zero-md/src/lib/katex-extension.js

Ridiculously simple zero-config markdown displayer

/* eslint-disable */
// @ts-nocheck
// Edited from https://github.com/UziTech/marked-katex-extension/blob/v5.1.1/src/index.js

//import katex from 'katex';

const inlineRule =
  /^(\${1,2})(?!\$)((?:\\.|[^\\\n])*?(?:\\.|[^\\\n\$]))\1(?=[\s?!\.,:？！。，：]|$)/
const inlineRuleNonStandard = /^(\${1,2})(?!\$)((?:\\.|[^\\\n])*?(?:\\.|[^\\\n\$]))\1/ // Non-standard, even if there are no spaces before and after $ or $$, try to parse

const blockRule = /^(\${1,2})\n((?:\\[^]|[^\\])+?)\n\1(?:\n|$)/

export default function (options = {}) {
  return {
    extensions: [
      inlineKatex(options, createRenderer(options, false)),
      blockKatex(options, createRenderer(options, true))
    ]
  }
}

/*
function createRenderer(options, newlineAfter) {
  return (token) => katex.renderToString(token.text, { ...options, displayMode: token.displayMode }) + (newlineAfter ? '\n' : '');
}
*/

function createRenderer() {
  return (token) => token.text
}

function inlineKatex(options, renderer) {
  const nonStandard = options && options.nonStandard
  const ruleReg = nonStandard ? inlineRuleNonStandard : inlineRule
  return {
    name: 'inlineKatex',
    level: 'inline',
    start(src) {
      let index
      let indexSrc = src

      while (indexSrc) {
        index = indexSrc.indexOf('$')
        if (index === -1) {
          return
        }
        const f = nonStandard ? index > -1 : index === 0 || indexSrc.charAt(index - 1) === ' '
        if (f) {
          const possibleKatex = indexSrc.substring(index)

          if (possibleKatex.match(ruleReg)) {
            return index
          }
        }

        indexSrc = indexSrc.substring(index + 1).replace(/^\$+/, '')
      }
    },
    tokenizer(src, tokens) {
      const match = src.match(ruleReg)
      if (match) {
        return {
          type: 'inlineKatex',
          raw: match[0],
          text: match[2].trim(),
          displayMode: match[1].length === 2
        }
      }
    },
    renderer
  }
}

function blockKatex(options, renderer) {
  return {
    name: 'blockKatex',
    level: 'block',
    tokenizer(src, tokens) {
      const match = src.match(blockRule)
      if (match) {
        return {
          type: 'blockKatex',
          raw: match[0],
          text: match[2].trim(),
          displayMode: match[1].length === 2
        }
      }
    },
    renderer
  }
}