Currently, gdb::optional is really minimal and can only be used for
lazy initialization. There's no way to get at the value contained
inside the optinal. This commit corrects that, by adding observer
methods, mostly copied from libstdc++'s implementation of C++17
std::optional.
This will be used in the following patch.
gdb/ChangeLog:
2017-04-04 Pedro Alves <palves@redhat.com>
* common/gdb_optional.h (gdb::optiona): Add operator->, operator*,
operator bool, has_value and get methods.
This patch introduces a bit of infrastructure -- namely, a minimal
std::optional analogue called gdb::optional, and an RAII template
class that works like make_cleanup_ui_out_tuple_begin_end or
make_cleanup_ui_out_list_begin_end -- and then uses these in the
Python code. This removes a number of cleanups and generally
simplifies this code.
std::optional is only available in C++17. Normally I would have had
this code check __cplusplus, but my gcc apparently isn't new enough to
find <optional>, even with -std=c++1z; so, because I could not test
it, the patch does not do this.
gdb/ChangeLog
2017-02-10 Tom Tromey <tom@tromey.com>
* ui-out.h (ui_out_emit_type): New class.
(ui_out_emit_tuple, ui_out_emit_list): New typedefs.
* python/py-framefilter.c (py_print_single_arg): Use gdb::optional
and ui_out_emit_tuple.
(enumerate_locals): Likewise.
(py_mi_print_variables, py_print_locals, py_print_args): Use
ui_out_emit_list.
(py_print_frame): Use gdb::optional, ui_out_emit_tuple,
ui_out_emit_list.
* common/gdb_optional.h: New file.
