cf2error.h revision 727dee178a392d20eb050d0c446f2fcc29058fa1 
1/***************************************************************************/
2/*                                                                         */
3/*  cf2error.h                                                             */
4/*                                                                         */
5/*    Adobe's code for error handling (specification).                     */
6/*                                                                         */
7/*  Copyright 2006-2013 Adobe Systems Incorporated.                        */
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35/*                                                                         */
36/***************************************************************************/
37
38
39#ifndef __CF2ERROR_H__
40#define __CF2ERROR_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 "cf2ft.h"
54
55
56FT_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 perservation 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 propogate 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
113FT_END_HEADER
114
115
116#endif /* __CF2ERROR_H__ */
117
118
119/* END */
120