org.springframework.data.mapping.model.SpELContext.java Source code

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Here is the source code for org.springframework.data.mapping.model.SpELContext.java

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/*
 * Copyright 2012-2019 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.data.mapping.model;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.expression.BeanFactoryResolver;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.PropertyAccessor;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * Simple factory to create {@link SpelExpressionParser} and {@link EvaluationContext} instances.
 *
 * @author Oliver Gierke
 */
public class SpELContext {

    private final SpelExpressionParser parser;
    private final PropertyAccessor accessor;
    private final @Nullable BeanFactory factory;

    /**
     * Creates a new {@link SpELContext} with the given {@link PropertyAccessor}. Defaults the
     * {@link SpelExpressionParser}.
     *
     * @param accessor
     */
    public SpELContext(PropertyAccessor accessor) {
        this(accessor, null, null);
    }

    /**
     * Creates a new {@link SpELContext} using the given {@link SpelExpressionParser} and {@link PropertyAccessor}. Will
     * default the {@link SpelExpressionParser} in case the given value for it is {@literal null}.
     *
     * @param parser
     * @param accessor
     */
    public SpELContext(SpelExpressionParser parser, PropertyAccessor accessor) {
        this(accessor, parser, null);
    }

    /**
     * Copy constructor to create a {@link SpELContext} using the given one's {@link PropertyAccessor} and
     * {@link SpelExpressionParser} as well as the given {@link BeanFactory}.
     *
     * @param source
     * @param factory
     */
    public SpELContext(SpELContext source, BeanFactory factory) {
        this(source.accessor, source.parser, factory);
    }

    /**
     * Creates a new {@link SpELContext} using the given {@link SpelExpressionParser}, {@link PropertyAccessor} and
     * {@link BeanFactory}. Will default the {@link SpelExpressionParser} in case the given value for it is
     * {@literal null}.
     *
     * @param accessor
     * @param parser
     * @param factory
     */
    private SpELContext(PropertyAccessor accessor, @Nullable SpelExpressionParser parser,
            @Nullable BeanFactory factory) {

        Assert.notNull(accessor, "PropertyAccessor must not be null!");

        this.parser = parser == null ? new SpelExpressionParser() : parser;
        this.accessor = accessor;
        this.factory = factory;
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.data.mapping.model.SpELContext#getParser()
     */
    public ExpressionParser getParser() {
        return this.parser;
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.data.mapping.model.SpELContext#getEvaluationContext(java.lang.Object)
     */
    public EvaluationContext getEvaluationContext(Object source) {

        StandardEvaluationContext evaluationContext = new StandardEvaluationContext(source);
        evaluationContext.addPropertyAccessor(accessor);

        if (factory != null) {
            evaluationContext.setBeanResolver(new BeanFactoryResolver(factory));
        }

        return evaluationContext;
    }
}