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encode.ts
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encode.ts
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import { htmlTrie } from "./generated/encode-html.js";
import { xmlReplacer, getCodePoint } from "./escape.js";
const htmlReplacer = /[\t\n\f!-,./:-@[-`{-}\u0080-\uFFFF]/g;
/**
* Encodes all characters in the input using HTML entities. This includes
* characters that are valid ASCII characters in HTML documents, such as `#`.
*
* To get a more compact output, consider using the `encodeNonAsciiHTML`
* function, which will only encode characters that are not valid in HTML
* documents, as well as non-ASCII characters.
*
* If a character has no equivalent entity, a numeric hexadecimal reference
* (eg. `ü`) will be used.
*/
export function encodeHTML(input: string): string {
return encodeHTMLTrieRe(htmlReplacer, input);
}
/**
* Encodes all non-ASCII characters, as well as characters not valid in HTML
* documents using HTML entities. This function will not encode characters that
* are valid in HTML documents, such as `#`.
*
* If a character has no equivalent entity, a numeric hexadecimal reference
* (eg. `ü`) will be used.
*/
export function encodeNonAsciiHTML(input: string): string {
return encodeHTMLTrieRe(xmlReplacer, input);
}
function encodeHTMLTrieRe(regExp: RegExp, input: string): string {
let returnValue = "";
let lastIndex = 0;
let match;
while ((match = regExp.exec(input)) !== null) {
const { index } = match;
returnValue += input.substring(lastIndex, index);
const char = input.charCodeAt(index);
let next = htmlTrie.get(char);
if (typeof next === "object") {
// We are in a branch. Try to match the next char.
if (index + 1 < input.length) {
const nextChar = input.charCodeAt(index + 1);
const value =
typeof next.n === "number"
? next.n === nextChar
? next.o
: undefined
: next.n.get(nextChar);
if (value !== undefined) {
returnValue += value;
lastIndex = regExp.lastIndex += 1;
continue;
}
}
next = next.v;
}
// We might have a tree node without a value; skip and use a numeric entity.
if (next === undefined) {
const cp = getCodePoint(input, index);
returnValue += `&#x${cp.toString(16)};`;
// Increase by 1 if we have a surrogate pair
lastIndex = regExp.lastIndex += Number(cp !== char);
} else {
returnValue += next;
lastIndex = index + 1;
}
}
return returnValue + input.substr(lastIndex);
}