[pdf-devel] type 4 functions

[Hardy Falk]

Hi there,

I have some difficulties with the spec:

From pdf_reference_1-7   section 3.39 
... expressions involving integers, real numbers, and boolean 
values only. ... For more
information on these operators, see Appendix B of the PostScript
 Language Reference, Third Edition.)
Although the semantics are those of the corresponding
PostScript operators, a PostScript interpreter is not required.

input and output 
of pdf functions are real numbers.
Excerpt from PLRM 8.3 "Operator Details":
  "num1 num2 add --> sum"
     returns the sum of num1 and num2.
     If both operands are integers and the result is
    within integer range, the result is an integer;
    otherwise, the result is a real number.

  "int1 int2 idiv --> quotient"
    divides int1 by int2 and returns the integer part of the
   quotient, with any fractional part discarded.
  Both operands of idiv must be integers and the result is
  an integer.

I am tempted to use double throughout, with conversions and 
checks for bit operations and idiv, 
but I am not sure whether the spec allows it. 
The alternative, a tagged union, leads to very clumsy code 

Any clarifications?  

Type 0,2 and 3 functions are working now. 
pdf_create_function takes dictionaries and streams.
testing works with a samples array in a dictionary, too.