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// file : libbuild2/prerequisite.hxx -*- C++ -*-
// license : MIT; see accompanying LICENSE file
#ifndef LIBBUILD2_PREREQUISITE_HXX
#define LIBBUILD2_PREREQUISITE_HXX
#include <libbuild2/types.hxx>
#include <libbuild2/forward.hxx>
#include <libbuild2/utility.hxx>
#include <libbuild2/scope.hxx>
#include <libbuild2/action.hxx>
#include <libbuild2/variable.hxx>
#include <libbuild2/target-key.hxx>
#include <libbuild2/diagnostics.hxx>
#include <libbuild2/prerequisite-key.hxx>
#include <libbuild2/export.hxx>
namespace build2
{
// Note that every data member except for the target is immutable (const).
//
class LIBBUILD2_SYMEXPORT prerequisite
{
public:
using scope_type = build2::scope;
using target_type = build2::target;
using target_type_type = build2::target_type;
// Note that unlike targets, for prerequisites an empty out directory
// means undetermined rather than being definitely in the out tree (but
// maybe we should make this explicit via optional<>; see the from-target
// constructor).
//
// It might seem natural to keep the reference to the owner target instead
// of to the scope. But that's not the semantics that we have, consider:
//
// foo/obj{x}: bar/cxx{y}
//
// bar/ here is relative to the scope, not to foo/. Plus, bar/ can resolve
// to either src or out.
//
const optional<project_name> proj;
const target_type_type& type;
const dir_path dir; // Normalized absolute or relative (to scope).
const dir_path out; // Empty, normalized absolute, or relative.
const string name;
const optional<string> ext; // Absent if unspecified.
const scope_type& scope;
// NULL if not yet resolved. Note that this should always be the "primary
// target", not a member of a target group.
//
// While normally only a matching rule should change this, if the
// prerequisite comes from the group, then it's possible that several
// rules will try to update it simultaneously. Thus the atomic.
//
mutable atomic<const target_type*> target {nullptr};
// Prerequisite-specific variables.
//
// Note that the lookup is often ad hoc (see bin.whole as an example).
// But see also parser::lookup_variable() if adding something here.
//
// @@ PERF: redo as vector so can make move constructor noexcept.
//
public:
variable_map vars;
// Return a value suitable for assignment. See target for details.
//
value&
assign (const variable& var) {return vars.assign (var);}
// Return a value suitable for appending. See target for details. Note
// that we have to explicitly pass the target that this prerequisite
// belongs to.
//
value&
append (const variable&, const target_type&);
public:
prerequisite (optional<project_name> p,
const target_type_type& t,
dir_path d,
dir_path o,
string n,
optional<string> e,
const scope_type& s)
: proj (move (p)),
type (t),
dir (move (d)),
out (move (o)),
name (move (n)),
ext (move (e)),
scope (s),
vars (*this, false /* shared */) {}
prerequisite (const target_type_type& t,
dir_path d,
dir_path o,
string n,
optional<string> e,
const scope_type& s)
: type (t),
dir (move (d)),
out (move (o)),
name (move (n)),
ext (move (e)),
scope (s),
vars (*this, false /* shared */) {}
// Make a prerequisite from a target. If the second argument is true,
// assume the targets mutex is locked (see ext_locked()/key_locked()
// for background).
//
explicit
prerequisite (const target_type&, bool locked = false);
// Note that the returned key "tracks" the prerequisite; that is, any
// updates to the prerequisite's members will be reflected in the key.
//
prerequisite_key
key () const
{
return prerequisite_key {proj, {&type, &dir, &out, &name, ext}, &scope};
}
// As above but remap the target type to the specified.
//
prerequisite_key
key (const target_type_type& tt) const
{
return prerequisite_key {proj, {&tt, &dir, &out, &name, ext}, &scope};
}
// Return true if this prerequisite instance (physically) belongs to the
// target's prerequisite list. Note that this test only works if you use
// references to the container elements and the container hasn't been
// resized since such a reference was obtained. Normally this function is
// used when iterating over a combined prerequisites range to detect if
// the prerequisite came from the group (see group_prerequisites).
//
bool
belongs (const target_type&) const;
// Prerequisite (target) type.
//
public:
template <typename T>
bool
is_a () const {return type.is_a<T> ();}
bool
is_a (const target_type_type& tt) const {return type.is_a (tt);}
public:
// Note that we have the noexcept specification even though vars
// (std::map) could potentially throw.
//
prerequisite (prerequisite&& x) noexcept
: proj (move (x.proj)),
type (x.type),
dir (move (x.dir)),
out (move (x.out)),
name (move (x.name)),
ext (move (x.ext)),
scope (x.scope),
target (x.target.load (memory_order_relaxed)),
vars (move (x.vars), *this, false /* shared */)
{}
prerequisite (const prerequisite& x, memory_order o = memory_order_consume)
: proj (x.proj),
type (x.type),
dir (x.dir),
out (x.out),
name (x.name),
ext (x.ext),
scope (x.scope),
target (x.target.load (o)),
vars (x.vars, *this, false /* shared */) {}
};
inline ostream&
operator<< (ostream& os, const prerequisite& p)
{
return os << p.key ();
}
using prerequisites = vector<prerequisite>;
LIBBUILD2_SYMEXPORT extern const prerequisites empty_prerequisites;
}
#endif // LIBBUILD2_PREREQUISITE_HXX
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