Add default element fallback

BZ: 122982

The element library class is a factory that receives an xml node and
instanciates the corresponding element. In some case, it would be usefull
not to fail if no matching builder is found but use a default one.

Add a setDefaultElementBuilder method to set the default builder to
fallback to, in case no  matching builder is found.

Change-Id: I58f0ada3450195a3ca7d878e4b666b0a9359b499
Signed-off-by: Kevin Rocard <kevinx.rocard@intel.com>
Reviewed-on: http://android.intel.com:8080/118042
Reviewed-by: Centelles, Sylvain <sylvain.centelles@intel.com>
Tested-by: Barthes, FabienX <fabienx.barthes@intel.com>
Reviewed-by: cactus <cactus@intel.com>
Tested-by: cactus <cactus@intel.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/parameter/DefaultElementLibrary.h b/parameter/DefaultElementLibrary.h
new file mode 100644
index 0000000..53a9059
--- /dev/null
+++ b/parameter/DefaultElementLibrary.h
@@ -0,0 +1,94 @@
+/*
+ * INTEL CONFIDENTIAL
+ * Copyright 2013 Intel
+ * Corporation All Rights Reserved.
+ *
+ * The source code contained or described herein and all documents related to
+ * the source code ("Material") are owned by Intel Corporation or its suppliers
+ * or licensors. Title to the Material remains with Intel Corporation or its
+ * suppliers and licensors. The Material contains trade secrets and proprietary
+ * and confidential information of Intel or its suppliers and licensors. The
+ * Material is protected by worldwide copyright and trade secret laws and
+ * treaty provisions. No part of the Material may be used, copied, reproduced,
+ * modified, published, uploaded, posted, transmitted, distributed, or
+ * disclosed in any way without Intel’s prior express written permission.
+ *
+ * No license under any patent, copyright, trade secret or other intellectual
+ * property right is granted to or conferred upon you by disclosure or delivery
+ * of the Materials, either expressly, by implication, inducement, estoppel or
+ * otherwise. Any license under such intellectual property rights must be
+ * express and approved by Intel in writing.
+ */
+#pragma once
+
+#include "ElementLibrary.h"
+#include "ElementBuilder.h"
+
+#include <map>
+#include <string>
+
+/** Factory that creates an element given an xml element. If no matching builder is found, it uses
+  * the default builder.
+  *
+  * @tparam CDefaultElementBuilder is the class of the element builder to use if no corresponding
+  *                                builder is found for a given xml element.
+  */
+template<class CDefaultElementBuilder>
+class CDefaultElementLibrary: public CElementLibrary
+{
+public:
+
+    explicit CDefaultElementLibrary(bool bEnableDefaultMechanism = true);
+    virtual ~CDefaultElementLibrary() {}
+
+    /** Enable the default builder fallback mechanism.
+      * @see createElement() for more detail on this mechanism.
+      *
+      * @param[in] bEnable if true/false, activate/deactivate the default builder mechanism.
+      */
+    void enableDefaultMechanism(bool bEnable) {
+        _bEnableDefaultMechanism = bEnable;
+    }
+
+
+    /** Create and return an element instanciated depending on an xmlElement.
+      *
+      * @param[in] xmlElement: The xml element used to find a matching builder
+      *
+      * @return If a matching builder is found, return an element created from the builder,
+      *         otherwise:
+      *             If the default mechanism is enable (@see enableDefaultMechanism),
+      *                 create the elemen with the default element builder.
+      *             otherwise, return NULL.
+      */
+    CElement* createElement(const CXmlElement& xmlElement) const;
+
+private:
+    bool _bEnableDefaultMechanism;
+    CDefaultElementBuilder _DefaultElementBuilder;
+};
+
+template<class CDefaultElementBuilder>
+CDefaultElementLibrary<CDefaultElementBuilder>::CDefaultElementLibrary(bool bEnableDefaultMechanism) :
+        _bEnableDefaultMechanism(bEnableDefaultMechanism),
+        _DefaultElementBuilder() {}
+
+template<class CDefaultElementBuilder>
+CElement* CDefaultElementLibrary<CDefaultElementBuilder>::createElement(const CXmlElement& xmlElement) const
+{
+    CElement* builtElement = CElementLibrary::createElement(xmlElement);
+
+    if (builtElement != NULL) {
+        // The element was created, return it
+        return builtElement;
+    }
+
+    if (!_bEnableDefaultMechanism) {
+        // The default builder mechanism is not enabled
+        return NULL;
+    }
+
+    // Use the default builder
+    return _DefaultElementBuilder.createElement(xmlElement);
+}
+