[Suif-talk] new walker status code: Walker::TruncateReplaced

[Karl Eisenhofer]

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I had a need for this fucntionality so I just added it since I couldn't
wait for a new release:

Occasionally when you replace a object during a walk
you do NOT want to walk the fields of the replaced in object.
You may know something about the new object such that it
never requires walking.  However, a walker does not permit
this when the replaced object is the top walked node.

Note:  It is possible to use the set_address(..) call and then
return Walker::Truncate, but it is not possible to find out what that
node is from the calling walker.  Only be returning Walker::Replaced,
which in turn walks the fields of the replaced object, can you determine
if the top node of a walk has been
replaced.

The new status code of Walker::TruncateReplace solves this problem by
allowing a user to specify whether to walk the fields of
a replacement or not.  The TruncateReplace status code has the same
requirements as the Replace status code (i.e. set_address(..) must be
called or it asserts).

The attachment is context diff of the code that enables this feature.
Note that files labeled <suif_souce_file>.[cpp,h].sav indicate the
new code, and the file sans the .sav extension are the original suif
source.

Have fun!

Karl



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*** aggregate_meta_class.cpp	Thu Aug 24 17:30:25 2000
--- aggregate_meta_class.cpp.sav	Thu Aug 24 15:46:53 2000
***************
*** 683,688 ****
--- 683,691 ----
  		return status;
  	    case Walker::Truncate:
  		return Walker::Continue;
+       case Walker::TruncateReplaced:
+         assert(w.get_address());
+         return Walker::Replaced;
  	    case Walker::Replaced:
  	    	instance = w.get_address();
  		assert(instance);
***************
*** 701,706 ****
--- 704,710 ----
          case Walker::Truncate:
              return Walker::Continue;
          case Walker::Replaced:
+         case Walker::TruncateReplaced:
              assert(false);
              break;
  	}
***************
*** 769,774 ****
--- 773,781 ----
  		return status;
  	    case Walker::Truncate:
  		return Walker::Continue;
+       case Walker::TruncateReplaced:
+         assert(w.get_address());
+         return Walker::Replaced;
  	    case Walker::Replaced:
  	    	instance = w.get_address();
  		assert(instance);
***************
*** 788,793 ****
--- 795,801 ----
          case Walker::Truncate:
              return Walker::Continue;
          case Walker::Replaced:
+         case Walker::TruncateReplaced:
              assert(false);
              break;
  	}
*** list_meta_class.cpp	Thu Aug 24 17:30:25 2000
--- list_meta_class.cpp.sav	Thu Aug 24 16:15:28 2000
***************
*** 233,238 ****
--- 233,239 ----
              case Walker::Continue:
  	    case Walker::Truncate:
  	    case Walker::Replaced:
+       case Walker::TruncateReplaced:
                  break;
              case Walker::Stop:
              case Walker::Abort:
*** walker.h	Thu Aug 24 17:30:25 2000
--- walker.h.sav	Thu Aug 24 15:46:53 2000
***************
*** 27,35 ****
  	      Stop,     // stop iteration
  	      Abort,    // stop with error condition
  	      Truncate, // do not walk subobjects of this object (pre-order only)
! 	      Replaced};// Object has been replaced with a new object.
  			// You must set the address of the new object by calling set_address before 
! 		 	// returning
  
          Walker(SuifEnv *the_env);
  
--- 27,36 ----
  	      Stop,     // stop iteration
  	      Abort,    // stop with error condition
  	      Truncate, // do not walk subobjects of this object (pre-order only)
! 	      Replaced, // Object has been replaced with a new object.
!         TruncateReplaced };  // Object has been replaced, but do not walk the fields of the new object (pre-order only)
  			// You must set the address of the new object by calling set_address before 
! 		 	// returning with status Replaced or TruncateReplaced
  
          Walker(SuifEnv *the_env);
  
*** group_walker.cpp	Thu Aug 24 17:34:10 2000
--- group_walker.cpp.sav	Thu Aug 24 16:13:12 2000
***************
*** 78,84 ****
      if (!w)
          return Walker::Continue;
      Walker::ApplyStatus status = (*w)(x);
!     if (status == Replaced)
  	set_address(w->get_address());
      return status;
      }
--- 78,84 ----
      if (!w)
          return Walker::Continue;
      Walker::ApplyStatus status = (*w)(x);
!     if (status == Replaced || status == TruncateReplaced)
  	set_address(w->get_address());
      return status;
      }
***************
*** 88,94 ****
  
  Walker::ApplyStatus ReplacingWalker::operator () (SuifObject *x) {
      Walker::ApplyStatus status = GroupWalker::operator()(x);
!     if (status == Replaced) {
  	SuifObject *y = (SuifObject *)get_address();
  	_map.enter_value(x,y);
  	SuifObject *parent = (SuifObject *)get_parent();
--- 88,94 ----
  
  Walker::ApplyStatus ReplacingWalker::operator () (SuifObject *x) {
      Walker::ApplyStatus status = GroupWalker::operator()(x);
!     if (status == Replaced || status == TruncateReplaced) {
  	SuifObject *y = (SuifObject *)get_address();
  	_map.enter_value(x,y);
  	SuifObject *parent = (SuifObject *)get_parent();

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