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Diffstat (limited to 'build2/algorithm.txx')
-rw-r--r-- | build2/algorithm.txx | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/build2/algorithm.txx b/build2/algorithm.txx new file mode 100644 index 0000000..7b0e498 --- /dev/null +++ b/build2/algorithm.txx @@ -0,0 +1,58 @@ +// file : build2/algorithm.txx -*- C++ -*- +// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd +// license : MIT; see accompanying LICENSE file + +namespace build2 +{ + template <typename T> + T* + execute_prerequisites (action a, target& t, const timestamp& mt) + { + //@@ 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. + // + bool e (mt == timestamp_nonexistent); + T* 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 (T* tmp = dynamic_cast<T*> (pt)) + r = tmp; + } + + assert (r != nullptr); + return e ? r : nullptr; + } +} |