jpayne@69: // © 2016 and later: Unicode, Inc. and others.
jpayne@69: // License & terms of use: http://www.unicode.org/copyright.html
jpayne@69: /*
jpayne@69: *******************************************************************************
jpayne@69: *
jpayne@69: *   Copyright (C) 2002-2012, International Business Machines
jpayne@69: *   Corporation and others.  All Rights Reserved.
jpayne@69: *
jpayne@69: *******************************************************************************
jpayne@69: */
jpayne@69: 
jpayne@69: #ifndef STRENUM_H
jpayne@69: #define STRENUM_H
jpayne@69: 
jpayne@69: #include "unicode/utypes.h"
jpayne@69: 
jpayne@69: #if U_SHOW_CPLUSPLUS_API
jpayne@69: 
jpayne@69: #include "unicode/uobject.h"
jpayne@69: #include "unicode/unistr.h"
jpayne@69: 
jpayne@69: /**
jpayne@69:  * \file 
jpayne@69:  * \brief C++ API: String Enumeration
jpayne@69:  */
jpayne@69:  
jpayne@69: U_NAMESPACE_BEGIN
jpayne@69: 
jpayne@69: /**
jpayne@69:  * Base class for 'pure' C++ implementations of uenum api.  Adds a
jpayne@69:  * method that returns the next UnicodeString since in C++ this can
jpayne@69:  * be a common storage format for strings.
jpayne@69:  *
jpayne@69:  * <p>The model is that the enumeration is over strings maintained by
jpayne@69:  * a 'service.'  At any point, the service might change, invalidating
jpayne@69:  * the enumerator (though this is expected to be rare).  The iterator
jpayne@69:  * returns an error if this has occurred.  Lack of the error is no
jpayne@69:  * guarantee that the service didn't change immediately after the
jpayne@69:  * call, so the returned string still might not be 'valid' on
jpayne@69:  * subsequent use.</p>
jpayne@69:  *
jpayne@69:  * <p>Strings may take the form of const char*, const char16_t*, or const
jpayne@69:  * UnicodeString*.  The type you get is determine by the variant of
jpayne@69:  * 'next' that you call.  In general the StringEnumeration is
jpayne@69:  * optimized for one of these types, but all StringEnumerations can
jpayne@69:  * return all types.  Returned strings are each terminated with a NUL.
jpayne@69:  * Depending on the service data, they might also include embedded NUL
jpayne@69:  * characters, so API is provided to optionally return the true
jpayne@69:  * length, counting the embedded NULs but not counting the terminating
jpayne@69:  * NUL.</p>
jpayne@69:  *
jpayne@69:  * <p>The pointers returned by next, unext, and snext become invalid
jpayne@69:  * upon any subsequent call to the enumeration's destructor, next,
jpayne@69:  * unext, snext, or reset.</p>
jpayne@69:  *
jpayne@69:  * ICU 2.8 adds some default implementations and helper functions
jpayne@69:  * for subclasses.
jpayne@69:  *
jpayne@69:  * @stable ICU 2.4 
jpayne@69:  */
jpayne@69: class U_COMMON_API StringEnumeration : public UObject { 
jpayne@69: public:
jpayne@69:     /**
jpayne@69:      * Destructor.
jpayne@69:      * @stable ICU 2.4
jpayne@69:      */
jpayne@69:     virtual ~StringEnumeration();
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Clone this object, an instance of a subclass of StringEnumeration.
jpayne@69:      * Clones can be used concurrently in multiple threads.
jpayne@69:      * If a subclass does not implement clone(), or if an error occurs,
jpayne@69:      * then NULL is returned.
jpayne@69:      * The caller must delete the clone.
jpayne@69:      *
jpayne@69:      * @return a clone of this object
jpayne@69:      *
jpayne@69:      * @see getDynamicClassID
jpayne@69:      * @stable ICU 2.8
jpayne@69:      */
jpayne@69:     virtual StringEnumeration *clone() const;
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * <p>Return the number of elements that the iterator traverses.  If
jpayne@69:      * the iterator is out of sync with its service, status is set to
jpayne@69:      * U_ENUM_OUT_OF_SYNC_ERROR, and the return value is zero.</p>
jpayne@69:      *
jpayne@69:      * <p>The return value will not change except possibly as a result of
jpayne@69:      * a subsequent call to reset, or if the iterator becomes out of sync.</p>
jpayne@69:      *
jpayne@69:      * <p>This is a convenience function. It can end up being very
jpayne@69:      * expensive as all the items might have to be pre-fetched
jpayne@69:      * (depending on the storage format of the data being
jpayne@69:      * traversed).</p>
jpayne@69:      *
jpayne@69:      * @param status the error code.
jpayne@69:      * @return number of elements in the iterator.
jpayne@69:      *
jpayne@69:      * @stable ICU 2.4 */
jpayne@69:     virtual int32_t count(UErrorCode& status) const = 0;
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * <p>Returns the next element as a NUL-terminated char*.  If there
jpayne@69:      * are no more elements, returns NULL.  If the resultLength pointer
jpayne@69:      * is not NULL, the length of the string (not counting the
jpayne@69:      * terminating NUL) is returned at that address.  If an error
jpayne@69:      * status is returned, the value at resultLength is undefined.</p>
jpayne@69:      *
jpayne@69:      * <p>The returned pointer is owned by this iterator and must not be
jpayne@69:      * deleted by the caller.  The pointer is valid until the next call
jpayne@69:      * to next, unext, snext, reset, or the enumerator's destructor.</p>
jpayne@69:      *
jpayne@69:      * <p>If the iterator is out of sync with its service, status is set
jpayne@69:      * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
jpayne@69:      *
jpayne@69:      * <p>If the native service string is a char16_t* string, it is
jpayne@69:      * converted to char* with the invariant converter.  If the
jpayne@69:      * conversion fails (because a character cannot be converted) then
jpayne@69:      * status is set to U_INVARIANT_CONVERSION_ERROR and the return
jpayne@69:      * value is undefined (though not NULL).</p>
jpayne@69:      *
jpayne@69:      * Starting with ICU 2.8, the default implementation calls snext()
jpayne@69:      * and handles the conversion.
jpayne@69:      * Either next() or snext() must be implemented differently by a subclass.
jpayne@69:      *
jpayne@69:      * @param status the error code.
jpayne@69:      * @param resultLength a pointer to receive the length, can be NULL.
jpayne@69:      * @return a pointer to the string, or NULL.
jpayne@69:      *
jpayne@69:      * @stable ICU 2.4 
jpayne@69:      */
jpayne@69:     virtual const char* next(int32_t *resultLength, UErrorCode& status);
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * <p>Returns the next element as a NUL-terminated char16_t*.  If there
jpayne@69:      * are no more elements, returns NULL.  If the resultLength pointer
jpayne@69:      * is not NULL, the length of the string (not counting the
jpayne@69:      * terminating NUL) is returned at that address.  If an error
jpayne@69:      * status is returned, the value at resultLength is undefined.</p>
jpayne@69:      *
jpayne@69:      * <p>The returned pointer is owned by this iterator and must not be
jpayne@69:      * deleted by the caller.  The pointer is valid until the next call
jpayne@69:      * to next, unext, snext, reset, or the enumerator's destructor.</p>
jpayne@69:      *
jpayne@69:      * <p>If the iterator is out of sync with its service, status is set
jpayne@69:      * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
jpayne@69:      *
jpayne@69:      * Starting with ICU 2.8, the default implementation calls snext()
jpayne@69:      * and handles the conversion.
jpayne@69:      *
jpayne@69:      * @param status the error code.
jpayne@69:      * @param resultLength a ponter to receive the length, can be NULL.
jpayne@69:      * @return a pointer to the string, or NULL.
jpayne@69:      *
jpayne@69:      * @stable ICU 2.4 
jpayne@69:      */
jpayne@69:     virtual const char16_t* unext(int32_t *resultLength, UErrorCode& status);
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * <p>Returns the next element a UnicodeString*.  If there are no
jpayne@69:      * more elements, returns NULL.</p>
jpayne@69:      *
jpayne@69:      * <p>The returned pointer is owned by this iterator and must not be
jpayne@69:      * deleted by the caller.  The pointer is valid until the next call
jpayne@69:      * to next, unext, snext, reset, or the enumerator's destructor.</p>
jpayne@69:      *
jpayne@69:      * <p>If the iterator is out of sync with its service, status is set
jpayne@69:      * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
jpayne@69:      *
jpayne@69:      * Starting with ICU 2.8, the default implementation calls next()
jpayne@69:      * and handles the conversion.
jpayne@69:      * Either next() or snext() must be implemented differently by a subclass.
jpayne@69:      *
jpayne@69:      * @param status the error code.
jpayne@69:      * @return a pointer to the string, or NULL.
jpayne@69:      *
jpayne@69:      * @stable ICU 2.4 
jpayne@69:      */
jpayne@69:     virtual const UnicodeString* snext(UErrorCode& status);
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * <p>Resets the iterator.  This re-establishes sync with the
jpayne@69:      * service and rewinds the iterator to start at the first
jpayne@69:      * element.</p>
jpayne@69:      *
jpayne@69:      * <p>Previous pointers returned by next, unext, or snext become
jpayne@69:      * invalid, and the value returned by count might change.</p>
jpayne@69:      *
jpayne@69:      * @param status the error code.
jpayne@69:      *
jpayne@69:      * @stable ICU 2.4 
jpayne@69:      */
jpayne@69:     virtual void reset(UErrorCode& status) = 0;
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Compares this enumeration to other to check if both are equal
jpayne@69:      *
jpayne@69:      * @param that The other string enumeration to compare this object to
jpayne@69:      * @return TRUE if the enumerations are equal. FALSE if not.
jpayne@69:      * @stable ICU 3.6 
jpayne@69:      */
jpayne@69:     virtual UBool operator==(const StringEnumeration& that)const;
jpayne@69:     /**
jpayne@69:      * Compares this enumeration to other to check if both are not equal
jpayne@69:      *
jpayne@69:      * @param that The other string enumeration to compare this object to
jpayne@69:      * @return TRUE if the enumerations are equal. FALSE if not.
jpayne@69:      * @stable ICU 3.6 
jpayne@69:      */
jpayne@69:     virtual UBool operator!=(const StringEnumeration& that)const;
jpayne@69: 
jpayne@69: protected:
jpayne@69:     /**
jpayne@69:      * UnicodeString field for use with default implementations and subclasses.
jpayne@69:      * @stable ICU 2.8
jpayne@69:      */
jpayne@69:     UnicodeString unistr;
jpayne@69:     /**
jpayne@69:      * char * default buffer for use with default implementations and subclasses.
jpayne@69:      * @stable ICU 2.8
jpayne@69:      */
jpayne@69:     char charsBuffer[32];
jpayne@69:     /**
jpayne@69:      * char * buffer for use with default implementations and subclasses.
jpayne@69:      * Allocated in constructor and in ensureCharsCapacity().
jpayne@69:      * @stable ICU 2.8
jpayne@69:      */
jpayne@69:     char *chars;
jpayne@69:     /**
jpayne@69:      * Capacity of chars, for use with default implementations and subclasses.
jpayne@69:      * @stable ICU 2.8
jpayne@69:      */
jpayne@69:     int32_t charsCapacity;
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Default constructor for use with default implementations and subclasses.
jpayne@69:      * @stable ICU 2.8
jpayne@69:      */
jpayne@69:     StringEnumeration();
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Ensures that chars is at least as large as the requested capacity.
jpayne@69:      * For use with default implementations and subclasses.
jpayne@69:      *
jpayne@69:      * @param capacity Requested capacity.
jpayne@69:      * @param status ICU in/out error code.
jpayne@69:      * @stable ICU 2.8
jpayne@69:      */
jpayne@69:     void ensureCharsCapacity(int32_t capacity, UErrorCode &status);
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Converts s to Unicode and sets unistr to the result.
jpayne@69:      * For use with default implementations and subclasses,
jpayne@69:      * especially for implementations of snext() in terms of next().
jpayne@69:      * This is provided with a helper function instead of a default implementation
jpayne@69:      * of snext() to avoid potential infinite loops between next() and snext().
jpayne@69:      *
jpayne@69:      * For example:
jpayne@69:      * \code
jpayne@69:      * const UnicodeString* snext(UErrorCode& status) {
jpayne@69:      *   int32_t resultLength=0;
jpayne@69:      *   const char *s=next(&resultLength, status);
jpayne@69:      *   return setChars(s, resultLength, status);
jpayne@69:      * }
jpayne@69:      * \endcode
jpayne@69:      *
jpayne@69:      * @param s String to be converted to Unicode.
jpayne@69:      * @param length Length of the string.
jpayne@69:      * @param status ICU in/out error code.
jpayne@69:      * @return A pointer to unistr.
jpayne@69:      * @stable ICU 2.8
jpayne@69:      */
jpayne@69:     UnicodeString *setChars(const char *s, int32_t length, UErrorCode &status);
jpayne@69: };
jpayne@69: 
jpayne@69: U_NAMESPACE_END
jpayne@69: 
jpayne@69: #endif /* U_SHOW_CPLUSPLUS_API */
jpayne@69: 
jpayne@69: /* STRENUM_H */
jpayne@69: #endif