/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.lang;

import java.io.Serializable;
import java.util.Iterator;
import java.util.NoSuchElementException;

import org.apache.commons.lang.text.StrBuilder;

A contiguous range of characters, optionally negated.
Instances are immutable.
#ThreadSafe#
Author:
Apache Software Foundation, Chris Feldhacker, Gary Gregory
Since:
1.0
Version:
$Id: CharRange.java 1057072 2011-01-10 01:55:57Z niallp $/**
 * <p>A contiguous range of characters, optionally negated.</p>
 * 
 * <p>Instances are immutable.</p>
 *
 * <p>#ThreadSafe#</p>
 * @author Apache Software Foundation
 * @author Chris Feldhacker
 * @author Gary Gregory
 * @since 1.0
 * @version $Id: CharRange.java 1057072 2011-01-10 01:55:57Z niallp $
 */
public final class CharRange implements Serializable {

    
Required for serialization support. Lang version 2.0. 
See Also:
Serializable/**
     * Required for serialization support. Lang version 2.0. 
     * 
     * @see java.io.Serializable
     */
    private static final long serialVersionUID = 8270183163158333422L;
    
    
The first character, inclusive, in the range. /** The first character, inclusive, in the range. */
    private final char start;
    
The last character, inclusive, in the range. /** The last character, inclusive, in the range. */
    private final char end;
    
True if the range is everything except the characters specified. /** True if the range is everything except the characters specified. */
    private final boolean negated;
    
    
Cached toString. /** Cached toString. */
    private transient String iToString;

    // Static
    //-----------------------------------------------------------------------
    
Constructs a CharRange over a single character.
Params:
ch –  only character in this range
See Also:
CharRange(char, char, boolean)
Returns:
the new CharRange object
Since:
2.5/**
     * <p>Constructs a <code>CharRange</code> over a single character.</p>
     *
     * @param ch  only character in this range
     * @return the new CharRange object
     * @see CharRange#CharRange(char, char, boolean)
     * @since 2.5
     */
    public static CharRange is(char ch) {
        return new CharRange(ch, ch, false);
    }

    
Constructs a negated CharRange over a single character.
Params:
ch –  only character in this range
See Also:
CharRange(char, char, boolean)
Returns:
the new CharRange object
Since:
2.5/**
     * <p>Constructs a negated <code>CharRange</code> over a single character.</p>
     *
     * @param ch  only character in this range
     * @return the new CharRange object
     * @see CharRange#CharRange(char, char, boolean)
     * @since 2.5
     */
    public static CharRange isNot(char ch) {
        return new CharRange(ch, ch, true);
    }

    
Constructs a CharRange over a set of characters.
Params:
start –  first character, inclusive, in this range
end –  last character, inclusive, in this range
See Also:
CharRange(char, char, boolean)
Returns:
the new CharRange object
Since:
2.5/**
     * <p>Constructs a <code>CharRange</code> over a set of characters.</p>
     *
     * @param start  first character, inclusive, in this range
     * @param end  last character, inclusive, in this range
     * @return the new CharRange object
     * @see CharRange#CharRange(char, char, boolean)
     * @since 2.5
     */
    public static CharRange isIn(char start, char end) {
        return new CharRange(start, end, false);
    }

    
Constructs a negated CharRange over a set of characters.
Params:
start –  first character, inclusive, in this range
end –  last character, inclusive, in this range
See Also:
CharRange(char, char, boolean)
Returns:
the new CharRange object
Since:
2.5/**
     * <p>Constructs a negated <code>CharRange</code> over a set of characters.</p>
     *
     * @param start  first character, inclusive, in this range
     * @param end  last character, inclusive, in this range
     * @return the new CharRange object
     * @see CharRange#CharRange(char, char, boolean)
     * @since 2.5
     */
    public static CharRange isNotIn(char start, char end) {
        return new CharRange(start, end, true);
    }

    //-----------------------------------------------------------------------
    
Constructs a CharRange over a single character.
Params:
ch –  only character in this range/**
     * <p>Constructs a <code>CharRange</code> over a single character.</p>
     *
     * @param ch  only character in this range
     */
    public CharRange(char ch) {
        this(ch, ch, false);
    }

    
Constructs a CharRange over a single character,
optionally negating the range.
A negated range includes everything except the specified char.
Params:
ch –  only character in this range
negated –  true to express everything except the range/**
     * <p>Constructs a <code>CharRange</code> over a single character,
     * optionally negating the range.</p>
     *
     * <p>A negated range includes everything except the specified char.</p>
     *
     * @param ch  only character in this range
     * @param negated  true to express everything except the range
     */
    public CharRange(char ch, boolean negated) {
        this(ch, ch, negated);
    }

    
Constructs a CharRange over a set of characters.
Params:
start –  first character, inclusive, in this range
end –  last character, inclusive, in this range/**
     * <p>Constructs a <code>CharRange</code> over a set of characters.</p>
     *
     * @param start  first character, inclusive, in this range
     * @param end  last character, inclusive, in this range
     */
    public CharRange(char start, char end) {
        this(start, end, false);
    }

    
Constructs a CharRange over a set of characters,
optionally negating the range.
A negated range includes everything except that defined by the
start and end characters.
If start and end are in the wrong order, they are reversed.
Thus a-e is the same as e-a.
Params:
start –  first character, inclusive, in this range
end –  last character, inclusive, in this range
negated –  true to express everything except the range/**
     * <p>Constructs a <code>CharRange</code> over a set of characters,
     * optionally negating the range.</p>
     *
     * <p>A negated range includes everything except that defined by the
     * start and end characters.</p>
     * 
     * <p>If start and end are in the wrong order, they are reversed.
     * Thus <code>a-e</code> is the same as <code>e-a</code>.</p>
     *
     * @param start  first character, inclusive, in this range
     * @param end  last character, inclusive, in this range
     * @param negated  true to express everything except the range
     */
    public CharRange(char start, char end, boolean negated) {
        super();
        if (start > end) {
            char temp = start;
            start = end;
            end = temp;
        }
        
        this.start = start;
        this.end = end;
        this.negated = negated;
    }

    // Accessors
    //-----------------------------------------------------------------------
    
Gets the start character for this character range.
Returns:
the start char (inclusive)/**
     * <p>Gets the start character for this character range.</p>
     * 
     * @return the start char (inclusive)
     */
    public char getStart() {
        return this.start;
    }

    
Gets the end character for this character range.
Returns:
the end char (inclusive)/**
     * <p>Gets the end character for this character range.</p>
     * 
     * @return the end char (inclusive)
     */
    public char getEnd() {
        return this.end;
    }

    
Is this CharRange negated.
A negated range includes everything except that defined by the
start and end characters.
Returns:
true is negated/**
     * <p>Is this <code>CharRange</code> negated.</p>
     * 
     * <p>A negated range includes everything except that defined by the
     * start and end characters.</p>
     *
     * @return <code>true</code> is negated
     */
    public boolean isNegated() {
        return negated;
    }

    // Contains
    //-----------------------------------------------------------------------
    
Is the character specified contained in this range.
Params:
ch –  the character to check
Returns:
true if this range contains the input character/**
     * <p>Is the character specified contained in this range.</p>
     *
     * @param ch  the character to check
     * @return <code>true</code> if this range contains the input character
     */
    public boolean contains(char ch) {
        return (ch >= start && ch <= end) != negated;
    }

    
Are all the characters of the passed in range contained in
this range.
Params:
range –  the range to check against
Throws:
IllegalArgumentException – if null input
Returns:
true if this range entirely contains the input range/**
     * <p>Are all the characters of the passed in range contained in
     * this range.</p>
     *
     * @param range  the range to check against
     * @return <code>true</code> if this range entirely contains the input range
     * @throws IllegalArgumentException if <code>null</code> input
     */
    public boolean contains(CharRange range) {
        if (range == null) {
            throw new IllegalArgumentException("The Range must not be null");
        }
        if (negated) {
            if (range.negated) {
                return start >= range.start && end <= range.end;
            }
            return range.end < start || range.start > end;
        }
        if (range.negated) {
            return start == 0 && end == Character.MAX_VALUE;
        }
        return start <= range.start && end >= range.end;
    }

    // Basics
    //-----------------------------------------------------------------------
    
Compares two CharRange objects, returning true if they represent
exactly the same range of characters defined in the same way.
Params:
obj –  the object to compare to
Returns:
true if equal/**
     * <p>Compares two CharRange objects, returning true if they represent
     * exactly the same range of characters defined in the same way.</p>
     * 
     * @param obj  the object to compare to
     * @return true if equal
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (obj instanceof CharRange == false) {
            return false;
        }
        CharRange other = (CharRange) obj;
        return start == other.start && end == other.end && negated == other.negated;
    }

    
Gets a hashCode compatible with the equals method.
Returns:
a suitable hashCode/**
     * <p>Gets a hashCode compatible with the equals method.</p>
     * 
     * @return a suitable hashCode
     */
    public int hashCode() {
        return 83 + start + 7 * end + (negated ? 1 : 0);
    }
    
    
Gets a string representation of the character range.
Returns:
string representation of this range/**
     * <p>Gets a string representation of the character range.</p>
     * 
     * @return string representation of this range
     */
    public String toString() {
        if (iToString == null) {
            StrBuilder buf = new StrBuilder(4);
            if (isNegated()) {
                buf.append('^');
            }
            buf.append(start);
            if (start != end) {
                buf.append('-');
                buf.append(end);
            }
            iToString = buf.toString();
        }
        return iToString;
    }

    // Expansions
    //-----------------------------------------------------------------------
    
Returns an iterator which can be used to walk through the characters described by this range.
#NotThreadSafe# the iterator is not threadsafe
Returns:
an iterator to the chars represented by this range
Since:
2.5/**
     * <p>Returns an iterator which can be used to walk through the characters described by this range.</p>
     *
     * <p>#NotThreadSafe# the iterator is not threadsafe</p>
     * @return an iterator to the chars represented by this range
     * @since 2.5
     */
    public Iterator iterator() {
        return new CharacterIterator(this);
    }

    
Character Iterator. 
#NotThreadSafe#
/**
     * Character {@link Iterator}.
     * <p>#NotThreadSafe#</p>
     */
    private static class CharacterIterator implements Iterator {
        
The current character /** The current character */
        private char current;

        private final CharRange range;
        private boolean hasNext;

        
Construct a new iterator for the character range.
Params:
r – The character range/**
         * Construct a new iterator for the character range.
         *
         * @param r The character range
         */
        private CharacterIterator(CharRange r) {
            range = r;
            hasNext = true;

            if (range.negated) {
                if (range.start == 0) {
                    if (range.end == Character.MAX_VALUE) {
                        // This range is an empty set
                        hasNext = false;
                    } else {
                        current = (char) (range.end + 1);
                    }
                } else {
                    current = 0;
                }
            } else {
                current = range.start;
            }
        }

        
Prepare the next character in the range.
/**
         * Prepare the next character in the range.
         */
        private void prepareNext() {
            if (range.negated) {
                if (current == Character.MAX_VALUE) {
                    hasNext = false;
                } else if (current + 1 == range.start) {
                    if (range.end == Character.MAX_VALUE) {
                        hasNext = false;
                    } else {
                        current = (char) (range.end + 1);
                    }
                } else {
                    current = (char) (current + 1);
                }
            } else if (current < range.end) {
                current = (char) (current + 1);
            } else {
                hasNext = false;
            }
        }

        
Has the iterator not reached the end character yet?
Returns:
true if the iterator has yet to reach the character date/**
         * Has the iterator not reached the end character yet?
         *
         * @return <code>true</code> if the iterator has yet to reach the character date
         */
        public boolean hasNext() {
            return hasNext;
        }

        
Return the next character in the iteration
Returns:
Character for the next character/**
         * Return the next character in the iteration
         *
         * @return <code>Character</code> for the next character
         */
        public Object next() {
            if (hasNext == false) {
                throw new NoSuchElementException();
            }
            char cur = current;
            prepareNext();
            return new Character(cur);
        }

        
Always throws UnsupportedOperationException.
Throws:
UnsupportedOperationException – 
See Also:
Iterator.remove()/**
         * Always throws UnsupportedOperationException.
         *
         * @throws UnsupportedOperationException
         * @see java.util.Iterator#remove()
         */
        public void remove() {
            throw new UnsupportedOperationException();
        }
    }
}