1 files changed, 109 insertions, 0 deletions
diff --git a/src/libstore/fetchers/fetchers.hh b/src/libstore/fetchers/fetchers.hh
new file mode 100644
index 000000000..4202e8339
--- /dev/null
+++ b/src/libstore/fetchers/fetchers.hh
@@ -0,0 +1,109 @@
+#pragma once
+
+#include "types.hh"
+#include "hash.hh"
+#include "path.hh"
+#include "tree-info.hh"
+
+#include <memory>
+#include <variant>
+
+#include <nlohmann/json_fwd.hpp>
+
+namespace nix { class Store; }
+
+namespace nix::fetchers {
+
+struct Input;
+
+struct Tree
+{
+    Path actualPath;
+    StorePath storePath;
+    TreeInfo info;
+};
+
+struct Input : std::enable_shared_from_this<Input>
+{
+    std::optional<Hash> narHash; // FIXME: implement
+
+    virtual std::string type() const = 0;
+
+    virtual ~Input() { }
+
+    virtual bool operator ==(const Input & other) const { return false; }
+
+    /* Check whether this is a "direct" input, that is, not
+       one that goes through a registry. */
+    virtual bool isDirect() const { return true; }
+
+    /* Check whether this is an "immutable" input, that is,
+       one that contains a commit hash or content hash. */
+    virtual bool isImmutable() const { return (bool) narHash; }
+
+    virtual bool contains(const Input & other) const { return false; }
+
+    virtual std::optional<std::string> getRef() const { return {}; }
+
+    virtual std::optional<Hash> getRev() const { return {}; }
+
+    virtual std::string to_string() const = 0;
+
+    typedef std::variant<std::string, int64_t> Attr;
+    typedef std::map<std::string, Attr> Attrs;
+
+    Attrs toAttrs() const;
+
+    std::pair<Tree, std::shared_ptr<const Input>> fetchTree(ref<Store> store) const;
+
+    virtual std::shared_ptr<const Input> applyOverrides(
+        std::optional<std::string> ref,
+        std::optional<Hash> rev) const;
+
+    virtual std::optional<Path> getSourcePath() const { return {}; }
+
+    virtual void markChangedFile(
+        std::string_view file,
+        std::optional<std::string> commitMsg) const
+    { assert(false); }
+
+    virtual void clone(const Path & destDir) const
+    {
+        throw Error("do not know how to clone input '%s'", to_string());
+    }
+
+private:
+
+    virtual std::pair<Tree, std::shared_ptr<const Input>> fetchTreeInternal(ref<Store> store) const = 0;
+
+    virtual Attrs toAttrsInternal() const = 0;
+};
+
+struct ParsedURL;
+
+struct InputScheme
+{
+    virtual ~InputScheme() { }
+
+    virtual std::unique_ptr<Input> inputFromURL(const ParsedURL & url) = 0;
+
+    virtual std::unique_ptr<Input> inputFromAttrs(const Input::Attrs & attrs) = 0;
+};
+
+std::unique_ptr<Input> inputFromURL(const ParsedURL & url);
+
+std::unique_ptr<Input> inputFromURL(const std::string & url);
+
+std::unique_ptr<Input> inputFromAttrs(const Input::Attrs & attrs);
+
+void registerInputScheme(std::unique_ptr<InputScheme> && fetcher);
+
+Input::Attrs jsonToAttrs(const nlohmann::json & json);
+
+nlohmann::json attrsToJson(const Input::Attrs & attrs);
+
+std::optional<std::string> maybeGetStrAttr(const Input::Attrs & attrs, const std::string & name);
+
+std::string getStrAttr(const Input::Attrs & attrs, const std::string & name);
+
+}