LinearRange.java

/*******************************************************************************
 * Copyright (c) 2012-2017 Codenvy, S.A.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.ide.api.editor.text;

/**
 * Range of text described using linear position (ie by character index starting from the text beginning).<br>
 * The range is normalized so that length is always non negative.
 */
public final class LinearRange {

    /** The offset of the start of the range. */
    private final int startOffset;
    /** The length of the range. */
    private final int length;

    private LinearRange(final int startIndex, final int length) {
        this.startOffset = startIndex;
        this.length = length;
    }

    /**
     * Returns the offset of the start of the range.
     * @return the start offset
     */
    public int getStartOffset() {
        return startOffset;
    }

    /**
     * Returns the length the range.<br>
     * The length is guaranteed to be non-negative
     * @return the length
     */
    public int getLength() {
        return length;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + length;
        result = prime * result + startOffset;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        LinearRange other = (LinearRange)obj;
        if (length != other.length) {
            return false;
        }
        if (startOffset != other.startOffset) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "LinearRange [startOffset=" + startOffset + ", length=" + length + "]";
    }

    /**
     * Begins range instantiation with the given range start.
     * @param startOffset the range start
     * @return a {@link PartialLinearRange}
     */
    public static PartialLinearRange createWithStart(final int startOffset) {
        return new PartialLinearRange(startOffset);
    }

    /** Intermediate class for partially initialized {@link LinearRange} instances. */
    public static class PartialLinearRange {

        /** the start offset. */
        private final int startOffset;

        private PartialLinearRange(final int startOffset) {
            this.startOffset = startOffset;
        }

        /**
         * Completes {@link LinearRange} instantiation with the given length.
         * @param length the range length
         * @return the range
         */
        public LinearRange andLength(int length) {
            if (length >= 0) {
                return new LinearRange(this.startOffset, length);
            } else {
                throw new IllegalArgumentException("Incoherent range - start=" + this.startOffset + " length=" + length);
            }
        }

        /**
         * Completes {@link LinearRange} instantiation with the given end.
         * @param length the range end
         * @return the range
         */
        public LinearRange andEnd(int endOffset) {
            if (endOffset > this.startOffset) {
                return new LinearRange(startOffset, endOffset - startOffset);
            } else {
                return new LinearRange(endOffset, startOffset - endOffset);
            }
        }
    
    }
}