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denoland-deno/cli/js/web/decode_utf8.ts

133 lines
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TypeScript

// This module is based on Bjoern Hoehrmann's DFA UTF-8 decoder.
// See http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
//
// Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
// `.apply` can actually take a typed array, though the type system doesn't
// really support it, so we have to "hack" it a bit to get past some of the
// strict type checks.
declare global {
interface CallableFunction extends Function {
apply<T, R>(
this: (this: T, ...args: number[]) => R,
thisArg: T,
args: Uint16Array
): R;
}
}
export function decodeUtf8(
input: Uint8Array,
fatal: boolean,
ignoreBOM: boolean
): string {
let outString = "";
// Prepare a buffer so that we don't have to do a lot of string concats, which
// are very slow.
const outBufferLength: number = Math.min(1024, input.length);
const outBuffer = new Uint16Array(outBufferLength);
let outIndex = 0;
let state = 0;
let codepoint = 0;
let type: number;
let i =
ignoreBOM && input[0] === 0xef && input[1] === 0xbb && input[2] === 0xbf
? 3
: 0;
for (; i < input.length; ++i) {
// Encoding error handling
if (state === 12 || (state !== 0 && (input[i] & 0xc0) !== 0x80)) {
if (fatal)
throw new TypeError(
`Decoder error. Invalid byte in sequence at position ${i} in data.`
);
outBuffer[outIndex++] = 0xfffd; // Replacement character
if (outIndex === outBufferLength) {
outString += String.fromCharCode.apply(null, outBuffer);
outIndex = 0;
}
state = 0;
}
// prettier-ignore
type = [
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
10,3,3,3,3,3,3,3,3,3,3,3,3,4,3,3, 11,6,6,6,5,8,8,8,8,8,8,8,8,8,8,8
][input[i]];
codepoint =
state !== 0
? (input[i] & 0x3f) | (codepoint << 6)
: (0xff >> type) & input[i];
// prettier-ignore
state = [
0,12,24,36,60,96,84,12,12,12,48,72, 12,12,12,12,12,12,12,12,12,12,12,12,
12, 0,12,12,12,12,12, 0,12, 0,12,12, 12,24,12,12,12,12,12,24,12,24,12,12,
12,12,12,12,12,12,12,24,12,12,12,12, 12,24,12,12,12,12,12,12,12,24,12,12,
12,12,12,12,12,12,12,36,12,36,12,12, 12,36,12,12,12,12,12,36,12,36,12,12,
12,36,12,12,12,12,12,12,12,12,12,12
][state + type];
if (state !== 0) continue;
// Add codepoint to buffer (as charcodes for utf-16), and flush buffer to
// string if needed.
if (codepoint > 0xffff) {
outBuffer[outIndex++] = 0xd7c0 + (codepoint >> 10);
if (outIndex === outBufferLength) {
outString += String.fromCharCode.apply(null, outBuffer);
outIndex = 0;
}
outBuffer[outIndex++] = 0xdc00 | (codepoint & 0x3ff);
if (outIndex === outBufferLength) {
outString += String.fromCharCode.apply(null, outBuffer);
outIndex = 0;
}
} else {
outBuffer[outIndex++] = codepoint;
if (outIndex === outBufferLength) {
outString += String.fromCharCode.apply(null, outBuffer);
outIndex = 0;
}
}
}
// Add a replacement character if we ended in the middle of a sequence or
// encountered an invalid code at the end.
if (state !== 0) {
if (fatal) throw new TypeError(`Decoder error. Unexpected end of data.`);
outBuffer[outIndex++] = 0xfffd; // Replacement character
}
// Final flush of buffer
outString += String.fromCharCode.apply(null, outBuffer.subarray(0, outIndex));
return outString;
}