m3tk/src/gast/ASTWalk.m3

MODULE ASTWalk EXPORTS ASTWalk, AST_WalkRep;
************************************************************************* Copyright (C) Olivetti 1989 All Rights reserved Use and copy of this software and preparation of derivative works based upon this software are permitted to any person, provided this same copyright notice and the following Olivetti warranty disclaimer are included in any copy of the software or any modification thereof or derivative work therefrom made by any person. This software is made available AS IS and Olivetti disclaims all warranties with respect to this software, whether expressed or implied under any law, including all implied warranties of merchantibility and fitness for any purpose. In no event shall Olivetti be liable for any damages whatsoever resulting from loss of use, data or profits or otherwise arising out of or in connection with the use or performance of this software. ************************************************************************* 

IMPORT AST;

REVEAL
  Handle = Handle_public BRANDED OBJECT
    ignoreChildren: BOOLEAN := FALSE;
    callOnEntry, callOnExit: BOOLEAN := TRUE;
    closure: Closure;
  OVERRIDES
      Visit := DoVisit;
  END;

REVEAL
  Closure = Closure_public BRANDED OBJECT
      handle: Handle := NIL;
  OVERRIDES
      init := Init;
  END;

PROCEDURE VisitNodes(n: AST.NODE; closure: Closure) RAISES ANY=
  VAR
    handle := NEW(Handle, callOnExit := FALSE);
  BEGIN
    closure.handle := handle;
    handle.closure := closure;
    TRY
      DoVisit(handle, n);
    EXCEPT
      Aborted =>
    END;
  END VisitNodes;

PROCEDURE ModeVisitNodes(n: AST.NODE; closure: Closure;
    vm: VisitModeControl) RAISES ANY=
  VAR
    handle := NEW(Handle);
  BEGIN
    handle.callOnEntry := VisitMode.Entry IN vm;
    handle.callOnExit := VisitMode.Exit IN vm;
    closure.handle := handle;
    handle.closure := closure;
    TRY
      DoVisit(handle, n);
    EXCEPT
      Aborted =>
    END;
  END ModeVisitNodes;

PROCEDURE DoVisit(handle: Handle; n: AST.NODE) RAISES ANY =
  BEGIN
    IF handle.callOnEntry THEN handle.closure.callback(n) END;
    IF NOT handle.ignoreChildren THEN n.walk(handle) END;
    IF handle.callOnExit THEN handle.closure.callback(n, VisitMode.Exit) END;
    handle.ignoreChildren := FALSE;
  END DoVisit;

PROCEDURE Init(c: Closure): Closure RAISES {}=
  BEGIN
    RETURN c;
  END Init;

TYPE
  NPClosure =
    Closure OBJECT
      np: NodeCallbackProc;
    OVERRIDES
      callback := CallNodeProc;
    END;

PROCEDURE CallNodeProc(c: NPClosure; n: AST.NODE;
                       <*UNUSED*> vm: VisitMode) RAISES {}=
  <*FATAL ANY*>
  BEGIN
    c.np(n);
  END CallNodeProc;

PROCEDURE NodeProcClosure(p: NodeCallbackProc): Closure RAISES {}=
  BEGIN
    RETURN NEW(NPClosure, np := p);
  END NodeProcClosure;

PROCEDURE IgnoreChildren(cl: Closure) RAISES {} =
  BEGIN
    cl.handle.ignoreChildren := TRUE;
  END IgnoreChildren;

PROCEDURE Abort() RAISES {Aborted} =
  BEGIN
    RAISE Aborted;
  END Abort;

PROCEDURE Null(<*UNUSED*> n: NODE; <*UNUSED*> handle: Handle) RAISES {}=
  BEGIN
  END Null;

BEGIN
END ASTWalk.