@zxing/text-encoding
Version:
Polyfill for the Encoding Living Standard's API.
97 lines • 4.44 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
var encodings_1 = require("../../encoding/encodings");
var finished_1 = require("../../encoding/finished");
var terminology_1 = require("../../encoding/terminology");
var utilities_1 = require("../../encoding/utilities");
var converCodeUnitToBytes_1 = require("./converCodeUnitToBytes");
/**
* @constructor
* @implements {Decoder}
* @param {boolean} utf16_be True if big-endian, false if little-endian.
* @param {{fatal: boolean}} options
*/
var UTF16Decoder = /** @class */ (function () {
function UTF16Decoder(utf16_be, options) {
this.utf16_be = utf16_be;
this.fatal = options.fatal;
/** @type {?number} */ this.utf16_lead_byte = null;
/** @type {?number} */ this.utf16_lead_surrogate = null;
}
/**
* @param {Stream} stream The stream of bytes being decoded.
* @param {number} bite The next byte read from the stream.
* @return {?(number|!Array.<number>)} The next code point(s)
* decoded, or null if not enough data exists in the input
* stream to decode a complete code point.
*/
UTF16Decoder.prototype.handler = function (stream, bite) {
// 1. If byte is end-of-stream and either utf-16 lead byte or
// utf-16 lead surrogate is not null, set utf-16 lead byte and
// utf-16 lead surrogate to null, and return error.
if (bite === terminology_1.end_of_stream && (this.utf16_lead_byte !== null ||
this.utf16_lead_surrogate !== null)) {
return encodings_1.decoderError(this.fatal);
}
// 2. If byte is end-of-stream and utf-16 lead byte and utf-16
// lead surrogate are null, return finished.
if (bite === terminology_1.end_of_stream && this.utf16_lead_byte === null &&
this.utf16_lead_surrogate === null) {
return finished_1.finished;
}
// 3. If utf-16 lead byte is null, set utf-16 lead byte to byte
// and return continue.
if (this.utf16_lead_byte === null) {
this.utf16_lead_byte = bite;
return null;
}
// 4. Let code unit be the result of:
var code_unit;
if (this.utf16_be) {
// utf-16be decoder flag is set
// (utf-16 lead byte << 8) + byte.
code_unit = (this.utf16_lead_byte << 8) + bite;
}
else {
// utf-16be decoder flag is unset
// (byte << 8) + utf-16 lead byte.
code_unit = (bite << 8) + this.utf16_lead_byte;
}
// Then set utf-16 lead byte to null.
this.utf16_lead_byte = null;
// 5. If utf-16 lead surrogate is not null, let lead surrogate
// be utf-16 lead surrogate, set utf-16 lead surrogate to null,
// and then run these substeps:
if (this.utf16_lead_surrogate !== null) {
var lead_surrogate = this.utf16_lead_surrogate;
this.utf16_lead_surrogate = null;
// 1. If code unit is in the range U+DC00 to U+DFFF,
// inclusive, return a code point whose value is 0x10000 +
// ((lead surrogate − 0xD800) << 10) + (code unit − 0xDC00).
if (utilities_1.inRange(code_unit, 0xDC00, 0xDFFF)) {
return 0x10000 + (lead_surrogate - 0xD800) * 0x400 +
(code_unit - 0xDC00);
}
// 2. Prepend the sequence resulting of converting code unit
// to bytes using utf-16be decoder flag to stream and return
// error.
stream.prepend(converCodeUnitToBytes_1.convertCodeUnitToBytes(code_unit, this.utf16_be));
return encodings_1.decoderError(this.fatal);
}
// 6. If code unit is in the range U+D800 to U+DBFF, inclusive,
// set utf-16 lead surrogate to code unit and return continue.
if (utilities_1.inRange(code_unit, 0xD800, 0xDBFF)) {
this.utf16_lead_surrogate = code_unit;
return null;
}
// 7. If code unit is in the range U+DC00 to U+DFFF, inclusive,
// return error.
if (utilities_1.inRange(code_unit, 0xDC00, 0xDFFF))
return encodings_1.decoderError(this.fatal);
// 8. Return code point code unit.
return code_unit;
};
return UTF16Decoder;
}());
exports.UTF16Decoder = UTF16Decoder;
//# sourceMappingURL=UTF16Decoder.js.map