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TiddlyWiki5/plugins/tiddlywiki/markdown-legacy/files/remarkable-katex.js

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"use strict";
/**
* Plugin for Remarkable Markdown processor which transforms $..$ and $$..$$ sequences into math HTML using the
* Katex package.
*/
const rkatex = (md, options) => {
const backslash = '\\';
const dollar = '$';
const opts = options || {};
const delimiter = opts.delimiter || dollar;
if (delimiter.length !== 1) { throw new Error('invalid delimiter'); }
const katex = require("katex");
/**
* Render the contents as KaTeX
*/
const renderKatex = (source, displayMode) => katex.renderToString(source,
{displayMode: displayMode,
throwOnError: false});
/**
* Parse '$$' as a block. Based off of similar method in remarkable.
*/
const parseBlockKatex = (state, startLine, endLine) => {
let haveEndMarker = false;
let pos = state.bMarks[startLine] + state.tShift[startLine];
let max = state.eMarks[startLine];
if (pos + 1 > max) { return false; }
const marker = state.src.charAt(pos);
if (marker !== delimiter) { return false; }
// scan marker length
let mem = pos;
pos = state.skipChars(pos, marker);
let len = pos - mem;
if (len !== 2) { return false; }
// search end of block
let nextLine = startLine;
for (;;) {
++nextLine;
if (nextLine >= endLine) { break; }
pos = mem = state.bMarks[nextLine] + state.tShift[nextLine];
max = state.eMarks[nextLine];
if (pos < max && state.tShift[nextLine] < state.blkIndent) { break; }
if (state.src.charAt(pos) !== delimiter) { continue; }
if (state.tShift[nextLine] - state.blkIndent >= 4) { continue; }
pos = state.skipChars(pos, marker);
if (pos - mem < len) { continue; }
pos = state.skipSpaces(pos);
if (pos < max) { continue; }
haveEndMarker = true;
break;
}
// If a fence has heading spaces, they should be removed from its inner block
len = state.tShift[startLine];
state.line = nextLine + (haveEndMarker ? 1 : 0);
const content = state.getLines(startLine + 1, nextLine, len, true)
.replace(/[ \n]+/g, ' ')
.trim();
state.tokens.push({type: 'katex', params: null, content: content, lines: [startLine, state.line],
level: state.level, block: true});
return true;
};
/**
* Look for '$' or '$$' spans in Markdown text. Based off of the 'fenced' parser in remarkable.
*/
const parseInlineKatex = (state, silent) => {
const start = state.pos;
const max = state.posMax;
let pos = start;
// Unexpected starting character
if (state.src.charAt(pos) !== delimiter) { return false; }
++pos;
while (pos < max && state.src.charAt(pos) === delimiter) { ++pos; }
// Capture the length of the starting delimiter -- closing one must match in size
const marker = state.src.slice(start, pos);
if (marker.length > 2) { return false; }
const spanStart = pos;
let escapedDepth = 0;
while (pos < max) {
const char = state.src.charAt(pos);
if (char === '{' && (pos == 0 || state.src.charAt(pos - 1) != backslash)) {
escapedDepth += 1;
} else if (char === '}' && (pos == 0 || state.src.charAt(pos - 1) != backslash)) {
escapedDepth -= 1;
if (escapedDepth < 0) { return false; }
} else if (char === delimiter && escapedDepth === 0) {
const matchStart = pos;
let matchEnd = pos + 1;
while (matchEnd < max && state.src.charAt(matchEnd) === delimiter) { ++matchEnd; }
if (matchEnd - matchStart === marker.length) {
if (!silent) {
const content = state.src.slice(spanStart, matchStart)
.replace(/[ \n]+/g, ' ')
.trim();
state.push({type: 'katex', content: content, block: marker.length > 1, level: state.level});
}
state.pos = matchEnd;
return true;
}
}
pos += 1;
}
if (!silent) { state.pending += marker; }
state.pos += marker.length;
return true;
};
md.inline.ruler.push('katex', parseInlineKatex, options);
md.block.ruler.push('katex', parseBlockKatex, options);
md.renderer.rules.katex = (tokens, idx) => renderKatex(tokens[idx].content, tokens[idx].block);
md.renderer.rules.katex.delimiter = delimiter;
};
module.exports = rkatex;