updates for Binding code - able to retrieve the type descriptor for a property and ask detailed questions (eg getAnnotations())

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

@@ -16,6 +16,8 @@
 
 package org.springframework.expression;
 
+import org.springframework.core.convert.TypeDescriptor;
+
 /**
  * An expression capable of evaluating itself against context objects. Encapsulates the details of a previously parsed
  * expression string. Provides a common abstraction for expression evaluation independent of any language like OGNL or
@@ -94,6 +96,26 @@ public interface Expression {
 	 */
 	public Class getValueType() throws EvaluationException;
 
+	/**
+	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method for
+	 * the given context.
+	 * 
+	 * @param context the context in 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) throws EvaluationException;
+
+	/**
+	 * Returns the most general type that can be passed to the {@link #setValue(EvaluationContext, Object)} method using
+	 * the default context.
+	 * 
+	 * @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() throws EvaluationException;
+
+	
 	/**
 	 * Returns the original string used to create this expression, unmodified.
 	 * 

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

@@ -16,6 +16,7 @@
 
 package org.springframework.expression.common;
 
+import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.EvaluationException;
 import org.springframework.expression.Expression;
@@ -78,6 +79,14 @@ public class CompositeStringExpression implements Expression {
 		return String.class;
 	}
 
+	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) {
+		return TypeDescriptor.valueOf(String.class);
+	}
+
+	public TypeDescriptor getValueTypeDescriptor() {
+		return TypeDescriptor.valueOf(String.class);
+	}
+
 	public void setValue(EvaluationContext context, Object value) throws EvaluationException {
 		throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
 	}

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

@@ -16,6 +16,7 @@
 
 package org.springframework.expression.common;
 
+import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.EvaluationException;
 import org.springframework.expression.Expression;
@@ -55,6 +56,14 @@ public class LiteralExpression implements Expression {
 		return String.class;
 	}
 
+	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) {
+		return TypeDescriptor.valueOf(String.class);
+	}
+
+	public TypeDescriptor getValueTypeDescriptor() {
+		return TypeDescriptor.valueOf(String.class);
+	}
+
 	public void setValue(EvaluationContext context, Object value) throws EvaluationException {
 		throw new EvaluationException(literalValue, "Cannot call setValue() on a LiteralExpression");
 	}

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

@@ -15,10 +15,12 @@
  */
 package org.springframework.expression.spel;
 
+import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.EvaluationException;
 import org.springframework.expression.Expression;
 import org.springframework.expression.common.ExpressionUtils;
+import org.springframework.expression.spel.ast.SpelNodeImpl;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
 
 /**
@@ -33,13 +35,13 @@ public class SpelExpression implements Expression {
 	
 	private final String expression;
 
-	public final SpelNode ast;
+	public final SpelNodeImpl ast;
 
 
 	/**
 	 * Construct an expression, only used by the parser.
 	 */
-	public SpelExpression(String expression, SpelNode ast) {
+	public SpelExpression(String expression, SpelNodeImpl ast) {
 		this.expression = expression;
 		this.ast = ast;
 	}
@@ -119,19 +121,35 @@ public class SpelExpression implements Expression {
 	 * {@inheritDoc}
 	 */
 	public Class getValueType(EvaluationContext context) throws EvaluationException {
-		// TODO both getValueType() methods could use getValueInternal and return a type descriptor from the resultant TypedValue
-		Object value = getValue(context);
-		return (value != null ? value.getClass() : null);
+		ExpressionState eState = new ExpressionState(context);
+		TypeDescriptor typeDescriptor = this.ast.getValueInternal(eState).getTypeDescriptor();
+		return typeDescriptor.getType();
 	}
 
+	/**
+	 * {@inheritDoc}
+	 */
+	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) throws EvaluationException {
+		ExpressionState eState = new ExpressionState(context);
+		TypeDescriptor typeDescriptor = this.ast.getValueInternal(eState).getTypeDescriptor();
+		return typeDescriptor;
+	}
+	
 	/**
 	 * {@inheritDoc}
 	 */
 	public Class getValueType() throws EvaluationException {
-		Object value = getValue();
-		return (value != null ? value.getClass() : null);
+		return this.ast.getValueInternal(new ExpressionState(new StandardEvaluationContext())).getTypeDescriptor().getType();
 	}
 
+	/**
+	 * {@inheritDoc}
+	 */
+	public TypeDescriptor getValueTypeDescriptor() throws EvaluationException {
+		return this.ast.getValueInternal(new ExpressionState(new StandardEvaluationContext())).getTypeDescriptor();
+	}
+
+	
 	/**
 	 * {@inheritDoc}
 	 */

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

@@ -24,7 +24,6 @@ import org.springframework.expression.ParserContext;
 import org.springframework.expression.common.TemplateAwareExpressionParser;
 import org.springframework.expression.spel.SpelExpression;
 import org.springframework.expression.spel.SpelMessages;
-import org.springframework.expression.spel.SpelNode;
 import org.springframework.expression.spel.SpelParseException;
 import org.springframework.expression.spel.ast.Assign;
 import org.springframework.expression.spel.ast.BooleanLiteral;
@@ -104,7 +103,7 @@ public class SpelExpressionParser extends TemplateAwareExpressionParser {
 			tokenStreamLength = tokenStream.size();
 			tokenStreamPointer = 0;
 			constructedNodes.clear();
-			SpelNode ast = eatExpression();
+			SpelNodeImpl ast = eatExpression();
 			if (moreTokens()) {
 				throw new SpelParseException(peekToken().startpos,SpelMessages.MORE_INPUT,toString(nextToken()));
 			}