com.github.sebhoss.contract.verifier.ELContractContext Maven / Gradle / Ivy

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/*
 * Copyright © 2012 Sebastian Hoß 
 * This work is free. You can redistribute it and/or modify it under the
 * terms of the Do What The Fuck You Want To Public License, Version 2,
 * as published by Sam Hocevar. See http://www.wtfpl.net/ for more details.
 */
package com.github.sebhoss.contract.verifier;

import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.ValueExpression;

import com.github.sebhoss.contract.annotation.Clause;

/**
 * {@link ContractContext} which uses an {@link ELContext} as basis.
 */
public final class ELContractContext implements ContractContext {

    private final ELContext         elContext;
    private final ExpressionFactory expressionFactory;

    /**
     * @param elContext
     *            The EL-context to use.
     * @param expressionFactory
     *            The EL-expression-factory to use.
     */
    public ELContractContext(final ELContext elContext, final ExpressionFactory expressionFactory) {
        this.elContext = elContext;
        this.expressionFactory = expressionFactory;
    }

    @Override
    public void setInvocationResult(final Object invocationResult) {
        elContext.getVariableMapper().setVariable(Clause.RETURN,
                expressionFactory.createValueExpression(invocationResult, invocationResult.getClass()));
    }

    @Override
    public boolean isInViolationWith(final Clause clause) {
        final ValueExpression valueExpression = expressionFactory.createValueExpression(elContext, clause.value(),
                Boolean.class);
        final Object clauseValid = valueExpression.getValue(elContext);

        return Boolean.FALSE.equals(clauseValid);
    }

}