FORMAT prefix parameter '#' not handled properly

[Charles Turner <chturne at gmail dot com>]

Evaluating (format #t "~#$" 3.14159) should return 3.1, since the length 
of the argument list is 1 (3.14159) and the # prefix parameter tells 
FORMAT to print that many fractional digits. Here are a couple of 
examples with the fix in place,

#|kawa:2|# (format #t "~#$" 3.14159)
3.1
#|kawa:3|# (format #t "~#$" 3.14159 1 2)
3.142

The current behaviour is to throw a NullPointerException, this is 
because the call dfmt.resolve(null, 0); in LispFormat#LispFormat calls 
getParam, which doesn't handle a args value of null properly. The patch 
for LispFormat makes a small modification to avoid calling this 
dfmt.resolve method, even if you fix getParam to handle null properly, 
this method replaces the LispRealFormat instance with a FixedRealFormat 
instance, having done that, we forget to check the paramCount stuff.

I'm not 100% happy with this fix, but it seems to work okay, I'm finding 
the logic in LispFormat a bit hard to follow for now.

I seem to have changed the indentation in LispFormat, no matter how I 
change the indentation to match the original, svn diff keeps saying it's 
different, sorry about that. I just ended up accepting how Emacs indents 
the line break in the middle of a param list.

The ReportFormat patch attached includes the fix for getParam. If this 
is acceptable, I'll send some test cases and change logs.

Charles.





Index: gnu/text/ReportFormat.java
===================================================================
--- gnu/text/ReportFormat.java	(revision 7065)
+++ gnu/text/ReportFormat.java	(working copy)
@@ -158,12 +158,12 @@
 
   protected static int getParam(int param, int defaultValue, Object[] args, int start)
   {
+    if (args == null || param == PARAM_UNSPECIFIED) 
+      return defaultValue;
     if (param == PARAM_FROM_COUNT)
       return args.length - start;
     if (param == PARAM_FROM_LIST)
-      return args == null ? defaultValue : getParam(args[start], defaultValue);
-    if (param == PARAM_UNSPECIFIED)
-      return defaultValue;
+      return getParam(args[start], defaultValue);
     // Need to mask off flags etc?
     return param;
   }

Index: gnu/kawa/functions/LispFormat.java
===================================================================
--- gnu/kawa/functions/LispFormat.java	(revision 7065)
+++ gnu/kawa/functions/LispFormat.java	(working copy)
@@ -153,7 +153,7 @@
 	      }
 	    dfmt.showPlus = seenAt;
 	    dfmt.internalPad = seenColon;
-	    if (dfmt.argsUsed == 0)
+	    if (dfmt.argsUsed == 0 && dfmt.arg1 != PARAM_FROM_COUNT)
 	      fmt = dfmt.resolve(null, 0);
 	    else
 	      fmt = dfmt;
@@ -919,6 +919,7 @@
     return start;
   }
 
+  @Override
   public String toString ()
   {
     StringBuffer sbuf = new StringBuffer();
@@ -1052,8 +1053,8 @@
       }
     else if (! skipIfFalse)
       {
-	int index = getParam(this.param, LispFormat.PARAM_FROM_LIST,
-					args, start);
+       int index = getParam(this.param, LispFormat.PARAM_FROM_LIST, 
+			    args, start);
 	if (param == LispFormat.PARAM_FROM_LIST)  start++;
 	if (index < 0 || index >= choices.length)
 	  {