diff options
Diffstat (limited to 'build2/algorithm.cxx')
| -rw-r--r-- | build2/algorithm.cxx | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/build2/algorithm.cxx b/build2/algorithm.cxx index a7126cc..cae6645 100644 --- a/build2/algorithm.cxx +++ b/build2/algorithm.cxx @@ -454,6 +454,54 @@ namespace build2 return e; } + target* + execute_prerequisites (const target_type& tt, + action a, target& t, const timestamp& mt) + { + bool e (mt == timestamp_nonexistent); + target* r (nullptr); + + for (target* pt: t.prerequisite_targets) + { + if (pt == nullptr) // Skip ignored. + continue; + + target_state ts (execute (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 (pt->is_a (tt)) + r = pt; + } + + assert (r != nullptr); + return e ? r : nullptr; + } + target_state noop_action (action a, target& t) { |