Files
binutils-gdb/gdb/cli/cli-utils.h
Pedro Alves 9d0faba9f5 Introduce generic command options framework
This commit adds a generic command options framework, that makes it
easy enough to add '-'-style options to commands in a uniform way,
instead of each command implementing option parsing in its own way.

Options are defined in arrays of option_def objects (for option
definition), and the same options definitions are used for supporting
TAB completion, and also for generating the relevant help fragment of
the "help" command.  See the gdb::options::build_help function, which
returns a string with the result of replacing %OPTIONS% in a template
string with an auto-generated "help" string fragment for all the
passed-in options.

Since most options in GDB are in the form of "-OPT", with a single
dash, this is the format that the framework supports.

I like to think of gdb's "-OPT" as the equivalent to getopt's long
options format ("--OPT"), and gdb's "/" as the equivalent to getopt's
short options format.  getopt's short options format allows mixing
several one-character options, like "ls -als", kind of similar to
gdb's "x /FMT" and "disassemble /MOD", etc.  While with gdb's "-"
options, the option is expected to have a full name, and to be
abbreviatable.  E.g., "watch -location", "break -function main", etc.

This patch only deals with "-" options.  The above comment serves more
to disclose why I don't think we should support mixing several
unrelated options in a single "-" option invocation, like "thread
apply -qcs" instead of "thread apply -q -c -s".

The following patches will add uses of the infrastructure to several
key commands.  Most notably, "print", "compile print", "backtrace",
"frame apply" and "thread apply".  I tried to add options to several
commands in order to make sure the framework didn't leave that many
open holes open.

Options use the same type as set commands -- enum var_types.  So
boolean options are var_boolean, enum options are var_enum, etc.  The
idea is to share code between settings commands and command options.
The "print" options will be based on the "set print" commands, and
their names will be the same.  Actually, their definitions will be the
same too.  There is a function to create "set/show" commands from an
array for option definitions:

 /* Install set/show commands for options defined in OPTIONS.  DATA is
    a pointer to the structure that holds the data associated with the
    OPTIONS array.  */
 extern void add_setshow_cmds_for_options (command_class cmd_class, void *data,
					   gdb::array_view<const option_def> options,
					   struct cmd_list_element **set_list,
					   struct cmd_list_element **show_list);

That will be used by several following patches.

Other features:

 - You can use the "--" delimiter to explicitly indicate end of
   options.  Several existing commands use this token sequence for
   this effect already, so this just standardizes it.

 - You can shorten option names, as long as unambiguous.  Currently,
   some commands allow this (e.g., break -function), while others do
   not (thread apply all -ascending).  As GDB allows abbreviating
   command names and other things, it feels more GDB-ish to allow
   abbreviating option names too, to me.

 - For boolean options, 0/1 stands for off/on, just like with boolean
   "set" commands.

 - For boolean options, "true" is implied, just like with boolean "set
   commands.

These are the option types supported, with a few examples:

 - boolean options (var_boolean).  The option's argument is optional.

   (gdb) print -pretty on -- *obj
   (gdb) print -pretty off -- *obj
   (gdb) print -p -- *obj
   (gdb) print -p 0 -- *obj

 - flag options (like var_boolean, but no option argument (on/off))

   (gdb) thread apply all -s COMMAND

 - enum options  (var_enum)

   (gdb) bt -entry-values compact
   (gdb) bt -e c

 - uinteger options (var_uinteger)

   (gdb) print -elements 100 -- *obj
   (gdb) print -e 100 -- *obj
   (gdb) print -elements unlimited -- *obj
   (gdb) print -e u -- *obj

 - zuinteger-unlimited options (var_zuinteger_unlimited)

   (gdb) print -max-depth 100 -- obj
   (gdb) print -max-depth -1 -- obj
   (gdb) print -max-depth unlimited -- obj

Other var_types could be supported, of course.  These were just the
types that I needed for the commands that I ported over, in the
following patches.

It was interesting (and unfortunate) to find that we need at least 3
different modes to cover the existing commands:

- Commands that require ending options with "--" if you specify any
  option: "print" and "compile print".

- Commands that do not want to require "--", and want to error out if
  you specify an unknown option (i.e., an unknown argument that starts
  with '-'): "compile code" / "compile file".

- Commands that do not want to require "--", and want to process
  unknown options themselves: "bt", because of "bt -COUNT",
  "thread/frame apply", because "-" is a valid command.

The different behavior is encoded in the process_options_mode enum,
passed to process_options/complete_options.

For testing, this patch adds one representative maintenance command
for each of the process_options_mode values, that are used by the
testsuite to exercise the options framework:

 (gdb) maint test-options require-delimiter
 (gdb) maint test-options unknown-is-error
 (gdb) maint test-options unknown-is-operand

and adds another command to help with TAB-completion testing:

 (gdb) maint show test-options-completion-result

See their description at the top of the maint-test-options.c file.

Docs/NEWS are in a patch later in the series.

gdb/ChangeLog:
2019-06-13  Pedro Alves  <palves@redhat.com>

	* Makefile.in (SUBDIR_CLI_SRCS): Add cli/cli-option.c.
	(COMMON_SFILES): Add maint-test-settings.c.
	* cli/cli-decode.c (boolean_enums): New global, factored out from
	...
	(add_setshow_boolean_cmd): ... here.
	* cli/cli-decode.h (boolean_enums): Declare.
	* cli/cli-option.c: New file.
	* cli/cli-option.h: New file.
	* cli/cli-setshow.c (parse_cli_boolean_value(const char **)): New,
	factored out from ...
	(parse_cli_boolean_value(const char *)): ... this.
	(is_unlimited_literal): Change parameter type to pointer to
	pointer.  Adjust and advance ARG pointer.
	(parse_cli_var_uinteger, parse_cli_var_zuinteger_unlimited)
	(parse_cli_var_enum): New, factored out from ...
	(do_set_command): ... this.  Adjust.
	* cli/cli-setshow.h (parse_cli_boolean_value)
	(parse_cli_var_uinteger, parse_cli_var_zuinteger_unlimited)
	(parse_cli_var_enum): Declare.
	* cli/cli-utils.c: Include "cli/cli-option.h".
	(get_ulongest): New.
	* cli/cli-utils.h (get_ulongest): Declare.
	(check_for_argument): New overloads.
	* maint-test-options.c: New file.

gdb/testsuite/ChangeLog:
2019-06-13  Pedro Alves  <palves@redhat.com>

	* gdb.base/options.c: New file.
	* gdb.base/options.exp: New file.
2019-06-13 00:18:12 +01:00

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C++

/* CLI utilities.
Copyright (C) 2011-2019 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef CLI_CLI_UTILS_H
#define CLI_CLI_UTILS_H
/* *PP is a string denoting a number. Get the number. Advance *PP
after the string and any trailing whitespace.
The string can either be a number, or "$" followed by the name of a
convenience variable, or ("$" or "$$") followed by digits.
TRAILER is a character which can be found after the number; most
commonly this is `-'. If you don't want a trailer, use \0. */
extern int get_number_trailer (const char **pp, int trailer);
/* Convenience. Like get_number_trailer, but with no TRAILER. */
extern int get_number (const char **);
/* Like the above, but takes a non-const "char **". */
extern int get_number (char **);
/* Like get_number_trailer, but works with ULONGEST, and throws on
error instead of returning 0. */
extern ULONGEST get_ulongest (const char **pp, int trailer = '\0');
/* Extract from ARGS the arguments [-q] [-t TYPEREGEXP] [--] NAMEREGEXP.
The caller is responsible to initialize *QUIET to false, *REGEXP
and *T_REGEXP to "".
extract_info_print_args can then be called iteratively to search
for valid arguments, as part of a 'main parsing loop' searching for
-q/-t/-- arguments together with other flags and options.
Returns true and updates *ARGS + one of *QUIET, *REGEXP, *T_REGEXP if
it finds a valid argument.
Returns false if no valid argument is found at the beginning of ARGS. */
extern bool extract_info_print_args (const char **args,
bool *quiet,
std::string *regexp,
std::string *t_regexp);
/* Throws an error telling the user that ARGS starts with an option
unrecognized by COMMAND. */
extern void report_unrecognized_option_error (const char *command,
const char *args);
/* Builds the help string for a command documented by PREFIX,
followed by the extract_info_print_args help for ENTITY_KIND. */
const char *info_print_args_help (const char *prefix,
const char *entity_kind);
/* Parse a number or a range.
A number will be of the form handled by get_number.
A range will be of the form <number1> - <number2>, and
will represent all the integers between number1 and number2,
inclusive. */
class number_or_range_parser
{
public:
/* Default construction. Must call init before calling
get_next. */
number_or_range_parser () {}
/* Calls init automatically. */
number_or_range_parser (const char *string);
/* STRING is the string to be parsed. */
void init (const char *string);
/* While processing a range, this fuction is called iteratively; At
each call it will return the next value in the range.
At the beginning of parsing a range, the char pointer
STATE->m_cur_tok will be advanced past <number1> and left
pointing at the '-' token. Subsequent calls will not advance the
pointer until the range is completed. The call that completes
the range will advance the pointer past <number2>. */
int get_number ();
/* Setup internal state such that get_next() returns numbers in the
START_VALUE to END_VALUE range. END_PTR is where the string is
advanced to when get_next() returns END_VALUE. */
void setup_range (int start_value, int end_value,
const char *end_ptr);
/* Returns true if parsing has completed. */
bool finished () const;
/* Return the string being parsed. When parsing has finished, this
points past the last parsed token. */
const char *cur_tok () const
{ return m_cur_tok; }
/* True when parsing a range. */
bool in_range () const
{ return m_in_range; }
/* When parsing a range, the final value in the range. */
int end_value () const
{ return m_end_value; }
/* When parsing a range, skip past the final token in the range. */
void skip_range ()
{
gdb_assert (m_in_range);
m_cur_tok = m_end_ptr;
m_in_range = false;
}
private:
/* No need for these. They are intentionally not defined anywhere. */
number_or_range_parser (const number_or_range_parser &);
number_or_range_parser &operator= (const number_or_range_parser &);
/* The string being parsed. When parsing has finished, this points
past the last parsed token. */
const char *m_cur_tok;
/* Last value returned. */
int m_last_retval;
/* When parsing a range, the final value in the range. */
int m_end_value;
/* When parsing a range, a pointer past the final token in the
range. */
const char *m_end_ptr;
/* True when parsing a range. */
bool m_in_range;
};
/* Accept a number and a string-form list of numbers such as is
accepted by get_number_or_range. Return TRUE if the number is
in the list.
By definition, an empty list includes all numbers. This is to
be interpreted as typing a command such as "delete break" with
no arguments. */
extern int number_is_in_list (const char *list, int number);
/* Reverse S to the last non-whitespace character without skipping past
START. */
extern const char *remove_trailing_whitespace (const char *start,
const char *s);
/* Same, for non-const S. */
static inline char *
remove_trailing_whitespace (const char *start, char *s)
{
return (char *) remove_trailing_whitespace (start, (const char *) s);
}
/* A helper function to extract an argument from *ARG. An argument is
delimited by whitespace. The return value is empty if no argument
was found. */
extern std::string extract_arg (char **arg);
/* A const-correct version of the above. */
extern std::string extract_arg (const char **arg);
/* A helper function that looks for an argument at the start of a
string. The argument must also either be at the end of the string,
or be followed by whitespace. Returns 1 if it finds the argument,
0 otherwise. If the argument is found, it updates *STR to point
past the argument and past any whitespace following the
argument. */
extern int check_for_argument (const char **str, const char *arg, int arg_len);
/* Same as above, but ARG's length is computed. */
static inline int
check_for_argument (const char **str, const char *arg)
{
return check_for_argument (str, arg, strlen (arg));
}
/* Same, for non-const STR. */
static inline int
check_for_argument (char **str, const char *arg, int arg_len)
{
return check_for_argument (const_cast<const char **> (str),
arg, arg_len);
}
static inline int
check_for_argument (char **str, const char *arg)
{
return check_for_argument (str, arg, strlen (arg));
}
/* A helper function that looks for a set of flags at the start of a
string. The possible flags are given as a null terminated string.
A flag in STR must either be at the end of the string,
or be followed by whitespace.
Returns 0 if no valid flag is found at the start of STR.
Otherwise updates *STR, and returns N (which is > 0),
such that FLAGS [N - 1] is the valid found flag. */
extern int parse_flags (const char **str, const char *flags);
/* qcs_flags struct regroups the flags parsed by parse_flags_qcs. */
struct qcs_flags
{
bool quiet = false;
bool cont = false;
bool silent = false;
};
/* A helper function that uses parse_flags to handle the flags qcs :
A flag -q sets FLAGS->QUIET to true.
A flag -c sets FLAGS->CONT to true.
A flag -s sets FLAGS->SILENT to true.
The caller is responsible to initialize *FLAGS to false before the (first)
call to parse_flags_qcs.
parse_flags_qcs can then be called iteratively to search for more
valid flags, as part of a 'main parsing loop' searching for -q/-c/-s
flags together with other flags and options.
Returns true and updates *STR and one of FLAGS->QUIET, FLAGS->CONT,
FLAGS->SILENT if it finds a valid flag.
Returns false if no valid flag is found at the beginning of STR.
Throws an error if a flag is found such that both FLAGS->CONT and
FLAGS->SILENT are true. */
extern bool parse_flags_qcs (const char *which_command, const char **str,
qcs_flags *flags);
#endif /* CLI_CLI_UTILS_H */