Nullability fine-tuning and related polishing

Issue: SPR-15720

Author: jhoeller

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

@@ -30,6 +30,12 @@
  */
 public interface Expression {
 
+	/**
+	 * Return the original string used to create this expression, unmodified.
+	 * @return the original expression string
+	 */
+	String getExpressionString();
+
 	/**
 	 * Evaluate this expression in the default standard context.
 	 * @return the evaluation result
@@ -39,23 +45,23 @@ public interface Expression {
 	Object getValue() throws EvaluationException;
 
 	/**
-	 * Evaluate this expression against the specified root object
-	 * @param rootObject the root object against which properties/etc will be resolved
+	 * 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
 	 */
 	@Nullable
-	Object getValue(Object rootObject) throws EvaluationException;
+	<T> T getValue(@Nullable Class<T> desiredResultType) throws EvaluationException;
 
 	/**
-	 * 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
+	 * 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
 	 */
 	@Nullable
-	<T> T getValue(@Nullable Class<T> desiredResultType) throws EvaluationException;
+	Object getValue(Object rootObject) throws EvaluationException;
 
 	/**
 	 * Evaluate the expression in the default context against the specified root object. If the
@@ -198,46 +204,45 @@ <T> T getValue(EvaluationContext context, Object rootObject, @Nullable Class<T>
 
 	/**
 	 * Determine if an expression can be written to, i.e. setValue() can be called.
-	 * @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
 	 */
-	boolean isWritable(EvaluationContext context) throws EvaluationException;
+	boolean isWritable(Object rootObject) 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
 	 */
-	boolean isWritable(EvaluationContext context, Object rootObject) throws EvaluationException;
+	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
 	 */
-	boolean isWritable(Object rootObject) throws EvaluationException;
+	boolean isWritable(EvaluationContext context, Object rootObject) throws EvaluationException;
 
 	/**
 	 * Set this expression in the provided context to the value provided.
-	 *
-	 * @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
 	 */
-	void setValue(EvaluationContext context, Object value) throws EvaluationException;
+	void setValue(Object rootObject, @Nullable 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 context the context in which to set the value of the expression
 	 * @param value the new value
 	 * @throws EvaluationException if there is a problem during evaluation
 	 */
-	void setValue(Object rootObject, Object value) throws EvaluationException;
+	void setValue(EvaluationContext context, @Nullable Object value) throws EvaluationException;
 
 	/**
 	 * Set this expression in the provided context to the value provided.
@@ -247,12 +252,6 @@ <T> T getValue(EvaluationContext context, Object rootObject, @Nullable Class<T>
 	 * @param value the new value
 	 * @throws EvaluationException if there is a problem during evaluation
 	 */
-	void setValue(EvaluationContext context, Object rootObject, Object value) throws EvaluationException;
-
-	/**
-	 * Returns the original string used to create this expression, unmodified.
-	 * @return the original expression string
-	 */
-	String getExpressionString();
+	void setValue(EvaluationContext context, Object rootObject, @Nullable Object value) throws EvaluationException;
 
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -21,6 +21,7 @@
 import org.springframework.expression.EvaluationException;
 import org.springframework.expression.Expression;
 import org.springframework.expression.TypedValue;
+import org.springframework.lang.Nullable;
 
 /**
  * Represents a template expression broken into pieces. Each piece will be an Expression
@@ -58,6 +59,10 @@ public final String getExpressionString() {
 		return this.expressionString;
 	}
 
+	public final Expression[] getExpressions() {
+		return this.expressions;
+	}
+
 	@Override
 	public String getValue() throws EvaluationException {
 		StringBuilder sb = new StringBuilder();
@@ -70,6 +75,12 @@ public String getValue() throws EvaluationException {
 		return sb.toString();
 	}
 
+	@Override
+	public <T> T getValue(@Nullable Class<T> expectedResultType) throws EvaluationException {
+		Object value = getValue();
+		return ExpressionUtils.convertTypedValue(null, new TypedValue(value), expectedResultType);
+	}
+
 	@Override
 	public String getValue(Object rootObject) throws EvaluationException {
 		StringBuilder sb = new StringBuilder();
@@ -82,6 +93,12 @@ public String getValue(Object rootObject) throws EvaluationException {
 		return sb.toString();
 	}
 
+	@Override
+	public <T> T getValue(Object rootObject, @Nullable Class<T> desiredResultType) throws EvaluationException {
+		Object value = getValue(rootObject);
+		return ExpressionUtils.convertTypedValue(null, new TypedValue(value), desiredResultType);
+	}
+
 	@Override
 	public String getValue(EvaluationContext context) throws EvaluationException {
 		StringBuilder sb = new StringBuilder();
@@ -94,6 +111,14 @@ public String getValue(EvaluationContext context) throws EvaluationException {
 		return sb.toString();
 	}
 
+	@Override
+	public <T> T getValue(EvaluationContext context, @Nullable Class<T> expectedResultType)
+			throws EvaluationException {
+
+		Object value = getValue(context);
+		return ExpressionUtils.convertTypedValue(context, new TypedValue(value), expectedResultType);
+	}
+
 	@Override
 	public String getValue(EvaluationContext context, Object rootObject) throws EvaluationException {
 		StringBuilder sb = new StringBuilder();
@@ -107,8 +132,11 @@ public String getValue(EvaluationContext context, Object rootObject) throws Eval
 	}
 
 	@Override
-	public Class<?> getValueType(EvaluationContext context) {
-		return String.class;
+	public <T> T getValue(EvaluationContext context, Object rootObject, @Nullable Class<T> desiredResultType)
+			throws EvaluationException {
+
+		Object value = getValue(context,rootObject);
+		return ExpressionUtils.convertTypedValue(context, new TypedValue(value), desiredResultType);
 	}
 
 	@Override
@@ -117,73 +145,50 @@ public Class<?> getValueType() {
 	}
 
 	@Override
-	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) {
-		return TypeDescriptor.valueOf(String.class);
-	}
-
-	@Override
-	public TypeDescriptor getValueTypeDescriptor() {
-		return TypeDescriptor.valueOf(String.class);
+	public Class<?> getValueType(EvaluationContext context) {
+		return String.class;
 	}
 
 	@Override
-	public void setValue(EvaluationContext context, Object value) throws EvaluationException {
-		throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
+	public Class<?> getValueType(Object rootObject) throws EvaluationException {
+		return String.class;
 	}
 
 	@Override
-	public <T> T getValue(EvaluationContext context, Class<T> expectedResultType) throws EvaluationException {
-		Object value = getValue(context);
-		return ExpressionUtils.convertTypedValue(context, new TypedValue(value), expectedResultType);
+	public Class<?> getValueType(EvaluationContext context, Object rootObject) throws EvaluationException {
+		return String.class;
 	}
 
 	@Override
-	public <T> T getValue(Class<T> expectedResultType) throws EvaluationException {
-		Object value = getValue();
-		return ExpressionUtils.convertTypedValue(null, new TypedValue(value), expectedResultType);
+	public TypeDescriptor getValueTypeDescriptor() {
+		return TypeDescriptor.valueOf(String.class);
 	}
 
 	@Override
-	public boolean isWritable(EvaluationContext context) {
-		return false;
-	}
-
-	public Expression[] getExpressions() {
-		return this.expressions;
+	public TypeDescriptor getValueTypeDescriptor(Object rootObject) throws EvaluationException {
+		return TypeDescriptor.valueOf(String.class);
 	}
 
-
 	@Override
-	public <T> T getValue(Object rootObject, Class<T> desiredResultType) throws EvaluationException {
-		Object value = getValue(rootObject);
-		return ExpressionUtils.convertTypedValue(null, new TypedValue(value), desiredResultType);
+	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) {
+		return TypeDescriptor.valueOf(String.class);
 	}
 
 	@Override
-	public <T> T getValue(EvaluationContext context, Object rootObject, Class<T> desiredResultType)
+	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, Object rootObject)
 			throws EvaluationException {
-		Object value = getValue(context,rootObject);
-		return ExpressionUtils.convertTypedValue(context, new TypedValue(value), desiredResultType);
-	}
-
-	@Override
-	public Class<?> getValueType(Object rootObject) throws EvaluationException {
-		return String.class;
-	}
 
-	@Override
-	public Class<?> getValueType(EvaluationContext context, Object rootObject) throws EvaluationException {
-		return String.class;
+		return TypeDescriptor.valueOf(String.class);
 	}
 
 	@Override
-	public TypeDescriptor getValueTypeDescriptor(Object rootObject) throws EvaluationException {
-		return TypeDescriptor.valueOf(String.class);
+	public boolean isWritable(Object rootObject) throws EvaluationException {
+		return false;
 	}
 
 	@Override
-	public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, Object rootObject) throws EvaluationException {
-		return TypeDescriptor.valueOf(String.class);
+	public boolean isWritable(EvaluationContext context) {
+		return false;
 	}
 
 	@Override
@@ -192,17 +197,17 @@ public boolean isWritable(EvaluationContext context, Object rootObject) throws E
 	}
 
 	@Override
-	public void setValue(EvaluationContext context, Object rootObject, Object value) throws EvaluationException {
+	public void setValue(Object rootObject, @Nullable Object value) throws EvaluationException {
 		throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
 	}
 
 	@Override
-	public boolean isWritable(Object rootObject) throws EvaluationException {
-		return false;
+	public void setValue(EvaluationContext context, @Nullable Object value) throws EvaluationException {
+		throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
 	}
 
 	@Override
-	public void setValue(Object rootObject, Object value) throws EvaluationException {
+	public void setValue(EvaluationContext context, Object rootObject, @Nullable Object value) throws EvaluationException {
 		throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
 	}