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wiki/server/renderers/modules/katex.mjs

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// Test if potential opening or closing delimieter
// Assumes that there is a "$" at state.src[pos]
function isValidDelim (state, pos) {
const max = state.posMax
let canOpen = true
let canClose = true
const prevChar = pos > 0 ? state.src.charCodeAt(pos - 1) : -1
const nextChar = pos + 1 <= max ? state.src.charCodeAt(pos + 1) : -1
// Check non-whitespace conditions for opening and closing, and
// check that closing delimeter isn't followed by a number
if (prevChar === 0x20/* " " */ || prevChar === 0x09/* \t */ ||
(nextChar >= 0x30/* "0" */ && nextChar <= 0x39/* "9" */)) {
canClose = false
}
if (nextChar === 0x20/* " " */ || nextChar === 0x09/* \t */) {
canOpen = false
}
return {
canOpen,
canClose
}
}
export default {
katexInline (state, silent) {
let match, token, res, pos
if (state.src[state.pos] !== '$') { return false }
res = isValidDelim(state, state.pos)
if (!res.canOpen) {
if (!silent) { state.pending += '$' }
state.pos += 1
return true
}
// First check for and bypass all properly escaped delimieters
// This loop will assume that the first leading backtick can not
// be the first character in state.src, which is known since
// we have found an opening delimieter already.
const start = state.pos + 1
match = start
while ((match = state.src.indexOf('$', 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
// Extract the math part without the $
.slice(start, match)
// Escape the curly braces since they will be interpreted as
// attributes by markdown-it-attrs (the "curly_attributes"
// core rule)
.replaceAll('{', '{{')
.replaceAll('}', '}}')
}
state.pos = match + 1
return true
},
katexBlock (state, start, end, silent) {
let firstLine; let lastLine; let next; let lastPos; let found = false
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
const 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
}
}