1 /****************************************************************************
2  *
3  * pserror.h
4  *
5  *   Adobe's code for error handling (specification).
6  *
7  * Copyright 2006-2013 Adobe Systems Incorporated.
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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