mirror of
https://github.com/denoland/deno.git
synced 2024-11-25 15:29:32 -05:00
80 lines
2.5 KiB
TypeScript
80 lines
2.5 KiB
TypeScript
// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
|
|
// The following code is based off:
|
|
// https://github.com/samthor/fast-text-encoding
|
|
//
|
|
// Copyright 2017 Sam Thorogood. All rights reserved.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
|
|
// use this file except in compliance with the License. You may obtain a copy of
|
|
// the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
// License for the specific language governing permissions and limitations under
|
|
// the License.
|
|
//
|
|
|
|
export function encodeUtf8(input: string): Uint8Array {
|
|
let pos = 0;
|
|
const len = input.length;
|
|
|
|
let at = 0; // output position
|
|
let tlen = Math.max(32, len + (len >> 1) + 7); // 1.5x size
|
|
let target = new Uint8Array((tlen >> 3) << 3); // ... but at 8 byte offset
|
|
|
|
while (pos < len) {
|
|
let value = input.charCodeAt(pos++);
|
|
if (value >= 0xd800 && value <= 0xdbff) {
|
|
// high surrogate
|
|
if (pos < len) {
|
|
const extra = input.charCodeAt(pos);
|
|
if ((extra & 0xfc00) === 0xdc00) {
|
|
++pos;
|
|
value = ((value & 0x3ff) << 10) + (extra & 0x3ff) + 0x10000;
|
|
}
|
|
}
|
|
if (value >= 0xd800 && value <= 0xdbff) {
|
|
continue; // drop lone surrogate
|
|
}
|
|
}
|
|
|
|
// expand the buffer if we couldn't write 4 bytes
|
|
if (at + 4 > target.length) {
|
|
tlen += 8; // minimum extra
|
|
tlen *= 1.0 + (pos / input.length) * 2; // take 2x the remaining
|
|
tlen = (tlen >> 3) << 3; // 8 byte offset
|
|
|
|
const update = new Uint8Array(tlen);
|
|
update.set(target);
|
|
target = update;
|
|
}
|
|
|
|
if ((value & 0xffffff80) === 0) {
|
|
// 1-byte
|
|
target[at++] = value; // ASCII
|
|
continue;
|
|
} else if ((value & 0xfffff800) === 0) {
|
|
// 2-byte
|
|
target[at++] = ((value >> 6) & 0x1f) | 0xc0;
|
|
} else if ((value & 0xffff0000) === 0) {
|
|
// 3-byte
|
|
target[at++] = ((value >> 12) & 0x0f) | 0xe0;
|
|
target[at++] = ((value >> 6) & 0x3f) | 0x80;
|
|
} else if ((value & 0xffe00000) === 0) {
|
|
// 4-byte
|
|
target[at++] = ((value >> 18) & 0x07) | 0xf0;
|
|
target[at++] = ((value >> 12) & 0x3f) | 0x80;
|
|
target[at++] = ((value >> 6) & 0x3f) | 0x80;
|
|
} else {
|
|
// FIXME: do we care
|
|
continue;
|
|
}
|
|
|
|
target[at++] = (value & 0x3f) | 0x80;
|
|
}
|
|
|
|
return target.slice(0, at);
|
|
}
|