FlowIR Syntax
-------------

FlowIR's syntax is intended to be a simple, easily parsed but easily
entered creation.  As I improve the parser, the syntax may likewise
become more convenient.  It is loosely based upon C.

The grammar is a set of procedures, which follow the following template:

  void procedure_name(<argument list>) {
    <variable declarations>
    <statements>  
  }

<argument list> and <variable declarations> look just like in C; so the
following would be valid:
  
  argument list: int x, int y
  variable declarations: int x, y;

<statements> have a generic form which looks like so:

  [var =] '[' opcode arg1=val1 arg2=val2 ']';

In this case, the opcode is the string name of one of the opcodes, such
as "loadv". The arg1 and arg2 are labels for its various inputs.  The
val1 and val2 are simple expressions that yield operands; if the parser
gets more advanced arbitrary expressions will be allowed here.  If the
optional [var =] is included, then the result of the opcode is assigned
to that variable.

Here are some examples:

  x = [add left=y right=z];
  x = [scanv vec=vecvar val=$FFFFFFFF];
                                   
There are also the following special forms:

1. Procedure calls:
                                   
  "queue" proc (arg[, arg]*);
  "tail" proc (arg[, arg]*);

The way to write the queue or tail opcode.  Example:

  queue display_count(output_handler, count)
  tail recurse(output_handler, new_count)

2. Common mathematical operations:

  var = left+right;
  var = left-right;
  var = left*right;
  var = left/right;

3. Casting assignment:

  var = "cast" other_var

  Casts as needed.  Used to convert types.

Other tokens:

  Numerical constants look like in C:
    0
    0xFF
  
  Identifiers look like in C:
    [a-z_A-Z][a-zA-Z_0-9]*