Add markdown preview, update rust.vim

sources_non_forked/markdown-preview.nvim/app/pages/katex.js

@@ -0,0 +1,207 @@
+// fork from https://github.com/waylonflinn/markdown-it-katex
+/* Process inline math */
+/*
+Like markdown-it-simplemath, this is a stripped down, simplified version of:
+https://github.com/runarberg/markdown-it-math
+It differs in that it takes (a subset of) LaTeX as input and relies on KaTeX
+for rendering output.
+*/
+
+/* jslint node: true */
+'use strict'
+
+// Test if potential opening or closing delimieter
+// Assumes that there is a "$" at state.src[pos]
+function isValidDelim (state, pos) {
+  var prevChar; var nextChar
+
+  var max = state.posMax
+
+  var can_open = true
+
+  var can_close = true
+
+  prevChar = pos > 0 ? state.src.charCodeAt(pos - 1) : -1
+  nextChar = pos + 1 <= max ? state.src.charCodeAt(pos + 1) : -1
+
+  // Check non-whitespace conditions for opening and closing, and
+  // check that closing delimeter isn't followed by a number
+  if (prevChar === 0x20/* " " */ || prevChar === 0x09/* \t */ ||
+            (nextChar >= 0x30/* "0" */ && nextChar <= 0x39/* "9" */)) {
+    can_close = false
+  }
+  if (nextChar === 0x20/* " " */ || nextChar === 0x09/* \t */) {
+    can_open = false
+  }
+
+  return {
+    can_open: can_open,
+    can_close: can_close
+  }
+}
+
+function math_inline (state, silent) {
+  var start, match, token, res, pos, esc_count
+
+  if (state.src[state.pos] !== '$') { return false }
+
+  res = isValidDelim(state, state.pos)
+  if (!res.can_open) {
+    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.can_close) {
+    if (!silent) { state.pending += '$' }
+    state.pos = start
+    return true
+  }
+
+  if (!silent) {
+    token = state.push('math_inline', 'math', 0)
+    token.markup = '$'
+    token.content = state.src.slice(start, match)
+  }
+
+  state.pos = match + 1
+  return true
+}
+
+function math_block (state, start, end, silent) {
+  var firstLine; var lastLine; var next; var lastPos; var found = false; var token
+
+  var pos = state.bMarks[start] + state.tShift[start]
+
+  var 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('math_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
+}
+
+export default function math_plugin (md, options) {
+  // Default options
+
+  options = options || {}
+  options.macros = options.macros || {}
+
+  // set KaTeX as the renderer for markdown-it-simplemath
+  var katexInline = function (latex) {
+    const opt = {
+      ...options
+    }
+    if (opt.displayMode === undefined) {
+      opt.displayMode = false
+    }
+    try {
+      return katex.renderToString(latex, opt)
+    } catch (error) {
+      if (opt.throwOnError) { console.log(error) }
+      return latex
+    }
+  }
+
+  var inlineRenderer = function (tokens, idx) {
+    return katexInline(tokens[idx].content)
+  }
+
+  var katexBlock = function (latex) {
+    const opt = {
+      ...options
+    }
+    if (opt.displayMode === undefined) {
+      opt.displayMode = true
+    }
+    try {
+      return '<p>' + katex.renderToString(latex, opt) + '</p>'
+    } catch (error) {
+      if (opt.throwOnError) { console.log(error) }
+      return latex
+    }
+  }
+
+  var blockRenderer = function (tokens, idx) {
+    return katexBlock(tokens[idx].content) + '\n'
+  }
+
+  md.inline.ruler.after('escape', 'math_inline', math_inline)
+  md.block.ruler.after('blockquote', 'math_block', math_block, {
+    alt: [ 'paragraph', 'reference', 'blockquote', 'list' ]
+  })
+  md.renderer.rules.math_inline = inlineRenderer
+  md.renderer.rules.math_block = blockRenderer
+}