42 lines
1.5 KiB
TypeScript
42 lines
1.5 KiB
TypeScript
const mathPattern = /(?<!\\)\$\$[\s\S]*?(?<!\\)\$\$|\\\[[\s\S]*?\\\]|\\\([^\n]*?\\\)|(?<![\\$])\$(?!\$)(?:\\.|[^\\$\n])+?(?<!\\)\$(?!\$)/g;
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const tokenPattern = /\uE000xiteng-math-(\d+)\uE001/g;
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function escapeHtml(value: string) {
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return value.replace(/[&<>"']/g, (character) => ({
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"&": "&",
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"<": "<",
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">": ">",
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'"': """,
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"'": "'"
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})[character]!);
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}
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export function protectMath(value: string) {
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const fragments: string[] = [];
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const source = value.replace(mathPattern, (fragment) => {
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const index = fragments.push(fragment) - 1;
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return `\uE000xiteng-math-${index}\uE001`;
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});
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return {source, fragments};
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}
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function mathFragmentKey(fragment: string, index: number) {
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let hash = 2166136261;
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for (let offset = 0; offset < fragment.length; offset += 1) {
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hash ^= fragment.charCodeAt(offset);
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hash = Math.imul(hash, 16777619);
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}
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return `${index}-${fragment.length}-${(hash >>> 0).toString(36)}`;
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}
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export function restoreMath(value: string, fragments: string[]) {
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return value.replace(tokenPattern, (_token, rawIndex: string, offset: number) => {
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const index = Number(rawIndex);
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const fragment = fragments[index] || "";
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const codeStart = value.lastIndexOf("<code", offset);
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const codeEnd = value.lastIndexOf("</code>", offset);
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if (codeStart > codeEnd) return escapeHtml(fragment);
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return `<span class="math-fragment" data-math-key="${mathFragmentKey(fragment, index)}">${escapeHtml(fragment)}</span>`;
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});
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}
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