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// file : butl/diagnostics -*- C++ -*-
// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUTL_DIAGNOSTICS
#define BUTL_DIAGNOSTICS
#include <cassert>
#include <ostream>
#include <sstream>
#include <utility> // move(), forward()
#include <butl/ft/exception> // uncaught_exceptions
#include <exception> // uncaught_exception(s)()
#include <butl/export>
#include <butl/utility>
namespace butl
{
// Diagnostic facility base infrastructure.
//
// Diagnostics destination stream (std::cerr by default). Note that its
// modification is not MT-safe. Also note that concurrent writing to the
// stream from multiple threads can result in interleaved characters. To
// prevent this an object of diag_lock type (see below) must be created prior
// to write operation.
//
LIBBUTL_EXPORT extern std::ostream* diag_stream;
// Acquire the diagnostics exclusive access mutex in ctor, release in dtor.
// An object of the type must be created prior to writing to diag_stream (see
// above).
//
struct LIBBUTL_EXPORT diag_lock
{
diag_lock ();
~diag_lock ();
};
struct diag_record;
template <typename> struct diag_prologue;
template <typename> struct diag_mark;
using diag_epilogue = void (const diag_record&);
struct LIBBUTL_EXPORT diag_record
{
template <typename T>
friend const diag_record&
operator<< (const diag_record& r, const T& x)
{
r.os << x;
return r;
}
diag_record ()
:
#ifdef __cpp_lib_uncaught_exceptions
uncaught_ (std::uncaught_exceptions ()),
#endif
empty_ (true),
epilogue_ (nullptr) {}
template <typename B>
explicit
diag_record (const diag_prologue<B>& p): diag_record () { *this << p;}
template <typename B>
explicit
diag_record (const diag_mark<B>& m): diag_record () { *this << m;}
~diag_record () noexcept (false);
bool
empty () const {return empty_;}
bool
full () const {return !empty_;}
void
flush () const;
void
append (const char* indent, diag_epilogue* e) const
{
// Ignore subsequent epilogues (e.g., from nested marks, etc).
//
if (empty_)
{
epilogue_ = e;
empty_ = false;
}
else if (indent != nullptr)
os << indent;
}
// Move constructible-only type.
//
// Older versions of libstdc++ don't have the ostringstream move support
// and accuratly detecting its version is non-trivial. So we always use
// the pessimized implementation with libstdc++. Luckily, GCC doesn't seem
// to be needing move due to copy/move elision.
//
#ifdef __GLIBCXX__
diag_record (diag_record&&);
#else
diag_record (diag_record&& r)
:
#ifdef __cpp_lib_uncaught_exceptions
uncaught_ (r.uncaught_),
#endif
empty_ (r.empty_),
epilogue_ (r.epilogue_),
os (std::move (r.os))
{
if (!empty_)
{
r.empty_ = true;
r.epilogue_ = nullptr;
}
}
#endif
diag_record& operator= (diag_record&&) = delete;
diag_record (const diag_record&) = delete;
diag_record& operator= (const diag_record&) = delete;
protected:
#ifdef __cpp_lib_uncaught_exceptions
const int uncaught_;
#endif
mutable bool empty_;
mutable diag_epilogue* epilogue_;
public:
mutable std::ostringstream os;
};
template <typename B>
struct diag_prologue: B
{
diag_prologue (const char* i = "\n ", diag_epilogue* e = nullptr)
: B (), indent_ (i), epilogue_ (e) {}
template <typename... A>
diag_prologue (A&&... a)
: B (std::forward<A> (a)...), indent_ ("\n "), epilogue_ (nullptr) {}
template <typename... A>
diag_prologue (diag_epilogue* e, A&&... a)
: B (std::forward<A> (a)...), indent_ ("\n "), epilogue_ (e) {}
template <typename... A>
diag_prologue (const char* i, diag_epilogue* e, A&&... a)
: B (std::forward<A> (a)...), indent_ (i), epilogue_ (e) {}
template <typename T>
diag_record
operator<< (const T& x) const
{
diag_record r;
r.append (indent_, epilogue_);
B::operator() (r);
r << x;
return r;
}
friend const diag_record&
operator<< (const diag_record& r, const diag_prologue& p)
{
r.append (p.indent_, p.epilogue_);
p (r);
return r;
}
private:
const char* indent_;
diag_epilogue* epilogue_;
};
template <typename B>
struct diag_mark: B
{
diag_mark (): B () {}
template <typename... A>
diag_mark (A&&... a): B (std::forward<A> (a)...) {}
template <typename T>
diag_record
operator<< (const T& x) const
{
return B::operator() () << x;
}
friend const diag_record&
operator<< (const diag_record& r, const diag_mark& m)
{
return r << m ();
}
};
template <typename B>
struct diag_noreturn_end: B
{
diag_noreturn_end (): B () {}
template <typename... A>
diag_noreturn_end (A&&... a): B (std::forward<A> (a)...) {}
[[noreturn]] friend void
operator<< (const diag_record& r, const diag_noreturn_end& e)
{
// We said that we never return which means this end mark cannot be used
// to "maybe not return". And not returning without any diagnostics is
// probably a mistake.
//
assert (r.full ());
e.B::operator() (r);
}
};
}
#endif // BUTL_DIAGNOSTICS
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