SPR-6230: SpEL improvements

Author: aclement

org.springframework.expression/src/main/java/org/springframework/expression/EvaluationContext.java

@@ -33,7 +33,7 @@
 public interface EvaluationContext {
 
 	/**
-	 * @return the root context object against which unqualified properties/methods/etc should be resolved
+	 * @return the default root context object against which unqualified properties/methods/etc should be resolved.  This can be overridden when evaluating an expression.
 	 */
 	TypedValue getRootObject();
 

org.springframework.expression/src/main/java/org/springframework/expression/Expression.java

@@ -36,15 +36,36 @@ public interface Expression {
 	 */
 	public Object getValue() throws EvaluationException;
 
+	/** 
+	 * Evaluate this expression against the specified root object
+	 * 
+	 * @param rootObject the root object against which properties/etc will be resolved
+	 * @return the evaluation result
+	 * @throws EvaluationException if there is a problem during evaluation
+	 */
+	public Object getValue(Object rootObject) throws EvaluationException;
+	
 	/**
-	 * Evaluate the expression in the default standard context. If the result of the evaluation does not match (and
+	 * Evaluate the expression in the default context. If the result of the evaluation does not match (and
 	 * cannot be converted to) the expected result type then an exception will be returned.
 	 * 
 	 * @param desiredResultType the class the caller would like the result to be
 	 * @return the evaluation result
 	 * @throws EvaluationException if there is a problem during evaluation
 	 */
 	public <T> T getValue(Class<T> desiredResultType) throws EvaluationException;
+	
+	/**
+	 * Evaluate the expression in the default context against the specified root object. If the 
+	 * result of the evaluation does not match (and cannot be converted to) the expected result type 
+	 * then an exception will be returned.
+	 * 
+	 * @param rootObject the root object against which properties/etc will be resolved
+	 * @param desiredResultType the class the caller would like the result to be
+	 * @return the evaluation result
+	 * @throws EvaluationException if there is a problem during evaluation
+	 */
+	public <T> T getValue(Object rootObject, Class<T> desiredResultType) throws EvaluationException;
 
 	/**
 	 * Evaluate this expression in the provided context and return the result of evaluation.
@@ -55,6 +76,17 @@ public interface Expression {
 	 */
 	public Object getValue(EvaluationContext context) throws EvaluationException;
 
+	/**
+	 * Evaluate this expression in the provided context and return the result of evaluation, but use
+	 * the supplied root context as an override for any default root object specified in the context.
+	 * 
+	 * @param context the context in which to evaluate the expression
+	 * @param rootObject the root object against which properties/etc will be resolved
+	 * @return the evaluation result
+	 * @throws EvaluationException if there is a problem during evaluation
+	 */
+	public Object getValue(EvaluationContext context, Object rootObject) throws EvaluationException;
+	
 	/**
 	 * Evaluate the expression in a specified context which can resolve references to properties, methods, types, etc -
 	 * the type of the evaluation result is expected to be of a particular class and an exception will be thrown if it
@@ -67,6 +99,20 @@ public interface Expression {
 	 */
 	public <T> T getValue(EvaluationContext context, Class<T> desiredResultType) throws EvaluationException;
 
+	/**
+	 * Evaluate the expression in a specified context which can resolve references to properties, methods, types, etc -
+	 * the type of the evaluation result is expected to be of a particular class and an exception will be thrown if it
+	 * is not and cannot be converted to that type.  The supplied root object overrides any default specified on the
+	 * supplied context.
+	 * 
+	 * @param context the context in which to evaluate the expression
+	 * @param rootObject the root object against which properties/etc will be resolved
+	 * @param desiredResultType the class the caller would like the result to be
+	 * @return the evaluation result
+	 * @throws EvaluationException if there is a problem during evaluation
+	 */
+	public <T> T getValue(EvaluationContext context, Object rootObject, Class<T> desiredResultType) throws EvaluationException;
+
 	/**
 	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method using
 	 * the default context.
@@ -76,6 +122,16 @@ public interface Expression {
 	 */
 	public Class getValueType() throws EvaluationException;
 
+	/**
+	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method using
+	 * the default context.
+	 * 
+	 * @param rootObject the root object against which to evaluate the expression
+	 * @return the most general type of value that can be set on this context
+	 * @throws EvaluationException if there is a problem determining the type
+	 */
+	public Class getValueType(Object rootObject) throws EvaluationException;
+
 	/**
 	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method for
 	 * the given context.
@@ -85,6 +141,17 @@ public interface Expression {
 	 * @throws EvaluationException if there is a problem determining the type
 	 */
 	public Class getValueType(EvaluationContext context) throws EvaluationException;
+	
+	/**
+	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method for
+	 * the given context.  The supplied root object overrides any specified in the context.
+	 * 
+	 * @param context the context in which to evaluate the expression
+	 * @param rootObject the root object against which to evaluate the expression
+	 * @return the most general type of value that can be set on this context
+	 * @throws EvaluationException if there is a problem determining the type
+	 */
+	public Class getValueType(EvaluationContext context, Object rootObject) throws EvaluationException;
 
 	/**
 	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method using
@@ -94,6 +161,16 @@ public interface Expression {
 	 * @throws EvaluationException if there is a problem determining the type
 	 */
 	public TypeDescriptor getValueTypeDescriptor() throws EvaluationException;
+	
+	/**
+	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method using
+	 * the default context.
+	 * 
+	 * @param rootObject the root object against which to evaluate the expression
+	 * @return a type descriptor for the most general type of value that can be set on this context
+	 * @throws EvaluationException if there is a problem determining the type
+	 */
+	public TypeDescriptor getValueTypeDescriptor(Object rootObject) throws EvaluationException;
 
 	/**
 	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method for
@@ -105,6 +182,17 @@ public interface Expression {
 	 */
 	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) throws EvaluationException;
 
+	/**
+	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method for
+	 * the given context. The supplied root object overrides any specified in the context.
+	 * 
+	 * @param context the context in which to evaluate the expression
+	 * @param rootObject the root object against which to evaluate the expression
+	 * @return a type descriptor for the most general type of value that can be set on this context
+	 * @throws EvaluationException if there is a problem determining the type
+	 */
+	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, Object rootObject) throws EvaluationException;
+
 	/**
 	 * Determine if an expression can be written to, i.e. setValue() can be called.
 	 * 
@@ -113,7 +201,27 @@ public interface Expression {
 	 * @throws EvaluationException if there is a problem determining if it is writable
 	 */
 	public boolean isWritable(EvaluationContext context) throws EvaluationException;
-	
+
+	/**
+	 * Determine if an expression can be written to, i.e. setValue() can be called.
+	 * The supplied root object overrides any specified in the context.
+	 * 
+	 * @param context the context in which the expression should be checked
+	 * @param rootObject the root object against which to evaluate the expression
+	 * @return true if the expression is writable
+	 * @throws EvaluationException if there is a problem determining if it is writable
+	 */
+	public boolean isWritable(EvaluationContext context, Object rootObject) throws EvaluationException;
+
+	/**
+	 * Determine if an expression can be written to, i.e. setValue() can be called.
+	 * 
+	 * @param rootObject the root object against which to evaluate the expression
+	 * @return true if the expression is writable
+	 * @throws EvaluationException if there is a problem determining if it is writable
+	 */
+	public boolean isWritable(Object rootObject) throws EvaluationException;
+
 	/**
 	 * Set this expression in the provided context to the value provided.
 	 * 
@@ -122,7 +230,27 @@ public interface Expression {
 	 * @throws EvaluationException if there is a problem during evaluation
 	 */
 	public void setValue(EvaluationContext context, Object value) throws EvaluationException;
+	
+	/**
+	 * Set this expression in the provided context to the value provided.
+	 * 
+	 * @param rootObject the root object against which to evaluate the expression
+	 * @param value the new value
+	 * @throws EvaluationException if there is a problem during evaluation
+	 */
+	public void setValue(Object rootObject, Object value) throws EvaluationException;
 
+	/**
+	 * Set this expression in the provided context to the value provided.
+	 * The supplied root object overrides any specified in the context.
+	 * 
+	 * @param context the context in which to set the value of the expression
+	 * @param rootObject the root object against which to evaluate the expression
+	 * @param value the new value
+	 * @throws EvaluationException if there is a problem during evaluation
+	 */
+	public void setValue(EvaluationContext context, Object rootObject, Object value) throws EvaluationException;
+	
 	/**
 	 * Returns the original string used to create this expression, unmodified.
 	 * 

org.springframework.expression/src/main/java/org/springframework/expression/ExpressionException.java

@@ -23,7 +23,7 @@
  * @author Andy Clement
  * @since 3.0
  */
-public class ExpressionException extends Exception {
+public class ExpressionException extends RuntimeException {
 
 	protected String expressionString;
 	protected int position; // -1 if not known - but should be known in all reasonable cases

org.springframework.expression/src/main/java/org/springframework/expression/PropertyAccessor.java

@@ -25,11 +25,6 @@
  * to determine if it can read or write them. Property resolvers are considered to be ordered and each will be called in
  * turn. The only rule that affects the call order is that any naming the target class directly in
  * getSpecifiedTargetClasses() will be called first, before the general resolvers.
- *
- * <p>If the cost of locating the property is expensive, in relation to actually retrieving its value, consider extending
- * CacheablePropertyAccessor rather than directly implementing PropertyAccessor. A CacheablePropertyAccessor enables the
- * discovery (resolution) of the property to be done once and then an object (an executor) returned and cached by the
- * infrastructure that can be used repeatedly to retrieve the property value.
  * 
  * @author Andy Clement
  * @since 3.0

org.springframework.expression/src/main/java/org/springframework/expression/TypedValue.java

@@ -33,7 +33,7 @@ public class TypedValue {
 
 	private final Object value;
 
-	private final TypeDescriptor typeDescriptor;
+	private TypeDescriptor typeDescriptor;
 
 
 	/**
@@ -43,7 +43,7 @@ public class TypedValue {
 	 */
 	public TypedValue(Object value) {
 		this.value = value;
-		this.typeDescriptor = TypeDescriptor.forObject(value);
+		this.typeDescriptor = null;// initialized when/if requested
 	}
 
 	/**
@@ -62,6 +62,9 @@ public Object getValue() {
 	}
 
 	public TypeDescriptor getTypeDescriptor() {
+		if (this.typeDescriptor==null) {
+			this.typeDescriptor = TypeDescriptor.forObject(value);
+		}
 		return this.typeDescriptor;
 	}
 

org.springframework.expression/src/main/java/org/springframework/expression/common/CompositeStringExpression.java

@@ -70,6 +70,15 @@ public String getValue(EvaluationContext context) throws EvaluationException {
 		}
 		return sb.toString();
 	}
+	
+	public String getValue(Object rootObject) throws EvaluationException {
+		StringBuilder sb = new StringBuilder();
+		for (Expression expression : this.expressions) {
+			sb.append(ObjectUtils.getDisplayString(expression.getValue(rootObject)));
+		}
+		return sb.toString();
+	}
+
 
 	public Class getValueType(EvaluationContext context) {
 		return String.class;
@@ -109,4 +118,57 @@ public Expression[] getExpressions() {
 		return expressions;
 	}
 
+
+	public <T> T getValue(Object rootObject, Class<T> desiredResultType) throws EvaluationException {
+		Object value = getValue(rootObject);
+		return ExpressionUtils.convert(null, value, desiredResultType);
+	}
+
+	public String getValue(EvaluationContext context, Object rootObject) throws EvaluationException {
+		StringBuilder sb = new StringBuilder();
+		for (Expression expression : this.expressions) {
+			sb.append(ObjectUtils.getDisplayString(expression.getValue(context,rootObject)));
+		}
+		return sb.toString();
+	}
+
+	public <T> T getValue(EvaluationContext context, Object rootObject, Class<T> desiredResultType)
+			throws EvaluationException {
+		Object value = getValue(context,rootObject);
+		return ExpressionUtils.convert(context, value, desiredResultType);
+	}
+
+	public Class getValueType(Object rootObject) throws EvaluationException {
+		return String.class;
+	}
+
+	public Class getValueType(EvaluationContext context, Object rootObject) throws EvaluationException {
+		return String.class;
+	}
+
+	public TypeDescriptor getValueTypeDescriptor(Object rootObject) throws EvaluationException {
+		return TypeDescriptor.valueOf(String.class);
+	}
+
+	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, Object rootObject)
+			throws EvaluationException {
+		return TypeDescriptor.valueOf(String.class);
+	}
+
+	public boolean isWritable(EvaluationContext context, Object rootObject) throws EvaluationException {
+		return false;
+	}
+
+	public void setValue(EvaluationContext context, Object rootObject, Object value) throws EvaluationException {
+		throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
+	}
+
+	public boolean isWritable(Object rootObject) throws EvaluationException {
+		return false;
+	}
+
+	public void setValue(Object rootObject, Object value) throws EvaluationException {
+		throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
+	}
+
 }