forked from Imagelibrary/binutils-gdb
5be5fa3ffd
cmd_list_element can contain a pointer to data that can be set and / or shown. This is achieved with a void* that points to the data that can be accessed, while var_type (of type enum var_types) tells how to interpret the data pointed to. With this pattern, the user of the cmd_list_element needs to know what the storage type associated with a given VAR_TYPES tag, and needs to do the proper casting. No automatic check at compile or run time enforces that the adequate cast is done. This looks something like: if (c->var_type == var_zuinteger) unsigned int v = *(unsigned int*)v->var_type; With this approach, it is easy to make an error. This patch aims at addressing the same problem as https://sourceware.org/pipermail/gdb-patches/2021-July/180920.html but uses a different approach. This patch proposes to add an abstraction around the var_types and void* pointer pair. The abstraction is meant to prevent the user from having to handle the cast and verify that the data is read or written as a type that is coherent with the setting's var_type. This is achieved by introducing the setting struct, and a set of templated get / set member functions. The template parameter is the type of the variable that holds the referred variable. For example, instantiating the member functions with bool will yield something similar to: bool get<bool> () const { gdb_assert (this->m_var_type == var_boolean); gdb_assert (this->m_var != nullptr); return *static_cast<bool *> (this->m_var); } void set<bool> (bool var) { gdb_assert (this->m_var_type == var_boolean); gdb_assert (this->m_var != nullptr); *static_cast<bool *> (this->m_var) = var; } With such abstractions available, the var_type and var members of cmd_list_element are replaced with a setting instance. No user visible change is expected after this patch. Tested on GNU/Linux x86_64, with no regression noticed. Change-Id: Ie1d08c3ceb8b30b3d7bf1efe036eb8acffcd2f34
66 lines
2.7 KiB
C++
66 lines
2.7 KiB
C++
/* Header file for GDB CLI set and show commands implementation.
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Copyright (C) 2000-2021 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_SETSHOW_H
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#define CLI_CLI_SETSHOW_H
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#include <string>
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struct cmd_list_element;
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/* Parse ARG, an option to a boolean variable.
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Returns 1 for true, 0 for false, and -1 if invalid. */
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extern int parse_cli_boolean_value (const char *arg);
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/* Same as above, but work with a pointer to pointer. ARG is advanced
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past a successfully parsed value. */
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extern int parse_cli_boolean_value (const char **arg);
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/* Parse ARG, an option to a var_uinteger or var_zuinteger variable.
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Either returns the parsed value on success or throws an error. If
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EXPRESSION is true, *ARG is parsed as an expression; otherwise, it
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is parsed with get_ulongest. It's not possible to parse the
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integer as an expression when there may be valid input after the
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integer, such as when parsing command options. E.g., "print
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-elements NUMBER -obj --". In such case, parsing as an expression
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would parse "-obj --" as part of the expression as well. */
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extern unsigned int parse_cli_var_uinteger (var_types var_type,
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const char **arg,
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bool expression);
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/* Like parse_cli_var_uinteger, for var_zuinteger_unlimited. */
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extern int parse_cli_var_zuinteger_unlimited (const char **arg,
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bool expression);
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/* Parse ARG, an option to a var_enum variable. ENUM is a
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null-terminated array of possible values. Either returns the parsed
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value on success or throws an error. ARG is advanced past the
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parsed value. */
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const char *parse_cli_var_enum (const char **args,
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const char *const *enums);
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extern void do_set_command (const char *arg, int from_tty,
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struct cmd_list_element *c);
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extern void do_show_command (const char *arg, int from_tty,
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struct cmd_list_element *c);
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/* Get a string version of VAR's value. */
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extern std::string get_setshow_command_value_string (const setting &var);
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extern void cmd_show_list (struct cmd_list_element *list, int from_tty);
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#endif /* CLI_CLI_SETSHOW_H */
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