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61 lines
2.6 KiB
JavaScript
61 lines
2.6 KiB
JavaScript
import { encoderError } from "../../encoding/encodings";
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import { finished } from "../../encoding/finished";
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import { indexShiftJISPointerFor } from "../../encoding/indexes";
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import { end_of_stream, isASCIICodePoint } from "../../encoding/terminology";
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import { inRange } from "../../encoding/utilities";
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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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*/
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export class ShiftJISEncoder {
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constructor(options) {
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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 an ASCII code point or U+0080, return a
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// byte whose value is code point.
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if (isASCIICodePoint(code_point) || code_point === 0x0080)
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return code_point;
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// 3. If code point is U+00A5, return byte 0x5C.
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if (code_point === 0x00A5)
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return 0x5C;
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// 4. If code point is U+203E, return byte 0x7E.
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if (code_point === 0x203E)
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return 0x7E;
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// 5. If code point is in the range U+FF61 to U+FF9F, inclusive,
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// return a byte whose value is code point − 0xFF61 + 0xA1.
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if (inRange(code_point, 0xFF61, 0xFF9F))
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return code_point - 0xFF61 + 0xA1;
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// 6. If code point is U+2212, set it to U+FF0D.
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if (code_point === 0x2212)
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code_point = 0xFF0D;
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// 7. Let pointer be the index Shift_JIS pointer for code point.
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const pointer = indexShiftJISPointerFor(code_point);
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// 8. If pointer is null, return error with code point.
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if (pointer === null)
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return encoderError(code_point);
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// 9. Let lead be Math.floor(pointer / 188).
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const lead = Math.floor(pointer / 188);
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// 10. Let lead offset be 0x81, if lead is less than 0x1F, and
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// 0xC1 otherwise.
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const lead_offset = (lead < 0x1F) ? 0x81 : 0xC1;
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// 11. Let trail be pointer % 188.
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const trail = pointer % 188;
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// 12. Let offset be 0x40, if trail is less than 0x3F, and 0x41
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// otherwise.
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const offset = (trail < 0x3F) ? 0x40 : 0x41;
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// 13. Return two bytes whose values are lead + lead offset and
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// trail + offset.
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return [lead + lead_offset, trail + offset];
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}
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}
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//# sourceMappingURL=ShiftJISEncoder.js.map
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