Critical Mass Modula-3: m3tk/src/ast/M3AST

m3tk/src/ast/M3AST_PG.i3

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<* 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: