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decode.js
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Tue, Mar 4, 17:02

decode.js
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import htmlDecodeTree from "./generated/decode-data-html.js";
import xmlDecodeTree from "./generated/decode-data-xml.js";
import decodeCodePoint from "./decode_codepoint.js";
// Re-export for use by eg. htmlparser2
export { htmlDecodeTree, xmlDecodeTree, decodeCodePoint };
export { replaceCodePoint, fromCodePoint } from "./decode_codepoint.js";
var CharCodes;
(function (CharCodes) {
CharCodes[CharCodes["NUM"] = 35] = "NUM";
CharCodes[CharCodes["SEMI"] = 59] = "SEMI";
CharCodes[CharCodes["ZERO"] = 48] = "ZERO";
CharCodes[CharCodes["NINE"] = 57] = "NINE";
CharCodes[CharCodes["LOWER_A"] = 97] = "LOWER_A";
CharCodes[CharCodes["LOWER_F"] = 102] = "LOWER_F";
CharCodes[CharCodes["LOWER_X"] = 120] = "LOWER_X";
/** Bit that needs to be set to convert an upper case ASCII character to lower case */
CharCodes[CharCodes["To_LOWER_BIT"] = 32] = "To_LOWER_BIT";
})(CharCodes || (CharCodes = {}));
export var BinTrieFlags;
(function (BinTrieFlags) {
BinTrieFlags[BinTrieFlags["VALUE_LENGTH"] = 49152] = "VALUE_LENGTH";
BinTrieFlags[BinTrieFlags["BRANCH_LENGTH"] = 16256] = "BRANCH_LENGTH";
BinTrieFlags[BinTrieFlags["JUMP_TABLE"] = 127] = "JUMP_TABLE";
})(BinTrieFlags || (BinTrieFlags = {}));
function getDecoder(decodeTree) {
return function decodeHTMLBinary(str, strict) {
let ret = "";
let lastIdx = 0;
let strIdx = 0;
while ((strIdx = str.indexOf("&", strIdx)) >= 0) {
ret += str.slice(lastIdx, strIdx);
lastIdx = strIdx;
// Skip the "&"
strIdx += 1;
// If we have a numeric entity, handle this separately.
if (str.charCodeAt(strIdx) === CharCodes.NUM) {
// Skip the leading "&#". For hex entities, also skip the leading "x".
let start = strIdx + 1;
let base = 10;
let cp = str.charCodeAt(start);
if ((cp | CharCodes.To_LOWER_BIT) === CharCodes.LOWER_X) {
base = 16;
strIdx += 1;
start += 1;
}
do
cp = str.charCodeAt(++strIdx);
while ((cp >= CharCodes.ZERO && cp <= CharCodes.NINE) ||
(base === 16 &&
(cp | CharCodes.To_LOWER_BIT) >= CharCodes.LOWER_A &&
(cp | CharCodes.To_LOWER_BIT) <= CharCodes.LOWER_F));
if (start !== strIdx) {
const entity = str.substring(start, strIdx);
const parsed = parseInt(entity, base);
if (str.charCodeAt(strIdx) === CharCodes.SEMI) {
strIdx += 1;
}
else if (strict) {
continue;
}
ret += decodeCodePoint(parsed);
lastIdx = strIdx;
}
continue;
}
let resultIdx = 0;
let excess = 1;
let treeIdx = 0;
let current = decodeTree[treeIdx];
for (; strIdx < str.length; strIdx++, excess++) {
treeIdx = determineBranch(decodeTree, current, treeIdx + 1, str.charCodeAt(strIdx));
if (treeIdx < 0)
break;
current = decodeTree[treeIdx];
const masked = current & BinTrieFlags.VALUE_LENGTH;
// If the branch is a value, store it and continue
if (masked) {
// If we have a legacy entity while parsing strictly, just skip the number of bytes
if (!strict || str.charCodeAt(strIdx) === CharCodes.SEMI) {
resultIdx = treeIdx;
excess = 0;
}
// The mask is the number of bytes of the value, including the current byte.
const valueLength = (masked >> 14) - 1;
if (valueLength === 0)
break;
treeIdx += valueLength;
}
}
if (resultIdx !== 0) {
const valueLength = (decodeTree[resultIdx] & BinTrieFlags.VALUE_LENGTH) >> 14;
ret +=
valueLength === 1
? String.fromCharCode(decodeTree[resultIdx] & ~BinTrieFlags.VALUE_LENGTH)
: valueLength === 2
? String.fromCharCode(decodeTree[resultIdx + 1])
: String.fromCharCode(decodeTree[resultIdx + 1], decodeTree[resultIdx + 2]);
lastIdx = strIdx - excess + 1;
}
}
return ret + str.slice(lastIdx);
};
}
export function determineBranch(decodeTree, current, nodeIdx, char) {
const branchCount = (current & BinTrieFlags.BRANCH_LENGTH) >> 7;
const jumpOffset = current & BinTrieFlags.JUMP_TABLE;
// Case 1: Single branch encoded in jump offset
if (branchCount === 0) {
return jumpOffset !== 0 && char === jumpOffset ? nodeIdx : -1;
}
// Case 2: Multiple branches encoded in jump table
if (jumpOffset) {
const value = char - jumpOffset;
return value < 0 || value >= branchCount
? -1
: decodeTree[nodeIdx + value] - 1;
}
// Case 3: Multiple branches encoded in dictionary
// Binary search for the character.
let lo = nodeIdx;
let hi = lo + branchCount - 1;
while (lo <= hi) {
const mid = (lo + hi) >>> 1;
const midVal = decodeTree[mid];
if (midVal < char) {
lo = mid + 1;
}
else if (midVal > char) {
hi = mid - 1;
}
else {
return decodeTree[mid + branchCount];
}
}
return -1;
}
const htmlDecoder = getDecoder(htmlDecodeTree);
const xmlDecoder = getDecoder(xmlDecodeTree);
/**
* Decodes an HTML string, allowing for entities not terminated by a semi-colon.
*
* @param str The string to decode.
* @returns The decoded string.
*/
export function decodeHTML(str) {
return htmlDecoder(str, false);
}
/**
* Decodes an HTML string, requiring all entities to be terminated by a semi-colon.
*
* @param str The string to decode.
* @returns The decoded string.
*/
export function decodeHTMLStrict(str) {
return htmlDecoder(str, true);
}
/**
* Decodes an XML string, requiring all entities to be terminated by a semi-colon.
*
* @param str The string to decode.
* @returns The decoded string.
*/
export function decodeXML(str) {
return xmlDecoder(str, true);
}
//# sourceMappingURL=decode.js.map

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