Cleanup

9 files changed, 145 insertions, 123 deletions

diff --git a/src/libutil/args.cc b/src/libutil/args.cc
index 257b4b6c4..c389090ae 100644
--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@@ -86,7 +86,7 @@ void Args::printHelp(const string & programName, std::ostream & out)
     for (auto & exp : expectedArgs) {
         std::cout << renderLabels({exp.label});
         // FIXME: handle arity > 1
-        if (exp.arity == 0) std::cout << "...";
+        if (exp.handler.arity == ArityAny) std::cout << "...";
         if (exp.optional) std::cout << "?";
     }
     std::cout << "\n";
@@ -127,8 +127,8 @@ bool Args::processFlag(Strings::iterator & pos, Strings::iterator end)
                 if (flag.handler.arity == ArityAny) break;
                 throw UsageError("flag '%s' requires %d argument(s)", name, flag.handler.arity);
             }
-            if (auto prefix = needsCompletion(*pos))
-                if (flag.completer)
+            if (flag.completer)
+                if (auto prefix = needsCompletion(*pos))
                     flag.completer(n, *prefix);
             args.push_back(*pos++);
         }
@@ -179,12 +179,17 @@ bool Args::processArgs(const Strings & args, bool finish)
 
     bool res = false;
 
-    if ((exp.arity == 0 && finish) ||
-        (exp.arity > 0 && args.size() == exp.arity))
+    if ((exp.handler.arity == ArityAny && finish) ||
+        (exp.handler.arity != ArityAny && args.size() == exp.handler.arity))
     {
         std::vector<std::string> ss;
-        for (auto & s : args) ss.push_back(s);
-        exp.handler(std::move(ss));
+        for (const auto &[n, s] : enumerate(args)) {
+            ss.push_back(s);
+            if (exp.completer)
+                if (auto prefix = needsCompletion(s))
+                    exp.completer(n, *prefix);
+        }
+        exp.handler.fun(ss);
         expectedArgs.pop_front();
         res = true;
     }
@@ -214,46 +219,17 @@ Args::Flag Args::Flag::mkHashTypeFlag(std::string && longName, HashType * ht)
     };
 }
 
-void completePath(size_t, std::string_view s)
+void completePath(size_t, std::string_view prefix)
 {
-    if (auto prefix = needsCompletion(s)) {
-        pathCompletions = true;
-        glob_t globbuf;
-        if (glob((*prefix + "*").c_str(), GLOB_NOESCAPE | GLOB_TILDE, nullptr, &globbuf) == 0) {
-            for (size_t i = 0; i < globbuf.gl_pathc; ++i)
-                completions->insert(globbuf.gl_pathv[i]);
-            globfree(&globbuf);
-        }
+    pathCompletions = true;
+    glob_t globbuf;
+    if (glob((std::string(prefix) + "*").c_str(), GLOB_NOESCAPE | GLOB_TILDE, nullptr, &globbuf) == 0) {
+        for (size_t i = 0; i < globbuf.gl_pathc; ++i)
+            completions->insert(globbuf.gl_pathv[i]);
+        globfree(&globbuf);
     }
 }
 
-void Args::expectPathArg(const std::string & label, string * dest, bool optional)
-{
-    expectedArgs.push_back({
-        .label = label,
-        .arity = 1,
-        .optional = optional,
-        .handler = {[=](std::vector<std::string> ss) {
-            completePath(0, ss[0]);
-            *dest = ss[0];
-        }}
-    });
-}
-
-void Args::expectPathArgs(const std::string & label, std::vector<std::string> * dest)
-{
-    expectedArgs.push_back({
-        .label = label,
-        .arity = 0,
-        .optional = false,
-        .handler = {[=](std::vector<std::string> ss) {
-            for (auto & s : ss)
-                completePath(0, s);
-            *dest = std::move(ss);
-        }}
-    });
-}
-
 Strings argvToStrings(int argc, char * * argv)
 {
     Strings args;
@@ -301,18 +277,22 @@ void Command::printHelp(const string & programName, std::ostream & out)
 MultiCommand::MultiCommand(const Commands & commands)
     : commands(commands)
 {
-    expectedArgs.push_back(ExpectedArg{"command", 1, true, [=](std::vector<std::string> ss) {
-        assert(!command);
-        if (auto prefix = needsCompletion(ss[0])) {
-            for (auto & [name, command] : commands)
-                if (hasPrefix(name, *prefix))
-                    completions->insert(name);
-        }
-        auto i = commands.find(ss[0]);
-        if (i == commands.end())
-            throw UsageError("'%s' is not a recognised command", ss[0]);
-        command = {ss[0], i->second()};
-    }});
+    expectArgs({
+        .label = "command",
+        .optional = true,
+        .handler = {[=](std::string s) {
+            assert(!command);
+            if (auto prefix = needsCompletion(s)) {
+                for (auto & [name, command] : commands)
+                    if (hasPrefix(name, *prefix))
+                        completions->insert(name);
+            }
+            auto i = commands.find(s);
+            if (i == commands.end())
+                throw UsageError("'%s' is not a recognised command", s);
+            command = {s, i->second()};
+        }}
+    });
 
     categories[Command::catDefault] = "Available commands";
 }
diff --git a/src/libutil/args.hh b/src/libutil/args.hh
index f93459c96..250244162 100644
--- a/src/libutil/args.hh
+++ b/src/libutil/args.hh
@@ -28,55 +28,60 @@ protected:
 
     static const size_t ArityAny = std::numeric_limits<size_t>::max();
 
+    struct Handler
+    {
+        std::function<void(std::vector<std::string>)> fun;
+        size_t arity;
+
+        Handler() {}
+
+        Handler(std::function<void(std::vector<std::string>)> && fun)
+            : fun(std::move(fun))
+            , arity(ArityAny)
+        { }
+
+        Handler(std::function<void()> && handler)
+            : fun([handler{std::move(handler)}](std::vector<std::string>) { handler(); })
+            , arity(0)
+        { }
+
+        Handler(std::function<void(std::string)> && handler)
+            : fun([handler{std::move(handler)}](std::vector<std::string> ss) {
+                handler(std::move(ss[0]));
+              })
+            , arity(1)
+        { }
+
+        Handler(std::function<void(std::string, std::string)> && handler)
+            : fun([handler{std::move(handler)}](std::vector<std::string> ss) {
+                handler(std::move(ss[0]), std::move(ss[1]));
+              })
+            , arity(2)
+        { }
+
+        Handler(std::vector<std::string> * dest)
+            : fun([=](std::vector<std::string> ss) { *dest = ss; })
+            , arity(ArityAny)
+        { }
+
+        template<class T>
+        Handler(T * dest)
+            : fun([=](std::vector<std::string> ss) { *dest = ss[0]; })
+            , arity(1)
+        { }
+
+        template<class T>
+        Handler(T * dest, const T & val)
+            : fun([=](std::vector<std::string> ss) { *dest = val; })
+            , arity(0)
+        { }
+    };
+
     /* Flags. */
     struct Flag
     {
         typedef std::shared_ptr<Flag> ptr;
 
-        struct Handler
-        {
-            std::function<void(std::vector<std::string>)> fun;
-            size_t arity;
-
-            Handler() {}
-
-            Handler(std::function<void(std::vector<std::string>)> && fun)
-                : fun(std::move(fun))
-                , arity(ArityAny)
-            { }
-
-            Handler(std::function<void()> && handler)
-                : fun([handler{std::move(handler)}](std::vector<std::string>) { handler(); })
-                , arity(0)
-            { }
-
-            Handler(std::function<void(std::string)> && handler)
-                : fun([handler{std::move(handler)}](std::vector<std::string> ss) {
-                    handler(std::move(ss[0]));
-                  })
-                , arity(1)
-            { }
-
-            Handler(std::function<void(std::string, std::string)> && handler)
-                : fun([handler{std::move(handler)}](std::vector<std::string> ss) {
-                    handler(std::move(ss[0]), std::move(ss[1]));
-                  })
-                , arity(2)
-            { }
-
-            template<class T>
-            Handler(T * dest)
-                : fun([=](std::vector<std::string> ss) { *dest = ss[0]; })
-                , arity(1)
-            { }
-
-            template<class T>
-            Handler(T * dest, const T & val)
-                : fun([=](std::vector<std::string> ss) { *dest = val; })
-                , arity(0)
-            { }
-        };
-
         std::string longName;
         char shortName = 0;
         std::string description;
@@ -99,9 +104,9 @@ protected:
     struct ExpectedArg
     {
         std::string label;
-        size_t arity = 0; // 0 = any
         bool optional = false;
-        std::function<void(std::vector<std::string>)> handler;
+        Handler handler;
+        std::function<void(size_t, std::string_view)> completer;
     };
 
     std::list<ExpectedArg> expectedArgs;
@@ -175,26 +180,30 @@ public:
         });
     }
 
+    void expectArgs(ExpectedArg && arg)
+    {
+        expectedArgs.emplace_back(std::move(arg));
+    }
+
     /* Expect a string argument. */
     void expectArg(const std::string & label, string * dest, bool optional = false)
     {
-        expectedArgs.push_back(ExpectedArg{label, 1, optional, [=](std::vector<std::string> ss) {
-            *dest = ss[0];
-        }});
+        expectArgs({
+            .label = label,
+            .optional = true,
+            .handler = {dest}
+        });
     }
 
-    void expectPathArg(const std::string & label, string * dest, bool optional = false);
-
     /* Expect 0 or more arguments. */
     void expectArgs(const std::string & label, std::vector<std::string> * dest)
     {
-        expectedArgs.push_back(ExpectedArg{label, 0, false, [=](std::vector<std::string> ss) {
-            *dest = std::move(ss);
-        }});
+        expectArgs({
+            .label = label,
+            .handler = {dest}
+        });
     }
 
-    void expectPathArgs(const std::string & label, std::vector<std::string> * dest);
-
     friend class MultiCommand;
 };
 
@@ -266,6 +275,6 @@ extern bool pathCompletions;
 
 std::optional<std::string> needsCompletion(std::string_view s);
 
-void completePath(size_t, std::string_view s);
+void completePath(size_t, std::string_view prefix);
 
 }
diff --git a/src/nix/cat.cc b/src/nix/cat.cc
index eeee1e529..b528a0507 100644
--- a/src/nix/cat.cc
+++ b/src/nix/cat.cc
@@ -25,7 +25,11 @@ struct CmdCatStore : StoreCommand, MixCat
 {
     CmdCatStore()
     {
-        expectPathArg("path", &path);
+        expectArgs({
+            .label = "path",
+            .handler = {&path},
+            .completer = completePath
+        });
     }
 
     std::string description() override
@@ -47,7 +51,11 @@ struct CmdCatNar : StoreCommand, MixCat
 
     CmdCatNar()
     {
-        expectPathArg("nar", &narPath);
+        expectArgs({
+            .label = "nar",
+            .handler = {&narPath},
+            .completer = completePath
+        });
         expectArg("path", &path);
     }
 
diff --git a/src/nix/command.hh b/src/nix/command.hh
index 6b4781303..0738c0f91 100644
--- a/src/nix/command.hh
+++ b/src/nix/command.hh
@@ -73,10 +73,7 @@ struct InstallablesCommand : virtual Args, SourceExprCommand
 {
     std::vector<std::shared_ptr<Installable>> installables;
 
-    InstallablesCommand()
-    {
-        expectArgs("installables", &_installables);
-    }
+    InstallablesCommand();
 
     void prepare() override;
 
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index 0f460c668..d5636eb47 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -31,7 +31,11 @@ struct CmdHash : Command
             .labels({"modulus"})
             .dest(&modulus);
         #endif
-        expectPathArgs("paths", &paths);
+        expectArgs({
+            .label = "paths",
+            .handler = {&paths},
+            .completer = completePath
+        });
     }
 
     std::string description() override
diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index c144a7e70..abc642e11 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -571,6 +571,14 @@ StorePathSet toDerivations(ref<Store> store,
     return drvPaths;
 }
 
+InstallablesCommand::InstallablesCommand()
+{
+    expectArgs({
+        .label = "installables",
+        .handler = {&_installables},
+    });
+}
+
 void InstallablesCommand::prepare()
 {
     if (_installables.empty() && useDefaultInstallables())
diff --git a/src/nix/ls.cc b/src/nix/ls.cc
index aac082422..dc7e370b9 100644
--- a/src/nix/ls.cc
+++ b/src/nix/ls.cc
@@ -85,7 +85,11 @@ struct CmdLsStore : StoreCommand, MixLs
 {
     CmdLsStore()
     {
-        expectPathArg("path", &path);
+        expectArgs({
+            .label = "path",
+            .handler = {&path},
+            .completer = completePath
+        });
     }
 
     Examples examples() override
@@ -117,7 +121,11 @@ struct CmdLsNar : Command, MixLs
 
     CmdLsNar()
     {
-        expectPathArg("nar", &narPath);
+        expectArgs({
+            .label = "nar",
+            .handler = {&narPath},
+            .completer = completePath
+        });
         expectArg("path", &path);
     }
 
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 2e7b14d08..c936f9cc2 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -767,7 +767,11 @@ struct CmdRepl : StoreCommand, MixEvalArgs
 
     CmdRepl()
     {
-        expectPathArgs("files", &files);
+        expectArgs({
+            .label = "files",
+            .handler = {&files},
+            .completer = completePath
+        });
     }
 
     std::string description() override
diff --git a/src/nix/run.cc b/src/nix/run.cc
index 3701ffe3d..f9b1298f1 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -149,7 +149,11 @@ struct CmdRun : InstallableCommand, RunCommon
 
     CmdRun()
     {
-        expectPathArgs("args", &args);
+        expectArgs({
+            .label = "args",
+            .handler = {&args},
+            .completer = completePath
+        });
     }
 
     std::string description() override