0.0.4 • Published 11 years ago
sub-stream v0.0.4
sub-stream
A simple-stream pull-filter for converting flat streams into nested streams.
subStream(stream, isHandle, propName) -> stream
Input is a flat stream that looks like header
, chunk
, chunk
, ..., header
, ...
In other words, you get header events followed by zero of more body chunks.
The output is a nested stream of headerWithSubStream
, headerWithSubStream
, ...
It's much easier to write filters that output flat streams than nested streams, especially when using the push-to-pull helper.
var subStream = require('sub-stream');
var pushToPull = require('push-to-pull');
// This is a madeup stream that emits 0 to 9 and then ends.
var stream = count(10);
// A filter that takes in a number and then outputs {size:n} followed by n monkeys.
var filter = pushToPull(function (emit) {
return function (err, num) {
// Forward end and error events through
if (num === undefined) return emit(err);
// Emit the flat stream events
emit(null, {size: num});
for (var i = 0; i < num; i++) {
emit(null, "Monkey " + i);
}
};
});
// Create a nested stream using count, filter, and subStream.
stream = subStream(filter(count(5)), function (item) {
return typeof item === "object";
}, "monkeys");
// Consume the nested stream
consume(stream, function (item) {
console.log(item);
consume(item.monkeys, console.log)(console.log);
})(console.log);