KPSC-Archive/math-render.js at main · KMUCS-KPSC/KPSC-Archive · 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
134
135
136
137
138
139
140
141
export function escapeHtml(value) {
  return String(value)
    .replaceAll("&", "&amp;")
    .replaceAll("<", "&lt;")
    .replaceAll(">", "&gt;");
}

export function isEscaped(text, index) {
  let backslashCount = 0;

  for (let cursor = index - 1; cursor >= 0 && text[cursor] === "\\"; cursor -= 1) {
    backslashCount += 1;
  }

  return backslashCount % 2 === 1;
}

export function consumeBalancedGroup(text, startIndex) {
  if (text[startIndex] !== "{") {
    return null;
  }

  let depth = 0;

  for (let index = startIndex; index < text.length; index += 1) {
    const char = text[index];

    if (char === "{" && !isEscaped(text, index)) {
      depth += 1;
    } else if (char === "}" && !isEscaped(text, index)) {
      depth -= 1;

      if (depth === 0) {
        return {
          content: text.slice(startIndex + 1, index),
          endIndex: index + 1,
        };
      }
    }
  }

  return null;
}

function wrapStandaloneMathtt(text) {
  let result = "";
  let index = 0;
  let mathMode = null;

  while (index < text.length) {
    if (!mathMode && text.startsWith("\\(", index)) {
      mathMode = "\\)";
      result += "\\(";
      index += 2;
      continue;
    }

    if (!mathMode && text.startsWith("\\[", index)) {
      mathMode = "\\]";
      result += "\\[";
      index += 2;
      continue;
    }

    if (mathMode === "\\)" && text.startsWith("\\)", index)) {
      mathMode = null;
      result += "\\)";
      index += 2;
      continue;
    }

    if (mathMode === "\\]" && text.startsWith("\\]", index)) {
      mathMode = null;
      result += "\\]";
      index += 2;
      continue;
    }

    if (text.startsWith("$$", index) && !isEscaped(text, index)) {
      mathMode = mathMode === "$$" ? null : "$$";
      result += "$$";
      index += 2;
      continue;
    }

    if (text[index] === "$" && !isEscaped(text, index) && mathMode !== "$$") {
      mathMode = mathMode === "$" ? null : "$";
      result += "$";
      index += 1;
      continue;
    }

    if (!mathMode && text.startsWith("\\mathtt{", index)) {
      const group = consumeBalancedGroup(text, index + "\\mathtt".length);

      if (group) {
        result += `\\(\\mathtt{${group.content}}\\)`;
        index = group.endIndex;
        continue;
      }
    }

    result += text[index];
    index += 1;
  }

  return result;
}

function normalizeBrokenThousandsSeparators(text) {
  let nextText = text;

  while (true) {
    const normalized = nextText.replace(/(\d)\\(?=\d{3}(?!\d))/g, "$1\\\\,");
    if (normalized === nextText) {
      return normalized;
    }
    nextText = normalized;
  }
}

export function prepareMathText(text) {
  return wrapStandaloneMathtt(
    normalizeBrokenThousandsSeparators(
      String(text)
        .replaceAll("\\%", "%")
        .replaceAll("\\_", "_")
        .replaceAll("\\texttt{", "\\mathtt{")
    )
  );
}

export function renderMathText(text) {
  return escapeHtml(prepareMathText(text));
}

export function queueMathTypeset() {
  if (window.MathJax?.typesetPromise) {
    window.MathJax.typesetPromise();
  }
}