Merge pull request #398 from gagern/aligned

Introduce an aligned environment

src/environments.js

@@ -176,3 +176,43 @@ defineEnvironment("cases", {
     }, context.mode);
     return res;
 });
+
+// An aligned environment is like the align* environment
+// except it operates within math mode.
+// Note that we assume \nomallineskiplimit to be zero,
+// so that \strut@ is the same as \strut.
+defineEnvironment("aligned", {
+}, function(context) {
+    var res = {
+        type: "array",
+        cols: []
+    };
+    res = parseArray(context.parser, res);
+    var emptyGroup = new ParseNode("ordgroup", [], context.mode);
+    var numCols = 0;
+    res.value.body.forEach(function(row) {
+        var i;
+        for (i = 1; i < row.length; i += 2) {
+            row[i].value.unshift(emptyGroup);
+        }
+        if (numCols < row.length) {
+            numCols = row.length;
+        }
+    });
+    for (var i = 0; i < numCols; ++i) {
+        var align = "r";
+        var pregap = 0;
+        if (i % 2 === 1) {
+            align = "l";
+        } else if (i > 0) {
+            pregap = 2; // one \qquad between columns
+        }
+        res.value.cols[i] = {
+            type: "align",
+            align: align,
+            pregap: pregap,
+            postgap: 0
+        };
+    }
+    return res;
+});

test/katex-spec.js

@@ -1672,6 +1672,15 @@ describe("A cases environment", function() {
 
 });
 
+describe("An aligned environment", function() {
+
+    it("should parse its input", function() {
+        expect("\\begin{aligned}a&=b&c&=d\\\\e&=f\\end{aligned}")
+            .toParse();
+    });
+
+});
+
 var getMathML = function(expr, settings) {
     var usedSettings = settings ? settings : defaultSettings;
 

test/screenshotter/ss_data.yaml

@@ -12,6 +12,11 @@
 # on the next line. See http://www.yaml.org/ for syntax details.
 
 Accents: \vec{A}\vec{x}\vec x^2\vec{x}_2^2\vec{A}^2\vec{xA}^2
+Aligned: |
+    \begin{aligned}
+        a &= 1 & b &= 2 \\
+        3a &= 3 & 17b &= 34
+    \end{aligned}
 Arrays: |
     \left(\begin{array}{|rl|c||}
         1&2&3\\