86 lines
2.2 KiB
JavaScript
86 lines
2.2 KiB
JavaScript
/* eslint no-constant-condition:0 */
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const findEndOfMath = function(delimiter, text, startIndex) {
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// Adapted from
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// https://github.com/Khan/perseus/blob/master/src/perseus-markdown.jsx
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let index = startIndex;
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let braceLevel = 0;
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const delimLength = delimiter.length;
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while (index < text.length) {
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const character = text[index];
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if (braceLevel <= 0 &&
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text.slice(index, index + delimLength) === delimiter) {
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return index;
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} else if (character === "\\") {
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index++;
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} else if (character === "{") {
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braceLevel++;
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} else if (character === "}") {
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braceLevel--;
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}
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index++;
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}
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return -1;
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};
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const escapeRegex = function(string) {
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return string.replace(/[-/\\^$*+?.()|[\]{}]/g, "\\$&");
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};
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const amsRegex = /^\\begin{/;
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const splitAtDelimiters = function(text, delimiters) {
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let index;
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const data = [];
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const regexLeft = new RegExp(
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"(" + delimiters.map((x) => escapeRegex(x.left)).join("|") + ")"
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);
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while (true) {
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index = text.search(regexLeft);
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if (index === -1) {
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break;
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}
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if (index > 0) {
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data.push({
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type: "text",
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data: text.slice(0, index),
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});
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text = text.slice(index); // now text starts with delimiter
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}
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// ... so this always succeeds:
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const i = delimiters.findIndex((delim) => text.startsWith(delim.left));
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index = findEndOfMath(delimiters[i].right, text, delimiters[i].left.length);
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if (index === -1) {
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break;
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}
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const rawData = text.slice(0, index + delimiters[i].right.length);
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const math = amsRegex.test(rawData)
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? rawData
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: text.slice(delimiters[i].left.length, index);
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data.push({
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type: "math",
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data: math,
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rawData,
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display: delimiters[i].display,
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});
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text = text.slice(index + delimiters[i].right.length);
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}
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if (text !== "") {
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data.push({
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type: "text",
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data: text,
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});
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}
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return data;
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};
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export default splitAtDelimiters;
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