ivory.smrf.model.builder.ExpressionGenerator.java Source code

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Here is the source code for ivory.smrf.model.builder.ExpressionGenerator.java

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/*
 * Ivory: A Hadoop toolkit for web-scale information retrieval
 *
 * 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 ivory.smrf.model.builder;

import ivory.core.exception.ConfigurationException;

import org.w3c.dom.Node;

import com.google.common.base.Preconditions;

/**
 * @author Don Metzler
 */
public abstract class ExpressionGenerator {

    public abstract void configure(Node domNode) throws ConfigurationException;

    public abstract Expression getExpression(String[] terms);

    @SuppressWarnings("unchecked")
    public static ExpressionGenerator create(String type, Node domNode) throws ConfigurationException {
        Preconditions.checkNotNull(type);
        Preconditions.checkNotNull(domNode);

        try {
            Class<? extends ExpressionGenerator> clz = (Class<? extends ExpressionGenerator>) Class.forName(type);
            ExpressionGenerator f = clz.newInstance();
            f.configure(domNode);

            return f;
        } catch (Exception e) {
            throw new ConfigurationException("Unable to instantiate ExpressionGenerator \"" + type + "\"!", e);
        }
    }
}