[patch] proof of concept implementation for dabbrev-expand for readline

[Dan Nicolaescu]

Hi, 

IMO a dabbrev-expand implementation in readline would be a good idea.

In emacs dabbrev-expand is bound by default to M-/ 
(AFAIK emacs had the original implementation for this idea. It is now
present in tcsh too)

What dabbrev-expand could do in readline/bash is to complete the word
the cursor is currently on with an item from history. Repeated
invocations complete with other matching items from history.

I have changed the implementation of "menu-complete" to behave like
"dabbrev-expand", i.e. complete with items from history. 

Here is my proof of concept patch.  It's a bit of a hack because
(among other things) history_completion_generator is only available in
bash, but not in readline. It could probably be moved to readline.

I am not sure what is the best way to integrate this in readline, so
for now I just made "menu-complete" do what dabbrev-expand is supposed
to do.
To test this, just do:

bind '"\M-/":menu-complete'

Can you please integrate this (or something similar) in readline/bash?
I could help with the needed code...

Thanks
        --dan

diff -rup ../bash-3.2.orig/bashline.c ./bashline.c
--- ../bash-3.2.orig/bashline.c       2006-07-29 13:39:30.000000000 -0700
+++ ./bashline.c                      2007-04-05 13:42:22.000000000 -0700
@@ -116,7 +116,7 @@ static char *hostname_completion_functio
 static char *command_subst_completion_function __P((const char *, int));
 
 static void build_history_completion_array __P((void));
-static char *history_completion_generator __P((const char *, int));
+char *history_completion_generator __P((const char *, int));
 static int dynamic_complete_history __P((int, int));
 
 static void initialize_hostname_list __P((void));
@@ -2466,7 +2466,7 @@ build_history_completion_array ()
     }
 }
 
-static char *
+char *
 history_completion_generator (hint_text, state)
      const char *hint_text;
      int state;

diff -rup ../bash-3.2.orig/lib/readline/complete.c ./lib/readline/complete.c
--- ../bash-3.2.orig/lib/readline/complete.c       2006-07-28 
08:35:49.000000000 -0700
+++ ./lib/readline/complete.c                      2007-04-14 
15:19:14.000000000 -0700
@@ -2112,6 +2112,7 @@ int
 rl_menu_complete (count, ignore)
      int count, ignore;
 {
+  extern char *history_completion_generator __P((const char *, int));
   rl_compentry_func_t *our_func;
   int matching_filenames, found_quote;
 
@@ -2135,12 +2136,17 @@ rl_menu_complete (count, ignore)
       match_list_index = match_list_size = 0;
       matches = (char **)NULL;
 
+      rl_filename_completion_desired = 0;
+      rl_attempted_completion_function = NULL;
+      
       /* Only the completion entry function can change these. */
-      set_completion_defaults ('%');
+      set_completion_defaults ('@');
 
-      our_func = rl_completion_entry_function
-                 ? rl_completion_entry_function
-                       : rl_filename_completion_function;
+      our_func = history_completion_generator;
+      
+/*    rl_completion_entry_function */
+/*                                     ? rl_completion_entry_function */
+/*                                                                    : 
rl_filename_completion_function; */
 
       /* We now look backwards for the start of a filename/variable word. */
       orig_end = rl_point;