+ add small parsing utility to eliminate redundant code

SGF-10

src/main/java/org/springframework/data/gemfire/config/ParsingUtils.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2010 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.data.gemfire.config;
+
+import java.util.List;
+
+import org.springframework.beans.factory.config.RuntimeBeanReference;
+import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.xml.ParserContext;
+import org.springframework.util.StringUtils;
+import org.springframework.util.xml.DomUtils;
+import org.w3c.dom.Element;
+
+/**
+ * Various minor utility used by the parser.
+ * 
+ * @author Costin Leau
+ */
+abstract class ParsingUtils {
+
+	static void setPropertyValue(Element element, BeanDefinitionBuilder builder, String attrName, String propertyName) {
+		String attr = element.getAttribute(attrName);
+		if (StringUtils.hasText(attr)) {
+			builder.addPropertyValue(propertyName, attr);
+		}
+	}
+
+	static void setPropertyReference(Element element, BeanDefinitionBuilder builder, String attrName, String propertyName) {
+		String attr = element.getAttribute(attrName);
+		if (StringUtils.hasText(attr)) {
+			builder.addPropertyReference(propertyName, attr);
+		}
+	}
+
+	/**
+	 * Utility method handling parsing of nested definition of the type:
+	 * <pre>
+	 *   <tag ref="someBean"/>
+	 * </pre>
+	 * or 
+	 * <pre>
+	 *   <tag>
+	 *     <bean .... />
+	 *   </tag>
+	 * </pre>
+	 * 
+	 * @param element
+	 * @return
+	 */
+	static Object parseRefOrNestedBeanDeclaration(ParserContext parserContext, Element element, BeanDefinitionBuilder builder) {
+		String attr = element.getAttribute("ref");
+		if (StringUtils.hasText(attr)) {
+			// check if there's a nested declaration as well
+			List<Element> childElements = DomUtils.getChildElements(element);
+			if (!childElements.isEmpty()) {
+				parserContext.getReaderContext().error(
+						"either use the 'ref' attribute or a nested bean declaration for '" + element.getLocalName()
+								+ "' element, but not both", element);
+
+			}
+			return new RuntimeBeanReference(attr);
+		}
+		// nested bean definition
+		else {
+			return parserContext.getDelegate().parsePropertySubElement(element, builder.getRawBeanDefinition());
+		}
+	}
+}