[m-rev.] For review: pretty print c_pointers as addresses

[Ralph Becket]

Branches: main
Estimated hours taken: 0.2

library/pprint.m:
	Pretty print c_pointers as "<<0xADDRESS>>" rather than just
	"<<c_pointer>>".  This allows us to distinguish between different
	C pointers.


Index: library/pprint.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/pprint.m,v
retrieving revision 1.22
diff -u -r1.22 pprint.m
--- library/pprint.m	19 Apr 2006 05:17:54 -0000	1.22
+++ library/pprint.m	14 Aug 2006 07:32:48 -0000
@@ -806,7 +806,10 @@
 
               then
 
-                text(Name)
+                ( if   Name = "<<c_pointer>>"
+                  then text(string.format("<<0x%x>>", [i(c_pointer_addr(X))]))
+                  else text(Name)
+                )
 
               else
 
@@ -818,6 +821,18 @@
             )
     ).
 
+
+% This really should be impure...
+%
+:- func c_pointer_addr(T) = int.
+
+:- pragma foreign_proc("C",
+    c_pointer_addr(X::in) = (Addr::out),
+    [promise_pure, will_not_call_mercury, will_not_modify_trail],
+"
+    Addr = (MR_Integer) X;
+").
+
 %-----------------------------------------------------------------------------%
 
     % We need to put parentheses around a subterm if its top-level
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