@zxing/text-encoding
Version:
Polyfill for the Encoding Living Standard's API.
39 lines • 1.49 kB
JavaScript
import { encoderError } from "../../encoding/encodings";
import { finished } from "../../encoding/finished";
import { indexPointerFor } from "../../encoding/indexes";
import { end_of_stream, isASCIICodePoint } from "../../encoding/terminology";
/**
* @constructor
* @implements {Encoder}
* @param {!Array.<?number>} index The encoding index.
* @param {{fatal: boolean}} options
*/
export class SingleByteEncoder {
constructor(index, options) {
this.index = index;
this.fatal = options.fatal;
}
/**
* @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;
}
}
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