Re: [RFA] New variable, 'max-completion-results'.

[Elena Zannoni <ezannoni@redhat.com>]

Klee Dienes writes:
 > The following patch adds a new user-visible variable to GDB, 
 > 'max-completion-results'.
 > 
 > It is used by the completion functions in symtab.c to limit the maximum 
 > number of results returned by the completion function, and defaults to 
 > 'unlimited'.  I find it particuarly useful when using GDB under emacs, 
 > to prevent situations where hitting <tab> at the wrong time can lead to 
 > hundreds of thousands of results having to be sorted by 
 > complete_command.
 > 

Needs a testcase (added to completion.exp) and documentation. Also, is
there any check that the new value makes sense? I.e. what if one
enters a negative number? Maybe that's a limitation of the set/show
command, though.


I get:

(gdb) set max-completion-results -2
(gdb) show max-completion-results 
The maximum number of entries to be returned from a completion operation is 
    4294967294.


 > Index: symtab.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/symtab.c,v
 > retrieving revision 1.75
 > diff -u -r1.75 symtab.c
 > --- symtab.c	28 Oct 2002 17:05:56 -0000	1.75
 > +++ symtab.c	4 Nov 2002 07:24:59 -0000
 > @@ -50,6 +50,8 @@
 >  #include <ctype.h>
 >  #include "cp-abi.h"
 >  
 > +static unsigned int max_completion_results = UINT_MAX;
 > +
 >  /* Prototypes for local functions */
 >  
 >  static void completion_list_add_name (char *, char *, int, char *, char *);
 > @@ -3090,6 +3092,7 @@
 >  
 >  /* Helper routine for make_symbol_completion_list.  */
 >  
 > +static unsigned int return_val_max;
 >  static int return_val_size;
 >  static int return_val_index;
 >  static char **return_val;
 > @@ -3120,10 +3123,11 @@
 >  
 >    /* clip symbols that cannot match */
 >  
 > +  if (return_val_index == return_val_max)


should be return_val_max - 1
(gdb) set max-completion-results 2
(gdb) p f <tab>
factorial   features.h  float       


 > +    return;
 > +
 >    if (strncmp (symname, sym_text, sym_text_len) != 0)
 > -    {
 > -      return;
 > -    }
 > +    return;
 >  
 >    /* We have a match for a completion, so add SYMNAME to the current list
 >       of matches. Note that the name is moved to freshly malloc'd space. */
 > @@ -3238,6 +3242,7 @@
 >  
 >    sym_text_len = strlen (sym_text);
 >  
 > +  return_val_max = max_completion_results;
 >    return_val_size = 100;
 >    return_val_index = 0;
 >    return_val = (char **) xmalloc ((return_val_size + 1) * sizeof (char *));
 > @@ -3419,6 +3424,7 @@
 >  
 >    sym_text_len = strlen (sym_text);
 >  
 > +  return_val_max = max_completion_results;
 >    return_val_size = 10;
 >    return_val_index = 0;
 >    return_val = (char **) xmalloc ((return_val_size + 1) * sizeof (char *));
 > @@ -3739,6 +3745,7 @@
 >  
 >  /* Helper routine for make_symbol_completion_list.  */
 >  
 > +static unsigned int sym_return_val_max;
 >  static int sym_return_val_size;
 >  static int sym_return_val_index;
 >  static struct symbol **sym_return_val;
 > @@ -3754,6 +3761,9 @@
 >    int i;
 >    char *sym_name;
 >  
 > +  if (sym_return_val_index >= sym_return_val_max)
 > +    return;
 > +

I haven't tried this one, but should it be sym_return_val_max-1?
because the index starts form 0.

Elena


 >    /* If there is no type information, we can't do anything, so skip */
 >    if (SYMBOL_TYPE (sym) == NULL)
 >      return;
 > @@ -3822,6 +3832,7 @@
 >      }
 >    oload_name_len = strlen (oload_name);
 >  
 > +  sym_return_val_max = max_completion_results;
 >    sym_return_val_size = 100;
 >    sym_return_val_index = 0;
 >    sym_return_val = (struct symbol **) xmalloc ((sym_return_val_size + 1) * sizeof (struct symbol *));
 > @@ -3965,6 +3976,8 @@
 >  void
 >  _initialize_symtab (void)
 >  {
 > +  struct cmd_list_element *cmd;
 > +
 >    add_info ("variables", variables_info,
 >  	 "All global and static variable names, or those matching REGEXP.");
 >    if (dbx_commands)
 > @@ -3998,6 +4011,13 @@
 >  
 >    add_com ("rbreak", class_breakpoint, rbreak_command,
 >  	   "Set a breakpoint for all functions matching REGEXP.");
 > +
 > +  cmd = add_set_cmd ("max-completion-results", class_obscure, var_uinteger,
 > +		     (char *) &max_completion_results,
 > +		     "Set the maximum number of entries to be returned from a completion o\
 > +peration.",
 > +                     &setlist);
 > +  add_show_from_set (cmd, &showlist);
 >  
 >    if (xdb_commands)
 >      {
 >