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Diffstat (limited to 'intl/icu/source/common/unicode/strenum.h')
| -rw-r--r-- | intl/icu/source/common/unicode/strenum.h | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/intl/icu/source/common/unicode/strenum.h b/intl/icu/source/common/unicode/strenum.h new file mode 100644 index 000000000..5a33f7f16 --- /dev/null +++ b/intl/icu/source/common/unicode/strenum.h @@ -0,0 +1,278 @@ +// Copyright (C) 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/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 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.</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 clone functions in all subclasses return a base class pointer + * because some compilers do not support covariant (same-as-this) + * return types; cast to the appropriate subclass if necessary. + * 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 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).</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 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.</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 UChar* 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 + +/* STRENUM_H */ +#endif |