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'databene commons' is an open source Java library by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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 org.databene.commons;

import java.lang.reflect.Array;

import org.databene.commons.converter.ToStringConverter;

/**
 * Helper class for building arrays.
 * @param  the component type of the array
 * @author Volker Bergmann
 * @since 0.2.04
 */
public class ArrayBuilder {
    
    private static final int DEFAULT_INITIAL_CAPACITY = 10;
    
    private static Escalator escalator = new LoggerEscalator();
    
    private Class componentType;
    private E[] buffer;
    private int elementCount;

    public ArrayBuilder(Class componentType) {
        this(componentType, DEFAULT_INITIAL_CAPACITY);
    }
    
    public ArrayBuilder(Class componentType, int initialCapacity) {
        this.componentType = componentType;
        this.buffer = createBuffer(initialCapacity);
    }

    /** @deprecated replaced with add(Element)
     * @param element the element to append
     * @return this */
    @Deprecated
    public ArrayBuilder append(E element) {
    	escalator.escalate(getClass().getName() + ".append() is deprecated, please use the add() method", 
    			getClass(), null);
        return add(element);
    }
    
    public ArrayBuilder add(E element) {
        if (buffer == null)
            throw new UnsupportedOperationException("ArrayBuilder cannot be reused after invoking toArray()");
        if (elementCount >= buffer.length - 1) {
            E[] newBuffer = createBuffer(buffer.length * 2);
            System.arraycopy(buffer, 0, newBuffer, 0, buffer.length);
            buffer = newBuffer;
        }
        buffer[elementCount++] = element;
        return this;
    }
    
	public void addAllIfNotContained(E... elements) {
		for (E element : elements)
			addIfNotContained(element);
	}

	public void addIfNotContained(E element) {
		if (!contains(element))
			add(element);
	}

    public boolean contains(E element) {
		for (int i = 0; i < elementCount; i++)
			if (NullSafeComparator.equals(buffer[i], element))
				return true;
		return false;
	}

	public void addAll(E[] elements) {
	    for (E element : elements)
	    	add(element);
    }
    
    public E[] toArray() {
        E[] result = ArrayUtil.newInstance(componentType, elementCount);
        System.arraycopy(buffer, 0, result, 0, elementCount);
        elementCount = 0;
        buffer = null;
        return result;
    }
    
    @Override
    public String toString() {
    	StringBuilder builder = new StringBuilder();
    	for (int i = 0; i < elementCount; i++) {
    		if (i > 0)
    			builder.append(", ");
    		builder.append(ToStringConverter.convert(buffer[i], "[NULL]"));
    	}
    	return builder.toString();
    }

    // private helpers -------------------------------------------------------------------------------------------------
    
    @SuppressWarnings("unchecked")
    private E[] createBuffer(int initialCapacity) {
        return (E[]) Array.newInstance(componentType, initialCapacity);
    }

}