mirror of
https://github.com/qist/tvbox.git
synced 2025-10-31 04:02:22 +00:00
86 lines
2.3 KiB
JavaScript
86 lines
2.3 KiB
JavaScript
import { end_of_stream, finished, isASCIIByte, decoderError, encoderError, isASCIICodePoint } from './text_decoder_utils.js'
|
||
import { indexPointerFor } from './text_decoder_indexes.js'
|
||
|
||
//
|
||
// 10. Legacy single-byte encodings
|
||
//
|
||
|
||
// 10.1 single-byte decoder
|
||
/**
|
||
* @implements {Decoder}
|
||
*/
|
||
export class SingleByteDecoder {
|
||
/**
|
||
* @param {!Array.<number>} index The encoding index.
|
||
* @param {{fatal: boolean}} options
|
||
*/
|
||
constructor(index, options) {
|
||
const { fatal } = options
|
||
this.fatal = fatal
|
||
this.index = index
|
||
}
|
||
/**
|
||
* @param {Stream} stream The stream of bytes being decoded.
|
||
* @param {number} bite The next byte read from the stream.
|
||
*/
|
||
handler(stream, bite) {
|
||
// 1. If byte is end-of-stream, return finished.
|
||
if (bite === end_of_stream)
|
||
return finished
|
||
|
||
// 2. If byte is an ASCII byte, return a code point whose value
|
||
// is byte.
|
||
if (isASCIIByte(bite))
|
||
return bite
|
||
|
||
// 3. Let code point be the index code point for byte − 0x80 in
|
||
// index single-byte.
|
||
var code_point = this.index[bite - 0x80]
|
||
|
||
// 4. If code point is null, return error.
|
||
if (code_point === null)
|
||
return decoderError(this.fatal)
|
||
|
||
// 5. Return a code point whose value is code point.
|
||
return code_point
|
||
}
|
||
}
|
||
|
||
// 10.2 single-byte encoder
|
||
/**
|
||
* @implements {Encoder}
|
||
*/
|
||
export class SingleByteEncoder {
|
||
/**
|
||
* @param {!Array.<?number>} index The encoding index.
|
||
*/
|
||
constructor(index) {
|
||
this.index = index
|
||
}
|
||
/**
|
||
* @param {Stream} stream Input stream.
|
||
* @param {number} code_point Next code point read from the stream.
|
||
* @return {(number|!Array.<number>)} Byte(s) to emit.
|
||
*/
|
||
handler(stream, code_point) {
|
||
// 1. If code point is end-of-stream, return finished.
|
||
if (code_point === end_of_stream)
|
||
return finished
|
||
|
||
// 2. If code point is an ASCII code point, return a byte whose
|
||
// value is code point.
|
||
if (isASCIICodePoint(code_point))
|
||
return code_point
|
||
|
||
// 3. Let pointer be the index pointer for code point in index
|
||
// single-byte.
|
||
const pointer = indexPointerFor(code_point, this.index)
|
||
|
||
// 4. If pointer is null, return error with code point.
|
||
if (pointer === null)
|
||
encoderError(code_point)
|
||
|
||
// 5. Return a byte whose value is pointer + 0x80.
|
||
return pointer + 0x80
|
||
}
|
||
} |