Declarations

Declarations are either global or local (to a process) and can contain declarations of clocks, bounded integers, constants, channels (although local channels are useless), and types. The syntax is described by the grammar for Declarations:

Declarations  ::= (VariableDecl | TypeDecl | Function)*
VariableDecl  ::= Type VariableID (',' VariableID)* ';'
VariableID    ::= ID ArrayDecl* [ '=' Initialiser ]
Initialiser   ::= Expression
               |  '{' Initialiser (',' Initialiser)* '}'
TypeDecls     ::= 'typedef' Type ID ArrayDecl* (',' ID ArrayDecl*)* ';'

Examples

• const int a 1;
  constant a with value 1 of type integer.
• bool b[8], c[4];
  two bit arrays b and c, with 8 and 4 elements respectively.
• int[0,100] a=5;
  an integer variable with the range [0, 100] initialised to 5.
• int a[2][3] = { { 1, 2, 3 }, { 4, 5, 6} };
  a multidimensional integer array with default range and an initialiser.
• clock x, y;
  two clocks x and y.
• chan d;
  a channel.
• urgent chan e;
  an urgent channel.

• struct { int a; bool b; } s1 = { 2, true };
  

  an instantiation of the structure from above where the members a and b are set to 2 and true.
• meta int swap;
  int a;
  int b;
  assign swap = a; a = b; b = swap;
  a meta variable is used to swap the contents of two integers.

Type Declarations

The typedef keyword is used to name types.

Example

The following declares a record type S containing an integer a, a boolean b and a clock c:

typedef struct 
{ 
  int a;   
  bool b;
  clock c;
} S;