Initial commit

Libraries/ReactIOS/diffRawProperties.js

@@ -0,0 +1,85 @@
+/**
+ * Copyright 2004-present Facebook. All Rights Reserved.
+ *
+ * @providesModule diffRawProperties
+ */
+'use strict';
+
+/**
+ * diffRawProperties takes two sets of props and a set of valid attributes
+ * and write to updatePayload the values that changed or were deleted
+ *
+ * @param {?object} updatePayload Overriden with the props that changed.
+ * @param {!object} prevProps Previous properties to diff against current
+ * properties. These properties are as supplied to component construction.
+ * @param {!object} prevProps Next "current" properties to diff against
+ * previous. These properties are as supplied to component construction.
+ * @return {?object}
+ */
+function diffRawProperties(updatePayload, prevProps, nextProps, validAttributes) {
+  var validAttributeConfig;
+  var nextProp;
+  var prevProp;
+  var isScalar;
+  var shouldUpdate;
+
+  for (var propKey in nextProps) {
+    validAttributeConfig = validAttributes[propKey];
+    if (!validAttributeConfig) {
+      continue; // not a valid native prop
+    }
+    prevProp = prevProps && prevProps[propKey];
+    nextProp = nextProps[propKey];
+    if (prevProp !== nextProp) {
+      // If you want a property's diff to be detected, you must configure it
+      // to be so - *or* it must be a scalar property. For now, we'll allow
+      // creation with any attribute that is not scalar, but we should
+      // eventually even reject those unless they are properly configured.
+      isScalar = typeof nextProp !== 'object' || nextProp === null;
+      shouldUpdate = isScalar ||
+        !prevProp ||
+        validAttributeConfig.diff &&
+        validAttributeConfig.diff(prevProp, nextProp);
+
+      if (shouldUpdate) {
+        updatePayload = updatePayload || {};
+        updatePayload[propKey] = nextProp;
+      }
+    }
+  }
+
+  // Also iterate through all the previous props to catch any that have been
+  // removed and make sure native gets the signal so it can reset them to the
+  // default.
+  for (var propKey in prevProps) {
+    validAttributeConfig = validAttributes[propKey];
+    if (!validAttributeConfig) {
+      continue; // not a valid native prop
+    }
+    if (updatePayload && updatePayload[propKey] !== undefined) {
+      continue; // Prop already specified
+    }
+    prevProp = prevProps[propKey];
+    nextProp = nextProps && nextProps[propKey];
+    if (prevProp !== nextProp) {
+      if (nextProp === undefined) {
+        nextProp = null; // null is a sentinel we explicitly send to native
+      }
+      // If you want a property's diff to be detected, you must configure it
+      // to be so - *or* it must be a scalar property. For now, we'll allow
+      // creation with any attribute that is not scalar, but we should
+      // eventually even reject those unless they are properly configured.
+      isScalar = typeof nextProp !== 'object' || nextProp === null;
+      shouldUpdate = isScalar && prevProp !== nextProp ||
+        validAttributeConfig.diff &&
+        validAttributeConfig.diff(prevProp, nextProp);
+      if (shouldUpdate) {
+        updatePayload = updatePayload || {};
+        updatePayload[propKey] = nextProp;
+      }
+    }
+  }
+  return updatePayload;
+}
+
+module.exports = diffRawProperties;