Call ConversionService for null SpEL values

Update SpEL boolean operators to always call the ConversionService
for null values. Primarily to allow null values to be treated as
false by overriding GenericConversionService.convertNullSource().

Issue: SPR-9445

spring-expression/src/main/java/org/springframework/expression/common/ExpressionUtils.java

 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -60,7 +60,7 @@ public abstract class ExpressionUtils {
 	@SuppressWarnings("unchecked")
 	public static <T> T convertTypedValue(EvaluationContext context, TypedValue typedValue, Class<T> targetType) {
 		Object value = typedValue.getValue();
-		if (targetType == null || ClassUtils.isAssignableValue(targetType, value)) {
+		if ((targetType == null) || (value != null && ClassUtils.isAssignableValue(targetType, value))) {
 			return (T) value;
 		}
 		if (context != null) {

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

 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -16,7 +16,6 @@
 
 package org.springframework.expression.spel.ast;
 
-import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.expression.EvaluationException;
 import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.ExpressionState;
@@ -29,6 +28,7 @@ import org.springframework.expression.spel.support.BooleanTypedValue;
  *
  * @author Andy Clement
  * @author Mark Fisher
+ * @author Oliver Becker
  * @since 3.0
  */
 public class OpAnd extends Operator {
@@ -39,38 +39,27 @@ public class OpAnd extends Operator {
 
 	@Override
 	public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
-		boolean leftValue;
-		boolean rightValue;
-
-		try {
-			TypedValue typedValue = getLeftOperand().getValueInternal(state);
-			this.assertTypedValueNotNull(typedValue);
-			leftValue = (Boolean)state.convertValue(typedValue, TypeDescriptor.valueOf(Boolean.class));
-		}
-		catch (SpelEvaluationException ee) {
-			ee.setPosition(getLeftOperand().getStartPosition());
-			throw ee;
-		}
-
-		if (leftValue == false) {
-			return BooleanTypedValue.forValue(false); // no need to evaluate right operand
+		if (getBooleanValue(state, getLeftOperand()) == false) {
+			// no need to evaluate right operand
+			return BooleanTypedValue.FALSE;
 		}
+		return BooleanTypedValue.forValue(getBooleanValue(state, getRightOperand()));
+	}
 
+	private boolean getBooleanValue(ExpressionState state, SpelNodeImpl operand) {
 		try {
-			TypedValue typedValue = getRightOperand().getValueInternal(state);
-			this.assertTypedValueNotNull(typedValue);
-			rightValue = (Boolean)state.convertValue(typedValue, TypeDescriptor.valueOf(Boolean.class));
+			Boolean value = operand.getValue(state, Boolean.class);
+			assertValueNotNull(value);
+			return value;
 		}
 		catch (SpelEvaluationException ee) {
-			ee.setPosition(getRightOperand().getStartPosition());
+			ee.setPosition(operand.getStartPosition());
 			throw ee;
 		}
-
-		return /* leftValue && */BooleanTypedValue.forValue(rightValue);
 	}
 
-	private void assertTypedValueNotNull(TypedValue typedValue) {
-		if (TypedValue.NULL.equals(typedValue)) {
+	private void assertValueNotNull(Boolean value) {
+		if (value == null) {
 			throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");
 		}
 	}

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

 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -16,9 +16,7 @@
 
 package org.springframework.expression.spel.ast;
 
-import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.expression.EvaluationException;
-import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.ExpressionState;
 import org.springframework.expression.spel.SpelEvaluationException;
 import org.springframework.expression.spel.SpelMessage;
@@ -29,6 +27,7 @@ import org.springframework.expression.spel.support.BooleanTypedValue;
  *
  * @author Andy Clement
  * @author Mark Fisher
+ * @author Oliver Becker
  * @since 3.0
  */
 public class OpOr extends Operator {
@@ -39,37 +38,27 @@ public class OpOr extends Operator {
 
 	@Override
 	public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException {
-		boolean leftValue;
-		boolean rightValue;
-		try {
-			TypedValue typedValue = getLeftOperand().getValueInternal(state);
-			this.assertTypedValueNotNull(typedValue);
-			leftValue = (Boolean)state.convertValue(typedValue, TypeDescriptor.valueOf(Boolean.class));
-		}
-		catch (SpelEvaluationException see) {
-			see.setPosition(getLeftOperand().getStartPosition());
-			throw see;
-		}
-
-		if (leftValue == true) {
-			return BooleanTypedValue.TRUE; // no need to evaluate right operand
+		if (getBooleanValue(state, getLeftOperand())) {
+			// no need to evaluate right operand
+			return BooleanTypedValue.TRUE;
 		}
+		return BooleanTypedValue.forValue(getBooleanValue(state, getRightOperand()));
+	}
 
+	private boolean getBooleanValue(ExpressionState state, SpelNodeImpl operand) {
 		try {
-			TypedValue typedValue = getRightOperand().getValueInternal(state);
-			this.assertTypedValueNotNull(typedValue);
-			rightValue = (Boolean)state.convertValue(typedValue, TypeDescriptor.valueOf(Boolean.class));
+			Boolean value = operand.getValue(state, Boolean.class);
+			assertValueNotNull(value);
+			return value;
 		}
-		catch (SpelEvaluationException see) {
-			see.setPosition(getRightOperand().getStartPosition()); // TODO end positions here and in similar situations
-			throw see;
+		catch (SpelEvaluationException ee) {
+			ee.setPosition(operand.getStartPosition());
+			throw ee;
 		}
-
-		return BooleanTypedValue.forValue(leftValue || rightValue);
 	}
 
-	private void assertTypedValueNotNull(TypedValue typedValue) {
-		if (TypedValue.NULL.equals(typedValue)) {
+	private void assertValueNotNull(Boolean value) {
+		if (value == null) {
 			throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");
 		}
 	}

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

 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -16,9 +16,7 @@
 
 package org.springframework.expression.spel.ast;
 
-import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.expression.EvaluationException;
-import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.ExpressionState;
 import org.springframework.expression.spel.SpelEvaluationException;
 import org.springframework.expression.spel.SpelMessage;
@@ -29,6 +27,7 @@ import org.springframework.expression.spel.support.BooleanTypedValue;
  *
  * @author Andy Clement
  * @author Mark Fisher
+ * @author Oliver Becker
  * @since 3.0
  */
 public class OperatorNot extends SpelNodeImpl { // Not is a unary operator so do not extend BinaryOperator
@@ -40,11 +39,10 @@ public class OperatorNot extends SpelNodeImpl { // Not is a unary operator so do
 	@Override
 	public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException {
 		try {
-			TypedValue typedValue = children[0].getValueInternal(state);
-			if (TypedValue.NULL.equals(typedValue)) {
+			Boolean value = children[0].getValue(state, Boolean.class);
+			if (value == null) {
 				throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");
 			}
-			boolean value = (Boolean) state.convertValue(typedValue, TypeDescriptor.valueOf(Boolean.class));
 			return BooleanTypedValue.forValue(!value);
 		}
 		catch (SpelEvaluationException see) {

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

@@ -130,18 +130,8 @@ public abstract class SpelNodeImpl implements SpelNode {
 		return (obj instanceof Class ? ((Class<?>) obj) : obj.getClass());
 	}
 
-	@SuppressWarnings("unchecked")
 	protected final <T> T getValue(ExpressionState state, Class<T> desiredReturnType) throws EvaluationException {
-		Object result = getValueInternal(state).getValue();
-		if (result != null && desiredReturnType != null) {
-			Class<?> resultType = result.getClass();
-			if (desiredReturnType.isAssignableFrom(resultType)) {
-				return (T) result;
-			}
-			// Attempt conversion to the requested type, may throw an exception
-			return ExpressionUtils.convert(state.getEvaluationContext(), result, desiredReturnType);
-		}
-		return (T) result;
+		return ExpressionUtils.convertTypedValue(state.getEvaluationContext(), getValueInternal(state), desiredReturnType);
 	}
 
 	public abstract TypedValue getValueInternal(ExpressionState expressionState) throws EvaluationException;

spring-expression/src/test/java/org/springframework/expression/spel/BooleanExpressionTests.java

 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -17,11 +17,15 @@
 package org.springframework.expression.spel;
 
 import org.junit.Test;
+import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.core.convert.support.GenericConversionService;
+import org.springframework.expression.spel.support.StandardTypeConverter;
 
 /**
  * Tests the evaluation of real boolean expressions, these use AND, OR, NOT, TRUE, FALSE
- * 
+ *
  * @author Andy Clement
+ * @author Oliver Becker
  */
 public class BooleanExpressionTests extends ExpressionTestCase {
 
@@ -83,4 +87,27 @@ public class BooleanExpressionTests extends ExpressionTestCase {
 		evaluateAndCheckError("!35.2", SpelMessage.TYPE_CONVERSION_ERROR, 1);
 		evaluateAndCheckError("! 'foob'", SpelMessage.TYPE_CONVERSION_ERROR, 2);
 	}
+
+	@Test
+	public void testConvertAndHandleNull() { // SPR-9445
+		// without null conversion
+		evaluateAndCheckError("null or true", SpelMessage.TYPE_CONVERSION_ERROR, 0, "null", "boolean");
+		evaluateAndCheckError("null and true", SpelMessage.TYPE_CONVERSION_ERROR, 0, "null", "boolean");
+		evaluateAndCheckError("!null", SpelMessage.TYPE_CONVERSION_ERROR, 1, "null", "boolean");
+		evaluateAndCheckError("null ? 'foo' : 'bar'", SpelMessage.TYPE_CONVERSION_ERROR, 0, "null", "boolean");
+
+		// with null conversion (null -> false)
+		GenericConversionService conversionService = new GenericConversionService() {
+			@Override
+			protected Object convertNullSource(TypeDescriptor sourceType, TypeDescriptor targetType) {
+				return targetType.getType() == Boolean.class ? false : null;
+			}
+		};
+		eContext.setTypeConverter(new StandardTypeConverter(conversionService));
+
+		evaluate("null or true", Boolean.TRUE, Boolean.class, false);
+		evaluate("null and true", Boolean.FALSE, Boolean.class, false);
+		evaluate("!null", Boolean.TRUE, Boolean.class, false);
+		evaluate("null ? 'foo' : 'bar'", "bar", String.class, false);
+	}
 }

spring-expression/src/test/java/org/springframework/expression/spel/ExpressionTestCase.java

 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -40,8 +40,8 @@ public abstract class ExpressionTestCase {
 	protected final static boolean SHOULD_BE_WRITABLE = true;
 	protected final static boolean SHOULD_NOT_BE_WRITABLE = false;
 
-	protected final static ExpressionParser parser = new SpelExpressionParser();
-	protected final static StandardEvaluationContext eContext = TestScenarioCreator.getTestEvaluationContext();
+	protected final ExpressionParser parser = new SpelExpressionParser();
+	protected final StandardEvaluationContext eContext = TestScenarioCreator.getTestEvaluationContext();
 
 	/**
 	 * Evaluate an expression and check that the actual result matches the expectedValue and the class of the result