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/*
**********************************************************************
* Copyright (c) 2002-2008, International Business Machines
* Corporation and others.  All Rights Reserved.
**********************************************************************
*/
#ifndef USETITER_H
#define USETITER_H

#include "unicode/utypes.h"
#include "unicode/uobject.h"
#include "unicode/unistr.h"

/**
 * \file 
 * \brief C++ API: UnicodeSetIterator iterates over the contents of a UnicodeSet.
 */

U_NAMESPACE_BEGIN

class UnicodeSet;
class UnicodeString;

/**
 *
 * UnicodeSetIterator iterates over the contents of a UnicodeSet. It
 * iterates over either code points or code point ranges. After all
 * code points or ranges have been returned, it returns the
 * multicharacter strings of the UnicodeSet, if any.
 *
 * This class is not intended to be subclassed. Consider any fields
 * or methods declared as "protected" to be private. The use of
 * protected in this class is an artifact of history.
 *
 * To iterate over code points and strings, use a loop like this:
 * <pre>
 * UnicodeSetIterator it(set);
 * while (it.next()) {
 * processItem(it.getString());
 * }
 * </pre>
 * Each item in the set is accessed as a string. Set elements
 * consisting of single code points are returned as strings containing
 * just the one code point.
 *
 * To iterate over code point ranges, instead of individual code points,
 * use a loop like this:
 * <pre>
 * UnicodeSetIterator it(set);
 * while (it.nextRange()) {
 * if (it.isString()) {
 * processString(it.getString());
 * } else {
 * processCodepointRange(it.getCodepoint(), it.getCodepointEnd());
 * }
 * }
 * </pre>
 * @author M. Davis
 * @stable ICU 2.4
 */
class U_COMMON_API UnicodeSetIterator : public UObject {

protected:

/**
 * Value of <tt>codepoint</tt> if the iterator points to a string.
 * If <tt>codepoint == IS_STRING</tt>, then examine
 * <tt>string</tt> for the current iteration result.
 * @stable ICU 2.4
 */
 enum { IS_STRING = -1 };

/**
 * Current code point, or the special value <tt>IS_STRING</tt>, if
 * the iterator points to a string.
 * @stable ICU 2.4
 */
 UChar32 codepoint;

/**
 * When iterating over ranges using <tt>nextRange()</tt>,
 * <tt>codepointEnd</tt> contains the inclusive end of the
 * iteration range, if <tt>codepoint != IS_STRING</tt>. If
 * iterating over code points using <tt>next()</tt>, or if
 * <tt>codepoint == IS_STRING</tt>, then the value of
 * <tt>codepointEnd</tt> is undefined.
 * @stable ICU 2.4
 */
 UChar32 codepointEnd;

/**
 * If <tt>codepoint == IS_STRING</tt>, then <tt>string</tt> points
 * to the current string. If <tt>codepoint != IS_STRING</tt>, the
 * value of <tt>string</tt> is undefined.
 * @stable ICU 2.4
 */
 const UnicodeString* string;

public:

/**
 * Create an iterator over the given set. The iterator is valid
 * only so long as <tt>set</tt> is valid.
 * @param set set to iterate over
 * @stable ICU 2.4
 */
 UnicodeSetIterator(const UnicodeSet& set);

/**
 * Create an iterator over nothing. <tt>next()</tt> and
 * <tt>nextRange()</tt> return false. This is a convenience
 * constructor allowing the target to be set later.
 * @stable ICU 2.4
 */
 UnicodeSetIterator();

/**
     * Destructor.
     * @stable ICU 2.4
     */
    virtual ~UnicodeSetIterator();

/**
 * Returns true if the current element is a string. If so, the
 * caller can retrieve it with <tt>getString()</tt>. If this
 * method returns false, the current element is a code point or
 * code point range, depending on whether <tt>next()</tt> or
 * <tt>nextRange()</tt> was called.
 * Elements of types string and codepoint can both be retrieved
 * with the function <tt>getString()</tt>.
 * Elements of type codepoint can also be retrieved with
 * <tt>getCodepoint()</tt>.
 * For ranges, <tt>getCodepoint()</tt> returns the starting codepoint
 * of the range, and <tt>getCodepointEnd()</tt> returns the end
 * of the range.
 * @stable ICU 2.4
 */
 inline UBool isString() const;

/**
 * Returns the current code point, if <tt>isString()</tt> returned
 * false. Otherwise returns an undefined result.
 * @stable ICU 2.4
 */
 inline UChar32 getCodepoint() const;

/**
 * Returns the end of the current code point range, if
 * <tt>isString()</tt> returned false and <tt>nextRange()</tt> was
 * called. Otherwise returns an undefined result.
 * @stable ICU 2.4
 */
 inline UChar32 getCodepointEnd() const;

/**
 * Returns the current string, if <tt>isString()</tt> returned
 * true. If the current iteration item is a code point, a UnicodeString
 * containing that single code point is returned.
 *
 * Ownership of the returned string remains with the iterator.
 * The string is guaranteed to remain valid only until the iterator is
 * advanced to the next item, or until the iterator is deleted.
 * 
 * @stable ICU 2.4
 */
 const UnicodeString& getString();

/**
 * Advances the iteration position to the next element in the set, 
 * which can be either a single code point or a string. 
 * If there are no more elements in the set, return false.
 *
 * 
 * If <tt>isString() == TRUE</tt>, the value is a
 * string, otherwise the value is a
 * single code point. Elements of either type can be retrieved
 * with the function <tt>getString()</tt>, while elements of
 * consisting of a single code point can be retrieved with
 * <tt>getCodepoint()</tt>
 *
 * The order of iteration is all code points in sorted order,
 * followed by all strings sorted order. Do not mix
 * calls to <tt>next()</tt> and <tt>nextRange()</tt> without
 * calling <tt>reset()</tt> between them. The results of doing so
 * are undefined.
 *
 * @return true if there was another element in the set.
 * @stable ICU 2.4
 */
 UBool next();

/**
 * Returns the next element in the set, either a code point range
 * or a string. If there are no more elements in the set, return
 * false. If <tt>isString() == TRUE</tt>, the value is a
 * string and can be accessed with <tt>getString()</tt>. Otherwise the value is a
 * range of one or more code points from <tt>getCodepoint()</tt> to
 * <tt>getCodepointeEnd()</tt> inclusive.
 *
 * The order of iteration is all code points ranges in sorted
 * order, followed by all strings sorted order. Ranges are
 * disjoint and non-contiguous. The value returned from <tt>getString()</tt>
 * is undefined unless <tt>isString() == TRUE</tt>. Do not mix calls to
 * <tt>next()</tt> and <tt>nextRange()</tt> without calling
 * <tt>reset()</tt> between them. The results of doing so are
 * undefined.
 *
 * @return true if there was another element in the set.
 * @stable ICU 2.4
 */
 UBool nextRange();

/**
 * Sets this iterator to visit the elements of the given set and
 * resets it to the start of that set. The iterator is valid only
 * so long as <tt>set</tt> is valid.
 * @param set the set to iterate over.
 * @stable ICU 2.4
 */
 void reset(const UnicodeSet& set);

/**
     * Resets this iterator to the start of the set.
     * @stable ICU 2.4
     */
    void reset();

/**
     * ICU "poor man's RTTI", returns a UClassID for this class.
     *
     * @stable ICU 2.4
     */
    static UClassID U_EXPORT2 getStaticClassID();

/**
     * ICU "poor man's RTTI", returns a UClassID for the actual class.
     *
     * @stable ICU 2.4
     */
    virtual UClassID getDynamicClassID() const;

// ======================= PRIVATES ===========================

protected:

// endElement and nextElements are really UChar32's, but we keep
    // them as signed int32_t's so we can do comparisons with
    // endElement set to -1.  Leave them as int32_t's.
    /** The set
     * @stable ICU 2.4
     */
    const UnicodeSet* set;
    /** End range
     * @stable ICU 2.4
     */
    int32_t endRange;
    /** Range
     * @stable ICU 2.4
     */
    int32_t range;
    /** End element
     * @stable ICU 2.4
     */
    int32_t endElement;
    /** Next element
     * @stable ICU 2.4
     */
    int32_t nextElement;
    //UBool abbreviated;
    /** Next string
     * @stable ICU 2.4
     */
    int32_t nextString;
    /** String count
     * @stable ICU 2.4
     */
    int32_t stringCount;

/**
     *  Points to the string to use when the caller asks for a
     *  string and the current iteration item is a code point, not a string.
     *  @internal
     */
    UnicodeString *cpString;

/** Copy constructor. Disallowed.
     * @stable ICU 2.4
     */
    UnicodeSetIterator(const UnicodeSetIterator&); // disallow

/** Assignment operator. Disallowed.
     * @stable ICU 2.4
     */
    UnicodeSetIterator& operator=(const UnicodeSetIterator&); // disallow

/** Load range
     * @stable ICU 2.4
     */
    virtual void loadRange(int32_t range);

};

inline UBool UnicodeSetIterator::isString() const {
    return codepoint == (UChar32)IS_STRING;
}

inline UChar32 UnicodeSetIterator::getCodepoint() const {
    return codepoint;
}

inline UChar32 UnicodeSetIterator::getCodepointEnd() const {
    return codepointEnd;
}

U_NAMESPACE_END

#endif