* transcode.c, include/ruby/encoding.c (rb_transcode_convertible):

new function. checking the existance of converter.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@19565 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Fri Sep 26 11:05:41 2008  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* transcode.c, include/ruby/encoding.c (rb_transcode_convertible):
+	  new function. checking the existance of converter.
+
 Fri Sep 26 10:35:50 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* variable.c (global_variable, struct trace_var): made function

include/ruby/encoding.h

@@ -209,6 +209,7 @@ typedef enum {
 typedef struct rb_econv_t rb_econv_t;
 
 VALUE rb_str_transcode(VALUE str, VALUE to, int ecflags, VALUE ecopts);
+int rb_transcode_convertible(const char* from_encoding, const char* to_encoding);
 
 int rb_econv_prepare_opts(VALUE opthash, VALUE *ecopts);
 

transcode.c

@@ -2839,6 +2839,20 @@ econv_s_search_convpath(int argc, VALUE *argv, VALUE klass)
     return convpath;
 }
 
+/*
+ * check the existance of converter.
+ * returns the count of the converting paths.
+ * result: >=0:success -1:failure
+ */
+int
+rb_transcode_convertible(const char* from_encoding, const char* to_encoding)
+{
+    VALUE convpath = Qnil;
+    transcode_search_path(from_encoding, to_encoding, search_convpath_i,
+			  &convpath);
+    return RTEST(convpath);
+}
+
 struct rb_econv_init_by_convpath_t {
     rb_econv_t *ec;
     int index;