Add a library computing, in memory, a git tree from a stage

Computed roots are given as the artifacts stage of a target. However,
to be usable as a root, we need the git tree identifier of that
root. Therefore, add a library doing this computation, avoiding
file-system operations whenever possible.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/buildtool/computed_roots/artifacts_root.hpp b/src/buildtool/computed_roots/artifacts_root.hpp
new file mode 100644
index 00000000..6ed727fa
--- /dev/null
+++ b/src/buildtool/computed_roots/artifacts_root.hpp
@@ -0,0 +1,34 @@
+// Copyright 2024 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef INCLUDED_SRC_BUILDTOOL_COMPUTED_ROOT_ARTIFACTS_ROOT_HPP
+#define INCLUDED_SRC_BUILDTOOL_COMPUTED_ROOT_ARTIFACTS_ROOT_HPP
+
+#include <optional>
+#include <string>
+
+#include "src/buildtool/build_engine/expression/expression_ptr.hpp"
+#include "src/buildtool/multithreading/async_map_consumer.hpp"
+
+/// \brief Compute to the git tree identifier, as hex string, corresponding to
+/// an artifact stage; return std::nullopt in case of errors
+/// \param stage Expression pointer supposed to represent a map from logical
+/// paths to known artifacts
+/// \param logger Logger to report problems; will be called with the fatal
+/// property in case of error
+auto ArtifactsRoot(ExpressionPtr const& stage,
+                   AsyncMapConsumerLoggerPtr const& logger)
+    -> std::optional<std::string>;
+
+#endif