From b9bead5efe0e7f7e704f365b7c55901416d69a3c Mon Sep 17 00:00:00 2001
From: Rafael Weinstein <rafaelw@chromium.org>
Date: Mon, 13 Jan 2014 16:04:08 -0800
Subject: [PATCH] add on- event bindings

R=arv
BUG=

Review URL: https://codereview.appspot.com/51740043
---
 src/polymer-expressions.js | 47 ++++++++++++++++++++++++++++++
 tests/tests.js             | 58 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)

diff --git a/src/polymer-expressions.js b/src/polymer-expressions.js
index 45e4547..21ac3f6 100644
--- a/src/polymer-expressions.js
+++ b/src/polymer-expressions.js
@@ -444,6 +444,43 @@
     });
   }
 
+  function isEventHandler(name) {
+    return name[0] === 'o' &&
+           name[1] === 'n' &&
+           name[2] === '-';
+  }
+
+  function prepareEventBinding(path, name) {
+    var eventType = name.substring(3);
+
+    return function(model, node, oneTime) {
+      var fn = path.getValueFrom(model);
+
+      function handler() {
+        if (!oneTime)
+          fn = path.getValueFrom(model);
+        fn.apply(model, arguments);
+      }
+
+      node.addEventListener(eventType, handler);
+
+      if (oneTime)
+        return;
+
+      function bindingValue() {
+        return '{{ ' + path + ' }}';
+      }
+
+      return {
+        open: bindingValue,
+        discardChanges: bindingValue,
+        close: function() {
+          node.removeEventListener(eventType, handler);
+        }
+      };
+    }
+  }
+
   function PolymerExpressions() {}
 
   PolymerExpressions.prototype = {
@@ -477,6 +514,16 @@
     },
 
     prepareBinding: function(pathString, name, node) {
+      if (isEventHandler(name)) {
+        var path = Path.get(pathString);
+        if (!path.valid) {
+          console.error('on-* bindings must be simple path expressions');
+          return;
+        }
+
+        return prepareEventBinding(path, name);
+      }
+
       if (Path.get(pathString).valid)
         return; // bail out early if pathString is simple path.
 
diff --git a/tests/tests.js b/tests/tests.js
index e9103ae..dcdf170 100644
--- a/tests/tests.js
+++ b/tests/tests.js
@@ -1544,6 +1544,64 @@ suite('PolymerExpressions', function() {
     });
   });
 
+  test('on-* event bindings', function(done) {
+    var div = createTestHtml(
+        '<template bind>' +
+          '<div on-foo="{{ handleFoo }}" ' +
+               'on-bar="{{ bar.handleBar }}" ' +
+               'on-baz="[[ handleBaz ]]">' +
+          '</div>' +
+        '</template>');
+
+    var model = {
+      callCount: 0,
+      receiverValue: undefined,
+      handleFoo: function() {
+        this.callCount++;
+        this.receiverValue = 'foo';
+      },
+      bar: {
+        handleBar: function() {
+          this.callCount++;
+          this.receiverValue = 'bar';
+        }
+      },
+      handleBaz: function() {
+        this.callCount++;
+        this.receiverValue = 'baz';
+      }
+    };
+
+    recursivelySetTemplateModel(div, model);
+
+    then(function() {
+      var target = div.childNodes[1];
+
+      dispatchEvent('foo', target);
+      assert.strictEqual(1, model.callCount);
+      assert.strictEqual('foo', model.receiverValue);
+
+      dispatchEvent('bar', target);
+      assert.strictEqual(2, model.callCount);
+      assert.strictEqual('bar', model.receiverValue);
+
+      dispatchEvent('baz', target);
+      assert.strictEqual(3, model.callCount);
+      assert.strictEqual('baz', model.receiverValue);
+
+      // should be ignored because of one-time binding
+      model.handleBaz = function() {
+        this.receiverValue = 'newBaz';
+      };
+
+      dispatchEvent('baz', target);
+      assert.strictEqual(4, model.callCount);
+      assert.strictEqual('baz', model.receiverValue);
+
+      done();
+    });
+  });
+
   test('Non-model path expressions', function() {
     assert.isFalse(getExpression_('a + b').nonModelPath);
     assert.isFalse(getExpression_('a + b > 3 + hello["kitty"]').nonModelPath);