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<script type="text/javascript">
/* global katex */
var findEndOfMath = function(delimiter, text, startIndex) {
// Adapted from
// https://github.com/Khan/perseus/blob/master/src/perseus-markdown.jsx
var index = startIndex;
var braceLevel = 0;
var delimLength = delimiter.length;
while (index < text.length) {
var character = text[index];
if (braceLevel <= 0 &&
text.slice(index, index + delimLength) === delimiter) {
return index;
} else if (character === "\\") {
index++;
} else if (character === "{") {
braceLevel++;
} else if (character === "}") {
braceLevel--;
}
index++;
}
return -1;
};
var splitAtDelimiters = function(startData, leftDelim, rightDelim, display) {
var finalData = [];
for (var i = 0; i < startData.length; i++) {
if (startData[i].type === "text") {
var text = startData[i].data;
var lookingForLeft = true;
var currIndex = 0;
var nextIndex;
nextIndex = text.indexOf(leftDelim);
if (nextIndex !== -1) {
currIndex = nextIndex;
finalData.push({
type: "text",
data: text.slice(0, currIndex)
});
lookingForLeft = false;
}
while (true) {
if (lookingForLeft) {
nextIndex = text.indexOf(leftDelim, currIndex);
if (nextIndex === -1) {
break;
}
finalData.push({
type: "text",
data: text.slice(currIndex, nextIndex)
});
currIndex = nextIndex;
} else {
nextIndex = findEndOfMath(
rightDelim,
text,
currIndex + leftDelim.length);
if (nextIndex === -1) {
break;
}
finalData.push({
type: "math",
data: text.slice(
currIndex + leftDelim.length,
nextIndex),
rawData: text.slice(
currIndex,
nextIndex + rightDelim.length),
display: display
});
currIndex = nextIndex + rightDelim.length;
}
lookingForLeft = !lookingForLeft;
}
finalData.push({
type: "text",
data: text.slice(currIndex)
});
} else {
finalData.push(startData[i]);
}
}
return finalData;
};
var splitWithDelimiters = function(text, delimiters) {
var data = [{type: "text", data: text}];
for (var i = 0; i < delimiters.length; i++) {
var delimiter = delimiters[i];
data = splitAtDelimiters(
data, delimiter.left, delimiter.right,
delimiter.display || false);
}
return data;
};
var renderMathInText = function(text, delimiters) {
var data = splitWithDelimiters(text, delimiters);
var fragment = document.createDocumentFragment();
for (var i = 0; i < data.length; i++) {
if (data[i].type === "text") {
fragment.appendChild(document.createTextNode(data[i].data));
} else {
var span = document.createElement("span");
var math = data[i].data;
try {
katex.render(math, span, {
displayMode: data[i].display
});
} catch (e) {
if (!(e instanceof katex.ParseError)) {
throw e;
}
console.error(
"KaTeX auto-render: Failed to parse `" + data[i].data +
"` with ",
e
);
fragment.appendChild(document.createTextNode(data[i].rawData));
continue;
}
fragment.appendChild(span);
}
}
return fragment;
};
var renderElem = function(elem, delimiters, ignoredTags) {
for (var i = 0; i < elem.childNodes.length; i++) {
var childNode = elem.childNodes[i];
if (childNode.nodeType === 3) {
// Text node
var frag = renderMathInText(childNode.textContent, delimiters);
i += frag.childNodes.length - 1;
elem.replaceChild(frag, childNode);
} else if (childNode.nodeType === 1) {
// Element node
var shouldRender = ignoredTags.indexOf(
childNode.nodeName.toLowerCase()) === -1;
if (shouldRender) {
renderElem(childNode, delimiters, ignoredTags);
}
}
// Otherwise, it's something else, and ignore it.
}
};
var defaultOptions = {
delimiters: [
{left: "$$", right: "$$", display: true},
{left: "\\[", right: "\\]", display: true},
{left: "\\(", right: "\\)", display: false}
// LaTeX uses this, but it ruins the display of normal `$` in text:
// {left: "$", right: "$", display: false}
],
ignoredTags: [
"script", "noscript", "style", "textarea", "pre", "code"
]
};
var extend = function(obj) {
// Adapted from underscore.js' `_.extend`. See LICENSE.txt for license.
var source, prop;
for (var i = 1, length = arguments.length; i < length; i++) {
source = arguments[i];
for (prop in source) {
if (Object.prototype.hasOwnProperty.call(source, prop)) {
obj[prop] = source[prop];
}
}
}
return obj;
};
var renderMathInElement = function(elem, options) {
if (!elem) {
throw new Error("No element provided to render");
}
options = extend({}, defaultOptions, options);
renderElem(elem, options.delimiters, options.ignoredTags);
};
renderMathInElement(document.body);
</script>
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