b38dea0597
Share Gaia assets and adapters, keep private profiles and development documents local, and update both public READMEs.
135 lines
3.3 KiB
JavaScript
Executable file
135 lines
3.3 KiB
JavaScript
Executable file
'use strict';
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var Transform = require('stream').Transform;
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var SEPARATOR = ':';
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var SEPARATOR_CODE = SEPARATOR.charCodeAt(0);
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/**
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* First ocurrence of where string occurs in a buffer.
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*
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* NOTE: this is not UTF8 safe generally we expect to find the correct
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* char fairly quickly unless the buffer is incorrectly formatted.
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*
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* @param {Buffer} buffer haystack.
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* @param {String} code needle.
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* @return {Numeric} -1 if not found index otherwise.
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*/
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function indexInBuffer(buffer, code) {
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if (buffer.length === 0)
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return -1;
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var index = 0;
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var length = buffer.length;
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do {
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if (buffer[index] === code) return index;
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} while (
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++index && index + 1 < length
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);
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return -1;
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}
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/**
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* converts an object to a string representation suitable for storage on disk.
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* Its very important to note that the length in the string refers to the utf8
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* size of the json content in bytes (as utf8) not the JS string length.
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*
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* @param {Object} object to stringify.
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* @return {String} serialized object.
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*/
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function stringify(object) {
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var json = JSON.stringify(object);
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var len = Buffer.byteLength(json);
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return len + SEPARATOR + json;
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}
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/**
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* attempts to parse a given buffer or string.
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*
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* @param {Uint8Array|Buffer} input in byteLength:{json..} format.
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* @return {Objec} JS object.
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*/
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function parse(input) {
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var stream = new Stream();
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var result;
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stream.once('data', function(data) {
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result = data;
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});
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stream.write(input);
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if (!result) {
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throw new Error(
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'no command available from parsing:' + input
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);
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}
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return result;
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}
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function Stream() {
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this._pendingLength = null;
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this._buffer = new Buffer(0);
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Transform.call(this, { objectMode: true });
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}
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Stream.prototype = {
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__proto__: Transform.prototype,
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_transform: function(chunk, encoding, cb) {
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if (!this._pendingLength) {
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var idx = indexInBuffer(chunk, SEPARATOR_CODE);
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// Nothing to do just buffer it...
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if (idx === -1) {
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this._buffer = Buffer.concat([this._buffer, chunk]);
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return cb();
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}
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// number of bytes in the json segment...
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var length = Buffer.concat([this._buffer, chunk.slice(0, idx)]);
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this._pendingLength = parseInt(length.toString(), 10);
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this._buffer = new Buffer(0);
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// We have transitioned to a pending length state so do another pass.
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return this._transform(chunk.slice(idx + 1), encoding, cb);
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}
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// Total length too small nothing to do...
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if (this._buffer.length + chunk.length < this._pendingLength) {
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this._buffer = Buffer.concat([this._buffer, chunk]);
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return cb();
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}
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var buffer = Buffer.concat([this._buffer, chunk]);
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var remainder = null;
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if (buffer.length > this._pendingLength) {
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remainder = buffer.slice(this._pendingLength);
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buffer = buffer.slice(0, this._pendingLength);
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}
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// Reset internal state and push current json string.
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this._pendingLength = null;
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this._buffer = new Buffer(0);
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this.push(JSON.parse(buffer.toString()));
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// If we have any remaining data we need to keep processing...
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if (remainder) {
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return this._transform(remainder, encoding, cb);
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}
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// Otherwise we are done yay....
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return cb();
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}
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};
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exports.parse = parse;
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exports.stringify = stringify;
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exports.Stream = Stream;
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exports.separator = SEPARATOR;
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