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// file : build/variable -*- C++ -*-
// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUILD_VARIABLE
#define BUILD_VARIABLE
#include <map>
#include <string>
#include <memory> // unique_ptr
#include <cstddef> // nullptr_t
#include <utility> // move(), pair, make_pair()
#include <cassert>
#include <functional> // hash, reference_wrapper
#include <typeindex>
#include <unordered_set>
#include <butl/prefix-map>
#include <build/types>
#include <build/target-type>
namespace build
{
struct value;
struct value_type
{
std::type_index id;
value* (*const factory) ();
};
// variable
//
// The two variables are considered the same if they have the same name.
//
struct variable
{
explicit
variable (std::string n, char p = '\0'): name (std::move (n)), pairs (p) {}
std::string name;
char pairs;
//const value_type* type = nullptr; // If NULL, then no fixed type.
};
inline bool
operator== (const variable& x, const variable& y) {return x.name == y.name;}
typedef std::reference_wrapper<const variable> variable_cref;
// value
//
struct value;
typedef std::unique_ptr<value> value_ptr;
struct value
{
public:
virtual value_ptr
clone () const = 0;
virtual bool
compare (const value&) const = 0;
virtual
~value () = default;
};
class list_value: public value, public names
{
public:
using names::names;
list_value () = default;
explicit list_value (names d): names (std::move (d)) {}
explicit list_value (name n) {emplace_back (std::move (n));}
explicit list_value (dir_path d) {emplace_back (std::move (d));}
explicit list_value (std::string s) {emplace_back (std::move (s));}
explicit list_value (const char* s) {emplace_back (s);}
virtual value_ptr
clone () const {return value_ptr (new list_value (*this));}
virtual bool
compare (const value& v) const
{
const list_value* lv (dynamic_cast<const list_value*> (&v));
return lv != nullptr && static_cast<const names&> (*this) == *lv;
}
// Pair (i.e., key-value) search. Note that this funtion assumes
// the list contains only pairs and keys are simple names. Returns
// NULL if not found.
//
const name*
find_pair (const std::string& key) const
{
for (auto i (begin ()); i != end (); i += 2)
if (i->value == key)
return &*++i;
return nullptr;
}
};
typedef std::unique_ptr<list_value> list_value_ptr;
// value_proxy
//
// A variable can be undefined, null, or contain some actual value.
// Note that once value_proxy is bound to a value, the only way to
// rebind it to a different value is by using explicit rebind(). In
// particular, assigning one value proxy to another will assing the
// values.
//
struct variable_map;
struct value_proxy
{
bool
defined () const {return p != nullptr;}
bool
null () const {return *p == nullptr;}
bool
empty () const;
explicit operator bool () const {return defined () && !null ();}
explicit operator value_ptr& () const {return *p;}
// Get interface. See available specializations below.
//
template <typename T>
T
as () const;
// Assign.
//
const value_proxy&
operator= (value_ptr) const;
const value_proxy&
operator= (const value_proxy&) const;
const value_proxy&
operator= (list_value) const;
const value_proxy&
operator= (std::string) const;
const value_proxy&
operator= (dir_path) const;
const value_proxy&
operator= (std::nullptr_t) const;
// Append.
//
const value_proxy&
operator+= (const value_proxy&) const;
const value_proxy&
operator+= (const list_value&) const;
const value_proxy&
operator+= (std::string) const; // Append simple name to list_value.
// Return true if this value belongs to the specified scope or target.
// Note that it can also be a target type/pattern-specific value.
//
template <typename T>
bool
belongs (const T& x) const {return vars == &x.vars;}
// Implementation details.
//
const variable_map* vars; // Variable map to which this value belongs.
value_proxy (): vars (nullptr), p (nullptr) {}
value_proxy (value_ptr* p, const variable_map* v)
: vars (p != nullptr ? v : nullptr), p (p) {}
template <typename T>
value_proxy (value_ptr& p, const T& x)
: value_proxy (&p, &x.vars) {}
// @@ To do this properly we seem to need ro_value_proxy?
//
value_proxy (const value_ptr* p, const variable_map* v)
: value_proxy (const_cast<value_ptr*> (p), v) {}
template <typename T>
value_proxy (const value_ptr& p, const T& x)
: value_proxy (const_cast<value_ptr&> (p), x) {}
void
rebind (const value_proxy& x) {vars = x.vars; p = x.p;}
private:
value_ptr* p;
};
template <>
inline value& value_proxy::
as<value&> () const {return **p;}
template <>
inline const value& value_proxy::
as<const value&> () const {return **p;}
template <>
inline list_value& value_proxy::
as<list_value&> () const
{
list_value* lv (dynamic_cast<list_value*> (p->get ()));
assert (lv != nullptr);
return *lv;
}
template <>
inline const list_value& value_proxy::
as<const list_value&> () const {return as<list_value&> ();}
template <>
inline const name* value_proxy::
as<const name*> () const
{
const auto& lv (as<const list_value&> ());
assert (lv.size () < 2);
return lv.empty () ? nullptr : &lv.front ();
}
template <>
inline const name& value_proxy::
as<const name&> () const
{
const auto& lv (as<const list_value&> ());
assert (lv.size () == 1);
return lv.front ();
}
template <>
std::string& value_proxy::
as<std::string&> () const;
template <>
const std::string& value_proxy::
as<const std::string&> () const;
template <>
dir_path& value_proxy::
as<dir_path&> () const;
template <>
const dir_path& value_proxy::
as<const dir_path&> () const;
template <>
bool value_proxy::
as<bool> () const;
}
namespace std
{
template <>
struct hash<build::variable>: hash<string>
{
size_t
operator() (const build::variable& v) const noexcept
{
return hash<string>::operator() (v.name);
}
};
}
namespace butl
{
template <>
struct compare_prefix<build::variable_cref>: compare_prefix<std::string>
{
typedef compare_prefix<std::string> base;
explicit
compare_prefix (char d): base (d) {}
bool
operator() (const build::variable& x, const build::variable& y) const
{
return base::operator() (x.name, y.name);
}
bool
prefix (const build::variable& p, const build::variable& k) const
{
return base::prefix (p.name, k.name);
}
};
}
namespace build
{
// variable_pool
//
struct variable_set: std::unordered_set<variable>
{
// @@ Need to check/set type?
//
const variable&
find (std::string name) {return *emplace (std::move (name)).first;}
const variable&
insert (variable v) {return *emplace (std::move (v)).first;}
};
extern variable_set variable_pool;
// variable_map
//
struct variable_map
{
using map_type = butl::prefix_map<variable_cref, value_ptr, '.'>;
using size_type = map_type::size_type;
using const_iterator = map_type::const_iterator;
const value_ptr*
find (const variable& var) const
{
auto i (m_.find (var));
return i != m_.end () ? &i->second : nullptr;
}
value_proxy
operator[] (const variable& var) const
{
return value_proxy (find (var), this);
}
value_proxy
operator[] (const std::string& name) const
{
return operator[] (variable_pool.find (name));
}
// The second member in the pair indicates whether new (NULL)
// value was set.
//
std::pair<value_proxy, bool>
assign (const variable& var)
{
auto r (m_.emplace (var, value_ptr ()));
return std::make_pair (value_proxy (&r.first->second, this), r.second);
}
std::pair<value_proxy, bool>
assign (const std::string& name)
{
return assign (variable_pool.find (name));
}
std::pair<const_iterator, const_iterator>
find_namespace (const std::string& ns) const
{
return m_.find_prefix (variable_pool.find (ns));
}
const_iterator
begin () const {return m_.begin ();}
const_iterator
end () const {return m_.end ();}
bool
empty () const {return m_.empty ();}
size_type
size () const {return m_.size ();}
private:
map_type m_;
};
// Target type/pattern-specific variables.
//
using variable_pattern_map = std::map<std::string, variable_map>;
using variable_type_map = std::map<std::reference_wrapper<const target_type>,
variable_pattern_map>;
//@@ In quite a few places we assume that we can store a reference
// to the returned value (e.g., install::lookup_install()). If
// we "instantiate" the value on the fly, then we will need to
// consider its lifetime.
}
#include <build/variable.ixx>
#endif // BUILD_VARIABLE
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