plugins/embeddedjsp/src/main/java/org/apache/struts2/el/ValueExpressionImpl.java - struts - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *  http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */
 package org.apache.struts2.el;

 import java.io.Externalizable;
 import java.io.IOException;
 import java.io.ObjectInput;
 import java.io.ObjectOutput;

 import javax.el.ELContext;
 import javax.el.ELException;
 import javax.el.ELResolver;
 import javax.el.Expression;
 import javax.el.ExpressionFactory;
 import javax.el.FunctionMapper;
 import javax.el.PropertyNotFoundException;
 import javax.el.PropertyNotWritableException;
 import javax.el.ValueExpression;
 import javax.el.VariableMapper;

 import org.apache.struts2.el.lang.ELSupport;
 import org.apache.struts2.el.lang.EvaluationContext;
 import org.apache.struts2.el.lang.ExpressionBuilder;
 import org.apache.struts2.el.parser.AstLiteralExpression;
 import org.apache.struts2.el.parser.Node;
 import org.apache.struts2.el.util.ReflectionUtil;

 /**
  * An <code>Expression</code> that can get or set a value.
  *
  * <p>
  * In previous incarnations of this API, expressions could only be read.
  * <code>ValueExpression</code> objects can now be used both to retrieve a
  * value and to set a value. Expressions that can have a value set on them are
  * referred to as l-value expressions. Those that cannot are referred to as
  * r-value expressions. Not all r-value expressions can be used as l-value
  * expressions (e.g. <code>"${1+1}"</code> or
  * <code>"${firstName} ${lastName}"</code>). See the EL Specification for
  * details. Expressions that cannot be used as l-values must always return
  * <code>true</code> from <code>isReadOnly()</code>.
  * </p>
  *
  * <p>
  * The {@link ExpressionFactory#createValueExpression} method
  * can be used to parse an expression string and return a concrete instance
  * of <code>ValueExpression</code> that encapsulates the parsed expression.
  * The {@link FunctionMapper} is used at parse time, not evaluation time,
  * so one is not needed to evaluate an expression using this class.
  * However, the {@link ELContext} is needed at evaluation time.</p>
  *
  * <p>The {@link #getValue}, {@link #setValue}, {@link #isReadOnly} and
  * {@link #getType} methods will evaluate the expression each time they are
  * called. The {@link ELResolver} in the <code>ELContext</code> is used to
  * resolve the top-level variables and to determine the behavior of the
  * <code>.</code> and <code>[]</code> operators. For any of the four methods,
  * the {@link ELResolver#getValue} method is used to resolve all properties
  * up to but excluding the last one. This provides the <code>base</code>
  * object. At the last resolution, the <code>ValueExpression</code> will
  * call the corresponding {@link ELResolver#getValue},
  * {@link ELResolver#setValue}, {@link ELResolver#isReadOnly} or
  * {@link ELResolver#getType} method, depending on which was called on
  * the <code>ValueExpression</code>.
  * </p>
  *
  * <p>See the notes about comparison, serialization and immutability in
  * the {@link Expression} javadocs.
  *
  * @see javax.el.ELResolver
  * @see javax.el.Expression
  * @see javax.el.ExpressionFactory
  * @see javax.el.ValueExpression
  *
  * @author Jacob Hookom [jacob@hookom.net]
  * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: markt $
  */
 public final class ValueExpressionImpl extends ValueExpression implements
         Externalizable {

     private Class expectedType;

     private String expr;

     private FunctionMapper fnMapper;

     private VariableMapper varMapper;

     private transient Node node;

     public ValueExpressionImpl() {

     }

     /**
      * @param expr expression
      * @param node node
      * @param fnMapper function mapper
      * @param varMapper variable mapper
      * @param expectedType expected type
      */
     public ValueExpressionImpl(String expr, Node node, FunctionMapper fnMapper,
             VariableMapper varMapper, Class expectedType) {
         this.expr = expr;
         this.node = node;
         this.fnMapper = fnMapper;
         this.varMapper = varMapper;
         this.expectedType = expectedType;
     }

     /*
      * (non-Javadoc)
      *
      * @see java.lang.Object#equals(java.lang.Object)
      */
     public boolean equals(Object obj) {
         return (obj instanceof ValueExpressionImpl && obj.hashCode() == this
                 .hashCode());
     }

     /*
      * (non-Javadoc)
      *
      * @see javax.el.ValueExpression#getExpectedType()
      */
     public Class getExpectedType() {
         return this.expectedType;
     }

     /**
      * Returns the type the result of the expression will be coerced to after
      * evaluation.
      *
      * @return the <code>expectedType</code> passed to the
      *         <code>ExpressionFactory.createValueExpression</code> method
      *         that created this <code>ValueExpression</code>.
      *
      * @see javax.el.Expression#getExpressionString()
      */
     public String getExpressionString() {
         return this.expr;
     }

     /**
      * @return
      * @throws ELException
      */
     private Node getNode() throws ELException {
         if (this.node == null) {
             this.node = ExpressionBuilder.createNode(this.expr);
         }
         return this.node;
     }

     /*
      * (non-Javadoc)
      *
      * @see javax.el.ValueExpression#getType(javax.el.ELContext)
      */
     public Class getType(ELContext context) throws PropertyNotFoundException,
             ELException {
         EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
                 this.varMapper);
         return this.getNode().getType(ctx);
     }

     /*
      * (non-Javadoc)
      *
      * @see javax.el.ValueExpression#getValue(javax.el.ELContext)
      */
     public Object getValue(ELContext context) throws PropertyNotFoundException,
             ELException {
         EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
                 this.varMapper);
         Object value = this.getNode().getValue(ctx);
         if (this.expectedType != null) {
             return ELSupport.coerceToType(value, this.expectedType);
         }
         return value;
     }

     /*
      * (non-Javadoc)
      *
      * @see java.lang.Object#hashCode()
      */
     public int hashCode() {
         return this.expr.hashCode();
     }

     /*
      * (non-Javadoc)
      *
      * @see javax.el.ValueExpression#isLiteralText()
      */
     public boolean isLiteralText() {
         try {
             return this.getNode() instanceof AstLiteralExpression;
         } catch (ELException ele) {
             return false;
         }
     }

     /*
      * (non-Javadoc)
      *
      * @see javax.el.ValueExpression#isReadOnly(javax.el.ELContext)
      */
     public boolean isReadOnly(ELContext context)
             throws PropertyNotFoundException, ELException {
         EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
                 this.varMapper);
         return this.getNode().isReadOnly(ctx);
     }

     public void readExternal(ObjectInput in) throws IOException,
             ClassNotFoundException {
         this.expr = in.readUTF();
         String type = in.readUTF();
         if (!"".equals(type)) {
             this.expectedType = ReflectionUtil.forName(type);
         }
         this.fnMapper = (FunctionMapper) in.readObject();
         this.varMapper = (VariableMapper) in.readObject();
     }

     /*
      * (non-Javadoc)
      *
      * @see javax.el.ValueExpression#setValue(javax.el.ELContext,
      *      java.lang.Object)
      */
     public void setValue(ELContext context, Object value)
             throws PropertyNotFoundException, PropertyNotWritableException,
             ELException {
         EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
                 this.varMapper);
         this.getNode().setValue(ctx, value);
     }

     public void writeExternal(ObjectOutput out) throws IOException {
         out.writeUTF(this.expr);
         out.writeUTF((this.expectedType != null) ? this.expectedType.getName()
                 : "");
         out.writeObject(this.fnMapper);
         out.writeObject(this.varMapper);
     }

     public String toString() {
         return "ValueExpression["+this.expr+"]";
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*/
	package org.apache.struts2.el;

	import java.io.Externalizable;
	import java.io.IOException;
	import java.io.ObjectInput;
	import java.io.ObjectOutput;

	import javax.el.ELContext;
	import javax.el.ELException;
	import javax.el.ELResolver;
	import javax.el.Expression;
	import javax.el.ExpressionFactory;
	import javax.el.FunctionMapper;
	import javax.el.PropertyNotFoundException;
	import javax.el.PropertyNotWritableException;
	import javax.el.ValueExpression;
	import javax.el.VariableMapper;

	import org.apache.struts2.el.lang.ELSupport;
	import org.apache.struts2.el.lang.EvaluationContext;
	import org.apache.struts2.el.lang.ExpressionBuilder;
	import org.apache.struts2.el.parser.AstLiteralExpression;
	import org.apache.struts2.el.parser.Node;
	import org.apache.struts2.el.util.ReflectionUtil;

	/**
	* An <code>Expression</code> that can get or set a value.
	*
	* <p>
	* In previous incarnations of this API, expressions could only be read.
	* <code>ValueExpression</code> objects can now be used both to retrieve a
	* value and to set a value. Expressions that can have a value set on them are
	* referred to as l-value expressions. Those that cannot are referred to as
	* r-value expressions. Not all r-value expressions can be used as l-value
	* expressions (e.g. <code>"${1+1}"</code> or
	* <code>"${firstName} ${lastName}"</code>). See the EL Specification for
	* details. Expressions that cannot be used as l-values must always return
	* <code>true</code> from <code>isReadOnly()</code>.
	* </p>
	*
	* <p>
	* The {@link ExpressionFactory#createValueExpression} method
	* can be used to parse an expression string and return a concrete instance
	* of <code>ValueExpression</code> that encapsulates the parsed expression.
	* The {@link FunctionMapper} is used at parse time, not evaluation time,
	* so one is not needed to evaluate an expression using this class.
	* However, the {@link ELContext} is needed at evaluation time.</p>
	*
	* <p>The {@link #getValue}, {@link #setValue}, {@link #isReadOnly} and
	* {@link #getType} methods will evaluate the expression each time they are
	* called. The {@link ELResolver} in the <code>ELContext</code> is used to
	* resolve the top-level variables and to determine the behavior of the
	* <code>.</code> and <code>[]</code> operators. For any of the four methods,
	* the {@link ELResolver#getValue} method is used to resolve all properties
	* up to but excluding the last one. This provides the <code>base</code>
	* object. At the last resolution, the <code>ValueExpression</code> will
	* call the corresponding {@link ELResolver#getValue},
	* {@link ELResolver#setValue}, {@link ELResolver#isReadOnly} or
	* {@link ELResolver#getType} method, depending on which was called on
	* the <code>ValueExpression</code>.
	* </p>
	*
	* <p>See the notes about comparison, serialization and immutability in
	* the {@link Expression} javadocs.
	*
	* @see javax.el.ELResolver
	* @see javax.el.Expression
	* @see javax.el.ExpressionFactory
	* @see javax.el.ValueExpression
	*
	* @author Jacob Hookom [jacob@hookom.net]
	* @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: markt $
	*/
	public final class ValueExpressionImpl extends ValueExpression implements
	Externalizable {

	private Class expectedType;

	private String expr;

	private FunctionMapper fnMapper;

	private VariableMapper varMapper;

	private transient Node node;

	public ValueExpressionImpl() {

	}

	/**
	* @param expr expression
	* @param node node
	* @param fnMapper function mapper
	* @param varMapper variable mapper
	* @param expectedType expected type
	*/
	public ValueExpressionImpl(String expr, Node node, FunctionMapper fnMapper,
	VariableMapper varMapper, Class expectedType) {
	this.expr = expr;
	this.node = node;
	this.fnMapper = fnMapper;
	this.varMapper = varMapper;
	this.expectedType = expectedType;
	}

	/*
	* (non-Javadoc)
	*
	* @see java.lang.Object#equals(java.lang.Object)
	*/
	public boolean equals(Object obj) {
	return (obj instanceof ValueExpressionImpl && obj.hashCode() == this
	.hashCode());
	}

	/*
	* (non-Javadoc)
	*
	* @see javax.el.ValueExpression#getExpectedType()
	*/
	public Class getExpectedType() {
	return this.expectedType;
	}

	/**
	* Returns the type the result of the expression will be coerced to after
	* evaluation.
	*
	* @return the <code>expectedType</code> passed to the
	* <code>ExpressionFactory.createValueExpression</code> method
	* that created this <code>ValueExpression</code>.
	*
	* @see javax.el.Expression#getExpressionString()
	*/
	public String getExpressionString() {
	return this.expr;
	}

	/**
	* @return
	* @throws ELException
	*/
	private Node getNode() throws ELException {
	if (this.node == null) {
	this.node = ExpressionBuilder.createNode(this.expr);
	}
	return this.node;
	}

	/*
	* (non-Javadoc)
	*
	* @see javax.el.ValueExpression#getType(javax.el.ELContext)
	*/
	public Class getType(ELContext context) throws PropertyNotFoundException,
	ELException {
	EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
	this.varMapper);
	return this.getNode().getType(ctx);
	}

	/*
	* (non-Javadoc)
	*
	* @see javax.el.ValueExpression#getValue(javax.el.ELContext)
	*/
	public Object getValue(ELContext context) throws PropertyNotFoundException,
	ELException {
	EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
	this.varMapper);
	Object value = this.getNode().getValue(ctx);
	if (this.expectedType != null) {
	return ELSupport.coerceToType(value, this.expectedType);
	}
	return value;
	}

	/*
	* (non-Javadoc)
	*
	* @see java.lang.Object#hashCode()
	*/
	public int hashCode() {
	return this.expr.hashCode();
	}

	/*
	* (non-Javadoc)
	*
	* @see javax.el.ValueExpression#isLiteralText()
	*/
	public boolean isLiteralText() {
	try {
	return this.getNode() instanceof AstLiteralExpression;
	} catch (ELException ele) {
	return false;
	}
	}

	/*
	* (non-Javadoc)
	*
	* @see javax.el.ValueExpression#isReadOnly(javax.el.ELContext)
	*/
	public boolean isReadOnly(ELContext context)
	throws PropertyNotFoundException, ELException {
	EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
	this.varMapper);
	return this.getNode().isReadOnly(ctx);
	}

	public void readExternal(ObjectInput in) throws IOException,
	ClassNotFoundException {
	this.expr = in.readUTF();
	String type = in.readUTF();
	if (!"".equals(type)) {
	this.expectedType = ReflectionUtil.forName(type);
	}
	this.fnMapper = (FunctionMapper) in.readObject();
	this.varMapper = (VariableMapper) in.readObject();
	}

	/*
	* (non-Javadoc)
	*
	* @see javax.el.ValueExpression#setValue(javax.el.ELContext,
	* java.lang.Object)
	*/
	public void setValue(ELContext context, Object value)
	throws PropertyNotFoundException, PropertyNotWritableException,
	ELException {
	EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
	this.varMapper);
	this.getNode().setValue(ctx, value);
	}

	public void writeExternal(ObjectOutput out) throws IOException {
	out.writeUTF(this.expr);
	out.writeUTF((this.expectedType != null) ? this.expectedType.getName()
	: "");
	out.writeObject(this.fnMapper);
	out.writeObject(this.varMapper);
	}

	public String toString() {
	return "ValueExpression["+this.expr+"]";
	}
	}