ExpressionState.getConfiguration() should never return null

Issue: SPR-11031
(cherry picked from commit 4aab315)

Author: jhoeller

spring-expression/src/main/java/org/springframework/expression/spel/ExpressionState.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 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.
@@ -30,14 +30,18 @@
 import org.springframework.expression.TypeComparator;
 import org.springframework.expression.TypeConverter;
 import org.springframework.expression.TypedValue;
+import org.springframework.util.Assert;
 
 /**
- * An ExpressionState is for maintaining per-expression-evaluation state, any changes to it are not seen by other
- * expressions but it gives a place to hold local variables and for component expressions in a compound expression to
- * communicate state. This is in contrast to the EvaluationContext, which is shared amongst expression evaluations, and
- * any changes to it will be seen by other expressions or any code that chooses to ask questions of the context.
+ * An ExpressionState is for maintaining per-expression-evaluation state, any changes to
+ * it are not seen by other expressions but it gives a place to hold local variables and
+ * for component expressions in a compound expression to communicate state. This is in
+ * contrast to the EvaluationContext, which is shared amongst expression evaluations, and
+ * any changes to it will be seen by other expressions or any code that chooses to ask
+ * questions of the context.
  *
- * <p>It also acts as a place for to define common utility routines that the various Ast nodes might need.
+ * <p>It also acts as a place for to define common utility routines that the various AST
+ * nodes might need.
  *
  * @author Andy Clement
  * @since 3.0
@@ -46,35 +50,33 @@ public class ExpressionState {
 
 	private final EvaluationContext relatedContext;
 
-	private Stack<VariableScope> variableScopes;
+	private final TypedValue rootObject;
 
-	private Stack<TypedValue> contextObjects;
+	private final SpelParserConfiguration configuration;
 
-	private final TypedValue rootObject;
+	private Stack<VariableScope> variableScopes;
 
-	private SpelParserConfiguration configuration;
+	private Stack<TypedValue> contextObjects;
 
 
 	public ExpressionState(EvaluationContext context) {
-		this.relatedContext = context;
-		this.rootObject = context.getRootObject();
+		this(context, context.getRootObject(), new SpelParserConfiguration(false, false));
 	}
 
 	public ExpressionState(EvaluationContext context, SpelParserConfiguration configuration) {
-		this.relatedContext = context;
-		this.configuration = configuration;
-		this.rootObject = context.getRootObject();
+		this(context, context.getRootObject(), configuration);
 	}
 
 	public ExpressionState(EvaluationContext context, TypedValue rootObject) {
-		this.relatedContext = context;
-		this.rootObject = rootObject;
+		this(context, rootObject, new SpelParserConfiguration(false, false));
 	}
 
 	public ExpressionState(EvaluationContext context, TypedValue rootObject, SpelParserConfiguration configuration) {
+		Assert.notNull(context, "EvaluationContext must not be null");
+		Assert.notNull(configuration, "SpelParserConfiguration must not be null");
 		this.relatedContext = context;
-		this.configuration = configuration;
 		this.rootObject = rootObject;
+		this.configuration = configuration;
 	}
 
 
@@ -90,23 +92,22 @@ private void ensureVariableScopesInitialized() {
 	 * The active context object is what unqualified references to properties/etc are resolved against.
 	 */
 	public TypedValue getActiveContextObject() {
-		if (this.contextObjects==null || this.contextObjects.isEmpty()) {
+		if (this.contextObjects == null || this.contextObjects.isEmpty()) {
 			return this.rootObject;
 		}
-
 		return this.contextObjects.peek();
 	}
 
 	public void pushActiveContextObject(TypedValue obj) {
-		if (this.contextObjects==null) {
-			this.contextObjects =  new Stack<TypedValue>();
+		if (this.contextObjects == null) {
+			this.contextObjects = new Stack<TypedValue>();
 		}
 		this.contextObjects.push(obj);
 	}
 
 	public void popActiveContextObject() {
-		if (this.contextObjects==null) {
-			this.contextObjects =  new Stack<TypedValue>();
+		if (this.contextObjects == null) {
+			this.contextObjects = new Stack<TypedValue>();
 		}
 		this.contextObjects.pop();
 	}
@@ -138,7 +139,8 @@ public Class<?> findType(String type) throws EvaluationException {
 	}
 
 	public Object convertValue(Object value, TypeDescriptor targetTypeDescriptor) throws EvaluationException {
-		return this.relatedContext.getTypeConverter().convertValue(value, TypeDescriptor.forObject(value), targetTypeDescriptor);
+		return this.relatedContext.getTypeConverter().convertValue(value,
+				TypeDescriptor.forObject(value), targetTypeDescriptor);
 	}
 
 	public TypeConverter getTypeConverter() {
@@ -151,9 +153,8 @@ public Object convertValue(TypedValue value, TypeDescriptor targetTypeDescriptor
 	}
 
 	/*
-	 * A new scope is entered when a function is invoked
+	 * A new scope is entered when a function is invoked.
 	 */
-
 	public void enterScope(Map<String, Object> argMap) {
 		ensureVariableScopesInitialized();
 		this.variableScopes.push(new VariableScope(argMap));
@@ -192,8 +193,8 @@ public TypedValue operate(Operation op, Object left, Object right) throws Evalua
 			return new TypedValue(returnValue);
 		}
 		else {
-			String leftType = (left==null?"null":left.getClass().getName());
-			String rightType = (right==null?"null":right.getClass().getName());
+			String leftType = (left == null ? "null" : left.getClass().getName());
+			String rightType = (right == null? "null" : right.getClass().getName());
 			throw new SpelEvaluationException(SpelMessage.OPERATOR_NOT_SUPPORTED_BETWEEN_TYPES, op, leftType, rightType);
 		}
 	}
@@ -210,16 +211,20 @@ public SpelParserConfiguration getConfiguration() {
 		return this.configuration;
 	}
 
+
 	/**
-	 * A new scope is entered when a function is called and it is used to hold the parameters to the function call.  If the names
-	 * of the parameters clash with those in a higher level scope, those in the higher level scope will not be accessible whilst
-	 * the function is executing.  When the function returns the scope is exited.
+	 * A new scope is entered when a function is called and it is used to hold the
+	 * parameters to the function call. If the names of the parameters clash with
+	 * those in a higher level scope, those in the higher level scope will not be
+	 * accessible whilst the function is executing. When the function returns,
+	 * the scope is exited.
 	 */
 	private static class VariableScope {
 
 		private final Map<String, Object> vars = new HashMap<String, Object>();
 
-		public VariableScope() { }
+		public VariableScope() {
+		}
 
 		public VariableScope(Map<String, Object> arguments) {
 			if (arguments != null) {

spring-expression/src/main/java/org/springframework/expression/spel/SpelParserConfiguration.java

@@ -49,8 +49,7 @@ public SpelParserConfiguration(boolean autoGrowNullReferences, boolean autoGrowC
 	 * @param autoGrowCollections if collections should automatically grow
 	 * @param maximumAutoGrowSize the maximum size that the collection can auto grow
 	 */
-	public SpelParserConfiguration(boolean autoGrowNullReferences,
-			boolean autoGrowCollections, int maximumAutoGrowSize) {
+	public SpelParserConfiguration(boolean autoGrowNullReferences, boolean autoGrowCollections, int maximumAutoGrowSize) {
 		this.autoGrowNullReferences = autoGrowNullReferences;
 		this.autoGrowCollections = autoGrowCollections;
 		this.maximumAutoGrowSize = maximumAutoGrowSize;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 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.
@@ -67,47 +67,20 @@ public String getName() {
 	}
 
 
-	static class AccessorLValue implements ValueRef {
-		private PropertyOrFieldReference ref;
-		private TypedValue contextObject;
-		private EvaluationContext eContext;
-		private boolean isAutoGrowNullReferences;
-
-		public AccessorLValue(
-				PropertyOrFieldReference propertyOrFieldReference,
-				TypedValue activeContextObject,
-				EvaluationContext evaluationContext, boolean isAutoGrowNullReferences) {
-			this.ref = propertyOrFieldReference;
-			this.contextObject = activeContextObject;
-			this.eContext =evaluationContext;
-			this.isAutoGrowNullReferences = isAutoGrowNullReferences;
-		}
-
-		public TypedValue getValue() {
-			return ref.getValueInternal(contextObject,eContext,isAutoGrowNullReferences);
-		}
-
-		public void setValue(Object newValue) {
-			ref.writeProperty(contextObject,eContext, ref.name, newValue);
-		}
-
-		public boolean isWritable() {
-			return true;
-		}
-
-	}
-
 	@Override
 	public ValueRef getValueRef(ExpressionState state) throws EvaluationException {
-		return new AccessorLValue(this,state.getActiveContextObject(),state.getEvaluationContext(),state.getConfiguration().isAutoGrowNullReferences());
+		return new AccessorLValue(this, state.getActiveContextObject(), state.getEvaluationContext(),
+				state.getConfiguration().isAutoGrowNullReferences());
 	}
 
 	@Override
 	public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
-		return getValueInternal(state.getActiveContextObject(), state.getEvaluationContext(), state.getConfiguration().isAutoGrowNullReferences());
+		return getValueInternal(state.getActiveContextObject(), state.getEvaluationContext(),
+				state.getConfiguration().isAutoGrowNullReferences());
 	}
 
-	private TypedValue getValueInternal(TypedValue contextObject, EvaluationContext eContext, boolean isAutoGrowNullReferences) throws EvaluationException {
+	private TypedValue getValueInternal(TypedValue contextObject, EvaluationContext eContext,
+			boolean isAutoGrowNullReferences) throws EvaluationException {
 
 		TypedValue result = readProperty(contextObject, eContext, this.name);
 
@@ -139,7 +112,7 @@ private TypedValue getValueInternal(TypedValue contextObject, EvaluationContext
 					try {
 						if (isWritableProperty(this.name,contextObject,eContext)) {
 							Map<?,?> newMap = HashMap.class.newInstance();
-							writeProperty(contextObject, eContext, name, newMap);
+							writeProperty(contextObject, eContext, this.name, newMap);
 							result = readProperty(contextObject, eContext, this.name);
 						}
 					}
@@ -158,7 +131,7 @@ private TypedValue getValueInternal(TypedValue contextObject, EvaluationContext
 				try {
 					if (isWritableProperty(this.name,contextObject,eContext)) {
 						Object newObject  = result.getTypeDescriptor().getType().newInstance();
-						writeProperty(contextObject, eContext, name, newObject);
+						writeProperty(contextObject, eContext, this.name, newObject);
 						result = readProperty(contextObject, eContext, this.name);
 					}
 				}
@@ -192,14 +165,11 @@ public String toStringAST() {
 
 	/**
 	 * Attempt to read the named property from the current context object.
-	 * @param state the evaluation state
-	 * @param name the name of the property
 	 * @return the value of the property
 	 * @throws SpelEvaluationException if any problem accessing the property or it cannot be found
 	 */
 	private TypedValue readProperty(TypedValue contextObject, EvaluationContext eContext, String name) throws EvaluationException {
 		Object targetObject = contextObject.getValue();
-
 		if (targetObject == null && this.nullSafe) {
 			return TypedValue.NULL;
 		}
@@ -249,8 +219,7 @@ private TypedValue readProperty(TypedValue contextObject, EvaluationContext eCon
 	}
 
 	private void writeProperty(TypedValue contextObject, EvaluationContext eContext, String name, Object newValue) throws SpelEvaluationException {
-
-		if (contextObject.getValue() == null && nullSafe) {
+		if (contextObject.getValue() == null && this.nullSafe) {
 			return;
 		}
 
@@ -353,4 +322,39 @@ else if (clazz.isAssignableFrom(targetType)) {
 		return resolvers;
 	}
 
+
+	private static class AccessorLValue implements ValueRef {
+
+		private final PropertyOrFieldReference ref;
+
+		private final TypedValue contextObject;
+
+		private final EvaluationContext eContext;
+
+		private final boolean autoGrowNullReferences;
+
+		public AccessorLValue(PropertyOrFieldReference propertyOrFieldReference, TypedValue activeContextObject,
+				EvaluationContext evaluationContext, boolean autoGrowNullReferences) {
+			this.ref = propertyOrFieldReference;
+			this.contextObject = activeContextObject;
+			this.eContext = evaluationContext;
+			this.autoGrowNullReferences = autoGrowNullReferences;
+		}
+
+		@Override
+		public TypedValue getValue() {
+			return this.ref.getValueInternal(this.contextObject, this.eContext, this.autoGrowNullReferences);
+		}
+
+		@Override
+		public void setValue(Object newValue) {
+			this.ref.writeProperty(this.contextObject, this.eContext, this.ref.name, newValue);
+		}
+
+		@Override
+		public boolean isWritable() {
+			return true;
+		}
+	}
+
 }