WIP Start getting store settings off config.hh

src/libstore/config-parse.hh

@@ -0,0 +1,14 @@
+#pragma once
+
+/**
+ * Look up the setting's name in a map, falling back on the default if
+ * it does not exist.
+ */
+#define CONFIG_ROW(FIELD)                                  \
+    .FIELD = {                                             \
+        .value = ({                                        \
+            auto p = get(params, descriptions.FIELD.name); \
+            p ? *p : defaults.FIELD.value;                 \
+        })                                                 \
+    }
+

src/libstore/path.cc

@@ -89,7 +89,7 @@ StorePath StoreDirConfig::parseStorePath(std::string_view path) const
         canonPath(std::string(path))
 #endif
         ;
-    if (dirOf(p) != storeDir)
+    if (dirOf(p) != storeDir.get())
         throw BadStorePath("path '%s' is not in the Nix store", p);
     return StorePath(baseNameOf(p));
 }

src/libstore/store-api.hh

@@ -99,8 +99,6 @@ typedef std::map<StorePath, std::optional<ContentAddress>> StorePathCAMap;
 
 struct StoreConfig : public StoreDirConfig
 {
-    using Params = StoreReference::Params;
-
     using StoreDirConfig::StoreDirConfig;
 
     StoreConfig() = delete;

src/libstore/store-dir-config.cc

@@ -0,0 +1,41 @@
+#include "store-dir-config.hh"
+#include "config-parse.hh"
+#include "util.hh"
+
+namespace nix {
+
+const StoreDirConfigT<JustValue> storeDirConfigDefaults = {
+    .storeDir =
+        {
+            .value = settings.nixStore,
+        },
+};
+
+const StoreDirConfigT<SettingInfo> storeDirConfigDescriptions = {
+    .storeDir =
+        {
+            .name = "store",
+            .description = R"(
+              Logical location of the Nix store, usually
+              `/nix/store`. Note that you can only copy store paths
+              between stores if they have the same `store` setting.
+            )",
+        },
+};
+
+StoreDirConfigT<JustValue> parseStoreDirConfig(const StoreReference::Params & params)
+{
+    constexpr auto & defaults = storeDirConfigDefaults;
+    constexpr auto & descriptions = storeDirConfigDescriptions;
+
+    return {
+        CONFIG_ROW(storeDir),
+    };
+}
+
+StoreDirConfig::StoreDirConfig(const StoreReference::Params & params)
+    : StoreDirConfigT<JustValue>{parseStoreDirConfig(params)}
+{
+}
+
+}

src/libstore/store-dir-config.hh

@@ -3,8 +3,9 @@
 #include "path.hh"
 #include "hash.hh"
 #include "content-address.hh"
+#include "store-reference.hh"
+#include "config-abstract.hh"
 #include "globals.hh"
-#include "config.hh"
 
 #include <map>
 #include <string>
@@ -18,22 +19,23 @@ struct SourcePath;
 MakeError(BadStorePath, Error);
 MakeError(BadStorePathName, BadStorePath);
 
-struct StoreDirConfig : public Config
+template<template<typename> class F>
+struct StoreDirConfigT
 {
-    using Config::Config;
+    F<Path> storeDir;
+};
 
-    StoreDirConfig() = delete;
+extern const StoreDirConfigT<JustValue> storeDirConfigDefaults;
 
-    virtual ~StoreDirConfig() = default;
+extern const StoreDirConfigT<SettingInfo> storeDirConfigDescriptions;
+
+StoreDirConfigT<JustValue> parseStoreDirConfig(const StoreReference::Params &);
 
-    const PathSetting storeDir_{this, settings.nixStore,
-        "store",
-        R"(
-          Logical location of the Nix store, usually
-          `/nix/store`. Note that you can only copy store paths
-          between stores if they have the same `store` setting.
-        )"};
-    const Path storeDir = storeDir_;
+struct StoreDirConfig : StoreDirConfigT<JustValue>
+{
+    StoreDirConfig(const StoreReference::Params & params);
+
+    virtual ~StoreDirConfig() = default;
 
     // pure methods
 

src/libutil/config-abstract.hh

@@ -0,0 +1,32 @@
+#pragma once
+///@type
+
+namespace nix {
+
+template<typename T>
+struct JustValue
+{
+    T value;
+
+    operator const T &() const
+    {
+        return value;
+    }
+    operator T &()
+    {
+        return value;
+    }
+    const T & get() const
+    {
+        return value;
+    }
+};
+
+template<typename T>
+struct SettingInfo
+{
+    std::string name;
+    std::string description;
+};
+
+}