runtime binding conversion executors

spring-binding/src/main/java/org/springframework/binding/convert/ConversionService.java

@@ -31,7 +31,7 @@ public interface ConversionService {
 	 * @param sourceClass the source class to convert from
 	 * @param targetClass the target class to convert to
 	 * @return the executor that can execute instance conversion, never null
-	 * @throws ConversionException an exception occured retrieving a converter for the source-to-target pair
+	 * @throws ConversionException an exception occurred retrieving a converter for the source-to-target pair
 	 */
 	public ConversionExecutor getConversionExecutor(Class sourceClass, Class targetClass) throws ConversionException;
 

spring-binding/src/main/java/org/springframework/binding/convert/support/ConversionExecutorImpl.java

@@ -0,0 +1,122 @@
+/*
+ * Copyright 2004-2007 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.binding.convert.support;
+
+import org.springframework.binding.convert.ConversionContext;
+import org.springframework.binding.convert.ConversionException;
+import org.springframework.binding.convert.ConversionExecutor;
+import org.springframework.binding.convert.Converter;
+import org.springframework.core.style.ToStringCreator;
+import org.springframework.util.Assert;
+
+/**
+ * A command object that is parameterized with the information necessary to perform a conversion of a source input to a
+ * target output.
+ * <p>
+ * Specifically, encapsulates knowledge about how to convert source objects to a specific target type using a specific
+ * converter.
+ * 
+ * @author Keith Donald
+ */
+class ConversionExecutorImpl implements ConversionExecutor {
+
+	/**
+	 * The source value type this executor will attempt to convert from.
+	 */
+	private final Class sourceClass;
+
+	/**
+	 * The target value type this executor will attempt to convert to.
+	 */
+	private final Class targetClass;
+
+	/**
+	 * The converter that will perform the conversion.
+	 */
+	private final Converter converter;
+
+	/**
+	 * Creates a conversion executor.
+	 * @param sourceClass the source type that the converter will convert from
+	 * @param targetClass the target type that the converter will convert to
+	 * @param converter the converter that will perform the conversion
+	 */
+	public ConversionExecutorImpl(Class sourceClass, Class targetClass, Converter converter) {
+		Assert.notNull(sourceClass, "The source class is required");
+		Assert.notNull(targetClass, "The target class is required");
+		Assert.notNull(converter, "The converter is required");
+		this.sourceClass = sourceClass;
+		this.targetClass = targetClass;
+		this.converter = converter;
+	}
+
+	/**
+	 * Returns the source class of conversions performed by this executor.
+	 * @return the source class
+	 */
+	public Class getSourceClass() {
+		return sourceClass;
+	}
+
+	/**
+	 * Returns the target class of conversions performed by this executor.
+	 * @return the target class
+	 */
+	public Class getTargetClass() {
+		return targetClass;
+	}
+
+	/**
+	 * Returns the converter that will perform the conversion.
+	 * @return the converter
+	 */
+	public Converter getConverter() {
+		return converter;
+	}
+
+	public Object execute(Object source) throws ConversionException {
+		return execute(source, null);
+	}
+
+	public Object execute(Object source, ConversionContext context) throws ConversionException {
+		if (targetClass.isInstance(source)) {
+			// source is already assignment compatible with target class
+			return source;
+		}
+		if (source != null && !sourceClass.isInstance(source)) {
+			throw new ConversionException(getSourceClass(), source, getTargetClass(), "Source object '" + source
+					+ "' is expected to be an instance of " + getSourceClass());
+		}
+		return converter.convert(source, targetClass, context);
+	}
+
+	public boolean equals(Object o) {
+		if (!(o instanceof ConversionExecutorImpl)) {
+			return false;
+		}
+		ConversionExecutorImpl other = (ConversionExecutorImpl) o;
+		return sourceClass.equals(other.sourceClass) && targetClass.equals(other.targetClass);
+	}
+
+	public int hashCode() {
+		return sourceClass.hashCode() + targetClass.hashCode();
+	}
+
+	public String toString() {
+		return new ToStringCreator(this).append("sourceClass", sourceClass).append("targetClass", targetClass)
+				.toString();
+	}
+}

spring-binding/src/main/java/org/springframework/binding/convert/support/ConversionServiceAwareConverter.java

@@ -15,8 +15,8 @@
  */
 package org.springframework.binding.convert.support;
 
-import org.springframework.binding.convert.ConversionExecutor;
 import org.springframework.binding.convert.ConversionService;
+import org.springframework.binding.convert.ConversionExecutor;
 import org.springframework.binding.expression.Expression;
 
 /**

spring-binding/src/main/java/org/springframework/binding/convert/support/ConverterPropertyEditorAdapter.java

@@ -40,8 +40,10 @@ public class ConverterPropertyEditorAdapter extends PropertyEditorSupport {
 	 */
 	public ConverterPropertyEditorAdapter(ConversionExecutor conversionExecutor) {
 		Assert.notNull(conversionExecutor, "A conversion executor is required");
-		Assert.isTrue(conversionExecutor.getSourceClass().equals(String.class),
-				"A string conversion executor is required");
+		if (conversionExecutor.getSourceClass() != null) {
+			Assert.isTrue(conversionExecutor.getSourceClass().equals(String.class),
+					"A string conversion executor is required");
+		}
 		this.conversionExecutor = conversionExecutor;
 	}
 

spring-binding/src/main/java/org/springframework/binding/convert/support/CustomConverterConfigurer.java

@@ -21,8 +21,8 @@ import org.springframework.beans.PropertyEditorRegistry;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
-import org.springframework.binding.convert.ConversionExecutor;
 import org.springframework.binding.convert.ConversionService;
+import org.springframework.binding.convert.ConversionExecutor;
 import org.springframework.util.Assert;
 
 /**

spring-binding/src/main/java/org/springframework/binding/convert/support/GenericConversionService.java

@@ -135,13 +135,13 @@ public class GenericConversionService implements ConversionService {
 			throw new IllegalStateException("No converters have been added to this service's registry");
 		}
 		if (targetClass.isAssignableFrom(sourceClass)) {
-			return new ConversionExecutor(sourceClass, targetClass, new NoOpConverter(sourceClass, targetClass));
+			return new ConversionExecutorImpl(sourceClass, targetClass, new NoOpConverter(sourceClass, targetClass));
 		}
 		Map sourceTargetConverters = findConvertersForSource(sourceClass);
 		Converter converter = findTargetConverter(sourceTargetConverters, targetClass);
 		if (converter != null) {
 			// we found a converter
-			return new ConversionExecutor(sourceClass, targetClass, converter);
+			return new ConversionExecutorImpl(sourceClass, targetClass, converter);
 		} else {
 			if (parent != null) {
 				// try the parent
@@ -172,8 +172,8 @@ public class GenericConversionService implements ConversionService {
 			return getConversionExecutor(sourceClass, (Class) targetType);
 		} else {
 			Assert.isInstanceOf(Converter.class, targetType, "Not a converter: ");
-			Converter conv = (Converter) targetType;
-			return new ConversionExecutor(sourceClass, Object.class, conv);
+			Converter converter = (Converter) targetType;
+			return new ConversionExecutorImpl(sourceClass, Object.class, converter);
 		}
 	}
 
@@ -196,8 +196,8 @@ public class GenericConversionService implements ConversionService {
 			Iterator it = sourceTargetConverters.entrySet().iterator();
 			while (it.hasNext()) {
 				Map.Entry entry = (Map.Entry) it.next();
-				executors
-						.add(new ConversionExecutor(sourceClass, (Class) entry.getKey(), (Converter) entry.getValue()));
+				executors.add(new ConversionExecutorImpl(sourceClass, (Class) entry.getKey(), (Converter) entry
+						.getValue()));
 			}
 			return (ConversionExecutor[]) executors.toArray(new ConversionExecutor[executors.size()]);
 		}

spring-binding/src/main/java/org/springframework/binding/convert/support/RuntimeBindingConversionExecutor.java

@@ -0,0 +1,59 @@
+package org.springframework.binding.convert.support;
+
+import org.springframework.binding.convert.ConversionContext;
+import org.springframework.binding.convert.ConversionException;
+import org.springframework.binding.convert.ConversionExecutor;
+import org.springframework.binding.convert.ConversionService;
+import org.springframework.util.Assert;
+
+/**
+ * A conversion executor that doesn't resolve its converter until its time to perform a conversion.
+ * @author Keith Donald
+ */
+public class RuntimeBindingConversionExecutor implements ConversionExecutor {
+
+	private Class targetClass;
+
+	private ConversionService conversionService;
+
+	/**
+	 * Creates a new runtime binding conversion executor.
+	 * @param targetClass the target type to convert to
+	 * @param conversionService the conversion service to get converters from
+	 */
+	public RuntimeBindingConversionExecutor(Class targetClass, ConversionService conversionService) {
+		Assert.notNull(targetClass, "The target class of the conversion is required");
+		Assert.notNull(conversionService, "The conversion service is required");
+		this.targetClass = targetClass;
+		this.conversionService = conversionService;
+	}
+
+	public Class getSourceClass() {
+		return null;
+	}
+
+	public Class getTargetClass() {
+		return targetClass;
+	}
+
+	public boolean equals(Object obj) {
+		if (!(obj instanceof RuntimeBindingConversionExecutor)) {
+			return false;
+		}
+		RuntimeBindingConversionExecutor o = (RuntimeBindingConversionExecutor) obj;
+		return targetClass.equals(o.targetClass);
+	}
+
+	public int hashCode() {
+		return targetClass.hashCode();
+	}
+
+	public Object execute(Object source) throws ConversionException {
+		return execute(source, null);
+	}
+
+	public Object execute(Object source, ConversionContext context) throws ConversionException {
+		return conversionService.getConversionExecutor(source.getClass(), targetClass).execute(source);
+	}
+
+}

spring-binding/src/main/java/org/springframework/binding/mapping/Mapping.java

@@ -23,7 +23,7 @@ import org.springframework.core.style.ToStringCreator;
 import org.springframework.util.Assert;
 
 /**
- * A single mapping definition, encapulating the information neccessary to map the result of evaluating an expression on
+ * A single mapping definition, encapsulating the information necessary to map the result of evaluating an expression on
  * a source object to a property on a target object, optionally applying a type conversion during the mapping process.
  * 
  * @author Keith Donald
@@ -69,7 +69,7 @@ public class Mapping implements AttributeMapper {
 	 * @param typeConverter a type converter
 	 * @param required whether or not this mapping is required
 	 */
-	protected Mapping(Expression sourceExpression, Expression targetExpression, ConversionExecutor typeConverter,
+	public Mapping(Expression sourceExpression, Expression targetExpression, ConversionExecutor typeConverter,
 			boolean required) {
 		Assert.notNull(sourceExpression, "The source expression is required");
 		Assert.notNull(targetExpression, "The target expression is required");

spring-binding/src/main/java/org/springframework/binding/mapping/MappingBuilder.java

@@ -15,9 +15,10 @@
  */
 package org.springframework.binding.mapping;
 
-import org.springframework.binding.convert.ConversionExecutor;
 import org.springframework.binding.convert.ConversionService;
+import org.springframework.binding.convert.ConversionExecutor;
 import org.springframework.binding.convert.support.DefaultConversionService;
+import org.springframework.binding.convert.support.RuntimeBindingConversionExecutor;
 import org.springframework.binding.expression.Expression;
 import org.springframework.binding.expression.ExpressionParser;
 import org.springframework.binding.expression.support.CollectionAddingExpression;
@@ -166,16 +167,14 @@ public class MappingBuilder {
 			targetExpression = sourceExpression;
 		}
 		ConversionExecutor typeConverter = null;
-		if (sourceType != null) {
-			Assert.notNull(targetType, "The target type is required when the source type is specified");
-			typeConverter = conversionService.getConversionExecutor(sourceType, targetType);
-		}
-		Mapping result;
-		if (required) {
-			result = new RequiredMapping(sourceExpression, targetExpression, typeConverter);
-		} else {
-			result = new Mapping(sourceExpression, targetExpression, typeConverter);
+		if (targetType != null) {
+			if (sourceType != null) {
+				typeConverter = conversionService.getConversionExecutor(sourceType, targetType);
+			} else {
+				typeConverter = new RuntimeBindingConversionExecutor(targetType, conversionService);
+			}
 		}
+		Mapping result = new Mapping(sourceExpression, targetExpression, typeConverter, required);
 		reset();
 		return result;
 	}

spring-binding/src/main/java/org/springframework/binding/mapping/RequiredMapping.java

@@ -1,38 +0,0 @@
-/*
- * Copyright 2004-2007 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.binding.mapping;
-
-import org.springframework.binding.convert.ConversionExecutor;
-import org.springframework.binding.expression.Expression;
-
-/**
- * A mapping that is required.
- * 
- * @author Keith Donald
- */
-public class RequiredMapping extends Mapping {
-
-	/**
-	 * Creates a required mapping.
-	 * @param sourceExpression the source mapping expression
-	 * @param targetPropertyExpression the target property expression
-	 * @param typeConverter a type converter
-	 */
-	public RequiredMapping(Expression sourceExpression, Expression targetPropertyExpression,
-			ConversionExecutor typeConverter) {
-		super(sourceExpression, targetPropertyExpression, typeConverter, true);
-	}
-}