org.thymeleaf.spring4.expression.ThymeleafEvaluationContext Maven / Gradle / Ivy

/*
 * =============================================================================
 * 
 *   Copyright (c) 2011-2016, The THYMELEAF team (http://www.thymeleaf.org)
 * 
 *   Licensed 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.thymeleaf.spring4.expression;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.expression.BeanFactoryResolver;
import org.springframework.context.expression.MapAccessor;
import org.springframework.core.convert.ConversionService;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.expression.spel.support.StandardTypeConverter;
import org.thymeleaf.expression.IExpressionObjects;
import org.thymeleaf.util.Validate;

/**
 * 
 *   Thymeleaf's basic implementation of the {@link IThymeleafEvaluationContext} interface, which in turn extends
 *   from Spring's {@link org.springframework.expression.EvaluationContext} interface.
 * 
 * 
 *   This implementation adds Thymeleaf's own property accessors
 *   (see {@link org.springframework.expression.PropertyAccessor}) for accessing
 *   the {@link org.thymeleaf.context.IContext} object in which variables are stored.
 * 
 * 
 *   Also, this evaluation context (which is usually instanced at the
 *   {@link org.thymeleaf.spring4.view.ThymeleafView} initialization) links the execution of expressions
 *   with the available {@link BeanFactory} and {@link ConversionService} instances, used during evaluation.
 * 
 * 
 *   Before executing a Spring EL expression using this evaluation context, it should be enriched with the
 *   variables to be made accessible (like #variableName), using a
 *   {@link ThymeleafEvaluationContextWrapper} object.
 * 
 *
 * @author Daniel Fernández
 *
 * @since 2.1.0
 *
 */
public final class ThymeleafEvaluationContext
            extends StandardEvaluationContext
            implements IThymeleafEvaluationContext {

    public static final String THYMELEAF_EVALUATION_CONTEXT_CONTEXT_VARIABLE_NAME = "thymeleaf::EvaluationContext";


    private static final MapAccessor MAP_ACCESSOR_INSTANCE = new MapAccessor();


    private final ApplicationContext applicationContext;

    private IExpressionObjects expressionObjects = null;
    private boolean variableAccessRestricted = false;




    public ThymeleafEvaluationContext(final ApplicationContext applicationContext, final ConversionService conversionService) {
        
        super();

        Validate.notNull(applicationContext, "Application Context cannot be null");
        // ConversionService CAN be null

        this.applicationContext = applicationContext;
        this.setBeanResolver(new BeanFactoryResolver(applicationContext));
        if (conversionService != null) {
            this.setTypeConverter(new StandardTypeConverter(conversionService));
        }

        this.addPropertyAccessor(SPELContextPropertyAccessor.INSTANCE);
        this.addPropertyAccessor(MAP_ACCESSOR_INSTANCE);

    }


    public ApplicationContext getApplicationContext() {
        return this.applicationContext;
    }


    @Override
    public Object lookupVariable(final String name) {
        if (this.expressionObjects != null && this.expressionObjects.containsObject(name)) {
            final Object result = this.expressionObjects.getObject(name);
            if (result != null) {
                return result;
            }
        }
        // fall back to superclass
        return super.lookupVariable(name);
    }




    public boolean isVariableAccessRestricted() {
        return this.variableAccessRestricted;
    }

    public void setVariableAccessRestricted(final boolean restricted) {
        this.variableAccessRestricted = restricted;
    }

    public IExpressionObjects getExpressionObjects() {
        return this.expressionObjects;
    }

    public void setExpressionObjects(final IExpressionObjects expressionObjects) {
        this.expressionObjects = expressionObjects;
    }


}