Add unsigned support and test code

lib/carto/tree/dimension.js

@@ -24,6 +24,10 @@ tree.Dimension.prototype = {
     toColor: function() {
         return new tree.Color([this.value, this.value, this.value]);
     },
+    round: function() {
+        this.value = Math.round(this.value);
+        return this;
+    },
     toString: function() {
         return this.value.toString();
     },

lib/carto/tree/reference.js

@@ -173,8 +173,15 @@ tree.Reference.validValue = function(env, selector, value) {
             }
             return true;
         }
-    } else if (tree.Reference.selector(selector).type == 'expression') {
+    } else if (tree.Reference.selector(selector).type === 'expression') {
         return true;
+    } else if (tree.Reference.selector(selector).type === 'unsigned') {
+        if (value.value[0].is === 'float') {
+            value.value[0].round();
+            return true;
+        } else {
+            return false;
+        }
     } else {
         if (tree.Reference.selector(selector).validate) {
             var valid = false;

test/rendering/unsigned.mml

@@ -0,0 +1,14 @@
+{
+    "srs": "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over",
+    "Stylesheet": [
+        "unsigned.mss"
+    ],
+    "Layer": [{
+        "name": "world",
+        "srs": "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over",
+        "Datasource": {
+            "file": "http://tilemill-data.s3.amazonaws.com/test_data/shape_demo.zip",
+            "type": "shape"
+        }
+    }]
+}

test/rendering/unsigned.mss

@@ -0,0 +1,6 @@
+#world {
+    text-size:10.5;
+    text-spacing:12.1;
+    text-name:[FOO];
+    text-face-name:'Foo';
+}

test/rendering/unsigned.result

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE Map[]>
+<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over" maximum-extent="-20037508.34,-20037508.34,20037508.34,20037508.34">
+
+
+<Style name="world" filter-mode="first" >
+  <Rule>
+    <TextSymbolizer size="11" spacing="12" face-name="Foo" ><![CDATA[[FOO]]]></TextSymbolizer>
+  </Rule>
+</Style>
+<Layer name="world"
+  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
+    <StyleName>world</StyleName>
+    <Datasource>
+       <Parameter name="file"><![CDATA[[absolute path]]]></Parameter>
+       <Parameter name="type"><![CDATA[shape]]></Parameter>
+    </Datasource>
+  </Layer>
+
+</Map>