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wiki/server/modules/rendering/markdown-katex/renderer.js

197 lines
5.5 KiB

const katex = require('katex')
const chemParse = require('./mhchem')
/* global WIKI */
// ------------------------------------
// Markdown - KaTeX Renderer
// ------------------------------------
//
// Includes code from https://github.com/liradb2000/markdown-it-katex
// Add \ce, \pu, and \tripledash to the KaTeX macros.
katex.__defineMacro('\\ce', function(context) {
return chemParse(context.consumeArgs(1)[0], 'ce')
})
katex.__defineMacro('\\pu', function(context) {
return chemParse(context.consumeArgs(1)[0], 'pu')
})
// Needed for \bond for the ~ forms
// Raise by 2.56mu, not 2mu. We're raising a hyphen-minus, U+002D, not
// a mathematical minus, U+2212. So we need that extra 0.56.
katex.__defineMacro('\\tripledash', '{\\vphantom{-}\\raisebox{2.56mu}{$\\mkern2mu' + '\\tiny\\text{-}\\mkern1mu\\text{-}\\mkern1mu\\text{-}\\mkern2mu$}}')
module.exports = {
init (mdinst, conf) {
const macros = {}
if (conf.useInline) {
mdinst.inline.ruler.after('escape', 'katex_inline', katexInline)
mdinst.renderer.rules.katex_inline = (tokens, idx) => {
try {
return katex.renderToString(tokens[idx].content, {
displayMode: false, macros
})
} catch (err) {
WIKI.logger.warn(err)
return tokens[idx].content
}
}
}
if (conf.useBlocks) {
mdinst.block.ruler.after('blockquote', 'katex_block', katexBlock, {
alt: [ 'paragraph', 'reference', 'blockquote', 'list' ]
})
mdinst.renderer.rules.katex_block = (tokens, idx) => {
try {
return `<p>` + katex.renderToString(tokens[idx].content, {
displayMode: true, macros
}) + `</p>`
} catch (err) {
WIKI.logger.warn(err)
return tokens[idx].content
}
}
}
}
}
// Test if potential opening or closing delimieter
// Assumes that there is a "$" at state.src[pos]
function isValidDelim (state, pos) {
let prevChar
let nextChar
let max = state.posMax
let canOpen = true
let canClose = true
prevChar = pos > 0 ? state.src.charCodeAt(pos - 1) : -1
nextChar = pos + 1 <= max ? state.src.charCodeAt(pos + 1) : -1
// Check non-whitespace conditions for opening and closing, and
// check that closing delimeter isn't followed by a number
if (prevChar === 0x20/* " " */ || prevChar === 0x09/* \t */ ||
(nextChar >= 0x30/* "0" */ && nextChar <= 0x39/* "9" */)) {
canClose = false
}
if (nextChar === 0x20/* " " */ || nextChar === 0x09/* \t */) {
canOpen = false
}
return {
canOpen: canOpen,
canClose: canClose
}
}
function katexInline (state, silent) {
let start, match, token, res, pos
if (state.src[state.pos] !== '$') { return false }
res = isValidDelim(state, state.pos)
if (!res.canOpen) {
if (!silent) { state.pending += '$' }
state.pos += 1
return true
}
// First check for and bypass all properly escaped delimieters
// This loop will assume that the first leading backtick can not
// be the first character in state.src, which is known since
// we have found an opening delimieter already.
start = state.pos + 1
match = start
while ((match = state.src.indexOf('$', match)) !== -1) {
// Found potential $, look for escapes, pos will point to
// first non escape when complete
pos = match - 1
while (state.src[pos] === '\\') { pos -= 1 }
// Even number of escapes, potential closing delimiter found
if (((match - pos) % 2) === 1) { break }
match += 1
}
// No closing delimter found. Consume $ and continue.
if (match === -1) {
if (!silent) { state.pending += '$' }
state.pos = start
return true
}
// Check if we have empty content, ie: $$. Do not parse.
if (match - start === 0) {
if (!silent) { state.pending += '$$' }
state.pos = start + 1
return true
}
// Check for valid closing delimiter
res = isValidDelim(state, match)
if (!res.canClose) {
if (!silent) { state.pending += '$' }
state.pos = start
return true
}
if (!silent) {
token = state.push('katex_inline', 'math', 0)
token.markup = '$'
token.content = state.src.slice(start, match)
}
state.pos = match + 1
return true
}
function katexBlock (state, start, end, silent) {
let firstLine; let lastLine; let next; let lastPos; let found = false; let token
let pos = state.bMarks[start] + state.tShift[start]
let max = state.eMarks[start]
if (pos + 2 > max) { return false }
if (state.src.slice(pos, pos + 2) !== '$$') { return false }
pos += 2
firstLine = state.src.slice(pos, max)
if (silent) { return true }
if (firstLine.trim().slice(-2) === '$$') {
// Single line expression
firstLine = firstLine.trim().slice(0, -2)
found = true
}
for (next = start; !found;) {
next++
if (next >= end) { break }
pos = state.bMarks[next] + state.tShift[next]
max = state.eMarks[next]
if (pos < max && state.tShift[next] < state.blkIndent) {
// non-empty line with negative indent should stop the list:
break
}
if (state.src.slice(pos, max).trim().slice(-2) === '$$') {
lastPos = state.src.slice(0, max).lastIndexOf('$$')
lastLine = state.src.slice(pos, lastPos)
found = true
}
}
state.line = next + 1
token = state.push('katex_block', 'math', 0)
token.block = true
token.content = (firstLine && firstLine.trim() ? firstLine + '\n' : '') +
state.getLines(start + 1, next, state.tShift[start], true) +
(lastLine && lastLine.trim() ? lastLine : '')
token.map = [ start, state.line ]
token.markup = '$$'
return true
}