// © 2016 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html /* ******************************************************************************* * * Copyright (C) 2002-2012, International Business Machines * Corporation and others. All Rights Reserved. * ******************************************************************************* */ #ifndef STRENUM_H #define STRENUM_H #include "unicode/utypes.h" #if U_SHOW_CPLUSPLUS_API #include "unicode/uobject.h" #include "unicode/unistr.h" /** * \file * \brief C++ API: String Enumeration */ U_NAMESPACE_BEGIN /** * Base class for 'pure' C++ implementations of uenum api. Adds a * method that returns the next UnicodeString since in C++ this can * be a common storage format for strings. * * <p>The model is that the enumeration is over strings maintained by * a 'service.' At any point, the service might change, invalidating * the enumerator (though this is expected to be rare). The iterator * returns an error if this has occurred. Lack of the error is no * guarantee that the service didn't change immediately after the * call, so the returned string still might not be 'valid' on * subsequent use.</p> * * <p>Strings may take the form of const char*, const char16_t*, or const * UnicodeString*. The type you get is determine by the variant of * 'next' that you call. In general the StringEnumeration is * optimized for one of these types, but all StringEnumerations can * return all types. Returned strings are each terminated with a NUL. * Depending on the service data, they might also include embedded NUL * characters, so API is provided to optionally return the true * length, counting the embedded NULs but not counting the terminating * NUL.</p> * * <p>The pointers returned by next, unext, and snext become invalid * upon any subsequent call to the enumeration's destructor, next, * unext, snext, or reset.</p> * * ICU 2.8 adds some default implementations and helper functions * for subclasses. * * @stable ICU 2.4 */ class U_COMMON_API StringEnumeration : public UObject { public: /** * Destructor. * @stable ICU 2.4 */ virtual ~StringEnumeration(); /** * Clone this object, an instance of a subclass of StringEnumeration. * Clones can be used concurrently in multiple threads. * If a subclass does not implement clone(), or if an error occurs, * then NULL is returned. * The caller must delete the clone. * * @return a clone of this object * * @see getDynamicClassID * @stable ICU 2.8 */ virtual StringEnumeration *clone() const; /** * <p>Return the number of elements that the iterator traverses. If * the iterator is out of sync with its service, status is set to * U_ENUM_OUT_OF_SYNC_ERROR, and the return value is zero.</p> * * <p>The return value will not change except possibly as a result of * a subsequent call to reset, or if the iterator becomes out of sync.</p> * * <p>This is a convenience function. It can end up being very * expensive as all the items might have to be pre-fetched * (depending on the storage format of the data being * traversed).</p> * * @param status the error code. * @return number of elements in the iterator. * * @stable ICU 2.4 */ virtual int32_t count(UErrorCode& status) const = 0; /** * <p>Returns the next element as a NUL-terminated char*. If there * are no more elements, returns NULL. If the resultLength pointer * is not NULL, the length of the string (not counting the * terminating NUL) is returned at that address. If an error * status is returned, the value at resultLength is undefined.</p> * * <p>The returned pointer is owned by this iterator and must not be * deleted by the caller. The pointer is valid until the next call * to next, unext, snext, reset, or the enumerator's destructor.</p> * * <p>If the iterator is out of sync with its service, status is set * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p> * * <p>If the native service string is a char16_t* string, it is * converted to char* with the invariant converter. If the * conversion fails (because a character cannot be converted) then * status is set to U_INVARIANT_CONVERSION_ERROR and the return * value is undefined (though not NULL).</p> * * Starting with ICU 2.8, the default implementation calls snext() * and handles the conversion. * Either next() or snext() must be implemented differently by a subclass. * * @param status the error code. * @param resultLength a pointer to receive the length, can be NULL. * @return a pointer to the string, or NULL. * * @stable ICU 2.4 */ virtual const char* next(int32_t *resultLength, UErrorCode& status); /** * <p>Returns the next element as a NUL-terminated char16_t*. If there * are no more elements, returns NULL. If the resultLength pointer * is not NULL, the length of the string (not counting the * terminating NUL) is returned at that address. If an error * status is returned, the value at resultLength is undefined.</p> * * <p>The returned pointer is owned by this iterator and must not be * deleted by the caller. The pointer is valid until the next call * to next, unext, snext, reset, or the enumerator's destructor.</p> * * <p>If the iterator is out of sync with its service, status is set * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p> * * Starting with ICU 2.8, the default implementation calls snext() * and handles the conversion. * * @param status the error code. * @param resultLength a ponter to receive the length, can be NULL. * @return a pointer to the string, or NULL. * * @stable ICU 2.4 */ virtual const char16_t* unext(int32_t *resultLength, UErrorCode& status); /** * <p>Returns the next element a UnicodeString*. If there are no * more elements, returns NULL.</p> * * <p>The returned pointer is owned by this iterator and must not be * deleted by the caller. The pointer is valid until the next call * to next, unext, snext, reset, or the enumerator's destructor.</p> * * <p>If the iterator is out of sync with its service, status is set * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p> * * Starting with ICU 2.8, the default implementation calls next() * and handles the conversion. * Either next() or snext() must be implemented differently by a subclass. * * @param status the error code. * @return a pointer to the string, or NULL. * * @stable ICU 2.4 */ virtual const UnicodeString* snext(UErrorCode& status); /** * <p>Resets the iterator. This re-establishes sync with the * service and rewinds the iterator to start at the first * element.</p> * * <p>Previous pointers returned by next, unext, or snext become * invalid, and the value returned by count might change.</p> * * @param status the error code. * * @stable ICU 2.4 */ virtual void reset(UErrorCode& status) = 0; /** * Compares this enumeration to other to check if both are equal * * @param that The other string enumeration to compare this object to * @return TRUE if the enumerations are equal. FALSE if not. * @stable ICU 3.6 */ virtual UBool operator==(const StringEnumeration& that)const; /** * Compares this enumeration to other to check if both are not equal * * @param that The other string enumeration to compare this object to * @return TRUE if the enumerations are equal. FALSE if not. * @stable ICU 3.6 */ virtual UBool operator!=(const StringEnumeration& that)const; protected: /** * UnicodeString field for use with default implementations and subclasses. * @stable ICU 2.8 */ UnicodeString unistr; /** * char * default buffer for use with default implementations and subclasses. * @stable ICU 2.8 */ char charsBuffer[32]; /** * char * buffer for use with default implementations and subclasses. * Allocated in constructor and in ensureCharsCapacity(). * @stable ICU 2.8 */ char *chars; /** * Capacity of chars, for use with default implementations and subclasses. * @stable ICU 2.8 */ int32_t charsCapacity; /** * Default constructor for use with default implementations and subclasses. * @stable ICU 2.8 */ StringEnumeration(); /** * Ensures that chars is at least as large as the requested capacity. * For use with default implementations and subclasses. * * @param capacity Requested capacity. * @param status ICU in/out error code. * @stable ICU 2.8 */ void ensureCharsCapacity(int32_t capacity, UErrorCode &status); /** * Converts s to Unicode and sets unistr to the result. * For use with default implementations and subclasses, * especially for implementations of snext() in terms of next(). * This is provided with a helper function instead of a default implementation * of snext() to avoid potential infinite loops between next() and snext(). * * For example: * \code * const UnicodeString* snext(UErrorCode& status) { * int32_t resultLength=0; * const char *s=next(&resultLength, status); * return setChars(s, resultLength, status); * } * \endcode * * @param s String to be converted to Unicode. * @param length Length of the string. * @param status ICU in/out error code. * @return A pointer to unistr. * @stable ICU 2.8 */ UnicodeString *setChars(const char *s, int32_t length, UErrorCode &status); }; U_NAMESPACE_END #endif /* U_SHOW_CPLUSPLUS_API */ /* STRENUM_H */ #endif