org.carrot2.util.attribute.constraint.ConstraintFactory.java Source code

Introduction

Here is the source code for org.carrot2.util.attribute.constraint.ConstraintFactory.java

Source

/*
 * Carrot2 project.
 *
 * Copyright (C) 2002-2010, Dawid Weiss, Stanisaw Osiski.
 * All rights reserved.
 *
 * Refer to the full license file "carrot2.LICENSE"
 * in the root folder of the repository checkout or at:
 * http://www.carrot2.org/carrot2.LICENSE
 */

package org.carrot2.util.attribute.constraint;

import java.lang.annotation.Annotation;
import java.util.ArrayList;
import java.util.List;

import org.carrot2.util.ExceptionUtils;

import com.google.common.collect.Lists;

/**
 * Builds constraint implementation from constraint annotations.
 */
public class ConstraintFactory {
    /**
     * Create a list of constraints based on the provided <code>annotations</code>.
     */
    public static List<Constraint> createConstraints(Annotation... annotations) {
        final ArrayList<Constraint> constraints = Lists.newArrayList();
        for (Annotation annotation : annotations) {
            if (isConstraintAnnotation(annotation.annotationType())) {
                constraints.add(createImplementation(annotation));
            }
        }

        return constraints;
    }

    /**
     * Returns <code>true</code> if the provided annotation is a constraint annotation.
     */
    static boolean isConstraintAnnotation(Class<? extends Annotation> ann) {
        return ann.isAnnotationPresent(IsConstraint.class);
    }

    /**
     * Creates a class implementing the provided constraint annotation.
     */
    static Constraint createImplementation(Annotation ann) {
        final IsConstraint constraintAnnotation = ann.annotationType().getAnnotation(IsConstraint.class);
        final Class<?> implClass = constraintAnnotation.implementation();
        if (!Constraint.class.isAssignableFrom(implClass)) {
            throw new IllegalArgumentException("Implementation class " + implClass.getClass().getName()
                    + " must implement " + Constraint.class.getName());
        }

        Constraint instance;
        try {
            instance = (Constraint) implClass.newInstance();
        } catch (Exception e) {
            throw ExceptionUtils.wrapAsRuntimeException(e);
        }
        instance.populate(ann);

        return instance;
    }
}