binutils-gdb/gdb/valprint.h
Pedro Alves 7d8062de98 Make "print" and "compile print" support -OPT options
This patch adds support for "print -option optval --", etc.
Likewise for "compile print".

We'll get:

~~~~~~
(gdb) help print
Print value of expression EXP.
Usage: print [[OPTION]... --] [/FMT] [EXP]

Options:
  -address [on|off]
    Set printing of addresses.

  -array [on|off]
    Set pretty formatting of arrays.

  -array-indexes [on|off]
    Set printing of array indexes.

  -elements NUMBER|unlimited
    Set limit on string chars or array elements to print.
    "unlimited" causes there to be no limit.

  -max-depth NUMBER|unlimited
    Set maximum print depth for nested structures, unions and arrays.
    When structures, unions, or arrays are nested beyond this depth then they
    will be replaced with either '{...}' or '(...)' depending on the language.
    Use "unlimited" to print the complete structure.

  -null-stop [on|off]
    Set printing of char arrays to stop at first null char.

  -object [on|off]
    Set printing of C++ virtual function tables.

  -pretty [on|off]
    Set pretty formatting of structures.

  -repeats NUMBER|unlimited
    Set threshold for repeated print elements.
    "unlimited" causes all elements to be individually printed.

  -static-members [on|off]
    Set printing of C++ static members.

  -symbol [on|off]
    Set printing of symbol names when printing pointers.

  -union [on|off]
    Set printing of unions interior to structures.

  -vtbl [on|off]
    Set printing of C++ virtual function tables.

Note: because this command accepts arbitrary expressions, if you
specify any command option, you must use a double dash ("--")
to mark the end of option processing.  E.g.: "print -o -- myobj".
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I want to highlight the comment above about "--".

At first, I thought we could make the print command parse the options,
and if the option wasn't recognized, fallback to parsing as an
expression.  Then, if the user wanted to disambiguate, he'd use the
"--" option delimiter.  For example, if you had a variable called
"object" and you wanted to print its negative, you'd have to do:

  (gdb) print -- -object

After getting that working, I saw that gdb.pascal/floats.exp
regressed, in these tests:

 gdb_test "print -r" " = -1\\.2(499.*|5|500.*)"
 gdb_test "print -(r)" " = -1.2(499.*|5|500.*)"
 gdb_test "print -(r + s)" " = -3\\.4(499.*|5|500.*)"

It's the first one that I found most concerning.  It regressed because
"-r" is the abbreviation of "-raw".  I realized then that the behavior
change was a bit risker than I'd like, considering scripts, wrappers
around gdb, etc., and even user expectation.  So instead, I made the
print command _require_ the "--" options delimiter if you want to
specify any option.  So:

  (gdb) print -r

is parsed as an expression, and

  (gdb) print -r --

is parsed as an option.

I noticed that that's also what lldb's expr (the equivalent of print)
does to handle the same problem.

Going back the options themselves, note that:

 - you can shorten option names, as long as unambiguous.
 - For boolean options, 0/1 stand for off/on.
 - For boolean options, "true" is implied.

So these are all equivalent:

 (gdb) print -object on -static-members off -pretty on -- foo
 (gdb) print -object -static-members off -pretty -- foo
 (gdb) print -object -static-members 0 -pretty -- foo
 (gdb) print -o -st 0 -p -- foo

TAB completion is fully supported:

  (gdb) p -[TAB]
  -address         -elements        -pretty          -symbol
  -array           -null-stop       -repeats         -union
  -array-indexes   -object          -static-members  -vtbl

Note that the code is organized such that some of the options and the
"set/show" commands code is shared.  In particular, the "print"
options and the corresponding "set print" commands are defined with
the same structures.  The commands are installed with the
gdb::option::add_setshow_cmds_for_options function.

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

	* compile/compile.c: Include "cli/cli-option.h".
	(compile_print_value): Scope data pointer is now a
	value_print_options pointer; adjust.
	(compile_print_command): Process options.  Scope data pointer is
	now a value_print_options pointer; adjust.
	(_initialize_compile): Update "compile print"'s help to include
	supported options.  Install a completer for "compile print".
	* cp-valprint.c (show_vtblprint, show_objectprint)
	(show_static_field_print): Delete.
	(_initialize_cp_valprint): Don't install "set print
	static-members", "set print vtbl", "set print object" here.
	* printcmd.c: Include "cli/cli-option.h" and
	"common/gdb_optional.h".
	(print_command_parse_format): Rework to fill in a
	value_print_options instead of a format_data.
	(print_value): Change parameter type from format_data pointer to
	value_print_options reference.  Adjust.
	(print_command_1): Process options.  Adjust to pass down a
	value_print_options.
	(print_command_completer): New.
	(_initialize_printcmd): Install print_command_completer as
	handle_brkchars completer for the "print" command.  Update
	"print"'s help to include supported options.
	* valprint.c: Include "cli/cli-option.h".
	(show_vtblprint, show_objectprint, show_static_field_print): Moved
	here from cp-valprint.c.
	(boolean_option_def, uinteger_option_def)
	(value_print_option_defs, make_value_print_options_def_group):
	New.  Use gdb::option::add_setshow_cmds_for_options to install
	"set print elements", "set print null-stop", "set print repeats",
	"set print pretty", "set print union", "set print array", "set
	print address", "set print symbol", "set print array-indexes".
	* valprint.h: Include <string> and "cli/cli-option.h".
	(make_value_print_options_def_group): Declare.
	(print_value): Change parameter type from format_data pointer to
	value_print_options reference.
	(print_command_completer): Declare.

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

	* gdb.base/options.exp: Build executable.
	(test-print): New procedure.
	(top level): Call it, once for "print" and another for "compile
	print".
2019-06-13 00:18:24 +01:00

281 lines
9.1 KiB
C++

/* Declarations for value printing routines for GDB, the GNU debugger.
Copyright (C) 1986-2019 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 VALPRINT_H
#define VALPRINT_H
#include "cli/cli-option.h"
/* This is used to pass formatting options to various value-printing
functions. */
struct value_print_options
{
/* Pretty-formatting control. */
enum val_prettyformat prettyformat;
/* Controls pretty formatting of arrays. */
int prettyformat_arrays;
/* Controls pretty formatting of structures. */
int prettyformat_structs;
/* Controls printing of virtual tables. */
int vtblprint;
/* Controls printing of nested unions. */
int unionprint;
/* Controls printing of addresses. */
int addressprint;
/* Controls looking up an object's derived type using what we find
in its vtables. */
int objectprint;
/* Maximum number of chars to print for a string pointer value or vector
contents, or UINT_MAX for no limit. Note that "set print elements 0"
stores UINT_MAX in print_max, which displays in a show command as
"unlimited". */
unsigned int print_max;
/* Print repeat counts if there are more than this many repetitions
of an element in an array. */
unsigned int repeat_count_threshold;
/* The global output format letter. */
int output_format;
/* The current format letter. This is set locally for a given call,
e.g. when the user passes a format to "print". */
int format;
/* Stop printing at null character? */
int stop_print_at_null;
/* True if we should print the index of each element when printing
an array. */
int print_array_indexes;
/* If nonzero, then dereference references, otherwise just print
them like pointers. */
int deref_ref;
/* If nonzero, print static fields. */
int static_field_print;
/* If nonzero, print static fields for Pascal. FIXME: C++ has a
flag, why not share with Pascal too? */
int pascal_static_field_print;
/* If non-zero don't do Python pretty-printing. */
int raw;
/* If nonzero, print the value in "summary" form.
If raw and summary are both non-zero, don't print non-scalar values
("..." is printed instead). */
int summary;
/* If nonzero, when printing a pointer, print the symbol to which it
points, if any. */
int symbol_print;
/* Maximum print depth when printing nested aggregates. */
int max_depth;
/* Whether "finish" should print the value. */
int finish_print;
};
/* Create an option_def_group for the value_print options, with OPTS
as context. */
extern gdb::option::option_def_group make_value_print_options_def_group
(value_print_options *opts);
/* The global print options set by the user. In general this should
not be directly accessed, except by set/show commands. Ordinary
code should call get_user_print_options instead. */
extern struct value_print_options user_print_options;
/* Initialize *OPTS to be a copy of the user print options. */
extern void get_user_print_options (struct value_print_options *opts);
/* Initialize *OPTS to be a copy of the user print options, but with
pretty-formatting disabled. */
extern void get_no_prettyformat_print_options (struct value_print_options *);
/* Initialize *OPTS to be a copy of the user print options, but using
FORMAT as the formatting option. */
extern void get_formatted_print_options (struct value_print_options *opts,
char format);
extern void maybe_print_array_index (struct type *index_type, LONGEST index,
struct ui_file *stream,
const struct value_print_options *);
extern void val_print_array_elements (struct type *, LONGEST,
CORE_ADDR, struct ui_file *, int,
struct value *,
const struct value_print_options *,
unsigned int);
extern void val_print_scalar_formatted (struct type *,
LONGEST,
struct value *,
const struct value_print_options *,
int,
struct ui_file *);
extern void print_binary_chars (struct ui_file *, const gdb_byte *,
unsigned int, enum bfd_endian, bool);
extern void print_octal_chars (struct ui_file *, const gdb_byte *,
unsigned int, enum bfd_endian);
extern void print_decimal_chars (struct ui_file *, const gdb_byte *,
unsigned int, bool, enum bfd_endian);
extern void print_hex_chars (struct ui_file *, const gdb_byte *,
unsigned int, enum bfd_endian, bool);
extern void print_char_chars (struct ui_file *, struct type *,
const gdb_byte *, unsigned int, enum bfd_endian);
extern void print_function_pointer_address (const struct value_print_options *options,
struct gdbarch *gdbarch,
CORE_ADDR address,
struct ui_file *stream);
extern int read_string (CORE_ADDR addr, int len, int width,
unsigned int fetchlimit,
enum bfd_endian byte_order,
gdb::unique_xmalloc_ptr<gdb_byte> *buffer,
int *bytes_read);
extern void val_print_optimized_out (const struct value *val,
struct ui_file *stream);
/* Prints "<not saved>" to STREAM. */
extern void val_print_not_saved (struct ui_file *stream);
extern void val_print_unavailable (struct ui_file *stream);
extern void val_print_invalid_address (struct ui_file *stream);
/* An instance of this is passed to generic_val_print and describes
some language-specific ways to print things. */
struct generic_val_print_decorations
{
/* Printing complex numbers: what to print before, between the
elements, and after. */
const char *complex_prefix;
const char *complex_infix;
const char *complex_suffix;
/* Boolean true and false. */
const char *true_name;
const char *false_name;
/* What to print when we see TYPE_CODE_VOID. */
const char *void_name;
/* Array start and end strings. */
const char *array_start;
const char *array_end;
};
extern void generic_val_print (struct type *type,
int embedded_offset, CORE_ADDR address,
struct ui_file *stream, int recurse,
struct value *original_value,
const struct value_print_options *options,
const struct generic_val_print_decorations *);
extern void generic_emit_char (int c, struct type *type, struct ui_file *stream,
int quoter, const char *encoding);
extern void generic_printstr (struct ui_file *stream, struct type *type,
const gdb_byte *string, unsigned int length,
const char *encoding, int force_ellipses,
int quote_char, int c_style_terminator,
const struct value_print_options *options);
/* Run the "output" command. ARGS and FROM_TTY are the usual
arguments passed to all command implementations, except ARGS is
const. */
extern void output_command (const char *args, int from_tty);
extern int val_print_scalar_type_p (struct type *type);
struct format_data
{
int count;
char format;
char size;
/* True if the value should be printed raw -- that is, bypassing
python-based formatters. */
unsigned char raw;
};
extern void print_command_parse_format (const char **expp, const char *cmdname,
value_print_options *opts);
/* Print VAL to console according to OPTS, including recording it to
the history. */
extern void print_value (value *val, const value_print_options &opts);
/* Completer for the "print", "call", and "compile print"
commands. */
extern void print_command_completer (struct cmd_list_element *ignore,
completion_tracker &tracker,
const char *text, const char *word);
/* Given an address ADDR return all the elements needed to print the
address in a symbolic form. NAME can be mangled or not depending
on DO_DEMANGLE (and also on the asm_demangle global variable,
manipulated via ''set print asm-demangle''). Return 0 in case of
success, when all the info in the OUT paramters is valid. Return 1
otherwise. */
extern int build_address_symbolic (struct gdbarch *,
CORE_ADDR addr,
int do_demangle,
std::string *name,
int *offset,
std::string *filename,
int *line,
int *unmapped);
/* Check to see if RECURSE is greater than or equal to the allowed
printing max-depth (see 'set print max-depth'). If it is then print an
ellipsis expression to STREAM and return true, otherwise return false.
LANGUAGE determines what type of ellipsis expression is printed. */
extern bool val_print_check_max_depth (struct ui_file *stream, int recurse,
const struct value_print_options *opts,
const struct language_defn *language);
#endif