Add sprintfAddHandler and use it.

This allows you to register a handler which knows how to convert types NQP doesn't know about to bigints.  (Eventually I hope to expand it to floating point values and strings as well.)

I'm not particularly attached to the name sprintfAddHandler, if someone has a better suggestion.

Author: colomon

src/HLL/sprintf.nqp

@@ -1,4 +1,6 @@
 my module sprintf {
+    my @handlers;
+
     grammar Syntax {
         token TOP {
             :my $*ARGS_USED := 0;
@@ -74,6 +76,12 @@ my module sprintf {
         }
 
         sub intify($number_representation) {
+            for @handlers -> $handler {
+                if $handler.mine($number_representation) {
+                    return $handler.int($number_representation);
+                }
+            }
+            
             my $result;
             if $number_representation > 0 {
                 $result := nqp::floor_n($number_representation);
@@ -316,4 +324,11 @@ my module sprintf {
     }
 
     nqp::bindcurhllsym('sprintf', &sprintf);
+
+    sub sprintfAddHandler($interface) {
+        @handlers.push($interface);
+    }
+
+    nqp::bindcurhllsym('sprintfAddHandler', &sprintfAddHandler);
+
 }

src/vm/jvm/QAST/Compiler.nqp

@@ -2015,6 +2015,20 @@ QAST::OperationsJAST.add_core_op('sprintf', -> $qastcomp, $op {
             |@operands )
     );
 });
+QAST::OperationsJAST.add_core_op('sprintfAddHandler', -> $qastcomp, $op {
+    my @operands := $op.list;
+    $qastcomp.as_jast(
+        QAST::Op.new(
+            :op('call'),
+            :returns(str),
+            QAST::Op.new(
+                :op('gethllsym'),
+                QAST::SVal.new( :value('nqp') ),
+                QAST::SVal.new( :value('sprintfAddHandler') )
+            ),
+            |@operands )
+    );
+});
 QAST::OperationsJAST.map_classlib_core_op('escape', $TYPE_OPS, 'escape', [$RT_STR], $RT_STR);
 QAST::OperationsJAST.map_classlib_core_op('flip', $TYPE_OPS, 'flip', [$RT_STR], $RT_STR);
 QAST::OperationsJAST.map_classlib_core_op('replace', $TYPE_OPS, 'replace', [$RT_STR, $RT_INT, $RT_INT, $RT_STR], $RT_STR);