1 | /**************************************************************************** |
2 | * |
3 | * pserror.h |
4 | * |
5 | * Adobe's code for error handling (specification). |
6 | * |
7 | * Copyright 2006-2013 Adobe Systems Incorporated. |
8 | * |
9 | * This software, and all works of authorship, whether in source or |
10 | * object code form as indicated by the copyright notice(s) included |
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13 | * LICENSE.TXT. Additionally, subject to the terms and conditions of the |
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36 | */ |
37 | |
38 | |
39 | #ifndef PSERROR_H_ |
40 | #define PSERROR_H_ |
41 | |
42 | |
43 | #include FT_MODULE_ERRORS_H |
44 | |
45 | #undef FTERRORS_H_ |
46 | |
47 | #undef FT_ERR_PREFIX |
48 | #define FT_ERR_PREFIX CF2_Err_ |
49 | #define FT_ERR_BASE FT_Mod_Err_CF2 |
50 | |
51 | |
52 | #include FT_ERRORS_H |
53 | #include "psft.h" |
54 | |
55 | |
56 | FT_BEGIN_HEADER |
57 | |
58 | |
59 | /* |
60 | * A poor-man error facility. |
61 | * |
62 | * This code being written in vanilla C, doesn't have the luxury of a |
63 | * language-supported exception mechanism such as the one available in |
64 | * Java. Instead, we are stuck with using error codes that must be |
65 | * carefully managed and preserved. However, it is convenient for us to |
66 | * model our error mechanism on a Java-like exception mechanism. |
67 | * When we assign an error code we are thus `throwing' an error. |
68 | * |
69 | * The preservation of an error code is done by coding convention. |
70 | * Upon a function call if the error code is anything other than |
71 | * `FT_Err_Ok', which is guaranteed to be zero, we |
72 | * will return without altering that error. This will allow the |
73 | * error to propagate and be handled at the appropriate location in |
74 | * the code. |
75 | * |
76 | * This allows a style of code where the error code is initialized |
77 | * up front and a block of calls are made with the error code only |
78 | * being checked after the block. If a new error occurs, the original |
79 | * error will be preserved and a functional no-op should result in any |
80 | * subsequent function that has an initial error code not equal to |
81 | * `FT_Err_Ok'. |
82 | * |
83 | * Errors are encoded by calling the `FT_THROW' macro. For example, |
84 | * |
85 | * { |
86 | * FT_Error e; |
87 | * |
88 | * |
89 | * ... |
90 | * e = FT_THROW( Out_Of_Memory ); |
91 | * } |
92 | * |
93 | */ |
94 | |
95 | |
96 | /* Set error code to a particular value. */ |
97 | FT_LOCAL( void ) |
98 | cf2_setError( FT_Error* error, |
99 | FT_Error value ); |
100 | |
101 | |
102 | /* |
103 | * A macro that conditionally sets an error code. |
104 | * |
105 | * This macro will first check whether `error' is set; |
106 | * if not, it will set it to `e'. |
107 | * |
108 | */ |
109 | #define CF2_SET_ERROR( error, e ) \ |
110 | cf2_setError( error, FT_THROW( e ) ) |
111 | |
112 | |
113 | FT_END_HEADER |
114 | |
115 | |
116 | #endif /* PSERROR_H_ */ |
117 | |
118 | |
119 | /* END */ |
120 | |