source/common/unicode/strenum.h - external/github.com/unicode-org/icu - Git at Google

 /*
 *******************************************************************************
 *
 *   Copyright (C) 2002-2005, 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;

 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
	/*
	*******************************************************************************
	*
	* Copyright (C) 2002-2005, 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;

	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