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40 lines
1.8 KiB
JavaScript
40 lines
1.8 KiB
JavaScript
import { finished } from "../../encoding/finished";
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import { end_of_stream } from "../../encoding/terminology";
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import { inRange } from "../../encoding/utilities";
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import { convertCodeUnitToBytes } from "./converCodeUnitToBytes";
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/**
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* @constructor
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* @implements {Encoder}
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* @param {boolean} utf16_be True if big-endian, false if little-endian.
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* @param {{fatal: boolean}} options
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*/
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export class UTF16Encoder {
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constructor(utf16_be, options) {
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this.utf16_be = utf16_be;
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this.fatal = options.fatal;
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}
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/**
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* @param {Stream} stream Input stream.
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* @param {number} code_point Next code point read from the stream.
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* @return {(number|!Array.<number>)} Byte(s) to emit.
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*/
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handler(stream, code_point) {
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// 1. If code point is end-of-stream, return finished.
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if (code_point === end_of_stream)
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return finished;
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// 2. If code point is in the range U+0000 to U+FFFF, inclusive,
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// return the sequence resulting of converting code point to
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// bytes using utf-16be encoder flag.
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if (inRange(code_point, 0x0000, 0xFFFF))
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return convertCodeUnitToBytes(code_point, this.utf16_be);
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// 3. Let lead be ((code point − 0x10000) >> 10) + 0xD800,
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// converted to bytes using utf-16be encoder flag.
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const lead = convertCodeUnitToBytes(((code_point - 0x10000) >> 10) + 0xD800, this.utf16_be);
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// 4. Let trail be ((code point − 0x10000) & 0x3FF) + 0xDC00,
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// converted to bytes using utf-16be encoder flag.
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const trail = convertCodeUnitToBytes(((code_point - 0x10000) & 0x3FF) + 0xDC00, this.utf16_be);
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// 5. Return a byte sequence of lead followed by trail.
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return lead.concat(trail);
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}
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}
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//# sourceMappingURL=UTF16Encoder.js.map
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