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// file : build/algorithm.txx -*- C++ -*-
// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
// license : MIT; see accompanying LICENSE file
#include <build/context>
#include <build/utility> // reverse_iterate
namespace build
{
template <executor_function* E>
target_state
execute_prerequisites (action a, target& t)
{
target_state ts (target_state::unchanged);
if (t.group != nullptr)
ts = execute_prerequisites<E> (a, *t.group);
for (target* pt: t.prerequisites)
{
if (pt == nullptr) // Skip ignored.
continue;
if (E (a, *pt) == target_state::changed)
ts = target_state::changed;
}
return ts;
}
template <executor_function* E>
target_state
reverse_execute_prerequisites (action a, target& t)
{
target_state ts (target_state::unchanged);
for (target* pt: reverse_iterate (t.prerequisites))
{
if (pt == nullptr) // Skip ignored.
continue;
if (E (a, *pt) == target_state::changed)
ts = target_state::changed;
}
if (t.group != nullptr)
{
if (reverse_execute_prerequisites<E> (a, *t.group) ==
target_state::changed)
ts = target_state::changed;
}
return ts;
}
template <executor_function* E>
bool
execute_prerequisites (action a, target& t, const timestamp& mt)
{
bool e (mt == timestamp_nonexistent);
if (t.group != nullptr)
{
if (execute_prerequisites<E> (a, *t.group, mt))
e = true;
}
for (target* pt: t.prerequisites)
{
if (pt == nullptr) // Skip ignored.
continue;
target_state ts (E (a, *pt));
if (!e)
{
// If this is an mtime-based target, then compare timestamps.
//
if (auto mpt = dynamic_cast<const mtime_target*> (pt))
{
timestamp mp (mpt->mtime ());
// What do we do if timestamps are equal? This can happen, for
// example, on filesystems that don't have subsecond resolution.
// There is not much we can do here except detect the case where
// the prerequisite was changed in this run which means the
// action must be executed on the target as well.
//
if (mt < mp || (mt == mp && ts == target_state::changed))
e = true;
}
else
{
// Otherwise we assume the prerequisite is newer if it was changed.
//
if (ts == target_state::changed)
e = true;
}
}
}
return e;
}
template <typename T, executor_function* E>
T*
execute_find_prerequisites (
action a, target& t, const timestamp& mt, bool& e)
{
//@@ Can factor the bulk of it into a non-template code. Can
// either do a function template that will do dynamic_cast check
// or can scan the target type info myself. I think latter.
//
T* r (nullptr);
if (t.group != nullptr)
r = execute_find_prerequisites<T, E> (a, *t.group, mt, e);
for (target* pt: t.prerequisites)
{
if (pt == nullptr) // Skip ignored.
continue;
target_state ts (E (a, *pt));
if (!e)
{
// If this is an mtime-based target, then compare timestamps.
//
if (auto mpt = dynamic_cast<const mtime_target*> (pt))
{
timestamp mp (mpt->mtime ());
// What do we do if timestamps are equal? This can happen, for
// example, on filesystems that don't have subsecond resolution.
// There is not much we can do here except detect the case where
// the prerequisite was changed in this run which means the
// action must be executed on the target as well.
//
if (mt < mp || (mt == mp && ts == target_state::changed))
e = true;
}
else
{
// Otherwise we assume the prerequisite is newer if it was changed.
//
if (ts == target_state::changed)
e = true;
}
}
if (T* tmp = dynamic_cast<T*> (pt))
r = tmp;
}
return r;
}
template <executor_function* E = execute>
target_state
default_action (action a, target& t)
{
return current_mode == execution_mode::first
? execute_prerequisites<E> (a, t)
: reverse_execute_prerequisites<E> (a, t);
}
template <executor_function* E>
target_state
perform_clean (action a, target& t)
{
// The reverse order of update: first delete the file, then clean
// prerequisites.
//
file& ft (dynamic_cast<file&> (t));
bool r (rmfile (ft.path (), ft));
// Update timestamp in case there are operations after us that
// could use the information.
//
ft.mtime (timestamp_nonexistent);
// Clean prerequisites.
//
target_state ts (reverse_execute_prerequisites<E> (a, t));
return r ? target_state::changed : ts;
}
}
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