Added option to preserve at-rule order

Fix #30

README.md

@@ -394,6 +394,13 @@ postcss([
 ```
 
 
+### `preserveAtRulesOrder` (default: `false`)
+
+Keeps your at-rules like media queries in the order to defined them.
+
+Ideally, this would be defaulted to `true` and it will be in the next major version. All of the tests expecations need to be updated and probably just drop support for `preserveAtRulesOrder: false`
+
+
 # Quick Reference/Notes
 
  - This plugin was spawned out of a [discussion on the `cssnext` repo](https://github.com/cssnext/cssnext/issues/99).

index.js

@@ -65,7 +65,10 @@ var defaults = {
 	variables: {},
 	// Preserve variables injected via JS with the `variables` option above
 	// before serializing to CSS (`false` will remove these variables from output)
-	preserveInjectedVariables: true
+	preserveInjectedVariables: true,
+	// Will write media queries in the same order as in the original file.
+	// Currently defaulted to false for legacy behavior. We can update to `true` in a major version
+	preserveAtRulesOrder: false
 };
 
 module.exports = postcss.plugin('postcss-css-variables', function(options) {
@@ -249,7 +252,7 @@ module.exports = postcss.plugin('postcss-css-variables', function(options) {
 				ruleToWorkOn.nodes.slice(0).forEach(function(node) {
 					if(node.type === 'decl') {
 						var decl = node;
-						resolveDecl(decl, map, opts.preserve, logResolveValueResult);
+						resolveDecl(decl, map, opts.preserve, opts.preserveAtRulesOrder, logResolveValueResult);
 					}
 				});
 			});

lib/resolve-decl.js

@@ -71,8 +71,9 @@ function eachMapItemDependencyOfDecl(variablesUsedList, map, decl, cb) {
 
 // Resolve the decl with the computed value
 // Also add in any media queries that change the value as necessary
-function resolveDecl(decl, map, /*optional*/shouldPreserve, /*optional*/logResolveValueResult) {
+function resolveDecl(decl, map, /*optional*/shouldPreserve, /*optional*/preserveAtRulesOrder, /*optional*/logResolveValueResult) {
 	shouldPreserve = shouldPreserve || false;
+	preserveAtRulesOrder = preserveAtRulesOrder || false;
 
 	// Make it chainable
 	var _logResolveValueResult = function(valueResults) {
@@ -93,6 +94,7 @@ function resolveDecl(decl, map, /*optional*/shouldPreserve, /*optional*/logResol
 	// Resolve the cascade dependencies
 	// Now find any at-rule declarations that need to be added below each rule
 	//console.log('resolveDecl 2');
+	var previousAtRuleNode;
 	eachMapItemDependencyOfDecl(valueResults.variablesUsed, map, decl, function(mimicDecl, mapItem) {
 		var ruleClone = shallowCloneNode(decl.parent);
 		var declClone = decl.clone();
@@ -129,14 +131,19 @@ function resolveDecl(decl, map, /*optional*/shouldPreserve, /*optional*/logResol
 				currentAtRuleNode = currentAtRuleNode.parent;
 			}
 
-			// Put the atRuleStructure after the declaration's rule
-			decl.parent.parent.insertAfter(decl.parent, parentAtRuleNode);
+			// Put the first atRuleStructure after the declaration's rule,
+			// and after that, put them right after the previous one
+			decl.parent.parent.insertAfter(preserveAtRulesOrder && previousAtRuleNode || decl.parent, parentAtRuleNode);
+
+			// Save referance of previous atRuleStructure
+			previousAtRuleNode = parentAtRuleNode
 		}
 		else {
 			ruleClone.selector = mimicDecl.parent.selector;
 
-			// Put the atRuleStructure after the declaration's rule
-			decl.parent.parent.insertAfter(decl.parent, ruleClone);
+			// Put the first atRuleStructure after the declaration's rule,
+			// and after that, put them right after the previous one
+			decl.parent.parent.insertAfter(preserveAtRulesOrder && previousAtRuleNode || decl.parent, ruleClone);
 		}
 	});
 

test/fixtures/media-query-nested-preserver-rule-order.css

@@ -0,0 +1,21 @@
+:root {
+	--width: 150px;
+}
+
+@media print {
+	@media (min-width: 1000px) {
+		:root {
+			--width: 300px;
+		}
+
+		@media (min-width: 1250px) {
+			:root {
+				--width: 450px;
+			}
+		}
+	}
+}
+
+.box {
+	width: var(--width);
+}

test/fixtures/media-query-nested-preserver-rule-order.expected.css

@@ -0,0 +1,26 @@
+.box {
+	width: 150px;
+}
+
+@media print {
+
+	@media (min-width: 1000px) {
+
+		.box{
+			width: 300px;
+		}
+	}
+}
+
+@media print {
+
+	@media (min-width: 1000px) {
+
+		@media (min-width: 1250px) {
+
+			.box {
+				width: 450px;
+			}
+		}
+	}
+}

test/fixtures/media-query-preserve-rule-order.css

@@ -0,0 +1,20 @@
+:root {
+	--width: 150px;
+}
+
+@media (min-width: 1000px) {
+  :root {
+    --width: 300px;
+  }
+}
+
+@media (min-width: 1250px) {
+  :root {
+    --width: 450px;
+  }
+}
+
+.box {
+	width: var(--width);
+
+}

test/fixtures/media-query-preserve-rule-order.expected.css

@@ -0,0 +1,15 @@
+.box {
+	width: 150px;
+}
+
+@media (min-width: 1000px) {
+	.box {
+		width: 300px;
+	}
+}
+
+@media (min-width: 1250px) {
+	.box {
+		width: 450px;
+	}
+}

test/test.js

@@ -135,7 +135,11 @@ describe('postcss-css-variables', function() {
 		test('should add rule declaration of property in @media', 'media-query');
 		test('should add rule declaration of property in @support', 'support-directive');
 
-		test('should work with nested @media', 'media-query-nested');
+		test('should work with @media, preserving rule order', 'media-query-preserve-rule-order', { preserveAtRulesOrder: true });
+
+		test('should work with nested @media', 'media-query-nested', { preserveAtRulesOrder: false });
+		test('should work with nested @media, preserving rule order', 'media-query-nested-preserver-rule-order', { preserveAtRulesOrder: true });
+
 
 		test('should cascade to nested rules', 'cascade-on-nested-rules');