added attribute handler

git-svn-id: file:///var/local/svn/basicwriter@28 daaaf23c-2e50-4459-9457-1e69db5a47bf

1 files changed, 138 insertions, 0 deletions

diff --git a/src/xml/XmlAttributeHandler.hpp b/src/xml/XmlAttributeHandler.hpp
new file mode 100644
index 0000000..8fae6c3
--- /dev/null
+++ b/src/xml/XmlAttributeHandler.hpp
@@ -0,0 +1,138 @@
+/*
+    Ousía
+    Copyright (C) 2014  Benjamin Paaßen, Andreas Stöckel
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _OUSIA_XML_XML_ATTRIBUTE_HANDLER_HPP_
+#define _OUSIA_XML_XML_ATTRIBUTE_HANDLER_HPP_
+
+#include <functional>
+#include <string>
+
+namespace ousia {
+namespace xml {
+
+/**
+ * The attribute handler class is responsible for handling attributes. It
+ * performs type checks and conversion. Note that the name of the attribute is
+ * not stored inside the handler, as the attribute handlers are meant to be used
+ * alongside a map.
+ */
+class XmlAttributeHandler {
+
+private:
+	/**
+	 * Specifies whether this attribute was actually handled (set to true once
+	 * the setter is called).
+	 */
+	bool handled;
+
+	/**
+	 * Specifies whether this attribute is required or not.
+	 */
+	bool required;
+
+	/**
+	 * Function which returns true if the given string is a valid entry for the
+	 * type the attribute handler represents.
+	 */
+	std::function<bool(const std::string&)> valid;
+
+	/**
+	 * Function which gets the attribute value and sets the type.
+	 */
+	std::function<void(const std::string&)> setter;
+
+	/**
+	 * Default value (as string) that should be used if no other value for that
+	 * attribute is given.
+	 */
+	const char *defaultValue;
+
+public:
+
+	/**
+	 * Constructor of the XmlAttributeHandler class.
+	 *
+	 * @param required if true, the attribute is marked as "required" and it
+	 * must occur in the xml.
+	 * @param valid is a function reference which specifies whether the given
+	 * string is valid.
+	 * @param setter is the function that is meant to actually set the value
+	 * of the attached class.
+	 * @param defaultValue if given (it does not equal the nullptr), the setter
+	 * is automatically called with the default value, unless the attribute is
+	 * actually specified in the XML.
+	 */
+	XmlAttributeHandler(bool required,
+			const std::function<bool(const std::string&)> &valid,
+			const std::function<void(const std::string&)> &setter,
+			const char *defaultValue = nullptr) :
+		handled(false), required(required), valid(valid), setter(setter),
+		defaultValue(defaultValue)
+	{
+		// Do nothing here
+	}
+
+	/**
+	 * Returns true if the given value for this attribute is valid.
+	 */
+	bool isValid(const std::string &value)
+	{
+		return valid(value);
+	}
+
+	/**
+	 * Calls the setter with the given value. The value should have been checked
+	 * for validity first.
+	 */
+	void executeSettter(const std::string &value)
+	{
+		handled = true;
+		setter(value);
+	}
+
+	/**
+	 * Returns true if this element is required.
+	 */
+	bool isRequired()
+	{
+		return required;
+	}
+
+	/**
+	 * Returns the default value.
+	 */
+	const char* getDefaultValue()
+	{
+		return defaultValue;
+	}
+
+	/**
+	 * Returns true if the attribute was handled.
+	 */
+	bool isHandled()
+	{
+		return handled;
+	}
+
+};
+
+}
+}
+
+#endif /* _OUSIA_XML_XML_ATTRIBUTE_HANDLER_HPP_ */
+