Move fetchers from libstore to libfetchers

src/libfetchers/indirect.cc

@@ -0,0 +1,140 @@
+#include "fetchers.hh"
+
+namespace nix::fetchers {
+
+std::regex flakeRegex("[a-zA-Z][a-zA-Z0-9_-]*", std::regex::ECMAScript);
+
+struct IndirectInput : Input
+{
+    std::string id;
+    std::optional<Hash> rev;
+    std::optional<std::string> ref;
+
+    std::string type() const override { return "indirect"; }
+
+    bool operator ==(const Input & other) const override
+    {
+        auto other2 = dynamic_cast<const IndirectInput *>(&other);
+        return
+            other2
+            && id == other2->id
+            && rev == other2->rev
+            && ref == other2->ref;
+    }
+
+    bool isDirect() const override
+    {
+        return false;
+    }
+
+    std::optional<std::string> getRef() const override { return ref; }
+
+    std::optional<Hash> getRev() const override { return rev; }
+
+    bool contains(const Input & other) const override
+    {
+        auto other2 = dynamic_cast<const IndirectInput *>(&other);
+        return
+            other2
+            && id == other2->id
+            && (!ref || ref == other2->ref)
+            && (!rev || rev == other2->rev);
+    }
+
+    ParsedURL toURL() const override
+    {
+        ParsedURL url;
+        url.scheme = "flake";
+        url.path = id;
+        if (ref) { url.path += '/'; url.path += *ref; };
+        if (rev) { url.path += '/'; url.path += rev->gitRev(); };
+        return url;
+    }
+
+    Attrs toAttrsInternal() const override
+    {
+        Attrs attrs;
+        attrs.emplace("id", id);
+        if (ref)
+            attrs.emplace("ref", *ref);
+        if (rev)
+            attrs.emplace("rev", rev->gitRev());
+        return attrs;
+    }
+
+    std::shared_ptr<const Input> applyOverrides(
+        std::optional<std::string> ref,
+        std::optional<Hash> rev) const override
+    {
+        if (!ref && !rev) return shared_from_this();
+
+        auto res = std::make_shared<IndirectInput>(*this);
+
+        if (ref) res->ref = ref;
+        if (rev) res->rev = rev;
+
+        return res;
+    }
+
+    std::pair<Tree, std::shared_ptr<const Input>> fetchTreeInternal(nix::ref<Store> store) const override
+    {
+        throw Error("indirect input '%s' cannot be fetched directly", to_string());
+    }
+};
+
+struct IndirectInputScheme : InputScheme
+{
+    std::unique_ptr<Input> inputFromURL(const ParsedURL & url) override
+    {
+        if (url.scheme != "flake") return nullptr;
+
+        auto path = tokenizeString<std::vector<std::string>>(url.path, "/");
+        auto input = std::make_unique<IndirectInput>();
+
+        if (path.size() == 1) {
+        } else if (path.size() == 2) {
+            if (std::regex_match(path[1], revRegex))
+                input->rev = Hash(path[1], htSHA1);
+            else if (std::regex_match(path[1], refRegex))
+                input->ref = path[1];
+            else
+                throw BadURL("in flake URL '%s', '%s' is not a commit hash or branch/tag name", url.url, path[1]);
+        } else if (path.size() == 3) {
+            if (!std::regex_match(path[1], refRegex))
+                throw BadURL("in flake URL '%s', '%s' is not a branch/tag name", url.url, path[1]);
+            input->ref = path[1];
+            if (!std::regex_match(path[2], revRegex))
+                throw BadURL("in flake URL '%s', '%s' is not a commit hash", url.url, path[2]);
+            input->rev = Hash(path[2], htSHA1);
+        } else
+            throw BadURL("GitHub URL '%s' is invalid", url.url);
+
+        // FIXME: forbid query params?
+
+        input->id = path[0];
+        if (!std::regex_match(input->id, flakeRegex))
+            throw BadURL("'%s' is not a valid flake ID", input->id);
+
+        return input;
+    }
+
+    std::unique_ptr<Input> inputFromAttrs(const Attrs & attrs) override
+    {
+        if (maybeGetStrAttr(attrs, "type") != "indirect") return {};
+
+        for (auto & [name, value] : attrs)
+            if (name != "type" && name != "id" && name != "ref" && name != "rev")
+                throw Error("unsupported indirect input attribute '%s'", name);
+
+        auto input = std::make_unique<IndirectInput>();
+        input->id = getStrAttr(attrs, "id");
+        input->ref = maybeGetStrAttr(attrs, "ref");
+        if (auto rev = maybeGetStrAttr(attrs, "rev"))
+            input->rev = Hash(*rev, htSHA1);
+        return input;
+    }
+};
+
+static auto r1 = OnStartup([] { registerInputScheme(std::make_unique<IndirectInputScheme>()); });
+
+}