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StringEnumeration Class Reference

Base class for 'pure' C++ implementations of uenum api. More...

#include <strenum.h>

Inheritance diagram for StringEnumeration:

UObject UMemory

Public Member Functions

virtual ~StringEnumeration ()
 Destructor.

virtual int32_t count (UErrorCode &status) const=0
virtual const char * next (int32_t *resultLength, UErrorCode &status)=0
virtual const UChar * unext (int32_t *resultLength, UErrorCode &status)=0
virtual const UnicodeStringsnext (UErrorCode &status)=0
virtual void reset (UErrorCode &status)=0

Detailed Description

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.

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.

Strings may take the form of const char*, const UChar*, 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.

The pointers returned by next, unext, and snext become invalid upon any subsequent call to the enumeration's destructor, next, unext, snext, or reset.

ICU 2.4


Constructor & Destructor Documentation

StringEnumeration::~StringEnumeration  )  [inline, virtual]
 

Destructor.

ICU 2.4


Member Function Documentation

virtual int32_t StringEnumeration::count UErrorCode status  )  const [pure virtual]
 

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.

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.

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).

Parameters:
status the error code.
Returns:
number of elements in the iterator.
ICU 2.4

virtual const char* StringEnumeration::next int32_t *  resultLength,
UErrorCode status
[pure virtual]
 

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.

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.

If the iterator is out of sync with its service, status is set to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.

If the native service string is a UChar* 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).

Parameters:
status the error code.
resultLength a pointer to receive the length, can be NULL.
Returns:
a pointer to the string, or NULL.
ICU 2.4

virtual void StringEnumeration::reset UErrorCode status  )  [pure virtual]
 

Resets the iterator. This re-establishes sync with the service and rewinds the iterator to start at the first element.

Previous pointers returned by next, unext, or snext become invalid, and the value returned by count might change.

Parameters:
status the error code.
ICU 2.4

virtual const UnicodeString* StringEnumeration::snext UErrorCode status  )  [pure virtual]
 

Returns the next element a UnicodeString*. If there are no more elements, returns NULL.

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.

If the iterator is out of sync with its service, status is set to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.

Parameters:
status the error code.
Returns:
a pointer to the string, or NULL.
ICU 2.4

virtual const UChar* StringEnumeration::unext int32_t *  resultLength,
UErrorCode status
[pure virtual]
 

Returns the next element as a NUL-terminated UChar*. 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.

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.

If the iterator is out of sync with its service, status is set to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.

Parameters:
status the error code.
resultLength a ponter to receive the length, can be NULL.
Returns:
a pointer to the string, or NULL.
ICU 2.4


The documentation for this class was generated from the following file:
Generated on Wed Sep 3 17:47:22 2003 for ICU 2.6 by doxygen 1.3.2