Allow to read git trees from global CAS as well as local workspace root

2 files changed, 18 insertions, 0 deletions

diff --git a/src/buildtool/common/repository_config.hpp b/src/buildtool/common/repository_config.hpp
index e1144789..e6237e3f 100644
--- a/src/buildtool/common/repository_config.hpp
+++ b/src/buildtool/common/repository_config.hpp
@@ -61,6 +61,11 @@ class RepositoryConfig {
                         : std::nullopt;
     }
 
+    [[nodiscard]] auto ReadTreeFromGitCAS(
+        std::string const& hex_id) const noexcept -> std::optional<GitTree> {
+        return git_cas_ ? GitTree::Read(git_cas_, hex_id) : std::nullopt;
+    }
+
     [[nodiscard]] auto WorkspaceRoot(std::string const& repo) const noexcept
         -> FileRoot const* {
         return Get<FileRoot>(
diff --git a/src/buildtool/file_system/file_root.hpp b/src/buildtool/file_system/file_root.hpp
index 10b04c66..893b028c 100644
--- a/src/buildtool/file_system/file_root.hpp
+++ b/src/buildtool/file_system/file_root.hpp
@@ -421,6 +421,19 @@ class FileRoot {
         return std::nullopt;
     }
 
+    [[nodiscard]] auto ReadTree(std::string const& tree_id) const noexcept
+        -> std::optional<GitTree> {
+        if (std::holds_alternative<git_root_t>(root_)) {
+            try {
+                auto const& cas = std::get<git_root_t>(root_).cas;
+                return GitTree::Read(cas, tree_id);
+            } catch (...) {
+                return std::nullopt;
+            }
+        }
+        return std::nullopt;
+    }
+
     // Create LOCAL or KNOWN artifact. Does not check existence for LOCAL.
     // `file_path` must reference a blob.
     [[nodiscard]] auto ToArtifactDescription(