grails.plugin.cache.web.filter.ExpressionEvaluator.java Source code

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Here is the source code for grails.plugin.cache.web.filter.ExpressionEvaluator.java

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/* Copyright 2012-2013 SpringSource.
 *
 * 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 grails.plugin.cache.web.filter;

import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.springframework.cache.Cache;
import org.springframework.core.LocalVariableTableParameterNameDiscoverer;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpressionParser;

/**
 * Based on package-scope org.springframework.cache.interceptor.ExpressionEvaluator
 *
 * @author Costin Leau
 * @author Burt Beckwith
 */
public class ExpressionEvaluator {

    protected SpelExpressionParser parser = new SpelExpressionParser();

    // shared param discoverer since it caches data internally
    protected ParameterNameDiscoverer paramNameDiscoverer = new LocalVariableTableParameterNameDiscoverer();

    protected Map<String, Expression> conditionCache = new ConcurrentHashMap<String, Expression>();
    protected Map<String, Expression> keyCache = new ConcurrentHashMap<String, Expression>();
    protected Map<String, Method> targetMethodCache = new ConcurrentHashMap<String, Method>();

    public EvaluationContext createEvaluationContext(Collection<Cache> caches, Method method, Object[] args,
            Class<?> targetClass) {
        CacheExpressionRootObject rootObject = new CacheExpressionRootObject(caches, method, targetClass);
        return new LazyParamAwareEvaluationContext(rootObject, paramNameDiscoverer, method, args, targetClass,
                targetMethodCache);
    }

    public boolean condition(String conditionExpression, Method method, EvaluationContext evalContext) {
        String key = toString(method, conditionExpression);
        Expression condExp = conditionCache.get(key);
        if (condExp == null) {
            condExp = parser.parseExpression(conditionExpression);
            conditionCache.put(key, condExp);
        }
        return condExp.getValue(evalContext, boolean.class);
    }

    public Object key(String keyExpression, Method method, EvaluationContext evalContext) {
        String key = toString(method, keyExpression);
        Expression keyExp = keyCache.get(key);
        if (keyExp == null) {
            keyExp = parser.parseExpression(keyExpression);
            keyCache.put(key, keyExp);
        }
        return keyExp.getValue(evalContext);
    }

    protected String toString(Method method, String expression) {
        return method.getDeclaringClass().getName() + '#' + method + '#' + expression;
    }
}