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/*
*******************************************************************************
*
* Copyright (C) 2009, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
* file name: errorcode.h
* encoding: US-ASCII
* tab size: 8 (not used)
* indentation:4
*
* created on: 2009mar10
* created by: Markus W. Scherer
*/
#ifndef __ERRORCODE_H__
#define __ERRORCODE_H__
/**
* \file
* \brief C++ API: ErrorCode class intended to make it easier to use
* ICU C and C++ APIs from C++ user code.
*/
#include "unicode/utypes.h"
#include "unicode/uobject.h"
U_NAMESPACE_BEGIN
/**
* Wrapper class for UErrorCode, with conversion operators for direct use
* in ICU C and C++ APIs.
* Intended to be used as a base class, where a subclass overrides
* the handleFailure() function so that it throws an exception,
* does an assert(), logs an error, etc.
* This is not an abstract base class. This class can be used and instantiated
* by itself, although it will be more useful when subclassed.
*
* Features:
* - The constructor initializes the internal UErrorCode to U_ZERO_ERROR,
* removing one common source of errors.
* - Same use in C APIs taking a UErrorCode * (pointer)
* and C++ taking UErrorCode & (reference) via conversion operators.
* - Possible automatic checking for success when it goes out of scope.
*
* Note: For automatic checking for success in the destructor, a subclass
* must implement such logic in its own destructor because the base class
* destructor cannot call a subclass function (like handleFailure()).
* The ErrorCode base class destructor does nothing.
*
* Note also: While it is possible for a destructor to throw an exception,
* it is generally unsafe to do so. This means that in a subclass the destructor
* and the handleFailure() function may need to take different actions.
*
* Sample code:
* \code
* class IcuErrorCode: public icu::ErrorCode {
* public:
* virtual ~IcuErrorCode() {
* // Safe because our handleFailure() does not throw exceptions.
* if(isFailure()) { handleFailure(); }
* }
* protected:
* virtual handleFailure() {
* log_failure(u_errorName(errorCode));
* exit(errorCode);
* }
* };
* IcuErrorCode error_code;
* UConverter *cnv = ucnv_open("Shift-JIS", error_code);
* length = ucnv_fromUChars(dest, capacity, src, length, error_code);
* ucnv_close(cnv);
* // IcuErrorCode destructor checks for success.
* \endcode
*
* @draft ICU 4.2
*/
class U_COMMON_API ErrorCode: public UMemory {
public:
/**
* Default constructor. Initializes its UErrorCode to U_ZERO_ERROR.
* @draft ICU 4.2
*/
ErrorCode() : errorCode(U_ZERO_ERROR) {}
/** Destructor, does nothing. See class documentation for details. @draft ICU 4.2 */
virtual ~ErrorCode() {}
/** Conversion operator, returns a reference. @draft ICU 4.2 */
operator UErrorCode & () { return errorCode; }
/** Conversion operator, returns a pointer. @draft ICU 4.2 */
operator UErrorCode * () { return &errorCode; }
/** Tests for U_SUCCESS(). @draft ICU 4.2 */
UBool isSuccess() const { return U_SUCCESS(errorCode); }
/** Tests for U_FAILURE(). @draft ICU 4.2 */
UBool isFailure() const { return U_FAILURE(errorCode); }
/** Returns the UErrorCode value. @draft ICU 4.2 */
UErrorCode get() const { return errorCode; }
/** Sets the UErrorCode value. @draft ICU 4.2 */
void set(UErrorCode value) { errorCode=value; }
/** Returns the UErrorCode value and resets it to U_ZERO_ERROR. @draft ICU 4.2 */
UErrorCode reset();
/**
* Checks for a failure code:
* \code
* if(isFailure()) { handleFailure(); }
* \endcode
* @draft ICU 4.2
*/
void check() const;
protected:
/**
* Internal UErrorCode, accessible to subclasses.
* @draft ICU 4.2
*/
UErrorCode errorCode;
/**
* Called by check() if isFailure() is true.
* A subclass should override this function to deal with a failure code:
* Throw an exception, log an error, terminate the program, or similar.
* @draft ICU 4.2
*/
virtual void handleFailure() const {}
};
U_NAMESPACE_END
#endif // __ERRORCODE_H__