binutils-gdb/gdb/location.h
Pedro Alves c6756f62e0 Rewrite/enhance explicit locations completer, parse left->right
One of the most annoying (to me) things about GDB's completion is when
you have overloads in your program, and you want to set a breakpoint
in one of them:

 void function(int);  // set breakpoint here.
 void function(long);

 (gdb) b -f func[TAB]
 (gdb) b -f function(       # ok, gdb completed as much as possible.
 (gdb) b -f function([TAB]  # show me the overloads, please.
 <_all_ symbols in the program are shown...>

E.g., when debugging GDB, that'd be:

 (gdb) b -f function([TAB]
 (anonymous namespace)::get_global()::global  pt_insn_get_offset@plt                       scm_new_port_table_entry
 asprintf                                     pt_pkt_alloc_decoder                         scm_new_port_table_entry@plt
 asprintf@plt                                 pt_pkt_alloc_decoder@plt                     scm_out_of_range
 bt_ctf_get_char_array                        pt_pkt_sync_forward                          scm_out_of_range@plt
 bt_ctf_get_char_array@plt                    pt_pkt_sync_forward@plt                      scm_putc
 bt_ctf_get_uint64                            pwrite                                       scm_putc@plt
 bt_ctf_get_uint64@plt                        pwrite@plt                                   scm_reverse_x
 bt_ctf_iter_read_event                       PyErr_Restore                                scm_reverse_x@plt
 bt_ctf_iter_read_event@plt                   PyErr_Restore@plt                            scm_set_port_filename_x
 <snip...>

Now that's a load of completely useless completions.

The reason GDB offers those is that the completer relies on readline
figuring out the completion word point in the input line based on the
language's word break characters, which include "(".  So readline
tells the completer to complete on "", the string that is after '('.
Likewise, if you type "function(i[TAB]" to try to complete to "int",
you're out of luck.  GDB shows you all the symbols in the program that
start with "i"...  This makes sense for the expression completer, as
what you'd want to type is e.g., a global variable, say:

(gdb) print function(i[TAB]

but, it makes no sense when specifying a function name for a
breakpoint location.

To get around that limitation, users need to quote the function name,
like:

 (gdb) b -f 'function([TAB]
 function(int)      function(long)
 (gdb) b 'function(i[TAB]
 (gdb) b 'function(int)' # now completes correctly!

Note that the quoting is only necessary for completion.  Creating the
breakpoint does not require the quoting:

 (gdb) b -f function(int) [RET]
 Breakpoint 1 at ....

This patch removes this limitation.

(
Actually, it's a necessary patch, though not sufficient.  That'll
start working correctly by the end of the series.  With this patch, if try it,
you'll see:

 (gdb) b -f function(i[TAB]
 (gdb) b -f function

i.e., gdb strips everything after the "(".  That's caused by some code
in symtab.c that'll be eliminated further down the series.  These
patches are all unfortunately interrelated, which is also the reason
new tests only appear much later in the series.
But let's ignore that reality for the remainder of the description.
)

So... this patch gets rid of the need for quoting.

It does that by adding a way for a completer to control the exact
completion word point that readline should start the completion
request for, instead of letting readline try to figure it out using
the current language's word break chars array, and often failing.

In the case above, we want the completer to figure out that it's
completing a function name that starts with "function(i".  It now
does.

It took me a while to figure out a way to ask readline to "use this
exact word point", and for a while I feared that it'd be impossible
with current readline (and having to rely on master readline for core
functionality is something I'd like to avoid very much).  Eventually,
after several different attempts, I came up with what is described in
the comment above gdb_custom_word_point_brkchars in the patch.

With this patch, the handle_brkchars phase of the explicit location
completer advances the expected word point as it parses the input line
left to right, until it figures out exactly what we're completing,
instead of expecting readline to break the string using the word break
characters, and then having the completer heuristically fix up a bad
decision by parsing the input string backwards.  This allows correctly
knowning that we're completing a symbol name after -function, complete
functions without quoting, etc.

Later, we'll make use of this same mechanims to implement a proper
linespec completer that avoids need for quoting too.

gdb/ChangeLog:
2017-07-17  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (ada_collect_symbol_completion_matches): Add
	complete_symbol_mode parameter.
	* cli/cli-cmds.c (complete_command): Get the completion result out
	of the handle_brkchars tracker if used a custom word point.
	* completer.c: Include "linespec.h".
	(enum explicit_location_match_type) <MATCH_LINE>: New enumerator.
	(advance_to_expression_complete_word_point): New.
	(completion_tracker::completes_to_completion_word): New.
	(complete_files_symbols): Pass down
	complete_symbol_mode::EXPRESSION.
	(explicit_options, probe_options): New.
	(collect_explicit_location_matches): Complete on the
	explictit_loc->foo instead of word.  Use
	linespec_complete_function.  Handle MATCH_LINE.  Handle offering
	keyword and options completions.
	(backup_text_ptr): Delete.
	(skip_keyword): New.
	(complete_explicit_location): Remove 'word' parameter.  Add
	language, quoted_arg_start and quoted_arg_end parameters.
	Rewrite, parsing left to right.
	(location_completer): Rewrite.
	(location_completer_handle_brkchars): New function.
	(symbol_completer): Pass down complete_symbol_mode::EXPRESSION.
	(enum complete_line_internal_reason): Adjust comments.
	(completion_tracker::discard_completions): New.
	(completer_handle_brkchars_func_for_completer): Handle
	location_completer.
	(gdb_custom_word_point_brkchars)
	(gdb_org_rl_basic_quote_characters): New.
	(gdb_completion_word_break_characters_throw)
	(completion_find_completion_word): Handle trackers that use a
	custom word point.
	(completion_tracker::advance_custom_word_point_by): New.
	(completion_tracker::build_completion_result): Don't rely on
	readline appending the quote char.
	(gdb_rl_attempted_completion_function_throw): Handle trackers that
	use a custom word point.
	(gdb_rl_attempted_completion_function): Restore
	rl_basic_quote_characters.
	* completer.h (class completion_tracker): Extend intro comment.
	(completion_tracker::set_quote_char)
	(completion_tracker::quote_char)
	(completion_tracker::set_use_custom_word_point)
	(completion_tracker::use_custom_word_point)
	(completion_tracker::custom_word_point)
	(completion_tracker::set_custom_word_point)
	(completion_tracker::advance_custom_word_point_by)
	(completion_tracker::completes_to_completion_word)
	(completion_tracker::discard_completions): New methods.
	(completion_tracker::m_quote_char)
	(completion_tracker::m_use_custom_word_point)
	(completion_tracker::m_custom_word_point): New fields.
	(advance_to_expression_complete_word_point): Declare.
	* f-lang.c (f_collect_symbol_completion_matches): Add
	complete_symbol_mode parameter.
	* language.h (struct language_defn)
	<la_collect_symbol_completion_matches>: Add complete_symbol_mode
	parameter.
	* linespec.c (linespec_keywords): Add NULL terminator.  Make extern.
	(linespec_complete_function): New function.
	(linespec_lexer_lex_keyword): Adjust.
	* linespec.h (linespec_keywords, linespec_complete_function): New
	declarations.
	* location.c (find_end_quote): New function.
	(explicit_location_lex_one): Add explicit_completion_info
	parameter.  Save quoting info.  Don't throw if being called for
	completion.  Don't handle Ada operators here.
	(is_cp_operator, skip_op_false_positives, first_of)
	(explicit_location_lex_one_function): New function.
	(string_to_explicit_location): Replace 'dont_throw' parameter with
	an explicit_completion_info pointer parameter.  Handle it.  Don't
	use explicit_location_lex_one to lex function names.  Use
	explicit_location_lex_one_function instead.
	* location.h (struct explicit_completion_info): New.
	(string_to_explicit_location): Replace 'dont_throw' parameter with
	an explicit_completion_info pointer parameter.
	* symtab.c (default_collect_symbol_completion_matches_break_on):
	Add complete_symbol_mode parameter.  Handle LINESPEC mode.
	(default_collect_symbol_completion_matches)
	(collect_symbol_completion_matches): Add complete_symbol_mode
	parameter.
	(collect_symbol_completion_matches_type): Pass down
	complete_symbol_mode::EXPRESSION.
	(collect_file_symbol_completion_matches): Add complete_symbol_mode
	parameter.  Handle LINESPEC mode.
	* symtab.h (complete_symbol_mode): New.
	(default_collect_symbol_completion_matches_break_on)
	(default_collect_symbol_completion_matches)
	(collect_symbol_completion_matches)
	(collect_file_symbol_completion_matches): Add complete_symbol_mode
	parameter.

gdb/testsuite/ChangeLog:
2017-07-17  Pedro Alves  <palves@redhat.com>

	* gdb.linespec/ls-errs.exp (do_test): Adjust expected output.
2017-07-17 20:21:33 +01:00

264 lines
8.4 KiB
C++

/* Data structures and API for event locations in GDB.
Copyright (C) 2013-2017 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 LOCATIONS_H
#define LOCATIONS_H 1
struct language_defn;
struct event_location;
/* An enumeration of possible signs for a line offset. */
enum offset_relative_sign
{
/* No sign */
LINE_OFFSET_NONE,
/* A plus sign ("+") */
LINE_OFFSET_PLUS,
/* A minus sign ("-") */
LINE_OFFSET_MINUS,
/* A special "sign" for unspecified offset. */
LINE_OFFSET_UNKNOWN
};
/* A line offset in a location. */
struct line_offset
{
/* Line offset and any specified sign. */
int offset;
enum offset_relative_sign sign;
};
/* An enumeration of the various ways to specify a stop event
location (used with create_breakpoint). */
enum event_location_type
{
/* A traditional linespec. */
LINESPEC_LOCATION,
/* An address in the inferior. */
ADDRESS_LOCATION,
/* An explicit location. */
EXPLICIT_LOCATION,
/* A probe location. */
PROBE_LOCATION
};
/* An explicit location. This structure is used to bypass the
parsing done on linespecs. It still has the same requirements
as linespecs, though. For example, source_filename requires
at least one other field. */
struct explicit_location
{
/* The source filename. Malloc'd. */
char *source_filename;
/* The function name. Malloc'd. */
char *function_name;
/* The name of a label. Malloc'd. */
char *label_name;
/* A line offset relative to the start of the symbol
identified by the above fields or the current symtab
if the other fields are NULL. */
struct line_offset line_offset;
};
/* Return the type of the given event location. */
extern enum event_location_type
event_location_type (const struct event_location *);
/* Return a malloc'd explicit string representation of the given
explicit location. The location must already be canonicalized/valid. */
extern char *
explicit_location_to_string (const struct explicit_location *explicit_loc);
/* Return a malloc'd linespec string representation of the given
explicit location. The location must already be canonicalized/valid. */
extern char *
explicit_location_to_linespec (const struct explicit_location *explicit_loc);
/* Return a string representation of the LOCATION.
This function may return NULL for unspecified linespecs,
e.g, LOCATION_LINESPEC and addr_string is NULL.
The result is cached in LOCATION. */
extern const char *
event_location_to_string (struct event_location *location);
/* A deleter for a struct event_location. */
struct event_location_deleter
{
void operator() (event_location *location) const;
};
/* A unique pointer for event_location. */
typedef std::unique_ptr<event_location, event_location_deleter>
event_location_up;
/* Create a new linespec location. */
extern event_location_up new_linespec_location (char **linespec);
/* Return the linespec location (a string) of the given event_location
(which must be of type LINESPEC_LOCATION). */
extern const char *
get_linespec_location (const struct event_location *location);
/* Create a new address location.
ADDR is the address corresponding to this event_location.
ADDR_STRING, a string of ADDR_STRING_LEN characters, is
the expression that was parsed to determine the address ADDR. */
extern event_location_up new_address_location (CORE_ADDR addr,
const char *addr_string,
int addr_string_len);
/* Return the address location (a CORE_ADDR) of the given event_location
(which must be of type ADDRESS_LOCATION). */
extern CORE_ADDR
get_address_location (const struct event_location *location);
/* Return the expression (a string) that was used to compute the address
of the given event_location (which must be of type ADDRESS_LOCATION). */
extern const char *
get_address_string_location (const struct event_location *location);
/* Create a new probe location. */
extern event_location_up new_probe_location (const char *probe);
/* Return the probe location (a string) of the given event_location
(which must be of type PROBE_LOCATION). */
extern const char *
get_probe_location (const struct event_location *location);
/* Initialize the given explicit location. */
extern void
initialize_explicit_location (struct explicit_location *explicit_loc);
/* Create a new explicit location. If not NULL, EXPLICIT is checked for
validity. If invalid, an exception is thrown. */
extern event_location_up
new_explicit_location (const struct explicit_location *explicit_loc);
/* Return the explicit location of the given event_location
(which must be of type EXPLICIT_LOCATION). */
extern struct explicit_location *
get_explicit_location (struct event_location *location);
/* A const version of the above. */
extern const struct explicit_location *
get_explicit_location_const (const struct event_location *location);
/* Return a copy of the given SRC location. */
extern event_location_up
copy_event_location (const struct event_location *src);
/* Attempt to convert the input string in *ARGP into an event_location.
ARGP is advanced past any processed input. Returns an event_location
(malloc'd) if an event location was successfully found in *ARGP,
NULL otherwise.
This function may call error() if *ARGP looks like properly formed,
but invalid, input, e.g., if it is called with missing argument parameters
or invalid options.
This function is intended to be used by CLI commands and will parse
explicit locations in a CLI-centric way. Other interfaces should use
string_to_event_location_basic if they want to maintain support for
legacy specifications of probe, address, and linespec locations. */
extern event_location_up
string_to_event_location (char **argp,
const struct language_defn *langauge);
/* Like string_to_event_location, but does not attempt to parse explicit
locations. */
extern event_location_up
string_to_event_location_basic (char **argp,
const struct language_defn *language);
/* Structure filled in by string_to_explicit_location to aid the
completer. */
struct explicit_completion_info
{
/* Pointer to the last option found. E.g., in "b -sou src.c -fun
func", LAST_OPTION is left pointing at "-fun func". */
const char *last_option = NULL;
/* These point to the start and end of a quoted argument, iff the
last argument was quoted. If parsing finds an incomplete quoted
string (e.g., "break -function 'fun"), then QUOTED_ARG_START is
set to point to the opening \', and QUOTED_ARG_END is left NULL.
If the last option is not quoted, then both are set to NULL. */
const char *quoted_arg_start = NULL;
const char *quoted_arg_end = NULL;
};
/* Attempt to convert the input string in *ARGP into an explicit location.
ARGP is advanced past any processed input. Returns an event_location
(malloc'd) if an explicit location was successfully found in *ARGP,
NULL otherwise.
If COMPLETION_INFO is NULL, this function may call error() if *ARGP
looks like improperly formed input, e.g., if it is called with
missing argument parameters or invalid options. If COMPLETION_INFO
is not NULL, this function will not throw any exceptions. */
extern event_location_up
string_to_explicit_location (const char **argp,
const struct language_defn *language,
explicit_completion_info *completion_info);
/* A convenience function for testing for unset locations. */
extern int event_location_empty_p (const struct event_location *location);
/* Set the location's string representation. If STRING is NULL, clear
the string representation. */
extern void
set_event_location_string (struct event_location *location,
const char *string);
#endif /* LOCATIONS_H */