[m-dev.] diff: fix bug in pprint__to_doc

[Fergus Henderson]

Estimated hours taken: 0.5

library/pprint.m:
	Fix a bug: there was an infinite loop in the code for `to_doc'.
	The recursive call to convert the term's arguments was
	happening even in the case where the term had no arguments.

Workspace: /home/pgrad/fjh/ws/hg
Index: library/pprint.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/pprint.m,v
retrieving revision 1.1
diff -u -d -r1.1 pprint.m
--- library/pprint.m	2000/05/03 09:56:46	1.1
+++ library/pprint.m	2000/05/09 12:13:25
@@ -454,25 +454,25 @@
     % This may throw an exception or cause a runtime abort if the term
     % in question has user-defined equality.
 
-to_doc(Depth, X) =
+to_doc(Depth, X) = Doc :-
+    deconstruct(X, Name, Arity, UnivArgs),
     ( if Arity = 0 then
-        text(Name)
+        Doc = text(Name)
       else if Depth =< 0 then
-        text(Name) `<>` text("(...)")
+        Doc = text(Name) `<>` text("(...)")
       else
-        text(Name) `<>`
-        parentheses(
-            group(
-                nest(2, line `<>` separated(id, comma_space_line, Args)) `<>`
-                line
+        Args = list__map(
+            ( func(UnivArg) = to_doc(Depth - 1, univ_value(UnivArg)) ),
+            UnivArgs
+        ),
+        Doc = text(Name) `<>`
+            parentheses(
+                group(
+                    nest(2,
+		        line `<>` separated(id, comma_space_line, Args)
+		    ) `<>` line
+                )
             )
-        )
-    )
-:-
-    deconstruct(X, Name, Arity, UnivArgs),
-    Args = list__map(
-        ( func(UnivArg) = to_doc(Depth - 1, univ_value(UnivArg)) ),
-        UnivArgs
     ).
 
 %------------------------------------------------------------------------------%

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3        |     -- the last words of T. S. Garp.
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