Triplets Overlay Implementation (#7053)

* Triplets Overlay Implementation

* Use cache for get_triplet_file_path()

* Code cleanup

2 files changed, 9 insertions, 3 deletions

diff --git a/toolsrc/include/vcpkg/vcpkgcmdarguments.h b/toolsrc/include/vcpkg/vcpkgcmdarguments.h
index cad013eb8..ff13ae6bf 100644
--- a/toolsrc/include/vcpkg/vcpkgcmdarguments.h
+++ b/toolsrc/include/vcpkg/vcpkgcmdarguments.h
@@ -88,6 +88,7 @@ namespace vcpkg
         std::unique_ptr<std::string> vcpkg_root_dir;
         std::unique_ptr<std::string> triplet;
         std::unique_ptr<std::vector<std::string>> overlay_ports;
+        std::unique_ptr<std::vector<std::string>> overlay_triplets;
         Optional<bool> debug = nullopt;
         Optional<bool> sendmetrics = nullopt;
         Optional<bool> printmetrics = nullopt;
diff --git a/toolsrc/include/vcpkg/vcpkgpaths.h b/toolsrc/include/vcpkg/vcpkgpaths.h
index b09169b02..a30e0c653 100644
--- a/toolsrc/include/vcpkg/vcpkgpaths.h
+++ b/toolsrc/include/vcpkg/vcpkgpaths.h
@@ -47,14 +47,17 @@ namespace vcpkg
 
     struct VcpkgPaths
     {
-        static Expected<VcpkgPaths> create(const fs::path& vcpkg_root_dir, const std::string& default_vs_path);
+        static Expected<VcpkgPaths> create(const fs::path& vcpkg_root_dir, 
+                                           const std::string& default_vs_path,
+                                           const std::vector<std::string>* triplets_dirs);
 
         fs::path package_dir(const PackageSpec& spec) const;
         fs::path build_info_file_path(const PackageSpec& spec) const;
         fs::path listfile_path(const BinaryParagraph& pgh) const;
-
-        const std::vector<std::string>& get_available_triplets() const;
+        
         bool is_valid_triplet(const Triplet& t) const;
+        const std::vector<std::string>& get_available_triplets() const;
+        const fs::path get_triplet_file_path(const Triplet& triplet) const;
 
         fs::path root;
         fs::path packages;
@@ -93,7 +96,9 @@ namespace vcpkg
         Lazy<std::vector<Toolset>> toolsets_vs2013;
 
         fs::path default_vs_path;
+        std::vector<fs::path> triplets_dirs;
 
         mutable std::unique_ptr<ToolCache> m_tool_cache;
+        mutable vcpkg::Cache<Triplet, fs::path> m_triplets_cache;
     };
 }