nom.tam.util.array.MultiArrayIterator Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of nom-tam-fits Show documentation
Java library for reading and writing FITS files. FITS, the Flexible Image Transport System, is the format commonly used in the archiving and transport of astronomical data.
There is a newer version: 1.21.0
Show newest version
/*
 * #%L
 * nom.tam FITS library
 * %%
 * Copyright (C) 1996 - 2024 nom-tam-fits
 * %%
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 * #L%
 */

package nom.tam.util.array;

import java.lang.reflect.Array;

import nom.tam.util.ArrayFuncs;

/**
 * Multi-dimensional array iterator (primarily for internal use)
 *
 * @param  the generic type of array at the base of a multi-dimensional array object. For example for a
 *                        float[][][] array the base would be float[].
 */
@SuppressWarnings({"deprecation"})
public class MultiArrayIterator {

    private final BaseArray baseArray;

    private final boolean baseIsNoSubArray;

    private boolean baseNextCalled = false;

    private final MultiArrayPointer pointer;

    /**
     * Creates a new iterator for a multidimensional array. The array is assumed to be monolithic containing only one
     * type of (non-array) elements.
     * 
     * @param baseArray the multidimensional array, whose elements we want to iterate over.
     */
    public MultiArrayIterator(BaseArray baseArray) {
        this.baseArray = baseArray;
        baseIsNoSubArray = !MultiArrayPointer.isSubArray(this.baseArray);
        pointer = new MultiArrayPointer(this.baseArray);
    }

    /**
     * 
     * Returns the element class of the multidimensional array. It is assumed that the array is monolithic containing
     * only elements of that type. This is effectively the same as {@link ArrayFuncs#getBaseClass(Object)}.
     * 
     * 
     * Note that prior to version 1.20, this did not return the expected type for 3D+ arrays.
     * 
     * 
     * @return the class of (non-array) elements contained in the multidimensional array.
     * 
     * @see    ArrayFuncs#getBaseClass(Object)
     */
    public Class deepComponentType() {
        return ArrayFuncs.getBaseClass(baseArray);
    }

    /**
     * Returns the next array element in the top-level array.
     * 
     * @return the next array element in the top-level array object.
     */
    @SuppressWarnings("unchecked")
    public BaseArray next() {
        if (baseIsNoSubArray) {
            if (baseNextCalled) {
                return null;
            }
            baseNextCalled = true;
            return baseArray;
        }
        Object result = null;
        while (result == null || Array.getLength(result) == 0) {
            result = pointer.next();
            if (result == MultiArrayPointer.END) {
                return null;
            }
        }
        return (BaseArray) result;
    }

    /**
     * Resets the iterator so it can be re-used again.
     */
    public void reset() {
        if (baseIsNoSubArray) {
            baseNextCalled = false;
        } else {
            pointer.reset();
        }
    }

    /**
     * Counts the number of base elements contained. Prior to version 1.20 this returned the number of elements
     * remaining from the current position, but by iterating over the remaining elements, s.t. a call to {@link #next()}
     * would always return null afterwards. As of version 1.20, it consistently returns the same based
     * element count regardless of the state of the iterator (effectively the same as
     * {@link ArrayFuncs#countElements(Object)}). Note that this call is expensive, especially for large
     * multidimensional arrays.
     * 
     * @return the number of base elements contained.
     * 
     * @see    ArrayFuncs#countElements(Object)
     */
    public int size() {
        return (int) ArrayFuncs.countElements(baseArray);
    }
}