bbea680797
This commit attempts to improve the help text that is generated for
gdb.Parameter objects when the user fails to provide their own
documentation.
Documentation for a gdb.Parameter is currently pulled from two
sources: the class documentation string, and the set_doc/show_doc
class attributes. Thus, a fully documented parameter might look like
this:
class Param_All (gdb.Parameter):
"""This is the class documentation string."""
show_doc = "Show the state of this parameter"
set_doc = "Set the state of this parameter"
def get_set_string (self):
val = "on"
if (self.value == False):
val = "off"
return "Test Parameter has been set to " + val
def __init__ (self, name):
super (Param_All, self).__init__ (name, gdb.COMMAND_DATA, gdb.PARAM_BOOLEAN)
self._value = True
Param_All ('param-all')
Then in GDB we see this:
(gdb) help set param-all
Set the state of this parameter
This is the class documentation string.
Which is fine. But, if the user skips both of the documentation parts
like this:
class Param_None (gdb.Parameter):
def get_set_string (self):
val = "on"
if (self.value == False):
val = "off"
return "Test Parameter has been set to " + val
def __init__ (self, name):
super (Param_None, self).__init__ (name, gdb.COMMAND_DATA, gdb.PARAM_BOOLEAN)
self._value = True
Param_None ('param-none')
Now in GDB we see this:
(gdb) help set param-none
This command is not documented.
This command is not documented.
That's not great, the duplicated text looks a bit weird. If we drop
different parts we get different results. Here's what we get if the
user drops the set_doc and show_doc attributes:
(gdb) help set param-doc
This command is not documented.
This is the class documentation string.
That kind of sucks, we say it's undocumented, then proceed to print
the documentation. Finally, if we drop the class documentation but
keep the set_doc and show_doc:
(gdb) help set param-set-show
Set the state of this parameter
This command is not documented.
That seems OK.
So, I think there's room for improvement.
With this patch, for the four cases above we now see this:
# All values provided by the user, no change in this case:
(gdb) help set param-all
Set the state of this parameter
This is the class documentation string.
# Nothing provided by the user, the first string is now different:
(gdb) help set param-none
Set the current value of 'param-none'.
This command is not documented.
# Only the class documentation is provided, the first string is
# changed as in the previous case:
(gdb) help set param-doc
Set the current value of 'param-doc'.
This is the class documentation string.
# Only the set_doc and show_doc are provided, this case is unchanged
# from before the patch:
(gdb) help set param-set-show
Set the state of this parameter
This command is not documented.
The one place where this change might be considered a negative is when
dealing with prefix commands. If we create a prefix command but don't
supply the set_doc / show_doc strings, then this is what we saw before
my patch:
(gdb) python Param_None ('print param-none')
(gdb) help set print
set print, set pr, set p
Generic command for setting how things print.
List of set print subcommands:
... snip ...
set print param-none -- This command is not documented.
... snip ...
And after my patch:
(gdb) python Param_None ('print param-none')
(gdb) help set print
set print, set pr, set p
Generic command for setting how things print.
List of set print subcommands:
... snip ...
set print param-none -- Set the current value of 'print param-none'.
... snip ...
This seems slightly less helpful than before, but I don't think its
terrible.
Additionally, I've changed what we print when the get_show_string
method is not provided in Python.
Back when gdb.Parameter was first added to GDB, we didn't provide a
show function when registering the internal command object within
GDB. As a result, GDB would make use of its "magic" mangling of the
show_doc string to create a sentence that would display the current
value (see deprecated_show_value_hack in cli/cli-setshow.c).
However, when we added support for the get_show_string method to
gdb.Parameter, there was an attempt to maintain backward compatibility
by displaying the show_doc string with the current value appended, see
get_show_value in py-param.c. Unfortunately, this isn't anywhere
close to what deprecated_show_value_hack does, and the results are
pretty poor, for example, this is GDB before my patch:
(gdb) show param-none
This command is not documented. off
I think we can all agree that this is pretty bad.
After my patch, we how show this:
(gdb) show param-none
The current value of 'param-none' is "off".
Which at least is a real sentence, even if it's not very informative.
This patch does change the way that the Python API behaves slightly,
but only in the cases when the user has missed providing GDB with some
information. In most cases I think the new behaviour is a lot better,
there's the one case (noted above) which is a bit iffy, but I think is
still OK.
I've updated the existing gdb.python/py-parameter.exp test to cover
the modified behaviour.
Finally, I've updated the documentation to (I hope) make it clearer
how the various bits of help text come together.
316 lines
11 KiB
C++
316 lines
11 KiB
C++
/* Header file for GDB command decoding library.
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Copyright (C) 2000-2022 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef CLI_CLI_DECODE_H
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#define CLI_CLI_DECODE_H
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/* This file defines the private interfaces for any code implementing
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command internals. */
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/* Include the public interfaces. */
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#include "command.h"
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#include "gdbsupport/gdb_regex.h"
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#include "cli-script.h"
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#include "completer.h"
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#include "gdbsupport/intrusive_list.h"
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#include "gdbsupport/buildargv.h"
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/* Not a set/show command. Note that some commands which begin with
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"set" or "show" might be in this category, if their syntax does
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not fall into one of the following categories. */
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enum cmd_types
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{
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not_set_cmd,
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set_cmd,
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show_cmd
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};
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/* This structure records one command'd definition. */
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struct cmd_list_element
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{
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cmd_list_element (const char *name_, enum command_class theclass_,
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const char *doc_)
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: name (name_),
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theclass (theclass_),
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cmd_deprecated (0),
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deprecated_warn_user (0),
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malloced_replacement (0),
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doc_allocated (0),
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name_allocated (0),
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hook_in (0),
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allow_unknown (0),
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abbrev_flag (0),
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type (not_set_cmd),
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doc (doc_)
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{
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memset (&function, 0, sizeof (function));
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}
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~cmd_list_element ()
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{
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if (doc && doc_allocated)
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xfree ((char *) doc);
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if (name_allocated)
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xfree ((char *) name);
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}
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DISABLE_COPY_AND_ASSIGN (cmd_list_element);
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/* For prefix commands, return a string containing prefix commands to
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get here: this one plus any others needed to get to it. Ends in a
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space. It is used before the word "command" in describing the
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commands reached through this prefix.
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For non-prefix commands, return an empty string. */
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std::string prefixname () const;
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/* Return a vector of strings describing the components of the full name
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of this command. For example, if this command is 'set AA BB CC',
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then the vector will contain 4 elements 'set', 'AA', 'BB', and 'CC'
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in that order. */
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std::vector<std::string> command_components () const;
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/* Return true if this command is an alias of another command. */
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bool is_alias () const
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{ return this->alias_target != nullptr; }
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/* Return true if this command is a prefix command. */
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bool is_prefix () const
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{ return this->subcommands != nullptr; }
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/* Return true if this command is a "command class help" command. For
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instance, a "stack" dummy command is registered so that one can do
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"help stack" and show help for all commands of the "stack" class. */
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bool is_command_class_help () const
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{ return this->func == nullptr; }
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void set_context (void *context)
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{
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gdb_assert (m_context == nullptr);
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m_context = context;
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}
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void *context () const
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{ return m_context; }
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/* Points to next command in this list. */
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struct cmd_list_element *next = nullptr;
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/* Name of this command. */
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const char *name;
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/* Command class; class values are chosen by application program. */
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enum command_class theclass;
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/* When 1 indicated that this command is deprecated. It may be
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removed from gdb's command set in the future. */
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unsigned int cmd_deprecated : 1;
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/* The user needs to be warned that this is a deprecated command.
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The user should only be warned the first time a command is
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used. */
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unsigned int deprecated_warn_user : 1;
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/* When functions are deprecated at compile time (this is the way
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it should, in general, be done) the memory containing the
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replacement string is statically allocated. In some cases it
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makes sense to deprecate commands at runtime (the testsuite is
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one example). In this case the memory for replacement is
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malloc'ed. When a command is undeprecated or re-deprecated at
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runtime we don't want to risk calling free on statically
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allocated memory, so we check this flag. */
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unsigned int malloced_replacement : 1;
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/* Set if the doc field should be xfree'd. */
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unsigned int doc_allocated : 1;
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/* Set if the name field should be xfree'd. */
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unsigned int name_allocated : 1;
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/* Flag that specifies if this command is already running its hook. */
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/* Prevents the possibility of hook recursion. */
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unsigned int hook_in : 1;
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/* For prefix commands only:
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nonzero means do not get an error if subcommand is not
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recognized; call the prefix's own function in that case. */
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unsigned int allow_unknown : 1;
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/* Nonzero says this is an abbreviation, and should not
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be mentioned in lists of commands.
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This allows "br<tab>" to complete to "break", which it
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otherwise wouldn't. */
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unsigned int abbrev_flag : 1;
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/* Type of "set" or "show" command (or SET_NOT_SET if not "set"
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or "show"). */
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ENUM_BITFIELD (cmd_types) type : 2;
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/* Function definition of this command. NULL for command class
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names and for help topics that are not really commands. NOTE:
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cagney/2002-02-02: This function signature is evolving. For
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the moment suggest sticking with either set_cmd_cfunc() or
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set_cmd_sfunc(). */
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cmd_func_ftype *func;
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/* The command's real callback. At present func() bounces through
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to one of the below. */
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union
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{
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/* Most commands don't need the cmd_list_element parameter passed to FUNC.
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They therefore register a command of this type, which doesn't have the
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cmd_list_element parameter. do_simple_func is installed as FUNC, and
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acts as a shim between the two. */
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cmd_simple_func_ftype *simple_func;
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}
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function;
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/* Documentation of this command (or help topic).
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First line is brief documentation; remaining lines form, with it,
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the full documentation. First line should end with a period.
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Entire string should also end with a period, not a newline. */
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const char *doc;
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/* For set/show commands. A method for printing the output to the
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specified stream. */
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show_value_ftype *show_value_func = nullptr;
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/* If this command is deprecated, this is the replacement name. */
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const char *replacement = nullptr;
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/* Hook for another command to be executed before this command. */
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struct cmd_list_element *hook_pre = nullptr;
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/* Hook for another command to be executed after this command. */
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struct cmd_list_element *hook_post = nullptr;
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/* Default arguments to automatically prepend to the user
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provided arguments when running this command or alias. */
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std::string default_args;
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/* Nonzero identifies a prefix command. For them, the address
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of the variable containing the list of subcommands. */
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struct cmd_list_element **subcommands = nullptr;
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/* The prefix command of this command. */
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struct cmd_list_element *prefix = nullptr;
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/* Completion routine for this command. */
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completer_ftype *completer = symbol_completer;
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/* Handle the word break characters for this completer. Usually
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this function need not be defined, but for some types of
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completers (e.g., Python completers declared as methods inside
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a class) the word break chars may need to be redefined
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depending on the completer type (e.g., for filename
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completers). */
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completer_handle_brkchars_ftype *completer_handle_brkchars = nullptr;
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/* Destruction routine for this command. If non-NULL, this is
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called when this command instance is destroyed. This may be
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used to finalize the CONTEXT field, if needed. */
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void (*destroyer) (struct cmd_list_element *self, void *context) = nullptr;
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/* Setting affected by "set" and "show". Not used if type is not_set_cmd. */
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gdb::optional<setting> var;
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/* Pointer to NULL terminated list of enumerated values (like
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argv). */
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const char *const *enums = nullptr;
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/* Pointer to command strings of user-defined commands */
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counted_command_line user_commands;
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/* Pointer to command that is hooked by this one, (by hook_pre)
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so the hook can be removed when this one is deleted. */
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struct cmd_list_element *hookee_pre = nullptr;
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/* Pointer to command that is hooked by this one, (by hook_post)
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so the hook can be removed when this one is deleted. */
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struct cmd_list_element *hookee_post = nullptr;
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/* Pointer to command that is aliased by this one, so the
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aliased command can be located in case it has been hooked. */
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struct cmd_list_element *alias_target = nullptr;
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/* Node to link aliases on an alias list. */
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using aliases_list_node_type
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= intrusive_list_node<cmd_list_element>;
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aliases_list_node_type aliases_list_node;
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/* Linked list of all aliases of this command. */
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using aliases_list_member_node_type
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= intrusive_member_node<cmd_list_element,
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&cmd_list_element::aliases_list_node>;
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using aliases_list_type
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= intrusive_list<cmd_list_element, aliases_list_member_node_type>;
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aliases_list_type aliases;
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/* If non-null, the pointer to a field in 'struct
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cli_suppress_notification', which will be set to true in cmd_func
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when this command is being executed. It will be set back to false
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when the command has been executed. */
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int *suppress_notification = nullptr;
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private:
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/* Local state (context) for this command. This can be anything. */
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void *m_context = nullptr;
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};
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/* Functions that implement commands about CLI commands. */
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extern void help_cmd (const char *, struct ui_file *);
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extern void apropos_cmd (struct ui_file *, struct cmd_list_element *,
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bool verbose, compiled_regex &, const char *);
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/* Used to mark commands that don't do anything. If we just leave the
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function field NULL, the command is interpreted as a help topic, or
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as a class of commands. */
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extern void not_just_help_class_command (const char *arg, int from_tty);
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/* Print only the first line of STR on STREAM.
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FOR_VALUE_PREFIX true indicates that the first line is output
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to be a prefix to show a value (see deprecated_show_value_hack):
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the first character is printed in uppercase, and the trailing
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dot character is not printed. */
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extern void print_doc_line (struct ui_file *stream, const char *str,
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bool for_value_prefix);
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/* The enums of boolean commands. */
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extern const char * const boolean_enums[];
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/* The enums of auto-boolean commands. */
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extern const char * const auto_boolean_enums[];
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/* Verify whether a given cmd_list_element is a user-defined command.
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Return 1 if it is user-defined. Return 0 otherwise. */
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extern int cli_user_command_p (struct cmd_list_element *);
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extern int find_command_name_length (const char *);
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#endif /* CLI_CLI_DECODE_H */
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