56 lines
1.6 KiB
JavaScript
56 lines
1.6 KiB
JavaScript
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import { inRange, encoderError, end_of_stream, finished, isASCIIByte, isASCIICodePoint } from './text_decoder_utils.js'
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// 15.5 x-user-defined
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// 15.5.1 x-user-defined decoder
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/**
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* @implements {Decoder}
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*/
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export class XUserDefinedDecoder {
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/**
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* @param {Stream} stream The stream of bytes being decoded.
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* @param {number} bite The next byte read from the stream.
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*/
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handler(stream, bite) {
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// 1. If byte is end-of-stream, return finished.
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if (bite === end_of_stream)
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return finished
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// 2. If byte is an ASCII byte, return a code point whose value
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// is byte.
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if (isASCIIByte(bite))
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return bite
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// 3. Return a code point whose value is 0xF780 + byte − 0x80.
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return 0xF780 + bite - 0x80
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}
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}
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// 15.5.2 x-user-defined encoder
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/**
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* @implements {Encoder}
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*/
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export class XUserDefinedEncoder {
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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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*/
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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 in the range U+F780 to U+F7FF, inclusive,
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// return a byte whose value is code point − 0xF780 + 0x80.
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if (inRange(code_point, 0xF780, 0xF7FF))
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return code_point - 0xF780 + 0x80
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// 4. Return error with code point.
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return encoderError(code_point)
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}
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}
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