pserror.h

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/*                                                                         */
/*  pserror.h                                                              */
/*                                                                         */
/*    Adobe's code for error handling (specification).                     */
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/***************************************************************************/
 
 
#ifndef PSERROR_H_
#define PSERROR_H_
 
 
#include FT_MODULE_ERRORS_H
 
#undef FTERRORS_H_
 
#undef  FT_ERR_PREFIX
#define FT_ERR_PREFIX  CF2_Err_
#define FT_ERR_BASE    FT_Mod_Err_CF2
 
 
#include FT_ERRORS_H
#include "psft.h"
 
 
FT_BEGIN_HEADER
 
 
  /*
   * A poor-man error facility.
   *
   * This code being written in vanilla C, doesn't have the luxury of a
   * language-supported exception mechanism such as the one available in
   * Java.  Instead, we are stuck with using error codes that must be
   * carefully managed and preserved.  However, it is convenient for us to
   * model our error mechanism on a Java-like exception mechanism.
   * When we assign an error code we are thus `throwing' an error.
   *
   * The preservation of an error code is done by coding convention.
   * Upon a function call if the error code is anything other than
   * `FT_Err_Ok', which is guaranteed to be zero, we
   * will return without altering that error.  This will allow the
   * error to propagate and be handled at the appropriate location in
   * the code.
   *
   * This allows a style of code where the error code is initialized
   * up front and a block of calls are made with the error code only
   * being checked after the block.  If a new error occurs, the original
   * error will be preserved and a functional no-op should result in any
   * subsequent function that has an initial error code not equal to
   * `FT_Err_Ok'.
   *
   * Errors are encoded by calling the `FT_THROW' macro.  For example,
   *
   * {
   *   FT_Error  e;
   *
   *
   *   ...
   *   e = FT_THROW( Out_Of_Memory );
   * }
   *
   */
 
 
  /* Set error code to a particular value. */
  FT_LOCAL( void )
  cf2_setError( FT_Error*  error,
                FT_Error   value );
 
 
  /*
   * A macro that conditionally sets an error code.
   *
   * This macro will first check whether `error' is set;
   * if not, it will set it to `e'.
   *
  */
#define CF2_SET_ERROR( error, e )              \
          cf2_setError( error, FT_THROW( e ) )
 
 
FT_END_HEADER
 
 
#endif /* PSERROR_H_ */
 
 
/* END */