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StackExchange MathJax editing code
// The MIT License (MIT)
//
// Copyright (c) 2016 Stack Exchange
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
// ===============================================
"use strict";
StackExchange.mathjaxEditing = (function () {
var ready = false; // true after initial typeset is complete
var pending = false; // true when MathJax has been requested
var preview = null; // the preview container
var inline = "$"; // the inline math delimiter
var blocks, start, end, last, braces; // used in searching for math
var math; // stores math until markdone is done
var HUB = MathJax.Hub;
//
// Runs after initial typeset
//
HUB.Queue(function () {
ready = true;
HUB.processUpdateTime = 50; // reduce update time so that we can cancel easier
HUB.Config({
"HTML-CSS": {
EqnChunk: 10,
EqnChunkFactor: 1
},
// reduce chunk for more frequent updates
SVG: {
EqnChunk: 10,
EqnChunkFactor: 1
}
});
});
//
// The pattern for math delimiters and special symbols
// needed for searching for math in the page.
//
var SPLIT = /(\$\$?|\\(?:begin|end)\{[a-z]*\*?\}|\\[\\{}$]|[{}]|(?:\n\s*)+|@@\d+@@)/i;
//
// The math is in blocks i through j, so
// collect it into one block and clear the others.
// Replace &, <, and > by named entities.
// For IE, put <br> at the ends of comments since IE removes \n.
// Clear the current math positions and store the index of the
// math, then push the math string onto the storage array.
//
function processMath(i, j, preProcess) {
var block = blocks.slice(i, j + 1).join("").replace(/&/g, "&amp;") // use HTML entity for &
.replace(/</g, "&lt;") // use HTML entity for <
.replace(/>/g, "&gt;") // use HTML entity for >
;
if (HUB.Browser.isMSIE) {
block = block.replace(/(%[^\n]*)\n/g, "$1<br/>\n")
}
while (j > i) {
blocks[j] = "";
j--;
}
blocks[i] = "@@" + math.length + "@@";
if (preProcess)
block = preProcess(block);
math.push(block);
start = end = last = null;
}
var capturingStringSplit;
if ("aba".split(/(b)/).length === 3) {
capturingStringSplit = function (str, regex) { return str.split(regex) }
}
else { // IE8
capturingStringSplit = function (str, regex) {
var result = [], match;
if (!regex.global) {
var source = regex.toString(),
flags = "";
source = source.replace(/^\/(.*)\/([im]*)$/, function (wholematch, re, fl) { flags = fl; return re; });
regex = new RegExp(source, flags + "g");
}
regex.lastIndex = 0;
var lastPos = 0;
while (match = regex.exec(str))
{
result.push(str.substring(lastPos, match.index));
result.push.apply(result, match.slice(1));
lastPos = match.index + match[0].length;
}
result.push(str.substring(lastPos));
return result;
}
}
//
// Break up the text into its component parts and search
// through them for math delimiters, braces, linebreaks, etc.
// Math delimiters must match and braces must balance.
// Don't allow math to pass through a double linebreak
// (which will be a paragraph).
//
function removeMath(text) {
start = end = last = null; // for tracking math delimiters
math = []; // stores math strings for latter
// Except for extreme edge cases, this should catch precisely those pieces of the markdown
// source that will later be turned into code spans. While MathJax will not TeXify code spans,
// we still have to consider them at this point; the following issue has happened several times:
//
// `$foo` and `$bar` are varibales. --> <code>$foo ` and `$bar</code> are variables.
var hasCodeSpans = /`/.test(text),
deTilde;
if (hasCodeSpans) {
text = text.replace(/~/g, "~T").replace(/(^|[^\\`])(`+)(?!`)([^\n]*?[^`\n])\2(?!`)/gm, function (wholematch) {
return wholematch.replace(/\$/g, "~D");
});
deTilde = function (text) { return text.replace(/~([TD])/g, function (wholematch, character) { return { T: "~", D: "$" }[character]; }) };
} else {
deTilde = function (text) { return text; };
}
blocks = capturingStringSplit(text.replace(/\r\n?/g, "\n"), SPLIT);
for (var i = 1, m = blocks.length; i < m; i += 2) {
var block = blocks[i];
if (block.charAt(0) === "@") {
//
// Things that look like our math markers will get
// stored and then retrieved along with the math.
//
blocks[i] = "@@" + math.length + "@@";
math.push(block);
}
else if (start) {
//
// If we are in math, look for the end delimiter,
// but don't go past double line breaks, and
// and balance braces within the math.
//
if (block === end) {
if (braces) {
last = i
}
else {
processMath(start, i, deTilde)
}
}
else if (block.match(/\n.*\n/)) {
if (last) {
i = last;
processMath(start, i, deTilde)
}
start = end = last = null;
braces = 0;
}
else if (block === "{") {
braces++
}
else if (block === "}" && braces) {
braces--
}
}
else {
//
// Look for math start delimiters and when
// found, set up the end delimiter.
//
if (block === inline || block === "$$") {
start = i;
end = block;
braces = 0;
}
else if (block.substr(1, 5) === "begin") {
start = i;
end = "\\end" + block.substr(6);
braces = 0;
}
}
}
if (last) {
processMath(start, last, deTilde)
}
return deTilde(blocks.join(""));
}
//
// Put back the math strings that were saved,
// and clear the math array (no need to keep it around).
//
function replaceMath(text) {
text = text.replace(/@@(\d+)@@/g, function (match, n) {
return math[n]
});
math = null;
return text;
}
//
// This is run to restart MathJax after it has finished
// the previous run (that may have been canceled)
//
function RestartMJ() {
pending = false;
HUB.cancelTypeset = false; // won't need to do this in the future
HUB.Queue(["Typeset", HUB, preview]);
}
//
// When the preview changes, cancel MathJax and restart,
// if we haven't done that already.
//
function UpdateMJ() {
if (!pending && ready) {
pending = true;
HUB.Cancel();
HUB.Queue(RestartMJ);
}
}
//
// Save the preview ID and the inline math delimiter.
// Create a converter for the editor and register a preConversion hook
// to handle escaping the math.
// Create a preview refresh hook to handle starting MathJax.
//
function prepareWmdForMathJax(editorObject, wmdId, delimiters) {
preview = document.getElementById("wmd-preview" + wmdId);
inline = delimiters[0][0];
var converterObject = editorObject.getConverter();
converterObject.hooks.chain("preConversion", removeMath);
converterObject.hooks.chain("preSafe", replaceMath);
editorObject.hooks.chain("onPreviewRefresh", UpdateMJ);
}
return {
prepareWmdForMathJax: prepareWmdForMathJax
}
})();
//
// Set up MathJax to allow canceling of typesetting, if it
// doesn't already have that.
//
(function () {
var HUB = MathJax.Hub;
if (!HUB.Cancel) {
HUB.cancelTypeset = false;
var CANCELMESSAGE = "MathJax Canceled";
HUB.Register.StartupHook("HTML-CSS Jax Config", function () {
var HTMLCSS = MathJax.OutputJax["HTML-CSS"],
TRANSLATE = HTMLCSS.Translate;
HTMLCSS.Augment({
Translate: function (script, state) {
if (HUB.cancelTypeset || state.cancelled) {
throw Error(CANCELMESSAGE)
}
return TRANSLATE.call(HTMLCSS, script, state);
}
});
});
HUB.Register.StartupHook("SVG Jax Config", function () {
var SVG = MathJax.OutputJax["SVG"],
TRANSLATE = SVG.Translate;
SVG.Augment({
Translate: function (script, state) {
if (HUB.cancelTypeset || state.cancelled) {
throw Error(CANCELMESSAGE)
}
return TRANSLATE.call(SVG, script, state);
}
});
});
HUB.Register.StartupHook("TeX Jax Config", function () {
var TEX = MathJax.InputJax.TeX,
TRANSLATE = TEX.Translate;
TEX.Augment({
Translate: function (script, state) {
if (HUB.cancelTypeset || state.cancelled) {
throw Error(CANCELMESSAGE)
}
return TRANSLATE.call(TEX, script, state);
}
});
});
var PROCESSERROR = HUB.processError;
HUB.processError = function (error, state, type) {
if (error.message !== CANCELMESSAGE) {
return PROCESSERROR.call(HUB, error, state, type)
}
MathJax.Message.Clear(0, 0);
state.jaxIDs = [];
state.jax = {};
state.scripts = [];
state.i = state.j = 0;
state.cancelled = true;
return null;
};
HUB.Cancel = function () {
this.cancelTypeset = true;
};
}
})();
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