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