org.apache.shale.test.el.MockValueExpression Maven / Gradle / Ivy
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* 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.shale.test.el;
import java.util.ArrayList;
import java.util.List;
import javax.el.ELContext;
import javax.el.ELResolver;
import javax.el.ValueExpression;
import javax.faces.context.FacesContext;
/**
* Mock implementation of ValueExpression.
*
* This implementation supports a limited subset of overall expression functionality:
*
* - A literal string that contains no expression delimiters.
* - An expression that starts with "#{" or "${", and ends with "}".
*
*/
public class MockValueExpression extends ValueExpression {
// ------------------------------------------------------------ Constructors
/**
* Serial version UID.
*/
private static final long serialVersionUID = -8649071428507512623L;
/**
* Construct a new expression for the specified expression string.
*
* @param expression Expression string to be evaluated
* @param expectedType Expected type of the result
*/
public MockValueExpression(String expression, Class expectedType) {
if (expression == null) {
throw new NullPointerException("Expression string cannot be null");
}
this.expression = expression;
this.expectedType = expectedType;
parse();
}
// ------------------------------------------------------ Instance Variables
/**
* The parsed elements of this expression.
*/
private String[] elements = null;
/**
* The expected result type for getValue() calls.
*/
private Class expectedType = null;
/**
* The original expression string used to create this expression.
*/
private String expression = null;
// ------------------------------------------------------ Expression Methods
/**
* Return true if this expression is equal to the
* specified expression.
*
* @param obj Object to be compared
*/
public boolean equals(Object obj) {
if ((obj != null) & (obj instanceof ValueExpression)) {
return expression.equals(((ValueExpression) obj).getExpressionString());
} else {
return false;
}
}
/**
* Return the original String used to create this expression,
* unmodified.
*/
public String getExpressionString() {
return this.expression;
}
/**
* Return the hash code for this expression.
*/
public int hashCode() {
return this.expression.hashCode();
}
/**
* Return true if the expression string for this expression
* contains only literal text.
*/
public boolean isLiteralText() {
return (expression.indexOf("${") < 0) && (expression.indexOf("#{") < 0);
}
// ------------------------------------------------- ValueExpression Methods
/**
* Return the type that the result of this expression will
* be coerced to.
*/
public Class getExpectedType() {
return this.expectedType;
}
/**
* Evaluate this expression relative to the specified context,
* and return the most general type that is acceptable for the
* value passed in a setValue() call.
*
* @param context ELContext for this evaluation
*/
public Class getType(ELContext context) {
if (context == null) {
throw new NullPointerException();
}
Object value = getValue(context);
if (value == null) {
return null;
} else {
return value.getClass();
}
}
/**
* Evaluate this expression relative to the specified context,
* and return the result.
*
* @param context ELContext for this evaluation
*/
public Object getValue(ELContext context) {
if (context == null) {
throw new NullPointerException();
}
if (isLiteralText()) {
return expression;
}
FacesContext fcontext = (FacesContext) context.getContext(FacesContext.class);
ELResolver resolver = fcontext.getApplication().getELResolver();
Object base = null;
for (int i = 0; i < elements.length; i++) {
base = resolver.getValue(context, base, elements[i]);
}
return fcontext.getApplication().getExpressionFactory().coerceToType(base, getExpectedType());
}
/**
* Evaluate this expression relative to the specified context,
* and return true if a call to setValue()
* will always fail.
*
* @param context ELContext for this evaluation
*/
public boolean isReadOnly(ELContext context) {
if (context == null) {
throw new NullPointerException();
}
if (isLiteralText()) {
return true;
}
FacesContext fcontext = (FacesContext) context.getContext(FacesContext.class);
ELResolver resolver = fcontext.getApplication().getELResolver();
Object base = null;
for (int i = 0; i < elements.length - 1; i++) {
base = resolver.getValue(context, base, elements[i]);
}
return resolver.isReadOnly(context, base, elements[elements.length - 1]);
}
/**
* Evaluate this expression relative to the specified context,
* and set the result to the specified value.
*
* @param context ELContext for this evaluation
* @param value Value to which the result should be set
*/
public void setValue(ELContext context, Object value) {
if (context == null) {
throw new NullPointerException();
}
FacesContext fcontext = (FacesContext) context.getContext(FacesContext.class);
ELResolver resolver = fcontext.getApplication().getELResolver();
Object base = null;
for (int i = 0; i < elements.length - 1; i++) {
base = resolver.getValue(context, base, elements[i]);
}
resolver.setValue(context, base, elements[elements.length - 1], value);
}
// --------------------------------------------------------- Private Methods
/**
* Parse the expression string into its constituent elemetns.
*/
private void parse() {
if (isLiteralText()) {
elements = new String[0];
return;
}
if (expression.startsWith("${") || expression.startsWith("#{")) {
if (expression.endsWith("}")) {
List names = new ArrayList();
StringBuffer expr = new StringBuffer(expression.substring(2, expression.length() - 1).replaceAll(" ", ""));
boolean isBlockOn = false;
for (int i = expr.length() - 1; i > -1; i--) {
if (expr.charAt(i) == ' ') {
expr.deleteCharAt(i);
} else if (expr.charAt(i) == ']') {
expr.deleteCharAt(i);
} else if (expr.charAt(i) == '[') {
expr.deleteCharAt(i);
} else if (expr.charAt(i) == '\'') {
if (!isBlockOn) {
expr.deleteCharAt(i);
} else {
names.add(0, expr.substring(i + 1));
expr.delete(i, expr.length());
}
isBlockOn = !isBlockOn;
} else if (expr.charAt(i) == '.' && !isBlockOn) {
names.add(0, expr.substring(i + 1));
expr.delete(i, expr.length());
}
}
if (expr.length() > 0) {
names.add(0, expr.toString());
}
elements = (String[]) names.toArray(new String[names.size()]);
} else {
throw new IllegalArgumentException(expression);
}
} else {
throw new IllegalArgumentException(expression);
}
}
}