/* ******************************************************************** * * 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