From d194f1fe51cb85b8a919b7ee9e3a7715b0ec9744 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Tue, 4 Apr 2017 20:03:25 +0100 Subject: [PATCH] gdb::optional: Add observers 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 * common/gdb_optional.h (gdb::optiona): Add operator->, operator*, operator bool, has_value and get methods. --- gdb/ChangeLog | 5 +++++ gdb/common/gdb_optional.h | 29 +++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 5e124c46c4c..f2b64b9e4d0 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2017-04-04 Pedro Alves + + * common/gdb_optional.h (gdb::optiona): Add operator->, operator*, + operator bool, has_value and get methods. + 2017-04-04 Pedro Alves * dwarf2read.c (struct file_entry): Add ctors, and initialize all diff --git a/gdb/common/gdb_optional.h b/gdb/common/gdb_optional.h index d991da123cf..fef7a73e02a 100644 --- a/gdb/common/gdb_optional.h +++ b/gdb/common/gdb_optional.h @@ -61,6 +61,31 @@ public: m_instantiated = true; } + /* Observers. */ + constexpr const T *operator-> () const + { return std::addressof (this->get ()); } + + T *operator-> () + { return std::addressof (this->get ()); } + + constexpr const T &operator* () const & + { return this->get (); } + + T &operator* () & + { return this->get (); } + + T &&operator* () && + { return std::move (this->get ()); } + + constexpr const T &&operator* () const && + { return std::move (this->get ()); } + + constexpr explicit operator bool () const noexcept + { return m_instantiated; } + + constexpr bool has_value () const noexcept + { return m_instantiated; } + private: /* Destroy the object. */ @@ -71,6 +96,10 @@ private: m_item.~T (); } + /* The get operations have m_instantiated as a precondition. */ + T &get () noexcept { return m_item; } + constexpr const T &get () const noexcept { return m_item; } + /* The object. */ union { -- 2.30.2