codekingpro/portable-devtools

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) 2009-2011, International Business Machines
7*   Corporation and others.  All Rights Reserved.
8*
9*******************************************************************************
10*   file name:  errorcode.h
11*   encoding:   UTF-8
12*   tab size:   8 (not used)
13*   indentation:4
14*
15*   created on: 2009mar10
16*   created by: Markus W. Scherer
17*/
18
19#ifndef __ERRORCODE_H__
20#define __ERRORCODE_H__
21
22/**
23 * \file 
24 * \brief C++ API: ErrorCode class intended to make it easier to use
25 *                 ICU C and C++ APIs from C++ user code.
26 */
27
28#include "unicode/utypes.h"
29
30#if U_SHOW_CPLUSPLUS_API
31
32#include "unicode/uobject.h"
33
34U_NAMESPACE_BEGIN
35
36/**
37 * Wrapper class for UErrorCode, with conversion operators for direct use
38 * in ICU C and C++ APIs.
39 * Intended to be used as a base class, where a subclass overrides
40 * the handleFailure() function so that it throws an exception,
41 * does an assert(), logs an error, etc.
42 * This is not an abstract base class. This class can be used and instantiated
43 * by itself, although it will be more useful when subclassed.
44 *
45 * Features:
46 * - The constructor initializes the internal UErrorCode to U_ZERO_ERROR,
47 *   removing one common source of errors.
48 * - Same use in C APIs taking a UErrorCode * (pointer)
49 *   and C++ taking UErrorCode & (reference) via conversion operators.
50 * - Possible automatic checking for success when it goes out of scope.
51 *
52 * Note: For automatic checking for success in the destructor, a subclass
53 * must implement such logic in its own destructor because the base class
54 * destructor cannot call a subclass function (like handleFailure()).
55 * The ErrorCode base class destructor does nothing.
56 *
57 * Note also: While it is possible for a destructor to throw an exception,
58 * it is generally unsafe to do so. This means that in a subclass the destructor
59 * and the handleFailure() function may need to take different actions.
60 *
61 * Sample code:
62 * \code
63 *   class IcuErrorCode: public icu::ErrorCode {
64 *   public:
65 *     virtual ~IcuErrorCode() {  // should be defined in .cpp as "key function"
66 *       // Safe because our handleFailure() does not throw exceptions.
67 *       if(isFailure()) { handleFailure(); }
68 *     }
69 *   protected:
70 *     virtual void handleFailure() const {
71 *       log_failure(u_errorName(errorCode));
72 *       exit(errorCode);
73 *     }
74 *   };
75 *   IcuErrorCode error_code;
76 *   UConverter *cnv = ucnv_open("Shift-JIS", error_code);
77 *   length = ucnv_fromUChars(dest, capacity, src, length, error_code);
78 *   ucnv_close(cnv);
79 *   // IcuErrorCode destructor checks for success.
80 * \endcode
81 *
82 * @stable ICU 4.2
83 */
84class U_COMMON_API ErrorCode: public UMemory {
85public:
86    /**
87     * Default constructor. Initializes its UErrorCode to U_ZERO_ERROR.
88     * @stable ICU 4.2
89     */
90    ErrorCode() : errorCode(U_ZERO_ERROR) {}
91    /** Destructor, does nothing. See class documentation for details. @stable ICU 4.2 */
92    virtual ~ErrorCode();
93    /** Conversion operator, returns a reference. @stable ICU 4.2 */
94    operator UErrorCode & () { return errorCode; }
95    /** Conversion operator, returns a pointer. @stable ICU 4.2 */
96    operator UErrorCode * () { return &errorCode; }
97    /** Tests for U_SUCCESS(). @stable ICU 4.2 */
98    UBool isSuccess() const { return U_SUCCESS(errorCode); }
99    /** Tests for U_FAILURE(). @stable ICU 4.2 */
100    UBool isFailure() const { return U_FAILURE(errorCode); }
101    /** Returns the UErrorCode value. @stable ICU 4.2 */
102    UErrorCode get() const { return errorCode; }
103    /** Sets the UErrorCode value. @stable ICU 4.2 */
104    void set(UErrorCode value) { errorCode=value; }
105    /** Returns the UErrorCode value and resets it to U_ZERO_ERROR. @stable ICU 4.2 */
106    UErrorCode reset();
107    /**
108     * Asserts isSuccess().
109     * In other words, this method checks for a failure code,
110     * and the base class handles it like this:
111     * \code
112     *   if(isFailure()) { handleFailure(); }
113     * \endcode
114     * @stable ICU 4.4
115     */
116    void assertSuccess() const;
117    /**
118     * Return a string for the UErrorCode value.
119     * The string will be the same as the name of the error code constant
120     * in the UErrorCode enum.
121     * @stable ICU 4.4
122     */
123    const char* errorName() const;
124
125protected:
126    /**
127     * Internal UErrorCode, accessible to subclasses.
128     * @stable ICU 4.2
129     */
130    UErrorCode errorCode;
131    /**
132     * Called by assertSuccess() if isFailure() is true.
133     * A subclass should override this function to deal with a failure code:
134     * Throw an exception, log an error, terminate the program, or similar.
135     * @stable ICU 4.2
136     */
137    virtual void handleFailure() const {}
138};
139
140U_NAMESPACE_END
141
142#endif /* U_SHOW_CPLUSPLUS_API */
143
144#endif  // __ERRORCODE_H__
145