Coding Style

Ada subset: use only a simple (VHDL like) subset of Ada: no tasking, no controlled types… VHDL users should easily understand that subset. Allowed Ada95 features: the standard library, child packages. Use assertions.

We try to follow the ‘GNU Coding Standards’ when possible: comments before declarations, two spaces at end of sentences, finish sentences with a dot. But: 3 spaces for indentation.

No trailing spaces, not TAB (HT).

Subprograms must have a comment before to describe it, like:

--  Analyze the concurrent statements of PARENT.
procedure Sem_Concurrent_Statement_Chain (Parent : Iir);

The line before the comment must be a blank line (unless this is the first declaration). Don’t repeat the comment before the subprogram body.

  • For subprograms:

    1. Declare on one line when possible:

      function Translate_Static_Aggregate (Aggr : Iir) return O_Cnode
      
    2. If not possible, put the return on the next line:

      function Translate_Static_String (Str_Type : Iir; Str_Ident : Name_Id)
                                       return O_Cnode
      
    3. If not possible, put parameters and return on the next line:

      function Create_String_Literal_Var_Inner
        (Str : Iir; Element_Type : Iir; Str_Type : O_Tnode) return Var_Type
      
    4. If not possible, return on the next line:

      function Translate_Shortcut_Operator
        (Imp : Iir_Implicit_Function_Declaration; Left, Right : Iir)
        return O_Enode
      
    5. If not possible, one parameter per line, just after subprogram name:

      procedure Translate_Static_Aggregate_1 (List : in out O_Array_Aggr_List;
                                              Aggr : Iir;
                                              Info : Iir;
                                              El_Type : Iir)
      
    6. If not possible, add a return after subprogram name:

      function Translate_Predefined_TF_Array_Element
        (Op : Predefined_Boolean_Logical;
         Left, Right : Iir;
         Res_Type : Iir;
         Loc : Iir)
        return O_Enode
      
    1. If not possible, ask yourself what is wrong! Shorten a name.
  • Rule for the ‘is’: one a new line only if the declarative part is not empty:

    procedure Translate_Assign (Target : Mnode; Expr : Iir; Target_Type : Iir)
    is
       Val : O_Enode;
    begin
    

    vs.

    function Translate_Static_Range_Dir (Expr : Iir) return O_Cnode is
    begin
    

    If the parametere line is too long with the ‘is’, put in on a separate line:

    procedure Predeclare_Scope_Type
      (Scope : in out Var_Scope_Type; Name : O_Ident) is
    
  • Generic instantiation: put the generic actual part on a new line:

    procedure Free is new Ada.Unchecked_Deallocation
      (Action_List, Action_List_Acc);
    
  • For if/then statement:

    1. ‘then’ on the same line:

      if Get_Expr_Staticness (Decl) = Locally then
      
    2. If not possible, ‘then’ is alone on its line aligned with the ‘if’:

      if Expr = Null_Iir
        or else Get_Kind (Expr) = Iir_Kind_Overflow_Literal
      then
      
    3. For a multiline condition, ‘or else’ and ‘and then’ should start lines.

  • ‘Local’ variable declaration: Do not initialize variables, constants must be declared before variables:

    is
       N_Info : constant Iir := Get_Sub_Aggregate_Info (Info);
       Assoc  : Iir;
       Sub    : Iir;
    begin
    

    If the initialization expression has a side effect (such as allocation), do not use a constant.