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Diffstat (limited to 'intl/icu/source/common/unicode/chariter.h')
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diff --git a/intl/icu/source/common/unicode/chariter.h b/intl/icu/source/common/unicode/chariter.h new file mode 100644 index 0000000000..45f4d984c7 --- /dev/null +++ b/intl/icu/source/common/unicode/chariter.h @@ -0,0 +1,734 @@ +// © 2016 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html +/* +******************************************************************** +* +* Copyright (C) 1997-2011, International Business Machines +* Corporation and others. All Rights Reserved. +* +******************************************************************** +*/ + +#ifndef CHARITER_H +#define CHARITER_H + +#include "unicode/utypes.h" + +#if U_SHOW_CPLUSPLUS_API + +#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) { + * char16_t 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 bool 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 bool 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 override = 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 char16_t 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) { + * char16_t 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) { + * char16_t 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 + * char16_t 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( char16_t c ) + * { + * cout << " " << c; + * } + * \endcode + * </pre> + * Traverse the text from start to finish + * <pre> + * \code + * void traverseForward(CharacterIterator& iter) + * { + * for(char16_t 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(char16_t 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) + * { + * char16_t 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 }; + + /** + * Destructor. + * @stable ICU 2.0 + */ + virtual ~CharacterIterator(); + + /** + * 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() 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 char16_t 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 char16_t 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 char16_t 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 char16_t 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 char16_t 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 char16_t 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 char16_t 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 numeric 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 + */ +#ifdef move32 + // One of the system headers right now is sometimes defining a conflicting macro we don't use +#undef move32 +#endif + 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 bool +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 /* U_SHOW_CPLUSPLUS_API */ + +#endif |