286 lines
9.0 KiB
TypeScript
286 lines
9.0 KiB
TypeScript
import { logger } from "./logger.js";
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import type { BytesLike } from "./index.js";
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///////////////////////////////
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export type UnicodeNormalizationForm = "NFC" | "NFD" | "NFKC" | "NFKD";
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export type Utf8ErrorReason =
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// A continuation byte was present where there was nothing to continue
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// - offset = the index the codepoint began in
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"UNEXPECTED_CONTINUE" |
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// An invalid (non-continuation) byte to start a UTF-8 codepoint was found
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// - offset = the index the codepoint began in
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"BAD_PREFIX" |
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// The string is too short to process the expected codepoint
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// - offset = the index the codepoint began in
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"OVERRUN" |
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// A missing continuation byte was expected but not found
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// - offset = the index the continuation byte was expected at
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"MISSING_CONTINUE" |
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// The computed code point is outside the range for UTF-8
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// - offset = start of this codepoint
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// - badCodepoint = the computed codepoint; outside the UTF-8 range
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"OUT_OF_RANGE" |
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// UTF-8 strings may not contain UTF-16 surrogate pairs
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// - offset = start of this codepoint
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// - badCodepoint = the computed codepoint; inside the UTF-16 surrogate range
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"UTF16_SURROGATE" |
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// The string is an overlong representation
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// - offset = start of this codepoint
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// - badCodepoint = the computed codepoint; already bounds checked
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"OVERLONG";
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export type Utf8ErrorFunc = (reason: Utf8ErrorReason, offset: number, bytes: ArrayLike<number>, output: Array<number>, badCodepoint?: number) => number;
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function errorFunc(reason: Utf8ErrorReason, offset: number, bytes: ArrayLike<number>, output: Array<number>, badCodepoint?: number): number {
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return logger.throwArgumentError(`invalid codepoint at offset ${ offset }; ${ reason }`, "bytes", bytes);
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}
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function ignoreFunc(reason: Utf8ErrorReason, offset: number, bytes: ArrayLike<number>, output: Array<number>, badCodepoint?: number): number {
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// If there is an invalid prefix (including stray continuation), skip any additional continuation bytes
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if (reason === "BAD_PREFIX" || reason === "UNEXPECTED_CONTINUE") {
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let i = 0;
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for (let o = offset + 1; o < bytes.length; o++) {
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if (bytes[o] >> 6 !== 0x02) { break; }
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i++;
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}
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return i;
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}
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// This byte runs us past the end of the string, so just jump to the end
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// (but the first byte was read already read and therefore skipped)
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if (reason === "OVERRUN") {
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return bytes.length - offset - 1;
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}
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// Nothing to skip
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return 0;
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}
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function replaceFunc(reason: Utf8ErrorReason, offset: number, bytes: ArrayLike<number>, output: Array<number>, badCodepoint?: number): number {
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// Overlong representations are otherwise "valid" code points; just non-deistingtished
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if (reason === "OVERLONG") {
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output.push((badCodepoint != null) ? badCodepoint: -1);
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return 0;
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}
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// Put the replacement character into the output
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output.push(0xfffd);
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// Otherwise, process as if ignoring errors
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return ignoreFunc(reason, offset, bytes, output, badCodepoint);
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}
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// Common error handing strategies
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export const Utf8ErrorFuncs: Readonly<Record<"error" | "ignore" | "replace", Utf8ErrorFunc>> = Object.freeze({
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error: errorFunc,
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ignore: ignoreFunc,
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replace: replaceFunc
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});
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// http://stackoverflow.com/questions/13356493/decode-utf-8-with-javascript#13691499
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function getUtf8CodePoints(_bytes: BytesLike, onError?: Utf8ErrorFunc): Array<number> {
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if (onError == null) { onError = Utf8ErrorFuncs.error; }
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const bytes = logger.getBytes(_bytes, "bytes");
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const result: Array<number> = [];
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let i = 0;
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// Invalid bytes are ignored
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while(i < bytes.length) {
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const c = bytes[i++];
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// 0xxx xxxx
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if (c >> 7 === 0) {
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result.push(c);
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continue;
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}
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// Multibyte; how many bytes left for this character?
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let extraLength = null;
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let overlongMask = null;
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// 110x xxxx 10xx xxxx
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if ((c & 0xe0) === 0xc0) {
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extraLength = 1;
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overlongMask = 0x7f;
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// 1110 xxxx 10xx xxxx 10xx xxxx
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} else if ((c & 0xf0) === 0xe0) {
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extraLength = 2;
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overlongMask = 0x7ff;
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// 1111 0xxx 10xx xxxx 10xx xxxx 10xx xxxx
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} else if ((c & 0xf8) === 0xf0) {
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extraLength = 3;
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overlongMask = 0xffff;
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} else {
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if ((c & 0xc0) === 0x80) {
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i += onError("UNEXPECTED_CONTINUE", i - 1, bytes, result);
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} else {
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i += onError("BAD_PREFIX", i - 1, bytes, result);
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}
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continue;
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}
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// Do we have enough bytes in our data?
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if (i - 1 + extraLength >= bytes.length) {
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i += onError("OVERRUN", i - 1, bytes, result);
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continue;
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}
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// Remove the length prefix from the char
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let res: null | number = c & ((1 << (8 - extraLength - 1)) - 1);
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for (let j = 0; j < extraLength; j++) {
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let nextChar = bytes[i];
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// Invalid continuation byte
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if ((nextChar & 0xc0) != 0x80) {
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i += onError("MISSING_CONTINUE", i, bytes, result);
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res = null;
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break;
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};
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res = (res << 6) | (nextChar & 0x3f);
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i++;
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}
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// See above loop for invalid continuation byte
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if (res === null) { continue; }
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// Maximum code point
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if (res > 0x10ffff) {
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i += onError("OUT_OF_RANGE", i - 1 - extraLength, bytes, result, res);
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continue;
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}
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// Reserved for UTF-16 surrogate halves
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if (res >= 0xd800 && res <= 0xdfff) {
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i += onError("UTF16_SURROGATE", i - 1 - extraLength, bytes, result, res);
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continue;
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}
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// Check for overlong sequences (more bytes than needed)
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if (res <= overlongMask) {
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i += onError("OVERLONG", i - 1 - extraLength, bytes, result, res);
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continue;
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}
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result.push(res);
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}
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return result;
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}
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// http://stackoverflow.com/questions/18729405/how-to-convert-utf8-string-to-byte-array
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export function toUtf8Bytes(str: string, form?: UnicodeNormalizationForm): Uint8Array {
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if (form != null) {
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logger.assertNormalize(form);
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str = str.normalize(form);
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}
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let result = [];
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for (let i = 0; i < str.length; i++) {
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const c = str.charCodeAt(i);
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if (c < 0x80) {
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result.push(c);
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} else if (c < 0x800) {
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result.push((c >> 6) | 0xc0);
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result.push((c & 0x3f) | 0x80);
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} else if ((c & 0xfc00) == 0xd800) {
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i++;
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const c2 = str.charCodeAt(i);
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if (i >= str.length || (c2 & 0xfc00) !== 0xdc00) {
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throw new Error("invalid utf-8 string");
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}
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// Surrogate Pair
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const pair = 0x10000 + ((c & 0x03ff) << 10) + (c2 & 0x03ff);
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result.push((pair >> 18) | 0xf0);
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result.push(((pair >> 12) & 0x3f) | 0x80);
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result.push(((pair >> 6) & 0x3f) | 0x80);
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result.push((pair & 0x3f) | 0x80);
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} else {
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result.push((c >> 12) | 0xe0);
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result.push(((c >> 6) & 0x3f) | 0x80);
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result.push((c & 0x3f) | 0x80);
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}
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}
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return new Uint8Array(result);
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};
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function escapeChar(value: number) {
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const hex = ("0000" + value.toString(16));
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return "\\u" + hex.substring(hex.length - 4);
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}
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export function _toEscapedUtf8String(bytes: BytesLike, onError?: Utf8ErrorFunc): string {
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return '"' + getUtf8CodePoints(bytes, onError).map((codePoint) => {
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if (codePoint < 256) {
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switch (codePoint) {
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case 8: return "\\b";
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case 9: return "\\t";
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case 10: return "\\n"
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case 13: return "\\r";
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case 34: return "\\\"";
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case 92: return "\\\\";
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}
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if (codePoint >= 32 && codePoint < 127) {
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return String.fromCharCode(codePoint);
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}
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}
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if (codePoint <= 0xffff) {
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return escapeChar(codePoint);
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}
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codePoint -= 0x10000;
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return escapeChar(((codePoint >> 10) & 0x3ff) + 0xd800) + escapeChar((codePoint & 0x3ff) + 0xdc00);
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}).join("") + '"';
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}
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export function _toUtf8String(codePoints: Array<number>): string {
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return codePoints.map((codePoint) => {
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if (codePoint <= 0xffff) {
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return String.fromCharCode(codePoint);
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}
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codePoint -= 0x10000;
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return String.fromCharCode(
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(((codePoint >> 10) & 0x3ff) + 0xd800),
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((codePoint & 0x3ff) + 0xdc00)
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);
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}).join("");
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}
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export function toUtf8String(bytes: BytesLike, onError?: Utf8ErrorFunc): string {
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return _toUtf8String(getUtf8CodePoints(bytes, onError));
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}
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export function toUtf8CodePoints(str: string, form?: UnicodeNormalizationForm): Array<number> {
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return getUtf8CodePoints(toUtf8Bytes(str, form));
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}
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