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// https://github.com/waylonflinn/markdown-it-katex/blob/master/index.js
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const katex = require('katex');
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const logger = new global.Hydro.Logger('katex');
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function isValidDelim(state, pos) {
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const max = state.posMax;
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const prevChar = pos > 0 ? state.src.charCodeAt(pos - 1) : -1;
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const nextChar = pos + 1 <= max ? state.src.charCodeAt(pos + 1) : -1;
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let canOpen = true;
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let canClose = true;
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if (prevChar === 0x09
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||/* \t */ (nextChar >= 0x30/* "0" */ && nextChar <= 0x39/* "9" */)) canClose = false;
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if (nextChar === 0x09/* \t */) canOpen = false;
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return {
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canOpen,
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canClose,
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};
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}
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function inline(state, silent) {
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let pos;
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if (state.src[state.pos] !== '$') return false;
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let res = isValidDelim(state, state.pos);
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if (!res.canOpen) {
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if (!silent) state.pending += '$';
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state.pos += 1;
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return true;
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}
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const start = state.pos + 1;
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let match = start;
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// eslint-disable-next-line no-cond-assign
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while ((match = state.src.indexOf('$', match)) !== -1) {
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pos = match - 1;
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while (state.src[pos] === '\\') pos -= 1;
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if ((match - pos) % 2) break;
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match += 1;
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}
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if (match === -1) {
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if (!silent) state.pending += '$';
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state.pos = start;
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return true;
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}
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if (match - start === 0) {
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if (!silent) state.pending += '$$';
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state.pos = start + 1;
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return true;
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}
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res = isValidDelim(state, match);
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if (!res.canClose) {
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if (!silent) state.pending += '$';
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state.pos = start;
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return true;
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}
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if (!silent) {
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const token = state.push('math_inline', 'math', 0);
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token.markup = '$';
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token.content = state.src.slice(start, match);
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}
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state.pos = match + 1;
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return true;
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}
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function block(state, start, end, silent) {
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let lastLine;
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let lastPos;
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let found = false;
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let pos = state.bMarks[start] + state.tShift[start];
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let max = state.eMarks[start];
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if (pos + 2 > max) return false;
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if (state.src.slice(pos, pos + 2) !== '$$') return false;
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pos += 2;
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let firstLine = state.src.slice(pos, max);
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if (silent) return true;
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if (firstLine.trim().slice(-2) === '$$') {
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firstLine = firstLine.trim().slice(0, -2);
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found = true;
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}
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let next = start;
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while (!found) {
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next++;
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if (next >= end) break;
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pos = state.bMarks[next] + state.tShift[next];
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max = state.eMarks[next];
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if (pos < max && state.tShift[next] < state.blkIndent) break;
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if (state.src.slice(pos, max).trim().slice(-2) === '$$') {
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lastPos = state.src.slice(0, max).lastIndexOf('$$');
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lastLine = state.src.slice(pos, lastPos);
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found = true;
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}
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}
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state.line = next + 1;
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const token = state.push('math_block', 'math', 0);
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token.block = true;
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token.content = (firstLine && firstLine.trim() ? `${firstLine}\n` : '')
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+ state.getLines(start + 1, next, state.tShift[start], true)
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+ (lastLine && lastLine.trim() ? lastLine : '');
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token.map = [start, state.line];
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token.markup = '$$';
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return true;
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}
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module.exports = function plugin(md) {
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const options = { throwOnError: false, strict: 'ignore' };
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const katexInline = function (latex) {
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options.displayMode = false;
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try {
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return katex.renderToString(latex, options);
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} catch (error) {
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if (options.throwOnError) logger.error(error);
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return latex;
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}
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};
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const inlineRenderer = function (tokens, idx) {
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return katexInline(tokens[idx].content);
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};
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const katexBlock = function (latex) {
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options.displayMode = true;
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try {
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return `<p>${katex.renderToString(latex, options)}</p>`;
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} catch (error) {
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if (options.throwOnError) logger.error(error);
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return latex;
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}
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};
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const blockRenderer = function (tokens, idx) {
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return `${katexBlock(tokens[idx].content)}\n`;
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};
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md.inline.ruler.after('escape', 'math_inline', inline);
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md.block.ruler.after('blockquote', 'math_block', block, {
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alt: ['paragraph', 'reference', 'blockquote', 'list'],
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});
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md.renderer.rules.math_inline = inlineRenderer;
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md.renderer.rules.math_block = blockRenderer;
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};
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