1 // Copyright (C) 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
4 *******************************************************************************
6 * Copyright (C) 2009-2011, International Business Machines
7 * Corporation and others. All Rights Reserved.
9 *******************************************************************************
10 * file name: errorcode.h
12 * tab size: 8 (not used)
15 * created on: 2009mar10
16 * created by: Markus W. Scherer
19 #ifndef __ERRORCODE_H__
20 #define __ERRORCODE_H__
24 * \brief C++ API: ErrorCode class intended to make it easier to use
25 * ICU C and C++ APIs from C++ user code.
28 #include "unicode/utypes.h"
29 #include "unicode/uobject.h"
34 * Wrapper class for UErrorCode, with conversion operators for direct use
35 * in ICU C and C++ APIs.
36 * Intended to be used as a base class, where a subclass overrides
37 * the handleFailure() function so that it throws an exception,
38 * does an assert(), logs an error, etc.
39 * This is not an abstract base class. This class can be used and instantiated
40 * by itself, although it will be more useful when subclassed.
43 * - The constructor initializes the internal UErrorCode to U_ZERO_ERROR,
44 * removing one common source of errors.
45 * - Same use in C APIs taking a UErrorCode * (pointer)
46 * and C++ taking UErrorCode & (reference) via conversion operators.
47 * - Possible automatic checking for success when it goes out of scope.
49 * Note: For automatic checking for success in the destructor, a subclass
50 * must implement such logic in its own destructor because the base class
51 * destructor cannot call a subclass function (like handleFailure()).
52 * The ErrorCode base class destructor does nothing.
54 * Note also: While it is possible for a destructor to throw an exception,
55 * it is generally unsafe to do so. This means that in a subclass the destructor
56 * and the handleFailure() function may need to take different actions.
60 * class IcuErrorCode: public icu::ErrorCode {
62 * virtual ~IcuErrorCode() { // should be defined in .cpp as "key function"
63 * // Safe because our handleFailure() does not throw exceptions.
64 * if(isFailure()) { handleFailure(); }
67 * virtual void handleFailure() const {
68 * log_failure(u_errorName(errorCode));
72 * IcuErrorCode error_code;
73 * UConverter *cnv = ucnv_open("Shift-JIS", error_code);
74 * length = ucnv_fromUChars(dest, capacity, src, length, error_code);
76 * // IcuErrorCode destructor checks for success.
81 class U_COMMON_API ErrorCode: public UMemory {
84 * Default constructor. Initializes its UErrorCode to U_ZERO_ERROR.
87 ErrorCode() : errorCode(U_ZERO_ERROR) {}
88 /** Destructor, does nothing. See class documentation for details. @stable ICU 4.2 */
90 /** Conversion operator, returns a reference. @stable ICU 4.2 */
91 operator UErrorCode & () { return errorCode; }
92 /** Conversion operator, returns a pointer. @stable ICU 4.2 */
93 operator UErrorCode * () { return &errorCode; }
94 /** Tests for U_SUCCESS(). @stable ICU 4.2 */
95 UBool isSuccess() const { return U_SUCCESS(errorCode); }
96 /** Tests for U_FAILURE(). @stable ICU 4.2 */
97 UBool isFailure() const { return U_FAILURE(errorCode); }
98 /** Returns the UErrorCode value. @stable ICU 4.2 */
99 UErrorCode get() const { return errorCode; }
100 /** Sets the UErrorCode value. @stable ICU 4.2 */
101 void set(UErrorCode value) { errorCode=value; }
102 /** Returns the UErrorCode value and resets it to U_ZERO_ERROR. @stable ICU 4.2 */
105 * Asserts isSuccess().
106 * In other words, this method checks for a failure code,
107 * and the base class handles it like this:
109 * if(isFailure()) { handleFailure(); }
113 void assertSuccess() const;
115 * Return a string for the UErrorCode value.
116 * The string will be the same as the name of the error code constant
117 * in the UErrorCode enum.
120 const char* errorName() const;
124 * Internal UErrorCode, accessible to subclasses.
127 UErrorCode errorCode;
129 * Called by assertSuccess() if isFailure() is true.
130 * A subclass should override this function to deal with a failure code:
131 * Throw an exception, log an error, terminate the program, or similar.
134 virtual void handleFailure() const {}
139 #endif // __ERRORCODE_H__