Add the \KaTeX command

Summary:
Add a command to print out a TeX-style logo for KaTeX. I think the
code is okay, but suggestions for the design of the logo are most welcome (I'll
post screenshots soon).

Test Plan: Make sure \KaTeX renders, and the tests still succeed.

Reviewers: alpert

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D3443

Parser.js

@@ -383,6 +383,11 @@ Parser.prototype.parseNucleus = function(pos) {
             throw new ParseError("Parse error: Expected numerator after '" +
                 nucleus.type + "'");
         }
+    } else if (nucleus.type === "\\KaTeX") {
+        return new ParseResult(
+            new ParseNode("katex", null),
+            nucleus.position
+        );
     } else if (funcToType[nucleus.type]) {
         // Otherwise if this is a no-argument function, find the type it
         // corresponds to in the map and return

buildTree.js

@@ -3,6 +3,8 @@ var Style = require("./Style");
 var parseTree = require("./parseTree");
 var utils = require("./utils");
 
+var ParseError = require("./ParseError");
+
 function Options(style, color) {
     this.style = style;
     this.color = color;
@@ -197,6 +199,16 @@ var groupTypes = {
 
     namedfn: function(group, options, prev) {
         return makeSpan("mop" + options.color, [textit(group.value.slice(1))]);
+    },
+
+    katex: function(group, options, prev) {
+        return makeSpan("katex-logo", [
+            makeSpan("k", [textit("K")]),
+            makeSpan("a", [textit("A")]),
+            makeSpan("t", [textit("T")]),
+            makeSpan("e", [textit("E")]),
+            makeSpan("x", [textit("X")])
+        ]);
     }
 };
 

static/katex.css

@@ -165,3 +165,21 @@ big parens
 .katex .green { color: #28ae7b; }
 .katex .gray { color: gray; }
 .katex .purple { color: #9d38bd; }
+
+.katex .katex-logo .a {
+    font-size: 0.75em;
+    margin-left: -0.32em;
+    position: relative;
+    top: -0.2em;
+}
+.katex .katex-logo .t {
+    margin-left: -0.23em;
+}
+.katex .katex-logo .e {
+    margin-left: -0.1667em;
+    position: relative;
+    top: 0.2155em;
+}
+.katex .katex-logo .x {
+    margin-left: -0.125em;
+}