nodeclub/common/textmath.js at 92a9025ad3c9383d8e6d68bc260f1a7749b924af · cnodejs/nodeclub · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
/**
 * Simplify by https://github.com/goessner/markdown-it-texmath
 */
function texmath(md) {
  texmath.rules.inline.forEach(function (rule) {
    md.inline.ruler.before('escape', rule.name, texmath.inline(rule)); // !important
    md.renderer.rules[rule.name] = function (tokens, idx) {
      return rule.tmpl.replace(/\$1/, tokens[idx].content);
    };
  });
  texmath.rules.block.forEach(function (rule) {
    md.block.ruler.before('fence', rule.name, texmath.block(rule)); // !important for ```math delimiters
    md.renderer.rules[rule.name] = function (tokens, idx) {
      return rule.tmpl
        .replace(/\$2/, tokens[idx].info) // equation number
        .replace(/\$1/, tokens[idx].content);
    };
  });
}

texmath.inline = (rule) => (state, silent) => {
  var pos = state.pos;
  var str = state.src;
  rule.rex.lastIndex = pos;

  if (!str.startsWith(rule.tag, pos)) return false;
  if (rule.pre && !rule.pre(str, pos)) return false;

  var match = rule.rex.exec(str);
  if (!match || pos >= rule.rex.lastIndex) return false;

  if (rule.post && !rule.post(str, rule.rex.lastIndex - 1)) return false;
  // match and valid post-condition ...
  if (!silent) {
    var token = state.push(rule.name, 'math', 0);
    token.content = match[1];
    token.markup = rule.tag;
  }
  state.pos = rule.rex.lastIndex;
  return true;
};

texmath.block = (rule) => (state, begLine, endLine, silent) => {
  var pos = state.bMarks[begLine] + state.tShift[begLine];
  var str = state.src;
  rule.rex.lastIndex = pos;

  if (!str.startsWith(rule.tag, pos)) return false;
  if (rule.pre && !rule.pre(str, pos)) return false;

  var match = rule.rex.exec(str);
  if (!match || pos >= rule.rex.lastIndex) return false;

  if (rule.post && !rule.post(str, rule.rex.lastIndex - 1)) return false;
  // match and valid post-condition ...
  if (!silent) {
    var endpos = rule.rex.lastIndex - 1;
    var curline;
    for (curline = begLine; curline < endLine; curline++) {
      // line for end of block math found
      if (endpos >= state.bMarks[curline] + state.tShift[curline] && endpos <= state.eMarks[curline]) {
        break;
      }
    }
    // "this will prevent lazy continuations from ever going past our end marker"
    // s. https://github.com/markdown-it/markdown-it-container/blob/master/index.js
    var oldLineMax = state.lineMax;
    var oldParent = state.parentType;
    state.lineMax = curline;
    state.parentType = 'math';
    // remove all leading '>' inside multiline formula
    if (oldParent === 'blockquote') {
      match[1] = match[1].replace(/(\n*?^(?:\s*>)+)/gm, '');
    }
    // 'math_block'
    var token = state.push(rule.name, 'math', 1);
    token.block = true;
    token.markup = rule.tag;
    token.content = match[1];
    token.info = match[match.length - 1]; // eq.no
    token.map = [begLine, curline];
    // restore state
    state.parentType = oldParent;
    state.lineMax = oldLineMax;
    state.line = curline + 1;
  }
  return true;
};

// used for enable/disable math rendering by `markdown-it`
texmath.inlineRuleNames = ['math_inline', 'math_inline_double'];
texmath.blockRuleNames = ['math_block', 'math_block_eqno'];

texmath.$_pre = function (str, beg) {
  // no backslash, digit before opening '$'
  return /[^\\0-9]/.test(str[beg - 1]);
};
texmath.$_post = function (str, end) {
  // no digit after closing '$'
  return /[^0-9]/.test(str[end + 1]);
};

texmath.rules = {
  inline: [{
    name: 'math_inline_double',
    rex: /\${2}((?:\S)|(?:\S.*?\S))\${2}/gy,
    tmpl: '<section><eqn>$1</eqn></section>',
    tag: '$$',
    displayMode: true,
    pre: texmath.$_pre,
    post: texmath.$_post
  }, {
    name: 'math_inline',
    rex: /\$((?:\S)|(?:\S.*?\S))\$/gy,
    tmpl: '<eq>$1</eq>',
    tag: '$',
    pre: texmath.$_pre,
    post: texmath.$_post
  }],
  block: [{
    name: 'math_block_eqno',
    rex: /\${2}([^$]+?)\${2}\s*?\(([^)\s]+?)\)/gmy,
    tmpl: '<section><eqn>$1</eqn><span>($2)</span></section>',
    tag: '$$'
  }, {
    name: 'math_block',
    rex: /\${2}([^$]+?)\${2}/gmy,
    tmpl: '<section><eqn>$1</eqn></section>',
    tag: '$$'
  }]
};

module.exports = texmath;