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197 lines
5.7 KiB
197 lines
5.7 KiB
/* Process inline math */ |
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/* |
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Like markdown-it-simplemath, this is a stripped down, simplified version of: |
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https://github.com/runarberg/markdown-it-math |
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It differs in that it takes (a subset of) LaTeX as input and relies on KaTeX |
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for rendering output. |
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*/ |
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/*jslint node: true */ |
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'use strict'; |
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var katex = require('katex'); |
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// Test if potential opening or closing delimieter |
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// Assumes that there is a "$" at state.src[pos] |
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function isValidDelim(state, pos) { |
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var prevChar, nextChar, |
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max = state.posMax, |
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can_open = true, |
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can_close = true; |
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prevChar = pos > 0 ? state.src.charCodeAt(pos - 1) : -1; |
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nextChar = pos + 1 <= max ? state.src.charCodeAt(pos + 1) : -1; |
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// Check non-whitespace conditions for opening and closing, and |
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// check that closing delimeter isn't followed by a number |
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if (prevChar === 0x20/* " " */ || prevChar === 0x09/* \t */ || |
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(nextChar >= 0x30/* "0" */ && nextChar <= 0x39/* "9" */)) { |
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can_close = false; |
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} |
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if (nextChar === 0x20/* " " */ || nextChar === 0x09/* \t */) { |
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can_open = false; |
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} |
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return { |
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can_open: can_open, |
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can_close: can_close |
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}; |
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} |
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function math_inline(state, silent) { |
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var start, match, token, res, pos, esc_count; |
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if (state.src[state.pos] !== "$") { return false; } |
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res = isValidDelim(state, state.pos); |
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if (!res.can_open) { |
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if (!silent) { state.pending += "$"; } |
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state.pos += 1; |
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return true; |
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} |
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// First check for and bypass all properly escaped delimieters |
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// This loop will assume that the first leading backtick can not |
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// be the first character in state.src, which is known since |
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// we have found an opening delimieter already. |
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start = state.pos + 1; |
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match = start; |
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while ((match = state.src.indexOf("$", match)) !== -1) { |
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// Found potential $, look for escapes, pos will point to |
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// first non escape when complete |
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pos = match - 1; |
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while (state.src[pos] === "\\") { pos -= 1; } |
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// Even number of escapes, potential closing delimiter found |
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if (((match - pos) % 2) == 1) { break; } |
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match += 1; |
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} |
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// No closing delimter found. Consume $ and continue. |
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if (match === -1) { |
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if (!silent) { state.pending += "$"; } |
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state.pos = start; |
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return true; |
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} |
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// Check if we have empty content, ie: $$. Do not parse. |
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if (match - start === 0) { |
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if (!silent) { state.pending += "$$"; } |
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state.pos = start + 1; |
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return true; |
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} |
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// Check for valid closing delimiter |
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res = isValidDelim(state, match); |
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if (!res.can_close) { |
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if (!silent) { state.pending += "$"; } |
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state.pos = start; |
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return true; |
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} |
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if (!silent) { |
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token = state.push('math_inline', 'math', 0); |
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token.markup = "$"; |
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token.content = state.src.slice(start, match); |
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} |
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state.pos = match + 1; |
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return true; |
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} |
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function math_block(state, start, end, silent) { |
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var firstLine, lastLine, next, lastPos, found = false, token, |
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pos = state.bMarks[start] + state.tShift[start], |
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max = state.eMarks[start] |
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if (pos + 2 > max) { return false; } |
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if (state.src.slice(pos, pos + 2) !== '$$') { return false; } |
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pos += 2; |
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firstLine = state.src.slice(pos, max); |
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if (silent) { return true; } |
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if (firstLine.trim().slice(-2) === '$$') { |
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// Single line expression |
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firstLine = firstLine.trim().slice(0, -2); |
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found = true; |
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} |
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for (next = start; !found;) { |
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next++; |
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if (next >= end) { break; } |
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pos = state.bMarks[next] + state.tShift[next]; |
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max = state.eMarks[next]; |
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if (pos < max && state.tShift[next] < state.blkIndent) { |
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// non-empty line with negative indent should stop the list: |
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break; |
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} |
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if (state.src.slice(pos, max).trim().slice(-2) === '$$') { |
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lastPos = state.src.slice(0, max).lastIndexOf('$$'); |
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lastLine = state.src.slice(pos, lastPos); |
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found = true; |
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} |
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} |
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state.line = next + 1; |
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token = state.push('math_block', 'math', 0); |
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token.block = true; |
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token.content = (firstLine && firstLine.trim() ? firstLine + '\n' : '') |
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+ state.getLines(start + 1, next, state.tShift[start], true) |
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+ (lastLine && lastLine.trim() ? lastLine : ''); |
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token.map = [start, state.line]; |
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token.markup = '$$'; |
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return true; |
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} |
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module.exports = function math_plugin(md, options) { |
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// Default options |
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options = options || {}; |
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// set KaTeX as the renderer for markdown-it-simplemath |
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var katexInline = function (latex) { |
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options.displayMode = false; |
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try { |
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return katex.renderToString(latex, options); |
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} |
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catch (error) { |
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if (options.throwOnError) { console.log(error); } |
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return latex; |
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} |
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}; |
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var inlineRenderer = function (tokens, idx) { |
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return katexInline(tokens[idx].content); |
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}; |
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var katexBlock = function (latex) { |
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options.displayMode = true; |
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try { |
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return "<p>" + katex.renderToString(latex, options) + "</p>"; |
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} |
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catch (error) { |
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if (options.throwOnError) { console.log(error); } |
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return latex; |
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} |
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} |
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var blockRenderer = function (tokens, idx) { |
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return katexBlock(tokens[idx].content) + '\n'; |
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} |
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md.inline.ruler.after('escape', 'math_inline', math_inline); |
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md.block.ruler.after('blockquote', 'math_block', math_block, { |
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alt: ['paragraph', 'reference', 'blockquote', 'list'] |
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}); |
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md.renderer.rules.math_inline = inlineRenderer; |
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md.renderer.rules.math_block = blockRenderer; |
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};
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