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@@ -0,0 +1,80 @@
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+import katex from 'katex';
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+
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+const inlineRule = /^(\${1,2})(?!\$)((?:\\.|[^\\\n])*?(?:\\.|[^\\\n\$]))\1(?=[\s?!\.,:?!。,:]|$)/;
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+const inlineRuleNonStandard = /^(\${1,2})(?!\$)((?:\\.|[^\\\n])*?(?:\\.|[^\\\n\$]))\1/; // Non-standard, even if there are no spaces before and after $ or $$, try to parse
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+
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+const blockRule = /^(\${1,2})\n((?:\\[^]|[^\\])+?)\n\1(?:\n|$)/;
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+
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+export default function(options = {}) {
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+ return {
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+ extensions: [
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+ inlineKatex(options, createRenderer(options, false)),
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+ blockKatex(options, createRenderer(options, true)),
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+ ],
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+ };
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+}
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+
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+function createRenderer(options, newlineAfter) {
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+ return (token) => katex.renderToString(token.text, { ...options, displayMode: token.displayMode }) + (newlineAfter ? '\n' : '');
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+}
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+
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+function inlineKatex(options, renderer) {
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+ const nonStandard = options && options.nonStandard;
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+ const ruleReg = nonStandard ? inlineRuleNonStandard : inlineRule;
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+ return {
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+ name: 'inlineKatex',
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+ level: 'inline',
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+ start(src) {
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+ let index;
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+ let indexSrc = src;
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+
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+ while (indexSrc) {
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+ index = indexSrc.indexOf('$');
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+ if (index === -1) {
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+ return;
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+ }
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+ const f = nonStandard ? index > -1 : index === 0 || indexSrc.charAt(index - 1) === ' ';
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+ if (f) {
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+ const possibleKatex = indexSrc.substring(index);
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+
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+ if (possibleKatex.match(ruleReg)) {
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+ return index;
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+ }
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+ }
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+
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+ indexSrc = indexSrc.substring(index + 1).replace(/^\$+/, '');
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+ }
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+ },
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+ tokenizer(src, tokens) {
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+ const match = src.match(ruleReg);
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+ if (match) {
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+ return {
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+ type: 'inlineKatex',
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+ raw: match[0],
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+ text: match[2].trim(),
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+ displayMode: match[1].length === 2,
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+ };
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+ }
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+ },
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+ renderer,
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+ };
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+}
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+
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+function blockKatex(options, renderer) {
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+ return {
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+ name: 'blockKatex',
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+ level: 'block',
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+ tokenizer(src, tokens) {
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+ const match = src.match(blockRule);
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+ if (match) {
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+ return {
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+ type: 'blockKatex',
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+ raw: match[0],
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+ text: match[2].trim(),
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+ displayMode: match[1].length === 2,
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+ };
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+ }
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+ },
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+ renderer,
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+ };
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+}
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