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// file : build/utility -*- C++ -*-
// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
// license : MIT; see accompanying LICENSE file
#ifndef BUILD_UTILITY
#define BUILD_UTILITY
#include <tuple>
#include <limits> // numeric_limits
#include <string>
#include <vector>
#include <utility>
#include <cstring> // strcmp()
#include <cassert>
#include <exception>
#include <unordered_set>
#include <unordered_map>
#include <build/map-key>
#include <build/path>
namespace build
{
// Empty string and path.
//
extern const std::string empty_string;
extern const path empty_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;}
};
// 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 () const -> decltype (this->x_.rbegin ())
{
return x_.rbegin ();
}
auto end () const -> decltype (this->x_.rend ())
{
return x_.rend ();
}
};
template <typename T>
inline reverse_range<T>
reverse_iterate (T& x)
{
return reverse_range<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;
// A pool of strings and, optionally, other accompanying data in which
// each entry is assigned an individual index (or id) of type I (e.g.,
// uint8_t, uint16_t, etc., depending on how many entries are expected).
// Index value 0 is reserved to indicate the no entry condition.
//
template <typename I, typename D>
struct string_table_element
{
const I i;
const D d;
};
template <typename I>
struct string_table_element<I, std::string>
{
const I i;
const std::string d;
};
template <typename D>
struct string_table_traits
{
// By default, look for the key() function in D. But you can
// also specialize this class template.
//
static const std::string&
key (const D& d) {return d.key ();}
};
template <>
struct string_table_traits<std::string>
{
static const std::string&
key (const std::string& d) {return d;}
};
template <typename I, typename D = std::string>
struct string_table
{
// Insert new entry unless one already exists.
//
I
insert (const D& d)
{
std::size_t i (vec_.size () + 1);
// Note: move(d) would be tricky since key still points to it.
//
auto r (map_.emplace (
key_type (&traits::key (d)),
value_type {static_cast<I> (i), d}));
if (r.second)
{
assert (i <= std::numeric_limits<I>::max ());
r.first->first.p = &traits::key (r.first->second.d); // Update key.
vec_.push_back (r.first);
}
return r.first->second.i;
}
// Find existing.
//
I
find (const std::string& k) const
{
auto i (map_.find (key_type (&k)));
return i != map_.end () ? i->second.i : 0;
}
// Reverse lookup.
//
const D&
operator[] (I i) const {assert (i > 0); return vec_[i - 1]->second.d;}
I
size () const {return static_cast<I> (vec_.size ());}
private:
using key_type = map_key<std::string>;
using value_type = string_table_element<I, D>;
using map_type = std::unordered_map<key_type, value_type>;
using traits = string_table_traits<D>;
map_type map_;
std::vector<typename map_type::const_iterator> vec_;
};
}
#endif // BUILD_UTILITY
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