70 lines
1.6 KiB
JavaScript
70 lines
1.6 KiB
JavaScript
'use strict';
|
|
|
|
var Buffer = require('safe-buffer').Buffer;
|
|
|
|
var StreamReader = function() {
|
|
this._queue = [];
|
|
this._queueSize = 0;
|
|
this._offset = 0;
|
|
};
|
|
|
|
StreamReader.prototype.put = function(buffer) {
|
|
if (!buffer || buffer.length === 0) return;
|
|
if (!Buffer.isBuffer(buffer)) buffer = Buffer.from(buffer);
|
|
this._queue.push(buffer);
|
|
this._queueSize += buffer.length;
|
|
};
|
|
|
|
StreamReader.prototype.read = function(length) {
|
|
if (length > this._queueSize) return null;
|
|
if (length === 0) return Buffer.alloc(0);
|
|
|
|
this._queueSize -= length;
|
|
|
|
var queue = this._queue,
|
|
remain = length,
|
|
first = queue[0],
|
|
buffers, buffer;
|
|
|
|
if (first.length >= length) {
|
|
if (first.length === length) {
|
|
return queue.shift();
|
|
} else {
|
|
buffer = first.slice(0, length);
|
|
queue[0] = first.slice(length);
|
|
return buffer;
|
|
}
|
|
}
|
|
|
|
for (var i = 0, n = queue.length; i < n; i++) {
|
|
if (remain < queue[i].length) break;
|
|
remain -= queue[i].length;
|
|
}
|
|
buffers = queue.splice(0, i);
|
|
|
|
if (remain > 0 && queue.length > 0) {
|
|
buffers.push(queue[0].slice(0, remain));
|
|
queue[0] = queue[0].slice(remain);
|
|
}
|
|
return Buffer.concat(buffers, length);
|
|
};
|
|
|
|
StreamReader.prototype.eachByte = function(callback, context) {
|
|
var buffer, n, index;
|
|
|
|
while (this._queue.length > 0) {
|
|
buffer = this._queue[0];
|
|
n = buffer.length;
|
|
|
|
while (this._offset < n) {
|
|
index = this._offset;
|
|
this._offset += 1;
|
|
callback.call(context, buffer[index]);
|
|
}
|
|
this._offset = 0;
|
|
this._queue.shift();
|
|
}
|
|
};
|
|
|
|
module.exports = StreamReader;
|