INTERFACE M3AST_TM;

(***************************************************************************)
(*                      Copyright (C) Olivetti 1989                        *)
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(***************************************************************************)

(* Copyright (C) 1991, Digital Equipment Corporation           *)
(* All rights reserved.                                        *)
(* See the file COPYRIGHT for a full description.              *)

(* This interface specifies some additional attributes that are
   notionally "temporary", most of which are to support the
   semantic analyser. The original notion of "temporary" was
   defined such that these attributes would not be saved in
   persistent ASTs, e.g. in AST "pickles". Certainly the interesting
   ones can all be recomputed with a single pass over the tree, and
   the expectation was that the compiler implementation would
   ensure that to be the case. In practice, some of the attributes
   have turned out to be more temporary than others, which
   should one day be relected in a restructuring. 

   As with "M3AST_AS" and "M3AST_SM", this interface only
   specifies an abstract representation of the attributes,
   leaving the exact representation to a companion interfaace,
   e.g. "M3AST_TM_F".*)

(*-----------------------Public attributes--------------------------------*)

(* The following attributes have the same status as those in "M3AST_SM"
   and can be relied on after semantic analysis is complete. *)

(* We often need to know which unit a TYPE_SPEC/DEF_ID belongs to. *)

   (* M3AST_AS.TYPE_SPEC, M3AST_AS.DEF_ID => tmp_unit_id: M3AST_AS.UNIT_ID *)

(*-----------------------Private attributes-------------------------------*)

(* Clients should make no assumptions about the value of any of the following
   attributes, which are private to the semantic analyser and other tools.
   Typically, a procedural interface will be provided elsewhere to
   some of the values. *)

(* A Modula-3 linker must assign a type code to all reference types.
   It turns out be convenient to also have such an attribute for
   semantic analysis. *)

   (* M3AST_AS.TYPE_SPEC => tmp_type_code: INTEGER; *)

(* To support the detection of recursive definitions, it is useful to
   flag a defining identifier as recursive (or not). *)

   (* M3AST_AS.DEF_ID => tmp_recursive: BOOLEAN; *)

(* To support setting of type attributes, instances of "Type_id" which have
   a "Named_type" as their "M3TYPE" have an attribute to allow the chain to be 
   followed.  A similar attribute is needed for "Exc_id". *)

   (* M3AST_AS.Type_id, M3AST_AS.Exc_id => tmp_type: M3AST_AS.M3TYPE_NULL *)

(* To set the type of an method override, and to check coverage of
   defaults, we need to get from a method or override to the "Object_type". *)

   (* M3AST_AS.METHOD_OVERRIDE =>  tmp_type: M3AST_AS.Object_type; *)

(* The attributes defined on an "M3AST_SM.Opaque_type_Revln in "M3AST_SM"
   only capture revelations local to an AST. The followwing attributes
   capture those revelation inherited from the imported interfaces. *)


   (* M3AST_SM.Opaque_type_Revln => 
        tmp_count := 0;
        tmp_concrete_rev: M3AST_SM.TYPE_SPEC_UNSET; 
        tmp_opaque_rev_s := SeqM3AST_AS_TYPE_SPEC.Null; *)

(* In any scope, there is the concept of the "most revealing" revelation,
   which is given by the following attribute. *)

   (* M3AST_AS.Opaque_type =>
        tmp_rev_type_spec: M3AST_SM.TYPE_SPEC_UNSET; *)

(* We build a hash table of DEF_IDs in interfaces for fast lookup. *)

   (* M3AST_AS.Interface => tmp_def_id_table: HashWord.Table; *)

(* IMPORT I AS J; the 'J' has a back pointer to 'I', so that we
   can go through the level of indirection. *)

   (* M3AST_AS.Interface_AS_id => tmp_used_id: M3AST_AS.Used_interface_id; *)

(* to support efficient handling of RAISES clauses, we have an attribute
   that says whether a check is needed. We also mark whether a procedure
   needs a check for a missing return. *)

   (* M3AST_AS.Proc_decl => 
        tmp_needs_raises: BOOLEAN;
        tmp_needs_return_check: BOOLEAN; *)  
 
   (* M3AST_AS.Raise_st => tmp_fatal: BOOLEAN; *)

END M3AST_TM.