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// © 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"
#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 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 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(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 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 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