m3tk/src/ast/M3AST_PG.i3

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 Copyright (C) 1993, Digital Equipment Corporation           
 All rights reserved.                                        
 See the file COPYRIGHT for a full description.              


<* PRAGMA FIELDS *>

INTERFACE M3AST_PG;

 Standard pragmas, as defined in the report, i.e. INLINE and
EXTERNAL.  There was a time when these were part of the language
syntax, so they are integrated more closely with the AST than other
pragmas, and it is expected that a Modula-3 parser will process these
pragmas and build the AST nodes that are specified in this interface.



IMPORT M3AST, M3AST_LX;

 We use the general approach to multiple inheritance here and
   introduce the class EXTERNAL_DECL to carry the information
   as to whether an Interface or DECL node is EXTERNAL. 
   So there is an attribute vEXTERNAL_DECL on Interface,
   Interface_gen_def and DECL nodes. 


 Generic interfaces can be EXTERNAL 


  
<* FIELDS OF M3AST_AS.Interface_gen_def
     vEXTERNAL_DECL: EXTERNAL_DECL; *>

 Interfaces can be EXTERNAL 


  
<* FIELDS OF M3AST_AS.Interface
     vEXTERNAL_DECL: EXTERNAL_DECL; *>

 The abstract syntax permits any DECL to be EXTERNAL, although the
static semantics are more restrictive. 


  
<* FIELDS OF M3AST_AS.DECL
     vEXTERNAL_DECL: EXTERNAL_DECL; *>

  <* FIELDS OF M3AST_AS.Proc_decl
     pg_inline: Inline_NULL; *>

TYPE
  Inline <: M3AST_LX.SRC_NODE_C;
  Inline_NULL = Inline;

 <*EXTERNAL L*> (DECL | INTERFACE) 


  
EXTERNAL_DECL <: M3AST.NODE;
  <* FIELDS OF EXTERNAL_DECL
     pg_external: External_NULL *>

  External <: M3AST_LX.SRC_NODE_C;
  <* FIELDS OF External
     lx_lang_spec: M3AST_LX.Text_rep *>

  External_NULL = External;
  External_NULL_UNSET = External_NULL;

 Since the semantic analyser chooses to use DEF_ID nodes to carry
most of the semantic information, it is convenient to propagate the
external information to some DEF_ID nodes.  Again we use multiple
inheritance, and in M3AST_SM the associated nodes will contain a
vEXTERNAL_ID attribute.  The value of the pg_external field is a
back pointer to the External node of the enclosing EXTERNAL
declaration.  The value of pg_external will be NIL if the
EXTERNAL_ID is not EXTERNAL. Note that for all EXTERNAL_ID nodes
in an interface that is EXTERNAL, the value of pg_external will not be
NIL. 


  
EXTERNAL_ID <: M3AST.NODE;    (* Ids that can be EXTERNAL *)
  <* FIELDS OF EXTERNAL_ID
     pg_external: External_NULL_UNSET *>

PROCEDURE IsA_EXTERNAL_DECL(n: M3AST.NODE;
    VAR(*out*) external_decl: EXTERNAL_DECL): BOOLEAN;

 ISTYPE(n, Interface) OR ISTYPE(n, DECL) 

PROCEDURE IsA_EXTERNAL_ID(n: M3AST.NODE;
    VAR(*out*) external_id: EXTERNAL_ID): BOOLEAN;

 Interface_id OR Proc_id OR Var_id OR Const_id OR Type_id OR Exc_id 
 This proc returns distinguished values that indicates UNSET. 


PROCEDURE UNSET_External(): External_NULL_UNSET;

END M3AST_PG.





interface M3AST is in: