes `combinedStream` to start drain the streams it manages. The function is +idempotent, and also emits a `'resume'` event each time which usually goes to +the stream that is currently being drained. + +### combinedStream.pause(); + +If `combinedStream.pauseStreams` is set to `false`, this does nothing. +Otherwise a `'pause'` event is emitted, this goes to the stream that is +currently being drained, so you can use it to apply back pressure. + +### combinedStream.end(); + +Sets `combinedStream.writable` to false, emits an `'end'` event, and removes +all streams from the queue. + +### combinedStream.destroy(); + +Same as `combinedStream.end()`, except it emits a `'close'` event instead of +`'end'`. + +## License + +combined-stream is licensed under the MIT license. |