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https://github.com/jackyzha0/quartz.git
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77 lines
3.4 KiB
JavaScript
77 lines
3.4 KiB
JavaScript
import { encoderError } from "../../encoding/encodings";
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import { finished } from "../../encoding/finished";
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import { index, indexGB18030RangesPointerFor, indexPointerFor } from "../../encoding/indexes";
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import { end_of_stream, isASCIICodePoint } from "../../encoding/terminology";
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/**
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* @constructor
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* @implements {Encoder}
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* @param {{fatal: boolean}} options
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* @param {boolean=} gbk_flag
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*/
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export class GB18030Encoder {
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constructor(options, gbk_flag = undefined) {
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this.gbk_flag = gbk_flag;
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this.fatal = options.fatal;
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// gb18030's decoder has an associated gbk flag (initially unset).
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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 an ASCII code point, return a byte whose
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// value is code point.
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if (isASCIICodePoint(code_point))
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return code_point;
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// 3. If code point is U+E5E5, return error with code point.
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if (code_point === 0xE5E5)
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return encoderError(code_point);
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// 4. If the gbk flag is set and code point is U+20AC, return
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// byte 0x80.
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if (this.gbk_flag && code_point === 0x20AC)
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return 0x80;
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// 5. Let pointer be the index pointer for code point in index
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// gb18030.
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let pointer = indexPointerFor(code_point, index('gb18030'));
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// 6. If pointer is not null, run these substeps:
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if (pointer !== null) {
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// 1. Let lead be Math.floor(pointer / 190) + 0x81.
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const lead = Math.floor(pointer / 190) + 0x81;
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// 2. Let trail be pointer % 190.
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const trail = pointer % 190;
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// 3. Let offset be 0x40 if trail is less than 0x3F and 0x41 otherwise.
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const offset = trail < 0x3F ? 0x40 : 0x41;
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// 4. Return two bytes whose values are lead and trail + offset.
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return [lead, trail + offset];
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}
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// 7. If gbk flag is set, return error with code point.
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if (this.gbk_flag)
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return encoderError(code_point);
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// 8. Set pointer to the index gb18030 ranges pointer for code
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// point.
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pointer = indexGB18030RangesPointerFor(code_point);
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// 9. Let byte1 be Math.floor(pointer / 10 / 126 / 10).
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const byte1 = Math.floor(pointer / 10 / 126 / 10);
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// 10. Set pointer to pointer − byte1 × 10 × 126 × 10.
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pointer = pointer - byte1 * 10 * 126 * 10;
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// 11. Let byte2 be Math.floor(pointer / 10 / 126).
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const byte2 = Math.floor(pointer / 10 / 126);
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// 12. Set pointer to pointer − byte2 × 10 × 126.
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pointer = pointer - byte2 * 10 * 126;
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// 13. Let byte3 be Math.floor(pointer / 10).
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const byte3 = Math.floor(pointer / 10);
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// 14. Let byte4 be pointer − byte3 × 10.
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const byte4 = pointer - byte3 * 10;
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// 15. Return four bytes whose values are byte1 + 0x81, byte2 +
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// 0x30, byte3 + 0x81, byte4 + 0x30.
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return [byte1 + 0x81,
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byte2 + 0x30,
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byte3 + 0x81,
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byte4 + 0x30];
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}
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}
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//# sourceMappingURL=GB18030Encoder.js.map
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