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The S-Space Package is a collection of algorithms for building Semantic Spaces as well as a highly-scalable library for designing new distributional semantics algorithms. Distributional algorithms process text corpora and represent the semantic for words as high dimensional feature vectors. This package also includes matrices, vectors, and numerous clustering algorithms. These approaches are known by many names, such as word spaces, semantic spaces, or distributed semantics and rest upon the Distributional Hypothesis: words that appear in similar contexts have similar meanings.

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/*
 * Copyright 2009 Keith Stevens 
 *
 * This file is part of the S-Space package and is covered under the terms and
 * conditions therein.
 *
 * The S-Space package is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation and distributed hereunder to you.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS" AND NO REPRESENTATIONS OR WARRANTIES,
 * EXPRESS OR IMPLIED ARE MADE.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, WE MAKE
 * NO REPRESENTATIONS OR WARRANTIES OF MERCHANT- ABILITY OR FITNESS FOR ANY
 * PARTICULAR PURPOSE OR THAT THE USE OF THE LICENSED SOFTWARE OR DOCUMENTATION
 * WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER
 * RIGHTS.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see .
 */

package edu.ucla.sspace.vector;

import java.io.Serializable;


/**
 * An decorator for a {@code Vector} that lets the backing data be viewed as a
 * {@link DoubleVector}.  In addition, the backing vector may be resized and
 * also viewed from an offset.  Furthermore, this class allows the viewed data
 * to be immutable, where all mutating operations throw {@link
 * UnsupportedOperationException}.  
 *
 * 
 *
 * The data-type of the backing vectors values is still preserved if mututaions
 * are allowed.  This class relies upon the {@link Vector#set(Number)
 * set(Number)} method of the backing vector to correctly convert a {@code
 * double} argument into the appropriate.  Note that in the event that the
 * backing data-type does not support {@code double} precision, this may result
 * in data loss.
 *
 * 
 *
 * Note that the original {@code Vector} may still be alterned even if this view
 * is marked as immutable. 
 *
 * @author Keith Stevens
 * @author David Jurgens
 */
class ViewVectorAsDoubleVector extends VectorView implements DoubleVector {

    private static final long serialVersionUID = 1L;

    /**
     * Creates a new {@link DoubleVector} view of the data in the provided
     * {@link Vector}.
     *
     * @param v the {@code Vector} to view as containing double data.
     */
    public ViewVectorAsDoubleVector(Vector v) {
        super(v);
    }

    /**
     * Creates a new, optionally immutable {@link DoubleVector} view of the data
     * in the provided {@link IntegerVector}.
     *
     * @param v the {@code IntegerVector} to view as containing double data.
     * @param isImmutable {@code true} if this view should not allow mutating
     *        operations to change the state of the backing vector
     */
    public ViewVectorAsDoubleVector(Vector v, boolean isImmutable) {
        super(v, isImmutable);
    }

    /**
     * Creates a new {@link DoubleVector} sub-view of the data in the provided
     * {@link Vector} using the offset and length to specify a viewing
     * region.
     *
     * @param v the {@code Vector} whose data is reflected in this view.
     * @param offset the index of {@code v} at which the first index of this
     *               view starts
     * @param length the length of this view.
     */
    public ViewVectorAsDoubleVector(Vector v, int offset, int length) {
        super(v, offset, length);
    }

    /**
     * Creates a new, optionally immutable {@link DoubleVector} sub-view of the
     * data in the provided {@link Vector} using the offset and length to
     * specify a viewing region.
     *
     * @param v the {@code Vector} whose data is reflected in this view.
     * @param offset the index of {@code v} at which the first index of this
     *               view starts
     * @param length the length of this view.
     * @param isImmutable {@code true} if this view should not allow mutating
     *        operations to change the state of the backing vector.
     */
    public ViewVectorAsDoubleVector(Vector v, int offset, int length,
                                    boolean isImmutable) {
        super(v, offset, length, isImmutable);
    }

    /**
     * {@inheritDoc}
     */
    public double add(int index, double delta) {
        if (isImmutable) 
            throw new UnsupportedOperationException(
                "Cannot modify an immutable vector");
        int mapped = getIndex(index);
        double value = vector.getValue(mapped).doubleValue();
        vector.set(mapped, value + delta);
        return value + delta;
    }

    /**
     * {@inheritDoc}
     */
    public void set(int index, double value) {
        if (isImmutable) 
            throw new UnsupportedOperationException(
                "Cannot modify an immutable vector");
        vector.set(getIndex(index), value);
    }

    /**
     * {@inheritDoc}
     */
    public double get(int index) {
        return vector.getValue(getIndex(index)).doubleValue();
    }

    /**
     * {@inheritDoc}
     */
    public Double getValue(int index) {
        return vector.getValue(getIndex(index)).doubleValue();
    }

    /**
     * {@inheritDoc}
     */
    public double[] toArray() {
        double[] r = new double[vectorLength - vectorOffset];
        for (int i = vectorOffset; i < vectorLength; ++i)
            r[i] = vector.getValue(i).doubleValue();
        return r;
    }
}