Added min and max builtins.

lib/less/functions.js

@@ -266,6 +266,41 @@ tree.functions = {
             throw { type: "Argument", message: "argument must be a number" };
         }
     },
+    _minmax: function (name, args) {
+        args = Array.prototype.slice.call(args);
+        switch(args.length) {
+        case 0: throw { type: "Argument", message: "one or more arguments required" };
+        case 1: return args[0];
+        }
+        var isMin = name == 'min';
+        function f (a, b) {
+            if(!(a instanceof tree.Dimension && b instanceof tree.Dimension)) {
+                return null;
+            }
+            var ua = a.unify();
+            var ub = b.unify();
+            if(ua.unit.compare(ub.unit) != 0) {
+                return null;
+            }
+            var val = ua.compare(ub);
+            if(isMin && val > 0 || !isMin && val < 0) {
+                return b;
+            }
+            return a;
+        }
+        var val = args.reduce(f);
+        if(val !== null) {
+            return val;
+        }
+        return new(tree.Anonymous)(name +
+            "(" + args.map(function (a) { return a.toCSS(); }).join(', ') + ")");
+    },
+    min: function () {
+        return this._minmax('min', arguments);
+    },
+    max: function () {
+        return this._minmax('max', arguments);
+    },
     argb: function (color) {
         return new(tree.Anonymous)(color.toARGB());