Basic support for writing XML namespaces

2 files changed, 68 insertions, 31 deletions

diff --git a/lib/xml/writer.js b/lib/xml/writer.js
index 418a4b9..66cc8de 100644
--- a/lib/xml/writer.js
+++ b/lib/xml/writer.js
@@ -1,36 +1,57 @@
+var _ = require("underscore");
 var xmlbuilder = require("xmlbuilder");
 
 
 exports.writeString = writeString;
 
 
-function writeString(root) {
-    var builder = xmlbuilder
-        .create(root.name, {
-            version: '1.0',
-            encoding: 'UTF-8',
-            standalone: true
-        });
-    root.children.forEach(function(child) {
-        writeNode(builder, child);
-    });
-    return builder.end();
-}
+function writeString(root, namespaces) {
+    var uriToPrefix = _.invert(namespaces);
+    
+    var nodeWriters = {
+        element: writeElement,
+        text: writeTextNode
+    };
 
-var nodeWriters = {
-    element: writeElement,
-    text: writeTextNode
-};
+    function writeNode(builder, node) {
+        return nodeWriters[node.type](builder, node);
+    }
 
-function writeNode(builder, node) {
-    return nodeWriters[node.type](builder, node);
-}
+    function writeElement(builder, element) {
+        var elementBuilder = builder.element(mapElementName(element.name), element.attributes);
+        element.children.forEach(function(child) {
+            writeNode(elementBuilder, child);
+        });
+    }
+    
+    function mapElementName(name) {
+        var longFormMatch = /^\{(.*)\}(.*)$/.exec(name);
+        if (longFormMatch) {
+            return uriToPrefix[longFormMatch[1]] + ":" + longFormMatch[2];
+        } else {
+            return name;
+        }
+    }
+    
+    function writeDocument(root) {
+        var builder = xmlbuilder
+            .create(root.name, {
+                version: '1.0',
+                encoding: 'UTF-8',
+                standalone: true
+            });
+        
+        _.forEach(namespaces, function(uri, prefix) {
+            builder.attribute("xmlns:" + prefix, uri);
+        });
+        
+        root.children.forEach(function(child) {
+            writeNode(builder, child);
+        });
+        return builder.end();
+    }
 
-function writeElement(builder, element) {
-    var elementBuilder = builder.element(element.name, element.attributes);
-    element.children.forEach(function(child) {
-        writeNode(elementBuilder, child);
-    });
+    return writeDocument(root);
 }
 
 function writeTextNode(builder, node) {
diff --git a/tests/xml/writer.tests.js b/tests/xml/writer.tests.js
index a542dc3..6c414c0 100644
--- a/tests/xml/writer.tests.js
+++ b/tests/xml/writer.tests.js
@@ -7,11 +7,11 @@ var test = require("../testing").test;
 
 describe('xml.writer', function() {
     test('writing empty root element writes out xml declaration and empty root element', function() {
-        assertXmlString(xml.element("root"), '<root/>');
+        assertXmlString(xml.element("root"), {}, '<root/>');
     });
     
     test('can write empty child elements', function() {
-        assertXmlString(xml.element("root", {}, [xml.element("album"), xml.element("single")]),
+        assertXmlString(xml.element("root", {}, [xml.element("album"), xml.element("single")]), {},
             '<root><album/><single/></root>');
     });
     
@@ -22,7 +22,7 @@ describe('xml.writer', function() {
                 xml.element("song")
             ])
         ]);
-        assertXmlString(element,
+        assertXmlString(element, {},
             '<root><album><year/><song/></album></root>');
     });
     
@@ -30,7 +30,7 @@ describe('xml.writer', function() {
         var element = xml.element("root", {}, [
             xml.element("album", {"title": "Everything in Transit"})
         ]);
-        assertXmlString(element,
+        assertXmlString(element, {},
             '<root><album title="Everything in Transit"/></root>');
     });
     
@@ -40,14 +40,30 @@ describe('xml.writer', function() {
                 xml.text("Everything in Transit")
             ])
         ]);
-        assertXmlString(element,
+        assertXmlString(element, {},
             '<root><album>Everything in Transit</album></root>');
     });
+    
+    test('can write child elements with long-form prefix when URI is namespace', function() {
+        var element = xml.element("root", {"m": "music"}, [
+            xml.element("{music}album")
+        ]);
+        assertXmlString(element, {"m": "music"},
+            '<root xmlns:m="music"><m:album/></root>');
+    });
+    
+    test('can write child elements with short-form prefix when URI is namespace', function() {
+        var element = xml.element("root", {"m": "music"}, [
+            xml.element("m:album")
+        ]);
+        assertXmlString(element, {"m": "music"},
+            '<root xmlns:m="music"><m:album/></root>');
+    });
 });
 
 
-function assertXmlString(element, expectedString) {
-    assert.equal(writer.writeString(element),
+function assertXmlString(element, namespaces, expectedString) {
+    assert.equal(writer.writeString(element, namespaces),
         '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' +
         expectedString);
 }