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[IMPROVE] Lazyload Katex Package (#15398)
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export { default as katex } from '../lib/katex'; | ||
import { Random } from 'meteor/random'; | ||
import { Tracker } from 'meteor/tracker'; | ||
import _ from 'underscore'; | ||
import s from 'underscore.string'; | ||
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import { callbacks } from '../../callbacks'; | ||
import { settings } from '../../settings'; | ||
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class Boundary { | ||
length() { | ||
return this.end - this.start; | ||
} | ||
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extract(str) { | ||
return str.substr(this.start, this.length()); | ||
} | ||
} | ||
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class Katex { | ||
constructor(katex) { | ||
this.katex = katex; | ||
this.delimitersMap = [ | ||
{ | ||
opener: '\\[', | ||
closer: '\\]', | ||
displayMode: true, | ||
enabled: () => this.isParenthesisSyntaxEnabled(), | ||
}, { | ||
opener: '\\(', | ||
closer: '\\)', | ||
displayMode: false, | ||
enabled: () => this.isParenthesisSyntaxEnabled(), | ||
}, { | ||
opener: '$$', | ||
closer: '$$', | ||
displayMode: true, | ||
enabled: () => this.isDollarSyntaxEnabled(), | ||
}, { | ||
opener: '$', | ||
closer: '$', | ||
displayMode: false, | ||
enabled: () => this.isDollarSyntaxEnabled(), | ||
}, | ||
]; | ||
} | ||
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findOpeningDelimiter(str, start) { | ||
const matches = this.delimitersMap.filter((options) => options.enabled()).map((options) => ({ | ||
options, | ||
pos: str.indexOf(options.opener, start), | ||
})); | ||
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const positions = matches.filter(({ pos }) => pos >= 0).map(({ pos }) => pos); | ||
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// No opening delimiters were found | ||
if (positions.length === 0) { | ||
return null; | ||
} | ||
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// Take the first delimiter found | ||
const minPos = Math.min.apply(Math, positions); | ||
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const matchIndex = matches.findIndex(({ pos }) => pos === minPos); | ||
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const match = matches[matchIndex]; | ||
return match; | ||
} | ||
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getLatexBoundaries(str, { options: { closer }, pos }) { | ||
const closerIndex = str.substr(pos + closer.length).indexOf(closer); | ||
if (closerIndex < 0) { | ||
return null; | ||
} | ||
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const inner = new Boundary(); | ||
const outer = new Boundary(); | ||
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inner.start = pos + closer.length; | ||
inner.end = inner.start + closerIndex; | ||
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outer.start = pos; | ||
outer.end = inner.end + closer.length; | ||
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return { | ||
outer, | ||
inner, | ||
}; | ||
} | ||
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// Searches for the first latex block in the given string | ||
findLatex(str) { | ||
let start = 0; | ||
let openingDelimiterMatch; | ||
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while ((openingDelimiterMatch = this.findOpeningDelimiter(str, start++)) != null) { | ||
const match = this.getLatexBoundaries(str, openingDelimiterMatch); | ||
if (match && match.inner.extract(str).trim().length) { | ||
match.options = openingDelimiterMatch.options; | ||
return match; | ||
} | ||
} | ||
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return null; | ||
} | ||
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// Breaks a message to what comes before, after and to the content of a | ||
// matched latex block | ||
extractLatex(str, match) { | ||
const before = str.substr(0, match.outer.start); | ||
const after = str.substr(match.outer.end); | ||
let latex = match.inner.extract(str); | ||
latex = s.unescapeHTML(latex); | ||
return { | ||
before, | ||
latex, | ||
after, | ||
}; | ||
} | ||
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// Takes a latex math string and the desired display mode and renders it | ||
// to HTML using the KaTeX library | ||
renderLatex = (latex, displayMode) => { | ||
try { | ||
return this.katex.renderToString(latex, { | ||
displayMode, | ||
macros: { | ||
'\\href': '\\@secondoftwo', | ||
}, | ||
}); | ||
} catch ({ message }) { | ||
return `<div class="katex-error katex-${ displayMode ? 'block' : 'inline' }-error">` | ||
+ `${ s.escapeHTML(message) }</div>`; | ||
} | ||
} | ||
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// Takes a string and renders all latex blocks inside it | ||
render(str, renderFunction) { | ||
let result = ''; | ||
while (this.findLatex(str) != null) { | ||
// Find the first latex block in the string | ||
const match = this.findLatex(str); | ||
const parts = this.extractLatex(str, match); | ||
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// Add to the reuslt what comes before the latex block as well as | ||
// the rendered latex content | ||
const rendered = renderFunction(parts.latex, match.options.displayMode); | ||
result += parts.before + rendered; | ||
// Set what comes after the latex block to be examined next | ||
str = parts.after; | ||
} | ||
result += str; | ||
return result; | ||
} | ||
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renderMessage = (message) => { | ||
if (_.isString(message)) { | ||
return this.render(message, this.renderLatex); | ||
} | ||
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if (!s.trim(message.html)) { | ||
return message; | ||
} | ||
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if (message.tokens == null) { | ||
message.tokens = []; | ||
} | ||
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message.html = this.render(message.html, (latex, displayMode) => { | ||
const token = `=!=${ Random.id() }=!=`; | ||
message.tokens.push({ | ||
token, | ||
text: this.renderLatex(latex, displayMode), | ||
}); | ||
return token; | ||
}); | ||
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return message; | ||
} | ||
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isEnabled = () => settings.get('Katex_Enabled') | ||
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isDollarSyntaxEnabled = () => settings.get('Katex_Dollar_Syntax') | ||
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isParenthesisSyntaxEnabled = () => settings.get('Katex_Parenthesis_Syntax') | ||
} | ||
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Tracker.autorun(async () => { | ||
if (!settings.get('Katex_Enabled')) { | ||
callbacks.remove('renderMessage', 'katex'); | ||
} | ||
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const [katex] = await Promise.all([import('katex'), import('./style.css'), import('../katex.min.css')]); | ||
const instance = new Katex(katex); | ||
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callbacks.add('renderMessage', instance.renderMessage, callbacks.priority.HIGH - 1, 'katex'); | ||
}); | ||
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export default { | ||
isEnabled: () => settings.get('Katex_Enabled'), | ||
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isDollarSyntaxEnabled: () => settings.get('Katex_Dollar_Syntax'), | ||
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isParenthesisSyntaxEnabled: () => settings.get('Katex_Parenthesis_Syntax'), | ||
}; |
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