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// file : build/algorithm.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
// license : MIT; see accompanying LICENSE file
#include <build/algorithm>
#include <memory> // unique_ptr
#include <utility> // move
#include <cassert>
#include <build/path>
#include <build/scope>
#include <build/target>
#include <build/prerequisite>
#include <build/rule>
#include <build/search>
#include <build/utility>
#include <build/diagnostics>
using namespace std;
namespace build
{
target&
search (prerequisite& p)
{
assert (p.target == nullptr);
if (target* t = p.type.search (p))
return *t;
return create_new_target (p);
}
void
match_impl (target& t)
{
for (auto tt (&t.type ());
tt != nullptr && !t.recipe ();
tt = tt->base)
{
auto i (rules.find (tt->id));
if (i == rules.end ()) // No rules registered for this target type.
continue;
const auto& rules (i->second); // Name map.
string hint; // @@ TODO
auto rs (hint.empty ()
? make_pair (rules.begin (), rules.end ())
: rules.find (hint));
for (auto i (rs.first); i != rs.second; ++i)
{
const string& n (i->first);
const rule& ru (i->second);
void* m;
{
auto g (
make_exception_guard (
[](target& t, const string& n)
{
info << "while matching rule " << n << " for target " << t;
},
t, n));
m = ru.match (t, hint);
}
if (m != nullptr)
{
// Do the ambiguity test.
//
bool ambig (false);
diag_record dr;
for (++i; i != rs.second; ++i)
{
const string& n1 (i->first);
const rule& ru1 (i->second);
void* m1;
{
auto g (
make_exception_guard (
[](target& t, const string& n1)
{
info << "while matching rule " << n1 << " for target "
<< t;
},
t, n1));
m1 = ru1.match (t, hint);
}
if (m1 != nullptr)
{
if (!ambig)
{
dr << fail << "multiple rules matching target " << t
<< info << "rule " << n << " matches";
ambig = true;
}
dr << info << "rule " << n1 << " also matches";
}
}
if (!ambig)
{
auto g (
make_exception_guard (
[](target& t, const string& n)
{
info << "while selecting rule " << n << " for target " << t;
},
t, n));
t.recipe (ru.select (t, m));
break;
}
else
dr << info << "use rule hint to disambiguate this match";
}
}
}
if (!t.recipe ())
fail << "no rule to update target " << t;
}
void
search_and_match (target& t)
{
for (prerequisite& p: t.prerequisites)
{
if (p.target == nullptr)
search (p);
match (*p.target);
}
}
target_state
update (target& t)
{
// Implementation with some multi-threading ideas in mind.
//
switch (target_state ts = t.state ())
{
case target_state::unknown:
{
t.state (target_state::failed); // So the rule can just throw.
auto g (
make_exception_guard (
[](target& t){info << "while updating target " << t;},
t));
ts = t.recipe () (t);
assert (ts != target_state::unknown && ts != target_state::failed);
t.state (ts);
return ts;
}
case target_state::uptodate:
case target_state::updated:
return ts;
case target_state::failed:
throw failed ();
}
}
target_state
update_prerequisites (target& t)
{
target_state ts (target_state::uptodate);
for (const prerequisite& p: t.prerequisites)
{
assert (p.target != nullptr);
if (update (*p.target) != target_state::uptodate)
ts = target_state::updated;
}
return ts;
}
bool
update_prerequisites (target& t, const timestamp& mt)
{
bool u (mt == timestamp_nonexistent);
for (const prerequisite& p: t.prerequisites)
{
assert (p.target != nullptr);
target& pt (*p.target);
target_state ts (update (pt));
if (!u)
{
// 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 updated in this run which means the
// target must be out of date.
//
if (mt < mp || mt == mp && ts == target_state::updated)
u = true;
}
else
{
// Otherwise we assume the prerequisite is newer if it was updated.
//
if (ts == target_state::updated)
u = true;
}
}
}
return u;
}
}
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