for Keith and his binder: fault in support for maps (if attempt made to reference into null map) and for general objects, e.g. foo.bar if foo was null, attempt to dynamically build foo.

git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@1513 50f2f4bb-b051-0410-bef5-90022cba6387

org.springframework.expression/src/main/java/org/springframework/expression/spel/SpelMessage.java

@@ -90,7 +90,9 @@ public enum SpelMessage {
 	RUN_OUT_OF_ARGUMENTS(Kind.ERROR,1051,"Unexpected ran out of arguments"),//
 	UNABLE_TO_GROW_COLLECTION(Kind.ERROR,1052,"Unable to grow collection"),//
 	UNABLE_TO_GROW_COLLECTION_UNKNOWN_ELEMENT_TYPE(Kind.ERROR,1053,"Unable to grow collection: unable to determine list element type"),//
-	UNABLE_TO_CREATE_LIST_FOR_INDEXING(Kind.ERROR,1054,"Unable to create a List for the following indexer"),//
+	UNABLE_TO_CREATE_LIST_FOR_INDEXING(Kind.ERROR,1054,"Unable to dynamically create a List to replace a null value"),//
+	UNABLE_TO_CREATE_MAP_FOR_INDEXING(Kind.ERROR,1055,"Unable to dynamically create a Map to replace a null value"),//
+	UNABLE_TO_DYNAMICALLY_CREATE_OBJECT(Kind.ERROR,1056,"Unable to dynamically create instance of ''{0}'' to replace a null value"),//
 	;
 
 	private Kind kind;

org.springframework.expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java

@@ -69,7 +69,16 @@ public class Indexer extends SpelNodeImpl {
 		}
 
 		// Indexing into a Map
-		if (targetObject instanceof Map) {
+		if (targetObjectTypeDescriptor.isMap()) {
+			if (targetObject == null) {
+			    // Current decision: attempt to index into null map == exception and does not just return null
+				throw new SpelEvaluationException(getStartPosition(),SpelMessage.CANNOT_INDEX_INTO_NULL_VALUE);
+//				if (targetObjectTypeDescriptor.isMapEntryTypeKnown()) {
+//					return new TypedValue(null,TypeDescriptor.valueOf(targetObjectTypeDescriptor.getMapValueType()));
+//				} else {
+//					return new TypedValue(null,TypeDescriptor.NULL);				
+//				}
+			}
 			Object possiblyConvertedKey = index;
 			if (targetObjectTypeDescriptor.isMapEntryTypeKnown()) {
 				possiblyConvertedKey = state.convertValue(index,TypeDescriptor.valueOf(targetObjectTypeDescriptor.getMapKeyType()));

org.springframework.expression/src/main/java/org/springframework/expression/spel/ast/PropertyOrFieldReference.java

@@ -17,6 +17,7 @@
 package org.springframework.expression.spel.ast;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -56,18 +57,50 @@ public class PropertyOrFieldReference extends SpelNodeImpl {
 	@Override
 	public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
 		TypedValue result = readProperty(state, this.name);
-		if (result.getValue()==null && state.configuredToCreateCollection() && result.getTypeDescriptor().getType().equals(List.class) && nextChildIs(Indexer.class)) {
-			// Create a new list ready for the indexer
-			try {
-				if (isWritable(state)) {
-					List newList = ArrayList.class.newInstance();
-					writeProperty(state, name, newList);
-					result = readProperty(state, this.name);
+		TypeDescriptor resultDescriptor = result.getTypeDescriptor();
+		// Dynamically create the objects if the user has requested that optional behaviour
+		if (result.getValue()==null && state.configuredToCreateCollectionOrMap() && nextChildIs(Indexer.class,PropertyOrFieldReference.class)) {
+			// Creating lists and maps
+			if ((resultDescriptor.getType().equals(List.class) || resultDescriptor.getType().equals(Map.class))) {
+				// Create a new collection or map ready for the indexer
+				if (resultDescriptor.getType().equals(List.class)) {
+					try { 
+						if (isWritable(state)) {
+							List newList = ArrayList.class.newInstance();
+							writeProperty(state, name, newList);
+							result = readProperty(state, this.name);
+						}
+					} catch (InstantiationException e) {
+						throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.UNABLE_TO_CREATE_LIST_FOR_INDEXING);
+					} catch (IllegalAccessException e) {
+						throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.UNABLE_TO_CREATE_LIST_FOR_INDEXING);
+					}
+				} else {
+					try { 
+						if (isWritable(state)) {
+							Map newMap = HashMap.class.newInstance();
+							writeProperty(state, name, newMap);
+							result = readProperty(state, this.name);
+						}
+					} catch (InstantiationException e) {
+						throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.UNABLE_TO_CREATE_MAP_FOR_INDEXING);
+					} catch (IllegalAccessException e) {
+						throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.UNABLE_TO_CREATE_MAP_FOR_INDEXING);
+					}
 				}
-			} catch (InstantiationException e) {
-				throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.UNABLE_TO_CREATE_LIST_FOR_INDEXING);
-			} catch (IllegalAccessException e) {
-				throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.UNABLE_TO_CREATE_LIST_FOR_INDEXING);
+			} else {
+				// 'simple' object
+				try { 
+					if (isWritable(state)) {
+						Object newObject  = result.getTypeDescriptor().getType().newInstance();
+						writeProperty(state, name, newObject);
+						result = readProperty(state, this.name);
+					}
+				} catch (InstantiationException e) {
+					throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.UNABLE_TO_DYNAMICALLY_CREATE_OBJECT,result.getTypeDescriptor().getType());
+				} catch (IllegalAccessException e) {
+					throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.UNABLE_TO_DYNAMICALLY_CREATE_OBJECT,result.getTypeDescriptor().getType());
+				}				
 			}
 		}
 		return result;

org.springframework.expression/src/main/java/org/springframework/expression/spel/ast/SpelNodeImpl.java

@@ -62,12 +62,25 @@ public abstract class SpelNodeImpl implements SpelNode, CommonTypeDescriptors {
 		return result;
 	}
 	
-	protected boolean nextChildIs(Class clazz) {
+	/**
+     * @return true if the next child is one of the specified classes
+     */
+	protected boolean nextChildIs(Class... clazzes) {
 		if (parent!=null) {
 			SpelNodeImpl[] peers = parent.children;
 			for (int i=0,max=peers.length;i<max;i++) {
 				if (peers[i]==this) {
-					return (i+1)<max && peers[i+1].getClass().equals(clazz);
+					if ((i+1)>=max) {
+						return false;
+					} else {
+						Class clazz = peers[i+1].getClass();
+						for (Class desiredClazz: clazzes) {
+							if (clazz.equals(desiredClazz)) {
+								return true;
+							}
+						}
+						return false;
+					}
 				}
 			}
 		}

org.springframework.expression/src/main/java/org/springframework/expression/spel/standard/SpelExpressionParserConfiguration.java

@@ -24,7 +24,13 @@ package org.springframework.expression.spel.standard;
  */
 public interface SpelExpressionParserConfiguration {
 
-	static final int CreateListsOnAttemptToIndexIntoNull = 0x0001;
+	/**
+	 * This option applies to maps/collections and regular objects.  If the initial part of an expression evaluates to null and then an
+	 * attempt is made to resolve an index '[]' or property against it, and this option is set, then the relevant object will be constructed so that
+	 * the index/property resolution can proceed.
+	 */
+	static final int CreateObjectIfAttemptToReferenceNull = 0x0001;
+	
 	static final int GrowListsOnIndexBeyondSize   = 0x0002;
 	
 }