Check in the pristine copy of ICU 4.6...

icu46/source/common/unicode/strenum.h

+/*
+*******************************************************************************
+*
+*   Copyright (C) 2002-2007, 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.
+     *
+     * @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>
+     *
+     * @param status the error code.
+     * @return a pointer to the string, or NULL.
+     *
+     * @stable ICU 2.4 
+     */
+    virtual const UnicodeString* snext(UErrorCode& status) = 0;
+
+    /**
+     * <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