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// file : build/utility -*- C++ -*-
// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUILD_UTILITY
#define BUILD_UTILITY
#include <tuple>
#include <string>
#include <utility>
#include <cstring> // strcmp()
#include <exception>
#include <unordered_set>
#include <build/path>
namespace build
{
// Empty string and path.
//
extern const std::string empty_string;
extern const path empty_path;
extern const dir_path empty_dir_path;
// Comparators.
//
struct compare_c_string
{
bool operator() (const char* x, const char* y) const
{
return std::strcmp (x, y) < 0;
}
};
struct compare_pointer_target
{
template <typename P>
bool operator() (const P& x, const P& y) const {return *x < *y;}
};
// Simple optional class template while waiting for std::optional.
//
template <typename T>
class optional
{
public:
typedef T value_type;
optional (): null_ (true) {}
optional (const T& v): value_ (v), null_ (false) {}
optional& operator= (const T& v) {value_ = v; null_ = false; return *this;}
T& value () {return value_;}
const T& value () const {return value_;}
T* operator-> () {return &value_;}
const T* operator-> () const {return &value_;}
T& operator* () {return value_;}
const T& operator* () const {return value_;}
explicit operator bool () const {return !null_;}
private:
T value_;
bool null_;
};
// Support for reverse iteration using range-based for-loop:
//
// for (... : reverse_iterate (x)) ...
//
template <typename T>
class reverse_range
{
T& x_;
public:
reverse_range (T& x): x_ (x) {}
auto begin () -> decltype (this->x_.rbegin ())
{
return x_.rbegin ();
}
auto end () -> decltype (this->x_.rend ())
{
return x_.rend ();
}
};
template <typename T>
inline reverse_range<T>
reverse_iterate (T& x)
{
return reverse_range<T> (x);
}
template <typename T>
inline reverse_range<const T>
reverse_iterate (const T& x)
{
return reverse_range<const T> (x);
}
// Call a function if there is an exception.
//
// Means we are in the body of a destructor that is being called
// as part of the exception stack unwindining. Used to compensate
// for the deficiencies of uncaught_exception() until C++17
// uncaught_exceptions() becomes available.
//
// @@ MT: will have to be TLS.
//
extern bool exception_unwinding_dtor;
template <typename F, typename T>
struct exception_guard;
template <typename F, typename... A>
inline exception_guard<F, std::tuple<A&&...>>
make_exception_guard (F f, A&&... a)
{
return exception_guard<F, std::tuple<A&&...>> (
std::move (f), std::forward_as_tuple (a...));
}
template <typename F, typename... A>
struct exception_guard<F, std::tuple<A...>>
{
typedef std::tuple<A...> T;
exception_guard (F f, T a): f_ (std::move (f)), a_ (std::move (a)) {}
~exception_guard ()
{
if (std::uncaught_exception ())
{
exception_unwinding_dtor = true;
call (std::index_sequence_for<A...> ());
exception_unwinding_dtor = false;
}
}
private:
template <std::size_t... I>
void
call (std::index_sequence<I...>) {f_ (std::get<I> (a_)...);}
F f_;
T a_;
};
// Pools (@@ perhaps move into a separate header).
//
struct string_pool: std::unordered_set<std::string>
{
const std::string&
find (const char* s) {return *emplace (s).first;}
};
extern string_pool extension_pool;
}
#endif // BUILD_UTILITY
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