org.zkoss.zk.xel.impl.SimpleEvaluator Maven / Gradle / Ivy
/* SimpleEvaluator.java
Purpose:
Description:
History:
Thu Aug 30 22:43:08 2007, Created by tomyeh
Copyright (C) 2007 Potix Corporation. All Rights Reserved.
{{IS_RIGHT
This program is distributed under LGPL Version 2.1 in the hope that
it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.zk.xel.impl;
import org.zkoss.xel.XelContext;
import org.zkoss.xel.FunctionMapper;
import org.zkoss.xel.VariableResolver;
import org.zkoss.xel.Expression;
import org.zkoss.xel.Expressions;
import org.zkoss.xel.ExpressionFactory;
import org.zkoss.xel.XelException;
import org.zkoss.xel.util.SimpleXelContext;
import org.zkoss.xel.util.DualFunctionMapper;
import org.zkoss.web.servlet.xel.RequestContext;
import org.zkoss.web.servlet.xel.RequestContexts;
import org.zkoss.zk.ui.Execution;
import org.zkoss.zk.ui.Executions;
import org.zkoss.zk.ui.Page;
import org.zkoss.zk.ui.Component;
import org.zkoss.zk.ui.sys.ExecutionCtrl;
import org.zkoss.zk.ui.sys.ExecutionsCtrl;
import org.zkoss.zk.xel.Evaluator;
/**
* A simple implementation of {@link Evaluator}.
*
* @author tomyeh
* @since 3.0.0
*/
public class SimpleEvaluator implements Evaluator {
private transient ExpressionFactory _expf;
private final Class _expfcls;
private final FunctionMapper _mapper;
/**
* @param expfcls the class that implements the expression factory.
* If null, the default one is used.
*/
public SimpleEvaluator(FunctionMapper mapper, Class expfcls) {
_expfcls = expfcls;
_mapper = mapper;
}
//Evaluator//
public Expression parseExpression(String expression, Class expectedType)
throws XelException {
return getExpressionFactory()
.parseExpression(newXelContext(null), expression, expectedType);
}
public Object evaluate(Page page, Expression expression)
throws XelException {
return expression.evaluate(newXelContext(page));
}
public Object evaluate(Component comp, Expression expression)
throws XelException {
return expression.evaluate(newXelContext(comp));
}
/** Returns the implementation class of the expression factory,
* or null to use the default.
*/
public Class getExpressionFactoryClass() {
return _expfcls;
}
/** Returns the expression factory. */
protected ExpressionFactory getExpressionFactory() {
if (_expf == null)
_expf = Expressions.newExpressionFactory(_expfcls);
return _expf;
}
/** Instantiate a XEL context.
* Don't reuse it since it has attributes (that shall not be kept
* after evaluation).
*/
protected XelContext newXelContext(Object ref) {
final FunctionMapper mapper = getFunctionMapper(ref);
final VariableResolver resolver = getVariableResolver(ref);
return new SimpleXelContext(resolver, mapper);
//Bug 1814838: don't cache the instance
}
/** Returns the function mapper, or null if not available.
*
* Default: returns the function mapper passed thru
* {@link #SimpleEvaluator}.
*
* @param ref the object,either page, component, or null.
* It is passed to {@link #evaluate}
*/
public FunctionMapper getFunctionMapper(Object ref) {
if (ref instanceof Component)
ref = ((Component)ref).getPage();
if (ref == null) {
ExecutionCtrl execCtrl = ExecutionsCtrl.getCurrentCtrl();
if (execCtrl != null)
ref = execCtrl.getCurrentPage();
}
return DualFunctionMapper.combine(
ref instanceof Page ? ((Page)ref).getFunctionMapper(): null,
_mapper);
}
/** Returns the variable resolver, or null if not available.
*
*
Default: it returns the variable resolver of the
* current execution, if any.
* Otherwise, it returns the current {@link RequestContext}, if any.
* If both not available, null is returned.
*
* @param ref the object,either page, component, or null.
* It is passed to {@link #evaluate}
*/
public VariableResolver getVariableResolver(Object ref) {
final Execution exec = Executions.getCurrent();
VariableResolver resolver = exec.getVariableResolver();
if (resolver == null) {
final RequestContext rc = RequestContexts.getCurrent();
if (rc != null)
resolver = rc.getVariableResolver();
if (resolver == null)
return null;
}
if (resolver instanceof ExecutionResolver)
((ExecutionResolver)resolver).setSelf(ref);
return resolver;
}
}