57 lines
1.1 KiB
JavaScript
57 lines
1.1 KiB
JavaScript
'use strict';
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const { Writable } = require('stream');
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const CHUNK_SIZE = 1024;
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const INITIAL_SIZE = 8 * CHUNK_SIZE;
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const INCREMENT_SIZE = 8 * CHUNK_SIZE;
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class WritableBuffer extends Writable {
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constructor() {
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super();
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this._buffer = Buffer.alloc(INITIAL_SIZE);
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this._size = 0;
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}
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get() {
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if (!this._size) {
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return null;
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}
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const data = Buffer.alloc(this._size);
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this._buffer.copy(data, 0, 0, this._size);
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return data;
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}
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_increaseAsNeeded(incomingSize) {
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if ((this._buffer.length - this._size) >= incomingSize) {
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return;
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}
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const freeSpace = this._buffer.length - this._size;
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const factor = Math.ceil((incomingSize - freeSpace) / INCREMENT_SIZE);
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const newBuffer = Buffer.alloc(this._buffer.length + (INCREMENT_SIZE * factor));
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this._buffer.copy(newBuffer, 0, 0, this._size);
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this._buffer = newBuffer;
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}
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_write(chunk, encoding, callback) {
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this._increaseAsNeeded(chunk.length);
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chunk.copy(this._buffer, this._size, 0);
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this._size += chunk.length;
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callback();
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}
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}
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module.exports = WritableBuffer;
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