Merge branch 'master' of github.com:mapbox/carto

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 * Add "name/" prefix for creating multiple instances of a symbolizer in the same
   attachment
+* Only output <Layer> tag when there's at least one style
+* Sort styles by location of first rule's index
 
 ### 0.2.3
 

lib/carto/renderer.js

@@ -48,7 +48,9 @@ carto.Renderer.prototype.render = function render(m, callback) {
         var matching = rulesets.filter(function(definition) {
             return definition.appliesTo(l.name, classes);
         });
-        _(inheritRules(matching, env)).each(function(rule) {
+        var rules = inheritRules(matching, env);
+        sorted = sortStyles(rules, env);
+        _(sorted).each(function(rule) {
             var style = new tree.Style(l.name, rule.attachment, rule);
             if (style) {
                 l.styles.push(style.name);
@@ -57,7 +59,9 @@ carto.Renderer.prototype.render = function render(m, callback) {
                 output.push(style.toXML(env));
             }
         });
-        output.push((new carto.tree.Layer(l)).toXML());
+        if (l.styles.length) {
+            output.push((new carto.tree.Layer(l)).toXML());
+        }
     });
 
     output.unshift(env.effects.map(function(e) {
@@ -165,6 +169,25 @@ function inheritRules(definitions, env) {
     return result;
 }
 
+function sortStyles(styles, env) {
+    styles.forEach(function(style) {
+        style.index = Infinity;
+        style.forEach(function(block) {
+            block.rules.forEach(function(rule) {
+                if (rule.index < style.index) {
+                    style.index = rule.index;
+                }
+            });
+        });
+    });
+
+    var result = styles.slice();
+    result.sort(function(a, b) {
+        return b.index - a.index;
+    });
+    return result;
+}
+
 // Find a rule like Map { background-color: #fff; },
 // if any, and return a list of properties to be inserted
 // into the <Map element of the resulting XML. Translates