Where Online Learning is simpler!

The C and C++ Include Header Files

/usr/include/unicode/strenum.h


$ cat -n /usr/include/unicode/strenum.h

     1	// © 2016 and later: Unicode, Inc. and others.
     2	// License & terms of use: http://www.unicode.org/copyright.html
     3	/*
     4	*******************************************************************************
     5	*
     6	*   Copyright (C) 2002-2012, International Business Machines
     7	*   Corporation and others.  All Rights Reserved.
     8	*
     9	*******************************************************************************
    10	*/
    11	
    12	#ifndef STRENUM_H
    13	#define STRENUM_H
    14	
    15	#include "unicode/utypes.h"
    16	
    17	#if U_SHOW_CPLUSPLUS_API
    18	
    19	#include "unicode/uobject.h"
    20	#include "unicode/unistr.h"
    21	
    22	/**
    23	 * \file 
    24	 * \brief C++ API: String Enumeration
    25	 */
    26	 
    27	U_NAMESPACE_BEGIN
    28	
    29	/**
    30	 * Base class for 'pure' C++ implementations of uenum api.  Adds a
    31	 * method that returns the next UnicodeString since in C++ this can
    32	 * be a common storage format for strings.
    33	 *
    34	 * <p>The model is that the enumeration is over strings maintained by
    35	 * a 'service.'  At any point, the service might change, invalidating
    36	 * the enumerator (though this is expected to be rare).  The iterator
    37	 * returns an error if this has occurred.  Lack of the error is no
    38	 * guarantee that the service didn't change immediately after the
    39	 * call, so the returned string still might not be 'valid' on
    40	 * subsequent use.</p>
    41	 *
    42	 * <p>Strings may take the form of const char*, const char16_t*, or const
    43	 * UnicodeString*.  The type you get is determine by the variant of
    44	 * 'next' that you call.  In general the StringEnumeration is
    45	 * optimized for one of these types, but all StringEnumerations can
    46	 * return all types.  Returned strings are each terminated with a NUL.
    47	 * Depending on the service data, they might also include embedded NUL
    48	 * characters, so API is provided to optionally return the true
    49	 * length, counting the embedded NULs but not counting the terminating
    50	 * NUL.</p>
    51	 *
    52	 * <p>The pointers returned by next, unext, and snext become invalid
    53	 * upon any subsequent call to the enumeration's destructor, next,
    54	 * unext, snext, or reset.</p>
    55	 *
    56	 * ICU 2.8 adds some default implementations and helper functions
    57	 * for subclasses.
    58	 *
    59	 * @stable ICU 2.4 
    60	 */
    61	class U_COMMON_API StringEnumeration : public UObject { 
    62	public:
    63	    /**
    64	     * Destructor.
    65	     * @stable ICU 2.4
    66	     */
    67	    virtual ~StringEnumeration();
    68	
    69	    /**
    70	     * Clone this object, an instance of a subclass of StringEnumeration.
    71	     * Clones can be used concurrently in multiple threads.
    72	     * If a subclass does not implement clone(), or if an error occurs,
    73	     * then nullptr is returned.
    74	     * The caller must delete the clone.
    75	     *
    76	     * @return a clone of this object
    77	     *
    78	     * @see getDynamicClassID
    79	     * @stable ICU 2.8
    80	     */
    81	    virtual StringEnumeration *clone() const;
    82	
    83	    /**
    84	     * <p>Return the number of elements that the iterator traverses.  If
    85	     * the iterator is out of sync with its service, status is set to
    86	     * U_ENUM_OUT_OF_SYNC_ERROR, and the return value is zero.</p>
    87	     *
    88	     * <p>The return value will not change except possibly as a result of
    89	     * a subsequent call to reset, or if the iterator becomes out of sync.</p>
    90	     *
    91	     * <p>This is a convenience function. It can end up being very
    92	     * expensive as all the items might have to be pre-fetched
    93	     * (depending on the storage format of the data being
    94	     * traversed).</p>
    95	     *
    96	     * @param status the error code.
    97	     * @return number of elements in the iterator.
    98	     *
    99	     * @stable ICU 2.4 */
   100	    virtual int32_t count(UErrorCode& status) const = 0;
   101	
   102	    /**
   103	     * <p>Returns the next element as a NUL-terminated char*.  If there
   104	     * are no more elements, returns nullptr.  If the resultLength pointer
   105	     * is not nullptr, the length of the string (not counting the
   106	     * terminating NUL) is returned at that address.  If an error
   107	     * status is returned, the value at resultLength is undefined.</p>
   108	     *
   109	     * <p>The returned pointer is owned by this iterator and must not be
   110	     * deleted by the caller.  The pointer is valid until the next call
   111	     * to next, unext, snext, reset, or the enumerator's destructor.</p>
   112	     *
   113	     * <p>If the iterator is out of sync with its service, status is set
   114	     * to U_ENUM_OUT_OF_SYNC_ERROR and nullptr is returned.</p>
   115	     *
   116	     * <p>If the native service string is a char16_t* string, it is
   117	     * converted to char* with the invariant converter.  If the
   118	     * conversion fails (because a character cannot be converted) then
   119	     * status is set to U_INVARIANT_CONVERSION_ERROR and the return
   120	     * value is undefined (though not nullptr).</p>
   121	     *
   122	     * Starting with ICU 2.8, the default implementation calls snext()
   123	     * and handles the conversion.
   124	     * Either next() or snext() must be implemented differently by a subclass.
   125	     *
   126	     * @param status the error code.
   127	     * @param resultLength a pointer to receive the length, can be nullptr.
   128	     * @return a pointer to the string, or nullptr.
   129	     *
   130	     * @stable ICU 2.4 
   131	     */
   132	    virtual const char* next(int32_t *resultLength, UErrorCode& status);
   133	
   134	    /**
   135	     * <p>Returns the next element as a NUL-terminated char16_t*.  If there
   136	     * are no more elements, returns nullptr.  If the resultLength pointer
   137	     * is not nullptr, the length of the string (not counting the
   138	     * terminating NUL) is returned at that address.  If an error
   139	     * status is returned, the value at resultLength is undefined.</p>
   140	     *
   141	     * <p>The returned pointer is owned by this iterator and must not be
   142	     * deleted by the caller.  The pointer is valid until the next call
   143	     * to next, unext, snext, reset, or the enumerator's destructor.</p>
   144	     *
   145	     * <p>If the iterator is out of sync with its service, status is set
   146	     * to U_ENUM_OUT_OF_SYNC_ERROR and nullptr is returned.</p>
   147	     *
   148	     * Starting with ICU 2.8, the default implementation calls snext()
   149	     * and handles the conversion.
   150	     *
   151	     * @param status the error code.
   152	     * @param resultLength a pointer to receive the length, can be nullptr.
   153	     * @return a pointer to the string, or nullptr.
   154	     *
   155	     * @stable ICU 2.4 
   156	     */
   157	    virtual const char16_t* unext(int32_t *resultLength, UErrorCode& status);
   158	
   159	    /**
   160	     * <p>Returns the next element a UnicodeString*.  If there are no
   161	     * more elements, returns nullptr.</p>
   162	     *
   163	     * <p>The returned pointer is owned by this iterator and must not be
   164	     * deleted by the caller.  The pointer is valid until the next call
   165	     * to next, unext, snext, reset, or the enumerator's destructor.</p>
   166	     *
   167	     * <p>If the iterator is out of sync with its service, status is set
   168	     * to U_ENUM_OUT_OF_SYNC_ERROR and nullptr is returned.</p>
   169	     *
   170	     * Starting with ICU 2.8, the default implementation calls next()
   171	     * and handles the conversion.
   172	     * Either next() or snext() must be implemented differently by a subclass.
   173	     *
   174	     * @param status the error code.
   175	     * @return a pointer to the string, or nullptr.
   176	     *
   177	     * @stable ICU 2.4 
   178	     */
   179	    virtual const UnicodeString* snext(UErrorCode& status);
   180	
   181	    /**
   182	     * <p>Resets the iterator.  This re-establishes sync with the
   183	     * service and rewinds the iterator to start at the first
   184	     * element.</p>
   185	     *
   186	     * <p>Previous pointers returned by next, unext, or snext become
   187	     * invalid, and the value returned by count might change.</p>
   188	     *
   189	     * @param status the error code.
   190	     *
   191	     * @stable ICU 2.4 
   192	     */
   193	    virtual void reset(UErrorCode& status) = 0;
   194	
   195	    /**
   196	     * Compares this enumeration to other to check if both are equal
   197	     *
   198	     * @param that The other string enumeration to compare this object to
   199	     * @return true if the enumerations are equal. false if not.
   200	     * @stable ICU 3.6 
   201	     */
   202	    virtual bool operator==(const StringEnumeration& that)const;
   203	    /**
   204	     * Compares this enumeration to other to check if both are not equal
   205	     *
   206	     * @param that The other string enumeration to compare this object to
   207	     * @return true if the enumerations are equal. false if not.
   208	     * @stable ICU 3.6 
   209	     */
   210	    virtual bool operator!=(const StringEnumeration& that)const;
   211	
   212	protected:
   213	    /**
   214	     * UnicodeString field for use with default implementations and subclasses.
   215	     * @stable ICU 2.8
   216	     */
   217	    UnicodeString unistr;
   218	    /**
   219	     * char * default buffer for use with default implementations and subclasses.
   220	     * @stable ICU 2.8
   221	     */
   222	    char charsBuffer[32];
   223	    /**
   224	     * char * buffer for use with default implementations and subclasses.
   225	     * Allocated in constructor and in ensureCharsCapacity().
   226	     * @stable ICU 2.8
   227	     */
   228	    char *chars;
   229	    /**
   230	     * Capacity of chars, for use with default implementations and subclasses.
   231	     * @stable ICU 2.8
   232	     */
   233	    int32_t charsCapacity;
   234	
   235	    /**
   236	     * Default constructor for use with default implementations and subclasses.
   237	     * @stable ICU 2.8
   238	     */
   239	    StringEnumeration();
   240	
   241	    /**
   242	     * Ensures that chars is at least as large as the requested capacity.
   243	     * For use with default implementations and subclasses.
   244	     *
   245	     * @param capacity Requested capacity.
   246	     * @param status ICU in/out error code.
   247	     * @stable ICU 2.8
   248	     */
   249	    void ensureCharsCapacity(int32_t capacity, UErrorCode &status);
   250	
   251	    /**
   252	     * Converts s to Unicode and sets unistr to the result.
   253	     * For use with default implementations and subclasses,
   254	     * especially for implementations of snext() in terms of next().
   255	     * This is provided with a helper function instead of a default implementation
   256	     * of snext() to avoid potential infinite loops between next() and snext().
   257	     *
   258	     * For example:
   259	     * \code
   260	     * const UnicodeString* snext(UErrorCode& status) {
   261	     *   int32_t resultLength=0;
   262	     *   const char *s=next(&resultLength, status);
   263	     *   return setChars(s, resultLength, status);
   264	     * }
   265	     * \endcode
   266	     *
   267	     * @param s String to be converted to Unicode.
   268	     * @param length Length of the string.
   269	     * @param status ICU in/out error code.
   270	     * @return A pointer to unistr.
   271	     * @stable ICU 2.8
   272	     */
   273	    UnicodeString *setChars(const char *s, int32_t length, UErrorCode &status);
   274	};
   275	
   276	U_NAMESPACE_END
   277	
   278	#endif /* U_SHOW_CPLUSPLUS_API */
   279	
   280	/* STRENUM_H */
   281	#endif