File size: 3,873 Bytes
dd8990d
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
142
143
144
145
146
147
148
149
150
151
152
153
import katex from 'katex';

const DELIMITER_LIST = [
	{ left: '$$', right: '$$', display: true },
	{ left: '$', right: '$', display: false },
	{ left: '\\pu{', right: '}', display: false },
	{ left: '\\ce{', right: '}', display: false },
	{ left: '\\(', right: '\\)', display: false },
	{ left: '\\[', right: '\\]', display: true },
	{ left: '\\begin{equation}', right: '\\end{equation}', display: true }
];

// const DELIMITER_LIST = [
//     { left: '$$', right: '$$', display: false },
//     { left: '$', right: '$', display: false },
// ];

// const inlineRule = /^(\${1,2})(?!\$)((?:\\.|[^\\\n])*?(?:\\.|[^\\\n\$]))\1(?=[\s?!\.,:?!。,:]|$)/;
// const blockRule = /^(\${1,2})\n((?:\\[^]|[^\\])+?)\n\1(?:\n|$)/;

let inlinePatterns = [];
let blockPatterns = [];

function escapeRegex(string) {
	return string.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
}

function generateRegexRules(delimiters) {
	delimiters.forEach((delimiter) => {
		const { left, right, display } = delimiter;
		// Ensure regex-safe delimiters
		const escapedLeft = escapeRegex(left);
		const escapedRight = escapeRegex(right);

		if (!display) {
			// For inline delimiters, we match everyting
			inlinePatterns.push(`${escapedLeft}((?:\\\\[^]|[^\\\\])+?)${escapedRight}`);
		} else {
			// Block delimiters doubles as inline delimiters when not followed by a newline
			inlinePatterns.push(`${escapedLeft}(?!\\n)((?:\\\\[^]|[^\\\\])+?)(?!\\n)${escapedRight}`);
			blockPatterns.push(`${escapedLeft}\\n((?:\\\\[^]|[^\\\\])+?)\\n${escapedRight}`);
		}
	});

	// Math formulas can end in special characters
	const inlineRule = new RegExp(
		`^(${inlinePatterns.join('|')})(?=[\\s?。,!-\/:-@[-\`{-~]|$)`,
		'u'
	);
	const blockRule = new RegExp(`^(${blockPatterns.join('|')})(?=[\\s?。,!-\/:-@[-\`{-~]|$)`, 'u');

	return { inlineRule, blockRule };
}

const { inlineRule, blockRule } = generateRegexRules(DELIMITER_LIST);

export default function (options = {}) {
	return {
		extensions: [inlineKatex(options), blockKatex(options)]
	};
}

function katexStart(src, displayMode: boolean) {
	let ruleReg = displayMode ? blockRule : inlineRule;

	let indexSrc = src;

	while (indexSrc) {
		let index = -1;
		let startIndex = -1;
		let startDelimiter = '';
		let endDelimiter = '';
		for (let delimiter of DELIMITER_LIST) {
			if (delimiter.display !== displayMode) {
				continue;
			}

			startIndex = indexSrc.indexOf(delimiter.left);
			if (startIndex === -1) {
				continue;
			}

			index = startIndex;
			startDelimiter = delimiter.left;
			endDelimiter = delimiter.right;
		}

		if (index === -1) {
			return;
		}

		// Check if the delimiter is preceded by a special character.
		// If it does, then it's potentially a math formula.
		const f = index === 0 || indexSrc.charAt(index - 1).match(/[\s?。,!-\/:-@[-`{-~]/);
		if (f) {
			const possibleKatex = indexSrc.substring(index);

			if (possibleKatex.match(ruleReg)) {
				return index;
			}
		}

		indexSrc = indexSrc.substring(index + startDelimiter.length).replace(endDelimiter, '');
	}
}

function katexTokenizer(src, tokens, displayMode: boolean) {
	let ruleReg = displayMode ? blockRule : inlineRule;
	let type = displayMode ? 'blockKatex' : 'inlineKatex';

	const match = src.match(ruleReg);

	if (match) {
		const text = match
			.slice(2)
			.filter((item) => item)
			.find((item) => item.trim());

		return {
			type,
			raw: match[0],
			text: text,
			displayMode
		};
	}
}

function inlineKatex(options) {
	return {
		name: 'inlineKatex',
		level: 'inline',
		start(src) {
			return katexStart(src, false);
		},
		tokenizer(src, tokens) {
			return katexTokenizer(src, tokens, false);
		}
	};
}

function blockKatex(options) {
	return {
		name: 'blockKatex',
		level: 'block',
		start(src) {
			return katexStart(src, true);
		},
		tokenizer(src, tokens) {
			return katexTokenizer(src, tokens, true);
		}
	};
}