Add tie symbol (~)

Summary:
Add real support for the tie symbol. Also, get rid of any of the
leftover bad support

Test Plan:
 - See the new normal tests succeed
 - See huxley tests didn't change except the new ones, which looks good

Reviewers: alpert

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D7772

Lexer.js

@@ -25,13 +25,15 @@ var mathNormals = [
     [/^{/, "{"],
     [/^}/, "}"],
     [/^[(\[]/, "open"],
-    [/^[)\]?!]/, "close"]
+    [/^[)\]?!]/, "close"],
+    [/^~/, "spacing"]
 ];
 
 var textNormals = [
     [/^[a-zA-Z0-9`!@*()-=+\[\]'";:?\/.,]/, "textord"],
     [/^{/, "{"],
-    [/^}/, "}"]
+    [/^}/, "}"],
+    [/^~/, "spacing"]
 ];
 
 // Build a regex to easily parse the functions

buildTree.js

@@ -317,13 +317,11 @@ var groupTypes = {
 
     spacing: function(group, options, prev) {
         if (group.value === "\\ " || group.value === "\\space" ||
-            group.value === " ") {
+            group.value === " " || group.value === "~") {
             return makeSpan(
                 ["mord", "mspace"],
                 [mathrm(group.value, group.mode)]
             );
-        } else if(group.value === "~") {
-            return makeSpan(["mord", "mspace"], [mathrm(" ", group.mode)]);
         } else {
             var spacingClassMap = {
                 "\\qquad": "qquad",

symbols.js

@@ -437,6 +437,11 @@ var symbols = {
             group: "spacing",
             replace: "\u00a0"
         },
+        "~": {
+            font: "main",
+            group: "spacing",
+            replace: "\u00a0"
+        },
         "\\,": {
             font: "main",
             group: "spacing"
@@ -565,6 +570,11 @@ var symbols = {
             font: "main",
             group: "spacing",
             replace: "\u00a0"
+        },
+        "~": {
+            font: "main",
+            group: "spacing",
+            replace: "\u00a0"
         }
     }
 };

test/huxley/Huxleyfile

@@ -20,7 +20,7 @@ url=http://localhost:7936/test/huxley/test.html?m=\alpha\beta\gamma\omega
 url=http://localhost:7936/test/huxley/test.html?m=a+b-c\cdot d/e
 
 [Spacing]
-url=http://localhost:7936/test/huxley/test.html?m=[-1][1-1]1%%3D1(%%3D1)\lvert a\rvert
+url=http://localhost:7936/test/huxley/test.html?m=[-1][1-1]1%%3D1(%%3D1)\lvert a\rvert~b
 
 [Functions]
 url=http://localhost:7936/test/huxley/test.html?m=\sin\cos\tan\ln\log
@@ -35,7 +35,7 @@ url=http://localhost:7936/test/huxley/test.html?m=\Huge{x}\LARGE{y}\normalsize{z
 url=http://localhost:7936/test/huxley/test.html?m=\tiny{a+b}a+b\Huge{a+b}&pre=x&post=M
 
 [Text]
-url=http://localhost:7936/test/huxley/test.html?m=\frac{a}{b}\text{c {ab} \ e}+fg
+url=http://localhost:7936/test/huxley/test.html?m=\frac{a}{b}\text{c~ {ab} \ e}+fg
 
 [KaTeX]
 url=http://localhost:7936/test/huxley/test.html?m=\KaTeX

test/katex-tests.js

@@ -534,3 +534,40 @@ describe("A color parser", function() {
         }).toThrow();
     });
 });
+
+describe("A tie parser", function() {
+    var mathTie = "a~b";
+    var textTie = "\\text{a~ b}";
+
+    it("should parse ties in math mode", function() {
+        expect(function() {
+            parseTree(mathTie);
+        }).not.toThrow();
+    });
+
+    it("should parse ties in text mode", function() {
+        expect(function() {
+            parseTree(textTie);
+        }).not.toThrow();
+    });
+
+    it("should produce spacing in math mode", function() {
+        var parse = parseTree(mathTie);
+
+        expect(parse[1].type).toMatch("spacing");
+    });
+
+    it("should produce spacing in text mode", function() {
+        var text = parseTree(textTie)[0];
+        var parse = text.value.value;
+
+        expect(parse[1].type).toMatch("spacing");
+    });
+
+    it("should not contract with spaces in text mode", function() {
+        var text = parseTree(textTie)[0];
+        var parse = text.value.value;
+
+        expect(parse[2].type).toMatch("spacing");
+    });
+});