Check in the pristine copy of ICU 4.6...

icu46/source/common/unicode/chariter.h

+/*
+********************************************************************
+*
+*   Copyright (C) 1997-2005, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+********************************************************************
+*/
+
+#ifndef CHARITER_H
+#define CHARITER_H
+
+#include "unicode/utypes.h"
+#include "unicode/uobject.h"
+#include "unicode/unistr.h"
+/**
+ * \file
+ * \brief C++ API: Character Iterator
+ */
+ 
+U_NAMESPACE_BEGIN
+/**
+ * Abstract class that defines an API for forward-only iteration
+ * on text objects.
+ * This is a minimal interface for iteration without random access
+ * or backwards iteration. It is especially useful for wrapping
+ * streams with converters into an object for collation or
+ * normalization.
+ *
+ * <p>Characters can be accessed in two ways: as code units or as
+ * code points.
+ * Unicode code points are 21-bit integers and are the scalar values
+ * of Unicode characters. ICU uses the type UChar32 for them.
+ * Unicode code units are the storage units of a given
+ * Unicode/UCS Transformation Format (a character encoding scheme).
+ * With UTF-16, all code points can be represented with either one
+ * or two code units ("surrogates").
+ * String storage is typically based on code units, while properties
+ * of characters are typically determined using code point values.
+ * Some processes may be designed to work with sequences of code units,
+ * or it may be known that all characters that are important to an
+ * algorithm can be represented with single code units.
+ * Other processes will need to use the code point access functions.</p>
+ *
+ * <p>ForwardCharacterIterator provides nextPostInc() to access
+ * a code unit and advance an internal position into the text object,
+ * similar to a <code>return text[position++]</code>.<br>
+ * It provides next32PostInc() to access a code point and advance an internal
+ * position.</p>
+ *
+ * <p>next32PostInc() assumes that the current position is that of
+ * the beginning of a code point, i.e., of its first code unit.
+ * After next32PostInc(), this will be true again.
+ * In general, access to code units and code points in the same
+ * iteration loop should not be mixed. In UTF-16, if the current position
+ * is on a second code unit (Low Surrogate), then only that code unit
+ * is returned even by next32PostInc().</p>
+ *
+ * <p>For iteration with either function, there are two ways to
+ * check for the end of the iteration. When there are no more
+ * characters in the text object:
+ * <ul>
+ * <li>The hasNext() function returns FALSE.</li>
+ * <li>nextPostInc() and next32PostInc() return DONE
+ *     when one attempts to read beyond the end of the text object.</li>
+ * </ul>
+ *
+ * Example:
+ * \code 
+ * void function1(ForwardCharacterIterator &it) {
+ *     UChar32 c;
+ *     while(it.hasNext()) {
+ *         c=it.next32PostInc();
+ *         // use c
+ *     }
+ * }
+ *
+ * void function1(ForwardCharacterIterator &it) {
+ *     UChar c;
+ *     while((c=it.nextPostInc())!=ForwardCharacterIterator::DONE) {
+ *         // use c
+ *      }
+ *  }
+ * \endcode
+ * </p>
+ *
+ * @stable ICU 2.0
+ */
+class U_COMMON_API ForwardCharacterIterator : public UObject {
+public:
+    /**
+     * Value returned by most of ForwardCharacterIterator's functions
+     * when the iterator has reached the limits of its iteration.
+     * @stable ICU 2.0
+     */
+    enum { DONE = 0xffff };
+    
+    /**
+     * Destructor.  
+     * @stable ICU 2.0
+     */
+    virtual ~ForwardCharacterIterator();
+    
+    /**
+     * Returns true when both iterators refer to the same
+     * character in the same character-storage object.  
+     * @param that The ForwardCharacterIterator to be compared for equality
+     * @return true when both iterators refer to the same
+     * character in the same character-storage object
+     * @stable ICU 2.0
+     */
+    virtual UBool operator==(const ForwardCharacterIterator& that) const = 0;
+    
+    /**
+     * Returns true when the iterators refer to different
+     * text-storage objects, or to different characters in the
+     * same text-storage object.  
+     * @param that The ForwardCharacterIterator to be compared for inequality
+     * @return true when the iterators refer to different
+     * text-storage objects, or to different characters in the
+     * same text-storage object
+     * @stable ICU 2.0
+     */
+    inline UBool operator!=(const ForwardCharacterIterator& that) const;
+    
+    /**
+     * Generates a hash code for this iterator.  
+     * @return the hash code.
+     * @stable ICU 2.0
+     */
+    virtual int32_t hashCode(void) const = 0;
+    
+    /**
+     * Returns a UClassID for this ForwardCharacterIterator ("poor man's
+     * RTTI").<P> Despite the fact that this function is public,
+     * DO NOT CONSIDER IT PART OF CHARACTERITERATOR'S API! 
+     * @return a UClassID for this ForwardCharacterIterator 
+     * @stable ICU 2.0
+     */
+    virtual UClassID getDynamicClassID(void) const = 0;
+    
+    /**
+     * 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 ICU 2.0
+     */
+    virtual UChar         nextPostInc(void) = 0;
+    
+    /**
+     * 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 code point.
+     * @stable ICU 2.0
+     */
+    virtual UChar32       next32PostInc(void) = 0;
+    
+    /**
+     * 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.
+     * @returns FALSE if there are no more code units or code points
+     * at or after the current position in the iteration range.
+     * @stable ICU 2.0
+     */
+    virtual UBool        hasNext() = 0;
+    
+protected:
+    /** Default constructor to be overridden in the implementing class. @stable ICU 2.0*/
+    ForwardCharacterIterator();
+    
+    /** Copy constructor to be overridden in the implementing class. @stable ICU 2.0*/
+    ForwardCharacterIterator(const ForwardCharacterIterator &other);
+    
+    /**
+     * Assignment operator to be overridden in the implementing class.
+     * @stable ICU 2.0
+     */
+    ForwardCharacterIterator &operator=(const ForwardCharacterIterator&) { return *this; }
+};
+
+/**
+ * Abstract class that defines an API for iteration
+ * on text objects.
+ * This is an interface for forward and backward iteration
+ * and random access into a text object.
+ *
+ * <p>The API provides backward compatibility to the Java and older ICU
+ * CharacterIterator classes but extends them significantly:
+ * <ol>
+ * <li>CharacterIterator is now a subclass of ForwardCharacterIterator.</li>
+ * <li>While the old API functions provided forward iteration with
+ *     "pre-increment" semantics, the new one also provides functions
+ *     with "post-increment" semantics. They are more efficient and should
+ *     be the preferred iterator functions for new implementations.
+ *     The backward iteration always had "pre-decrement" semantics, which
+ *     are efficient.</li>
+ * <li>Just like ForwardCharacterIterator, it provides access to
+ *     both code units and code points. Code point access versions are available
+ *     for the old and the new iteration semantics.</li>
+ * <li>There are new functions for setting and moving the current position
+ *     without returning a character, for efficiency.</li>
+ * </ol>
+ *
+ * See ForwardCharacterIterator for examples for using the new forward iteration
+ * functions. For backward iteration, there is also a hasPrevious() function
+ * that can be used analogously to hasNext().
+ * The old functions work as before and are shown below.</p>
+ *
+ * <p>Examples for some of the new functions:</p>
+ *
+ * Forward iteration with hasNext():
+ * \code
+ * void forward1(CharacterIterator &it) {
+ *     UChar32 c;
+ *     for(it.setToStart(); it.hasNext();) {
+ *         c=it.next32PostInc();
+ *         // use c
+ *     }
+ *  }
+ * \endcode
+ * Forward iteration more similar to loops with the old forward iteration,
+ * showing a way to convert simple for() loops:
+ * \code
+ * void forward2(CharacterIterator &it) {
+ *     UChar c;
+ *     for(c=it.firstPostInc(); c!=CharacterIterator::DONE; c=it.nextPostInc()) {
+ *          // use c
+ *      }
+ * }
+ * \endcode
+ * Backward iteration with setToEnd() and hasPrevious():
+ * \code
+ *  void backward1(CharacterIterator &it) {
+ *      UChar32 c;
+ *      for(it.setToEnd(); it.hasPrevious();) {
+ *         c=it.previous32();
+ *          // use c
+ *      }
+ *  }
+ * \endcode
+ * Backward iteration with a more traditional for() loop:
+ * \code
+ * void backward2(CharacterIterator &it) {
+ *     UChar c;
+ *     for(c=it.last(); c!=CharacterIterator::DONE; c=it.previous()) {
+ *         // use c
+ *      }
+ *  }
+ * \endcode
+ *
+ * Example for random access:
+ * \code
+ *  void random(CharacterIterator &it) {
+ *      // set to the third code point from the beginning
+ *      it.move32(3, CharacterIterator::kStart);
+ *      // get a code point from here without moving the position
+ *      UChar32 c=it.current32();
+ *      // get the position
+ *      int32_t pos=it.getIndex();
+ *      // get the previous code unit
+ *      UChar u=it.previous();
+ *      // move back one more code unit
+ *      it.move(-1, CharacterIterator::kCurrent);
+ *      // set the position back to where it was
+ *      // and read the same code point c and move beyond it
+ *      it.setIndex(pos);
+ *      if(c!=it.next32PostInc()) {
+ *          exit(1); // CharacterIterator inconsistent
+ *      }
+ *  }
+ * \endcode
+ *
+ * <p>Examples, especially for the old API:</p>
+ *
+ * Function processing characters, in this example simple output
+ * <pre>
+ * \code
+ *  void processChar( UChar c )
+ *  {
+ *      cout << " " << c;
+ *  }
+ * \endcode
+ * </pre>
+ * Traverse the text from start to finish
+ * <pre> 
+ * \code
+ *  void traverseForward(CharacterIterator& iter)
+ *  {
+ *      for(UChar c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
+ *          processChar(c);
+ *      }
+ *  }
+ * \endcode
+ * </pre>
+ * Traverse the text backwards, from end to start
+ * <pre>
+ * \code
+ *  void traverseBackward(CharacterIterator& iter)
+ *  {
+ *      for(UChar c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) {
+ *          processChar(c);
+ *      }
+ *  }
+ * \endcode
+ * </pre>
+ * Traverse both forward and backward from a given position in the text. 
+ * Calls to notBoundary() in this example represents some additional stopping criteria.
+ * <pre>
+ * \code
+ * void traverseOut(CharacterIterator& iter, int32_t pos)
+ * {
+ *      UChar c;
+ *      for (c = iter.setIndex(pos);
+ *      c != CharacterIterator.DONE && (Unicode::isLetter(c) || Unicode::isDigit(c));
+ *          c = iter.next()) {}
+ *      int32_t end = iter.getIndex();
+ *      for (c = iter.setIndex(pos);
+ *          c != CharacterIterator.DONE && (Unicode::isLetter(c) || Unicode::isDigit(c));
+ *          c = iter.previous()) {}
+ *      int32_t start = iter.getIndex() + 1;
+ *  
+ *      cout << "start: " << start << " end: " << end << endl;
+ *      for (c = iter.setIndex(start); iter.getIndex() < end; c = iter.next() ) {
+ *          processChar(c);
+ *     }
+ *  }
+ * \endcode
+ * </pre>
+ * Creating a StringCharacterIterator and calling the test functions
+ * <pre>
+ * \code
+ *  void CharacterIterator_Example( void )
+ *   {
+ *       cout << endl << "===== CharacterIterator_Example: =====" << endl;
+ *       UnicodeString text("Ein kleiner Satz.");
+ *       StringCharacterIterator iterator(text);
+ *       cout << "----- traverseForward: -----------" << endl;
+ *       traverseForward( iterator );
+ *       cout << endl << endl << "----- traverseBackward: ----------" << endl;
+ *       traverseBackward( iterator );
+ *       cout << endl << endl << "----- traverseOut: ---------------" << endl;
+ *       traverseOut( iterator, 7 );
+ *       cout << endl << endl << "-----" << endl;
+ *   }
+ * \endcode
+ * </pre>
+ *
+ * @stable ICU 2.0
+ */
+class U_COMMON_API CharacterIterator : public ForwardCharacterIterator {
+public:
+    /**
+     * Origin enumeration for the move() and move32() functions.
+     * @stable ICU 2.0
+     */
+    enum EOrigin { kStart, kCurrent, kEnd };
+
+    /**
+     * Returns a pointer to a new CharacterIterator of the same
+     * concrete class as this one, and referring to the same
+     * character in the same text-storage object as this one.  The
+     * caller is responsible for deleting the new clone.  
+     * @return a pointer to a new CharacterIterator
+     * @stable ICU 2.0
+     */
+    virtual CharacterIterator* clone(void) const = 0;
+
+    /**
+     * 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 ICU 2.0
+     */
+    virtual UChar         first(void) = 0;
+
+    /**
+     * 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 ICU 2.0
+     */
+    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 ICU 2.0
+     */
+    virtual UChar32       first32(void) = 0;
+
+    /**
+     * 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 ICU 2.0
+     */
+    virtual UChar32       first32PostInc(void);
+
+    /**
+     * Sets the iterator to refer to the first code unit or code point in its
+     * iteration range. This can be used to begin a forward
+     * iteration with nextPostInc() or next32PostInc().
+     * @return the start position of the iteration range
+     * @stable ICU 2.0
+     */
+    inline int32_t    setToStart();
+
+    /**
+     * 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.
+     * @stable ICU 2.0
+     */
+    virtual UChar         last(void) = 0;
+        
+    /**
+     * 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.
+     * @stable ICU 2.0
+     */
+    virtual UChar32       last32(void) = 0;
+
+    /**
+     * Sets the iterator to the end of its iteration range, just behind
+     * the last code unit or code point. This can be used to begin a backward
+     * iteration with previous() or previous32().
+     * @return the end position of the iteration range
+     * @stable ICU 2.0
+     */
+    inline int32_t    setToEnd();
+
+    /**
+     * 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.  
+     * @param position the "position"-th code unit in the text-storage object
+     * @return the "position"-th code unit.
+     * @stable ICU 2.0
+     */
+    virtual UChar         setIndex(int32_t position) = 0;
+
+    /**
+     * 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).
+     * @param position the "position"-th code unit in the text-storage object
+     * @return the "position"-th code point.
+     * @stable ICU 2.0
+     */
+    virtual UChar32       setIndex32(int32_t position) = 0;
+
+    /**
+     * Returns the code unit the iterator currently refers to. 
+     * @return the current code unit. 
+     * @stable ICU 2.0
+     */
+    virtual UChar         current(void) const = 0;
+        
+    /**
+     * Returns the code point the iterator currently refers to.  
+     * @return the current code point.
+     * @stable ICU 2.0
+     */
+    virtual UChar32       current32(void) const = 0;
+        
+    /**
+     * 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.
+     * @stable ICU 2.0
+     */
+    virtual UChar         next(void) = 0;
+        
+    /**
+     * 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.
+     * @stable ICU 2.0
+     */
+    virtual UChar32       next32(void) = 0;
+        
+    /**
+     * 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.
+     * @stable ICU 2.0
+     */
+    virtual UChar         previous(void) = 0;
+
+    /**
+     * 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. 
+     * @stable ICU 2.0
+     */
+    virtual UChar32       previous32(void) = 0;
+
+    /**
+     * 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, return TRUE otherwise.
+     * @stable ICU 2.0
+     */
+    virtual UBool        hasPrevious() = 0;
+
+    /**
+     * Returns the numeric index in the underlying text-storage
+     * object of the character returned by first().  Since it's
+     * possible to create an iterator that iterates across only
+     * part of a text-storage object, this number isn't
+     * necessarily 0.  
+     * @returns the numeric index in the underlying text-storage
+     * object of the character returned by first().
+     * @stable ICU 2.0
+     */
+    inline int32_t       startIndex(void) const;
+        
+    /**
+     * Returns the numeric index in the underlying text-storage
+     * object of the position immediately BEYOND the character
+     * returned by last().  
+     * @return the numeric index in the underlying text-storage
+     * object of the position immediately BEYOND the character
+     * returned by last().
+     * @stable ICU 2.0
+     */
+    inline int32_t       endIndex(void) const;
+        
+    /**
+     * Returns the numeric index in the underlying text-storage
+     * object of the character the iterator currently refers to
+     * (i.e., the character returned by current()).  
+     * @return the numberic index in the text-storage object of 
+     * the character the iterator currently refers to
+     * @stable ICU 2.0
+     */
+    inline int32_t       getIndex(void) const;
+
+    /**
+     * Returns the length of the entire text in the underlying
+     * text-storage object.
+     * @return the length of the entire text in the text-storage object
+     * @stable ICU 2.0
+     */
+    inline int32_t           getLength() const;
+
+    /**
+     * 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.
+     * @param delta the position relative to origin. A positive delta means forward;
+     * a negative delta means backward.
+     * @param origin Origin enumeration {kStart, kCurrent, kEnd}
+     * @return the new position
+     * @stable ICU 2.0
+     */
+    virtual int32_t      move(int32_t delta, EOrigin origin) = 0;
+
+    /**
+     * 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.
+     * @param delta the position relative to origin. A positive delta means forward;
+     * a negative delta means backward.
+     * @param origin Origin enumeration {kStart, kCurrent, kEnd}
+     * @return the new position
+     * @stable ICU 2.0
+     */
+    virtual int32_t      move32(int32_t delta, EOrigin origin) = 0;
+
+    /**
+     * Copies the text under iteration into the UnicodeString
+     * referred to by "result".  
+     * @param result Receives a copy of the text under iteration.  
+     * @stable ICU 2.0
+     */
+    virtual void            getText(UnicodeString&  result) = 0;
+
+protected:
+    /**
+     * Empty constructor.
+     * @stable ICU 2.0
+     */
+    CharacterIterator();
+
+    /**
+     * Constructor, just setting the length field in this base class.
+     * @stable ICU 2.0
+     */
+    CharacterIterator(int32_t length);
+
+    /**
+     * Constructor, just setting the length and position fields in this base class.
+     * @stable ICU 2.0
+     */
+    CharacterIterator(int32_t length, int32_t position);
+
+    /**
+     * Constructor, just setting the length, start, end, and position fields in this base class.
+     * @stable ICU 2.0
+     */
+    CharacterIterator(int32_t length, int32_t textBegin, int32_t textEnd, int32_t position);
+  
+    /**
+     * Copy constructor.
+     *
+     * @param that The CharacterIterator to be copied
+     * @stable ICU 2.0
+     */
+    CharacterIterator(const CharacterIterator &that);
+
+    /**
+     * Assignment operator.  Sets this CharacterIterator to have the same behavior,
+     * as the one passed in.
+     * @param that The CharacterIterator passed in.
+     * @return the newly set CharacterIterator.
+     * @stable ICU 2.0
+     */
+    CharacterIterator &operator=(const CharacterIterator &that);
+
+    /**
+     * Base class text length field.
+     * Necessary this for correct getText() and hashCode().
+     * @stable ICU 2.0
+     */
+    int32_t textLength;
+
+    /**
+     * Base class field for the current position.
+     * @stable ICU 2.0
+     */
+    int32_t  pos;
+
+    /**
+     * Base class field for the start of the iteration range.
+     * @stable ICU 2.0
+     */
+    int32_t  begin;
+
+    /**
+     * Base class field for the end of the iteration range.
+     * @stable ICU 2.0
+     */
+    int32_t  end;
+};
+
+inline UBool
+ForwardCharacterIterator::operator!=(const ForwardCharacterIterator& that) const {
+    return !operator==(that);
+}
+
+inline int32_t
+CharacterIterator::setToStart() {
+    return move(0, kStart);
+}
+
+inline int32_t
+CharacterIterator::setToEnd() {
+    return move(0, kEnd);
+}
+
+inline int32_t
+CharacterIterator::startIndex(void) const {
+    return begin;
+}
+
+inline int32_t
+CharacterIterator::endIndex(void) const {
+    return end;
+}
+
+inline int32_t
+CharacterIterator::getIndex(void) const {
+    return pos;
+}
+
+inline int32_t
+CharacterIterator::getLength(void) const {
+    return textLength;
+}
+
+U_NAMESPACE_END
+#endif