Special tokens

The following special tokens may be used in the text of FWEB macro definitions:

ANSI C-compatible tokens

      ##          -- Paste tokens on either side to form a new identifier.
      #parameter  -- Convert parameter to string (without expansion).
     

For example,

     @m FORTRAN(type, name) type _##name()
     @m TRACE(where) puts("At " #where)
     @a
     FORTRAN(int, fcalc); // Expands to int _fcalc();
     TRACE(predictor); // Expands to puts("At " "predictor");
     

Extensions to ANSI C macro syntax

The most frequently used extensions are the following ones associated with variable arguments: #0, #n, and #.. FORTRAN-77 users should also employ #:0 to allow symbolic rather than numeric statement labels. Try not to use the other extensions; they are experimental, complicated, and unlikely to work in all situations.

In the following list, the forms #{n} and #[n] may not work correctly in complicated situations. This is a design deficiency that may be corrected someday.

#*param

Like #parameter, but pass a quoted string through unchanged.

#!param

Don't expand argument.

#'param

Convert parameter to a single-quoted string (no expansion).

#"param

Convert parameter to a double-quoted string (no expansion).

#0

Number of variable arguments.

#n

n-th variable argument, counting from 1.

#{0}

Like #0, but the argument may be a macro expression known at run time.

#{n}

Like #n, but the argument may be a macro expression.

#[0]

The total number of arguments (fixed + variable). (The argument inside the brackets may be a macro expression.)

#[n]

The nth argument (including the fixed ones), counting from 1. (The argument inside the brackets may be a macro expressions.

#.

Comma-separated list of all variable arguments.

#:0

Unique statement number (expanded in phase 1).

#:nnn

Unique statement number for each invocation of this macro (expanded in phase 2).

#<

Begin a module name.

#,

Internal comma; doesn't delimit macro argument.

A few examples of the more important of these tokens are as follows:

     @c
     @m FPRINTF(fmt,...) fprintf(fp,fmt,#.)
             // Use the whole list of variable args.
     @m B(...) printf("There were %i arguments\n", #0)
             // Use the number of var args.
     
     @n
     @
     @m DONE #:0 // Symbolic statement label in FORTRAN.
     @a
             goto DONE
             ...
     DONE:
             call endup