Re: [pdf-devel] Error management in type 4 functions

[David Vazquez]

Well, I tell you points of the task description.

On the one hand, we need a list of syntax errors and a way to
report them in `pdf_fp_func_4_new'. I think that a PDF_BADSYNTAX
return value would works fine. But if more defailed errors are
required, an extra argument is valid. Anyway, the syntax
constructions in the language are `if' and 'ifelse'. They seem
like:

  { ... } if
  { ... } { ... } ifelse

Indeed, whole PostScript code should be wrapped with braces
too. So, we could report bad balanced braces and missing { ... }
construct.
     
On the other hand, we can use the same way to report errors to caller
from `pdf_fp_func_eval'. In this case, we suggest the following generic
interpretation errors:

  - Bad number of inputs
  - Bad number of outputs
  - Math error
  - Internal error

Math error consists of division-by-zero, negative square root, etc,
and internal error would be arised, for example, when the stack of
a type 4 function overflows.

Regards,
David.