| /* |
| ******************************************************************** |
| * |
| * Copyright (C) 1997-1999, International Business Machines |
| * Corporation and others. All Rights Reserved. |
| * |
| ******************************************************************** |
| */ |
| |
| #ifndef CHARITER_H |
| #define CHARITER_H |
| |
| #include "unicode/utypes.h" |
| #include "unicode/unistr.h" |
| |
| /** |
| * 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: |
| * <pre> |
| *   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 |
| *   } |
| *   } |
| * </pre></p> |
| */ |
| class U_COMMON_API ForwardCharacterIterator { |
| public: |
| /** |
| * Value returned by most of ForwardCharacterIterator's functions |
| * when the iterator has reached the limits of its iteration. */ |
| enum { DONE = 0xffff }; |
| |
| /** |
| * Destructor. |
| * @stable |
| */ |
| virtual ~ForwardCharacterIterator() {} |
| |
| /** |
| * Returns true when both iterators refer to the same |
| * character in the same character-storage object. |
| * @stable |
| */ |
| 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. |
| * @stable |
| */ |
| inline UBool operator!=(const ForwardCharacterIterator& that) const; |
| |
| /** |
| * Generates a hash code for this iterator. |
| * @stable |
| */ |
| 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! |
| * @stable |
| */ |
| 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. |
| * @draft |
| */ |
| 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. |
| * @draft |
| */ |
| 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. |
| */ |
| virtual UBool hasNext() = 0; |
| |
| protected: |
| ForwardCharacterIterator() {} |
| ForwardCharacterIterator(const ForwardCharacterIterator&) {} |
| 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(): |
| *   void forward1(CharacterIterator &it) { |
| *   UChar32 c; |
| *   for(it.setToStart(); it.hasNext();) { |
| *   c=it.next32PostInc(); |
| *   // use c |
| *   } |
| *   } |
| * |
| * Forward iteration more similar to loops with the old forward iteration, |
| * showing a way to convert simple for() loops: |
| *   void forward2(CharacterIterator &it) { |
| *   UChar c; |
| *   for(c=it.firstPostInc(); c!=CharacterIterator::DONE; c=it.nextPostInc()) { |
| *   // use c |
| *   } |
| *   } |
| * |
| * Backward iteration with setToEnd() and hasPrevious(): |
| *   void backward1(CharacterIterator &it) { |
| *   UChar32 c; |
| *   for(it.setToEnd(); it.hasPrevious();) { |
| *   c=it.previous32(); |
| *   // use c |
| *   } |
| *   } |
| * |
| * Backward iteration with a more traditional for() loop: |
| *   void backward2(CharacterIterator &it) { |
| *   UChar c; |
| *   for(c=it.last(); c!=CharacterIterator::DONE; c=it.previous()) { |
| *   // use c |
| *   } |
| *   } |
| * |
| * Example for random access: |
| *   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 |
| *   } |
| *   } |
| * |
| * <p>Examples, especially for the old API:</p> |
| * |
| * Function processing characters, in this example simple output |
| * <pre> |
| *   void processChar( UChar c ) |
| *   { |
| *   cout << " " << c; |
| *   } |
| * </pre> |
| * Traverse the text from start to finish |
| * <pre> |
| *   void traverseForward(CharacterIterator& iter) |
| *   { |
| *   for(UChar c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) { |
| *   processChar(c); |
| *   } |
| *   } |
| * </pre> |
| * Traverse the text backwards, from end to start |
| * <pre> |
| *   void traverseBackward(CharacterIterator& iter) |
| *   { |
| *   for(UChar c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) { |
| *   processChar(c); |
| *   } |
| *   } |
| * </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> |
| *   void traverseOut(CharacterIterator& iter, UTextOffset pos) |
| *   { |
| *   UChar c; |
| *   for (c = iter.setIndex(pos); |
| *   c != CharacterIterator.DONE && (Unicode::isLetter(c) || Unicode::isDigit(c)); |
| *   c = iter.next()) {} |
| *   UTextOffset end = iter.getIndex(); |
| *   for (c = iter.setIndex(pos); |
| *   c != CharacterIterator.DONE && (Unicode::isLetter(c) || Unicode::isDigit(c)); |
| *   c = iter.previous()) {} |
| *   UTextOffset start = iter.getIndex() + 1; |
| *   |
| *   cout << "start: " << start << " end: " << end << endl; |
| *   for (c = iter.setIndex(start); iter.getIndex() < end; c = iter.next() ) { |
| *   processChar(c); |
| *   } |
| *   } |
| * </pre> |
| * Creating a StringCharacterIterator and calling the test functions |
| * <pre> |
| *   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; |
| *   } |
| * </pre> |
| */ |
| class U_COMMON_API CharacterIterator : public ForwardCharacterIterator { |
| public: |
| /** |
| * Origin enumeration for the move() and move32() functions. |
| */ |
| 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. |
| * @stable |
| */ |
| 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(). |
| * @draft |
| */ |
| 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(). |
| * @draft |
| */ |
| 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. |
| * @draft |
| */ |
| 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(). |
| * @draft |
| */ |
| 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 |
| * @draft |
| */ |
| inline UTextOffset 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(). |
| * @draft |
| */ |
| 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(). |
| * @draft |
| */ |
| 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 |
| * @draft |
| */ |
| inline UTextOffset 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. |
| * @draft |
| */ |
| virtual UChar setIndex(UTextOffset 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). |
| * @draft |
| */ |
| virtual UChar32 setIndex32(UTextOffset position) = 0; |
| |
| /** |
| * Returns the code unit the iterator currently refers to. |
| * @draft |
| */ |
| virtual UChar current(void) const = 0; |
| |
| /** |
| * Returns the code point the iterator currently refers to. |
| * @draft |
| */ |
| 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. |
| * @draft |
| */ |
| 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(). |
| * @draft |
| */ |
| virtual UChar32 next32(void) = 0; |
| |
| /** |
| * Advances to the previous code unit in the iteration rance |
| * (toward startIndex()), and returns that code unit. If there are |
| * no more code units to return, returns DONE. |
| * @draft |
| */ |
| virtual UChar previous(void) = 0; |
| |
| /** |
| * Advances to the previous code point in the iteration rance |
| * (toward startIndex()), and returns that code point. If there are |
| * no more code points to return, returns DONE. |
| * @draft |
| */ |
| 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. |
| */ |
| 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. |
| * @stable |
| */ |
| inline UTextOffset startIndex(void) const; |
| |
| /** |
| * Returns the numeric index in the underlying text-storage |
| * object of the position immediately BEYOND the character |
| * returned by last(). |
| * @stable |
| */ |
| inline UTextOffset 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()). |
| * @stable |
| */ |
| inline UTextOffset getIndex(void) const; |
| |
| /** |
| * Returns the length of the entire text in the underlying |
| * text-storage object. |
| */ |
| 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. |
| * @return the new position |
| */ |
| virtual UTextOffset 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. |
| * @return the new position |
| */ |
| virtual UTextOffset 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 |
| */ |
| virtual void getText(UnicodeString& result) = 0; |
| |
| protected: |
| CharacterIterator() {} |
| CharacterIterator(int32_t length); |
| CharacterIterator(int32_t length, UTextOffset position); |
| CharacterIterator(int32_t length, UTextOffset begin, UTextOffset end, UTextOffset position); |
| CharacterIterator(const CharacterIterator &that); |
| |
| CharacterIterator &operator=(const CharacterIterator &that); |
| |
| int32_t textLength; // need this for correct getText() and hashCode() |
| UTextOffset pos; |
| UTextOffset begin; |
| UTextOffset end; |
| }; |
| |
| inline UBool |
| ForwardCharacterIterator::operator!=(const ForwardCharacterIterator& that) const { |
| return !operator==(that); |
| } |
| |
| inline UTextOffset |
| CharacterIterator::setToStart() { |
| return move(0, kStart); |
| } |
| |
| inline UTextOffset |
| CharacterIterator::setToEnd() { |
| return move(0, kEnd); |
| } |
| |
| inline UTextOffset |
| CharacterIterator::startIndex(void) const { |
| return begin; |
| } |
| |
| inline UTextOffset |
| CharacterIterator::endIndex(void) const { |
| return end; |
| } |
| |
| inline UTextOffset |
| CharacterIterator::getIndex(void) const { |
| return pos; |
| } |
| |
| inline int32_t |
| CharacterIterator::getLength(void) const { |
| return textLength; |
| } |
| |
| #endif |
