115 lines
3.1 KiB
JavaScript
115 lines
3.1 KiB
JavaScript
'use strict';
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var util = require('util'),
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Match = require ('../match');
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/**
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* This class matches UTF-16 and UTF-32, both big- and little-endian. The
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* BOM will be used if it is present.
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*/
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module.exports.UTF_16BE = function() {
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this.name = function() {
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return 'UTF-16BE';
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};
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this.match = function(det) {
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var input = det.fRawInput;
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if (input.length >= 2 && ((input[0] & 0xff) == 0xfe && (input[1] & 0xff) == 0xff)) {
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var confidence = 100;
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return new Match(det, this, confidence);
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}
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// TODO: Do some statistics to check for unsigned UTF-16BE
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return null;
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};
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};
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module.exports.UTF_16LE = function() {
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this.name = function() {
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return 'UTF-16LE';
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};
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this.match = function(det) {
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var input = det.fRawInput;
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if (input.length >= 2 && ((input[0] & 0xff) == 0xff && (input[1] & 0xff) == 0xfe)) {
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// An LE BOM is present.
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if (input.length >= 4 && input[2] == 0x00 && input[3] == 0x00) {
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// It is probably UTF-32 LE, not UTF-16
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return null;
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}
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var confidence = 100;
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return new Match(det, this, confidence);
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}
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// TODO: Do some statistics to check for unsigned UTF-16LE
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return null;
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}
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};
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function UTF_32() {};
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UTF_32.prototype.match = function(det) {
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var input = det.fRawInput,
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limit = (det.fRawLength / 4) * 4,
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numValid = 0,
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numInvalid = 0,
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hasBOM = false,
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confidence = 0;
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if (limit == 0) {
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return null;
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}
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if (this.getChar(input, 0) == 0x0000FEFF) {
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hasBOM = true;
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}
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for (var i = 0; i < limit; i += 4) {
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var ch = this.getChar(input, i);
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if (ch < 0 || ch >= 0x10FFFF || (ch >= 0xD800 && ch <= 0xDFFF)) {
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numInvalid += 1;
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} else {
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numValid += 1;
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}
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}
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// Cook up some sort of confidence score, based on presence of a BOM
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// and the existence of valid and/or invalid multi-byte sequences.
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if (hasBOM && numInvalid == 0) {
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confidence = 100;
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} else if (hasBOM && numValid > numInvalid * 10) {
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confidence = 80;
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} else if (numValid > 3 && numInvalid == 0) {
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confidence = 100;
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} else if (numValid > 0 && numInvalid == 0) {
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confidence = 80;
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} else if (numValid > numInvalid * 10) {
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// Probably corrupt UTF-32BE data. Valid sequences aren't likely by chance.
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confidence = 25;
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}
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// return confidence == 0 ? null : new CharsetMatch(det, this, confidence);
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return confidence == 0 ? null : new Match(det, this, confidence);
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};
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module.exports.UTF_32BE = function() {
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this.name = function() {
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return 'UTF-32BE';
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};
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this.getChar = function(input, index) {
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return (input[index + 0] & 0xff) << 24 | (input[index + 1] & 0xff) << 16 |
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(input[index + 2] & 0xff) << 8 | (input[index + 3] & 0xff);
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};
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};
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util.inherits(module.exports.UTF_32BE, UTF_32);
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module.exports.UTF_32LE = function() {
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this.name = function() {
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return 'UTF-32LE';
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};
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this.getChar = function(input, index) {
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return (input[index + 3] & 0xff) << 24 | (input[index + 2] & 0xff) << 16 |
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(input[index + 1] & 0xff) << 8 | (input[index + 0] & 0xff);
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};
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};
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util.inherits(module.exports.UTF_32LE, UTF_32);
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