/*
**********************************************************************
*   Copyright (C) 1998-2001, International Business Machines
*   Corporation and others.  All Rights Reserved.
**********************************************************************
*/

#ifndef UCHRITER_H
#define UCHRITER_H

#include "unicode/utypes.h"
#include "unicode/chariter.h"

U_NAMESPACE_BEGIN

/**
 * A concrete subclass of CharacterIterator that iterates over the
 * characters (code units or code points) in a UChar array.
 * It's possible not only to create an
 * iterator that iterates over an entire UChar array, but also to
 * create one that iterates over only a subrange of a UChar array
 * (iterators over different subranges of the same UChar array don't
 * compare equal).
 * @see CharacterIterator
 * @see ForwardCharacterIterator
 * @stable
 */
class U_COMMON_API UCharCharacterIterator : public CharacterIterator {
public:
  /**
   * Create an iterator over the UChar array referred to by "textPtr".
   * The iteration range is 0 to <code>length-1</code>.
   * text is only aliased, not adopted (the
   * destructor will not delete it).
   * @param textPtr The UChar array to be iterated over
   * @param length The length of the UChar array
   * @stable
   */
  UCharCharacterIterator(const UChar* textPtr, int32_t length);

  /**
   * Create an iterator over the UChar array referred to by "textPtr".
   * The iteration range is 0 to <code>length-1</code>.
   * text is only aliased, not adopted (the
   * destructor will not delete it).
   * The starting
   * position is specified by "position". If "position" is outside the valid
   * iteration range, the behavior of this object is undefined.
   * @param textPtr The UChar array to be iteratd over
   * @param length The length of the UChar array
   * @param position The starting position of the iteration
   * @stable
   */
  UCharCharacterIterator(const UChar* textPtr, int32_t length,
                         int32_t position);

  /**
   * Create an iterator over the UChar array referred to by "textPtr".
   * The iteration range is 0 to <code>end-1</code>.
   * text is only aliased, not adopted (the
   * destructor will not delete it).
   * The starting
   * position is specified by "position". If begin and end do not
   * form a valid iteration range or "position" is outside the valid
   * iteration range, the behavior of this object is undefined.
   * @param textPtr The UChar array to be iterated over
   * @param length The length of the UChar array
   * @param textBegin  The begin position of the iteration range
   * @param textEnd    The end position of the iteration range
   * @param position    The starting position of the iteration
   * @stable
   */
  UCharCharacterIterator(const UChar* textPtr, int32_t length,
                         int32_t textBegin,
                         int32_t textEnd,
                         int32_t position);

  /**
   * Copy constructor.  The new iterator iterates over the same range
   * of the same string as "that", and its initial position is the
   * same as "that"'s current position.  
   * @param that The UCharCharacterIterator to be copied
   * @stable
   */
  UCharCharacterIterator(const UCharCharacterIterator&  that);

  /**
   * Destructor. 
   * @stable
   */
  ~UCharCharacterIterator();

  /**
   * Assignment operator.  *this is altered to iterate over the sane
   * range of the same string as "that", and refers to the same
   * character within that string as "that" does. 
   * @param that The object to be copied
   * @return the newly created object 
   * @stable
   */
  UCharCharacterIterator&
  operator=(const UCharCharacterIterator&    that);

  /**
   * Returns true if the iterators iterate over the same range of the
   * same string and are pointing at the same character.  
   * @param that The ForwardCharacterIterator used to be compared for equality
   * @return true if the iterators iterate over the same range of the
   * same string and are pointing at the same character.
   * @stable
   */
  virtual UBool          operator==(const ForwardCharacterIterator& that) const;

  /**
   * Generates a hash code for this iterator.  
   * @return the hash code.
   * @stable
   */
  virtual int32_t         hashCode(void) const;

  /**
   * Returns a new UCharCharacterIterator referring to the same
   * character in the same range of the same string as this one.  The
   * caller must delete the new iterator.  
   * @return the CharacterIterator newly created
   * @stable
   */
  virtual CharacterIterator* clone(void) const;
                                
  /**
   * Sets the iterator to refer to the first code unit in its
   * iteration range, and returns that code unit.
   * This can be used to begin an iteration with next().
   * @return the first code unit in its iteration range.
   * @stable
   */
  virtual UChar         first(void);

  /**
   * Sets the iterator to refer to the first code unit in its
   * iteration range, returns that code unit, and moves the position
   * to the second code unit. This is an alternative to setToStart()
   * for forward iteration with nextPostInc().
   * @return the first code unit in its iteration range
   * @stable
   */
  virtual UChar         firstPostInc(void);

  /**
   * Sets the iterator to refer to the first code point in its
   * iteration range, and returns that code unit,
   * This can be used to begin an iteration with next32().
   * Note that an iteration with next32PostInc(), beginning with,
   * e.g., setToStart() or firstPostInc(), is more efficient.
   * @return the first code point in its iteration range
   * @stable
   */
  virtual UChar32       first32(void);

  /**
   * Sets the iterator to refer to the first code point in its
   * iteration range, returns that code point, and moves the position
   * to the second code point. This is an alternative to setToStart()
   * for forward iteration with next32PostInc().
   * @return the first code point in its iteration range.
   * @stable
   */
  virtual UChar32       first32PostInc(void);

  /**
   * Sets the iterator to refer to the last code unit in its
   * iteration range, and returns that code unit.
   * This can be used to begin an iteration with previous().
   * @return the last code unit in its iteration range.
   * @stable
   */
  virtual UChar         last(void);

  /**
   * Sets the iterator to refer to the last code point in its
   * iteration range, and returns that code unit.
   * This can be used to begin an iteration with previous32().
   * @return the last code point in its iteration range.
   * @stable
   */
  virtual UChar32       last32(void);

  /**
   * Sets the iterator to refer to the "position"-th code unit
   * in the text-storage object the iterator refers to, and
   * returns that code unit.  
   * @position the position within the text-storage object
   * @return the code unit
   * @stable
   */
  virtual UChar         setIndex(int32_t position);

  /**
   * Sets the iterator to refer to the beginning of the code point
   * that contains the "position"-th code unit
   * in the text-storage object the iterator refers to, and
   * returns that code point.
   * The current position is adjusted to the beginning of the code point
   * (its first code unit).
   * @position the position within the text-storage object
   * @return the code unit
   * @stable
   */
  virtual UChar32       setIndex32(int32_t position);

  /**
   * Returns the code unit the iterator currently refers to.  
   * @return the code unit the iterator currently refers to.
   * @stable
   */
  virtual UChar         current(void) const;

  /**
   * Returns the code point the iterator currently refers to.  
   * @return the code point the iterator currently refers to.
   * @stable
   */
  virtual UChar32       current32(void) const;

  /**
   * Advances to the next code unit in the iteration range (toward
   * endIndex()), and returns that code unit.  If there are no more
   * code units to return, returns DONE. 
   * @return the next code unit in the iteration range. 
   * @stable
   */
  virtual UChar         next(void);

  /**
   * Gets the current code unit for returning and advances to the next code unit
   * in the iteration range
   * (toward endIndex()).  If there are
   * no more code units to return, returns DONE.
   * @return the current code unit.
   * @stable
   */
  virtual UChar         nextPostInc(void);
        
  /**
   * Advances to the next code point in the iteration range (toward
   * endIndex()), and returns that code point.  If there are no more
   * code points to return, returns DONE.  
   * Note that iteration with "pre-increment" semantics is less
   * efficient than iteration with "post-increment" semantics
   * that is provided by next32PostInc().
   * @return the next code point in the iteration range.
   * @stable
   */
  virtual UChar32       next32(void);

  /**
   * Gets the current code point for returning and advances to the next code point
   * in the iteration range
   * (toward endIndex()).  If there are
   * no more code points to return, returns DONE.
   * @return the current point.
   * @stable
   */
  virtual UChar32       next32PostInc(void);
        
  /**
   * Returns FALSE if there are no more code units or code points
   * at or after the current position in the iteration range.
   * This is used with nextPostInc() or next32PostInc() in forward
   * iteration.
   * @return FALSE if there are no more code units or code points
   * at or after the current position in the iteration range.
   * @stable
   */
  virtual UBool        hasNext();

  /**
   * Advances to the previous code unit in the iteration range (toward
   * startIndex()), and returns that code unit.  If there are no more
   * code units to return, returns DONE.  
   * @return the previous code unit in the iteration range.
   * @stable
   */
  virtual UChar         previous(void);

  /**
   * Advances to the previous code point in the iteration range (toward
   * startIndex()), and returns that code point.  If there are no more
   * code points to return, returns DONE.
   * @return the previous code point in the iteration range.  
   * @stable
   */
  virtual UChar32       previous32(void);

  /**
   * Returns FALSE if there are no more code units or code points
   * before the current position in the iteration range.
   * This is used with previous() or previous32() in backward
   * iteration.
   * @return FALSE if there are no more code units or code points
   * before the current position in the iteration range.
   * @stable
   */
  virtual UBool        hasPrevious();

  /**
   * Moves the current position relative to the start or end of the
   * iteration range, or relative to the current position itself.
   * The movement is expressed in numbers of code units forward
   * or backward by specifying a positive or negative delta.
   * @delta the position relative to origin. A positive delta means forward;
   * a negative delta means backward.
   * @origin Origin enumeration {kStart, kCurrent, kEnd}
   * @return the new position
   * @stable
   */
  virtual int32_t      move(int32_t delta, EOrigin origin);

  /**
   * Moves the current position relative to the start or end of the
   * iteration range, or relative to the current position itself.
   * The movement is expressed in numbers of code points forward
   * or backward by specifying a positive or negative delta.
   * @delta the position relative to origin. A positive delta means forward;
   * a negative delta means backward.
   * @origin Origin enumeration {kStart, kCurrent, kEnd}
   * @return the new position
   * @stable
   */
  virtual int32_t      move32(int32_t delta, EOrigin origin);

  /**
   * Sets the iterator to iterate over a new range of text
   * @stable
   */
  void setText(const UChar* newText, int32_t newTextLength);
  
  /**
   * Copies the UChar array under iteration into the UnicodeString
   * referred to by "result".  Even if this iterator iterates across
   * only a part of this string, the whole string is copied.
   * @param result Receives a copy of the text under iteration.  
   * @stable
   */
  virtual void            getText(UnicodeString& result);

  /**
   * Return a class ID for this object (not really public) 
   * @return a class ID for this object.  
   * @stable
   */
  virtual UClassID         getDynamicClassID(void) const 
    { return getStaticClassID(); }

  /**
   * Return a class ID for this class (not really public) 
   * @return a class ID for this class  
   * @stable
   */
  static UClassID          getStaticClassID(void) 
    { return (UClassID)(&fgClassID); }

protected:
  UCharCharacterIterator();
        
  const UChar*            text;

private:
  static const char       fgClassID;
};

U_NAMESPACE_END
#endif
