Merge pull request #3587 from NixOS/bash-completion

Generic shell completion support for the 'nix' command

12 files changed, 190 insertions, 21 deletions

diff --git a/src/nix/build.cc b/src/nix/build.cc
index 83d47acd4..474337208 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -18,6 +18,7 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixProfile
             .description = "path of the symlink to the build result",
             .labels = {"path"},
             .handler = {&outLink},
+            .completer = completePath
         });
 
         addFlag({
diff --git a/src/nix/cat.cc b/src/nix/cat.cc
index fd91f2036..b528a0507 100644
--- a/src/nix/cat.cc
+++ b/src/nix/cat.cc
@@ -25,7 +25,11 @@ struct CmdCatStore : StoreCommand, MixCat
 {
     CmdCatStore()
     {
-        expectArg("path", &path);
+        expectArgs({
+            .label = "path",
+            .handler = {&path},
+            .completer = completePath
+        });
     }
 
     std::string description() override
@@ -47,7 +51,11 @@ struct CmdCatNar : StoreCommand, MixCat
 
     CmdCatNar()
     {
-        expectArg("nar", &narPath);
+        expectArgs({
+            .label = "nar",
+            .handler = {&narPath},
+            .completer = completePath
+        });
         expectArg("path", &path);
     }
 
diff --git a/src/nix/command.cc b/src/nix/command.cc
index 71b027719..803a36e84 100644
--- a/src/nix/command.cc
+++ b/src/nix/command.cc
@@ -108,6 +108,7 @@ MixProfile::MixProfile()
         .description = "profile to update",
         .labels = {"path"},
         .handler = {&profile},
+        .completer = completePath
     });
 }
 
diff --git a/src/nix/command.hh b/src/nix/command.hh
index 6b4781303..faa19c8ea 100644
--- a/src/nix/command.hh
+++ b/src/nix/command.hh
@@ -38,6 +38,8 @@ struct EvalCommand : virtual StoreCommand, MixEvalArgs
     ref<EvalState> getEvalState();
 
     std::shared_ptr<EvalState> evalState;
+
+    void completeFlakeRef(std::string_view prefix);
 };
 
 struct MixFlakeOptions : virtual Args
@@ -63,6 +65,8 @@ struct SourceExprCommand : virtual Args, EvalCommand, MixFlakeOptions
     virtual Strings getDefaultFlakeAttrPaths();
 
     virtual Strings getDefaultFlakeAttrPathPrefixes();
+
+    void completeInstallable(std::string_view prefix);
 };
 
 enum RealiseMode { Build, NoBuild, DryRun };
@@ -73,10 +77,7 @@ struct InstallablesCommand : virtual Args, SourceExprCommand
 {
     std::vector<std::shared_ptr<Installable>> installables;
 
-    InstallablesCommand()
-    {
-        expectArgs("installables", &_installables);
-    }
+    InstallablesCommand();
 
     void prepare() override;
 
@@ -92,10 +93,7 @@ struct InstallableCommand : virtual Args, SourceExprCommand
 {
     std::shared_ptr<Installable> installable;
 
-    InstallableCommand()
-    {
-        expectArg("installable", &_installable, true);
-    }
+    InstallableCommand();
 
     void prepare() override;
 
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 6eee781aa..b6cc7eb54 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -28,7 +28,14 @@ public:
 
     FlakeCommand()
     {
-        expectArg("flake-url", &flakeUrl, true);
+        expectArgs({
+            .label = "flake-url",
+            .optional = true,
+            .handler = {&flakeUrl},
+            .completer = {[&](size_t, std::string_view prefix) {
+                completeFlakeRef(prefix);
+            }}
+        });
     }
 
     FlakeRef getFlakeRef()
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index 366314227..d5636eb47 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -31,7 +31,11 @@ struct CmdHash : Command
             .labels({"modulus"})
             .dest(&modulus);
         #endif
-        expectArgs("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 a06022f8c..cae85b34e 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -11,6 +11,7 @@
 #include "flake/flake.hh"
 #include "eval-cache.hh"
 #include "url.hh"
+#include "registry.hh"
 
 #include <regex>
 #include <queue>
@@ -77,7 +78,8 @@ SourceExprCommand::SourceExprCommand()
         .shortName = 'f',
         .description = "evaluate FILE rather than the default",
         .labels = {"file"},
-        .handler = {&file}
+        .handler = {&file},
+        .completer = completePath
     });
 
     addFlag({
@@ -105,6 +107,76 @@ Strings SourceExprCommand::getDefaultFlakeAttrPathPrefixes()
     };
 }
 
+void SourceExprCommand::completeInstallable(std::string_view prefix)
+{
+    if (file) return; // FIXME
+
+    /* Look for flake output attributes that match the
+       prefix. */
+    try {
+        auto hash = prefix.find('#');
+        if (hash != std::string::npos) {
+            auto fragment = prefix.substr(hash + 1);
+            auto flakeRefS = std::string(prefix.substr(0, hash));
+            // FIXME: do tilde expansion.
+            auto flakeRef = parseFlakeRef(flakeRefS, absPath("."));
+
+            auto state = getEvalState();
+
+            auto evalCache = openEvalCache(*state,
+                std::make_shared<flake::LockedFlake>(lockFlake(*state, flakeRef, lockFlags)),
+                true);
+
+            auto root = evalCache->getRoot();
+
+            /* Complete 'fragment' relative to all the
+               attrpath prefixes as well as the root of the
+               flake. */
+            auto attrPathPrefixes = getDefaultFlakeAttrPathPrefixes();
+            attrPathPrefixes.push_back("");
+
+            for (auto & attrPathPrefixS : attrPathPrefixes) {
+                auto attrPathPrefix = parseAttrPath(*state, attrPathPrefixS);
+                auto attrPathS = attrPathPrefixS + std::string(fragment);
+                auto attrPath = parseAttrPath(*state, attrPathS);
+
+                std::string lastAttr;
+                if (!attrPath.empty() && !hasSuffix(attrPathS, ".")) {
+                    lastAttr = attrPath.back();
+                    attrPath.pop_back();
+                }
+
+                auto attr = root->findAlongAttrPath(attrPath);
+                if (!attr) continue;
+
+                auto attrs = attr->getAttrs();
+                for (auto & attr2 : attrs) {
+                    if (hasPrefix(attr2, lastAttr)) {
+                        auto attrPath2 = attr->getAttrPath(attr2);
+                        /* Strip the attrpath prefix. */
+                        attrPath2.erase(attrPath2.begin(), attrPath2.begin() + attrPathPrefix.size());
+                        completions->insert(flakeRefS + "#" + concatStringsSep(".", attrPath2));
+                    }
+                }
+            }
+
+            /* And add an empty completion for the default
+               attrpaths. */
+            if (fragment.empty()) {
+                for (auto & attrPath : getDefaultFlakeAttrPaths()) {
+                    auto attr = root->findAlongAttrPath(parseAttrPath(*state, attrPath));
+                    if (!attr) continue;
+                    completions->insert(flakeRefS + "#");
+                }
+            }
+        }
+    } catch (Error & e) {
+        warn(e.msg());
+    }
+
+    completeFlakeRef(prefix);
+}
+
 ref<EvalState> EvalCommand::getEvalState()
 {
     if (!evalState)
@@ -112,6 +184,29 @@ ref<EvalState> EvalCommand::getEvalState()
     return ref<EvalState>(evalState);
 }
 
+void EvalCommand::completeFlakeRef(std::string_view prefix)
+{
+    if (prefix == "")
+        completions->insert(".");
+
+    completeDir(0, prefix);
+
+    /* Look for registry entries that match the prefix. */
+    for (auto & registry : fetchers::getRegistries(getStore())) {
+        for (auto & entry : registry->entries) {
+            auto from = entry.from->to_string();
+            if (!hasPrefix(prefix, "flake:") && hasPrefix(from, "flake:")) {
+                std::string from2(from, 6);
+                if (hasPrefix(from2, prefix))
+                    completions->insert(from2);
+            } else {
+                if (hasPrefix(from, prefix))
+                    completions->insert(from);
+            }
+        }
+    }
+}
+
 Buildable Installable::toBuildable()
 {
     auto buildables = toBuildables();
@@ -551,6 +646,17 @@ StorePathSet toDerivations(ref<Store> store,
     return drvPaths;
 }
 
+InstallablesCommand::InstallablesCommand()
+{
+    expectArgs({
+        .label = "installables",
+        .handler = {&_installables},
+        .completer = {[&](size_t, std::string_view prefix) {
+            completeInstallable(prefix);
+        }}
+    });
+}
+
 void InstallablesCommand::prepare()
 {
     if (_installables.empty() && useDefaultInstallables())
@@ -560,6 +666,18 @@ void InstallablesCommand::prepare()
     installables = parseInstallables(getStore(), _installables);
 }
 
+InstallableCommand::InstallableCommand()
+{
+    expectArgs({
+        .label = "installable",
+        .optional = true,
+        .handler = {&_installable},
+        .completer = {[&](size_t, std::string_view prefix) {
+            completeInstallable(prefix);
+        }}
+    });
+}
+
 void InstallableCommand::prepare()
 {
     installable = parseInstallable(getStore(), _installable);
diff --git a/src/nix/ls.cc b/src/nix/ls.cc
index b9716a6a1..dc7e370b9 100644
--- a/src/nix/ls.cc
+++ b/src/nix/ls.cc
@@ -85,7 +85,11 @@ struct CmdLsStore : StoreCommand, MixLs
 {
     CmdLsStore()
     {
-        expectArg("path", &path);
+        expectArgs({
+            .label = "path",
+            .handler = {&path},
+            .completer = completePath
+        });
     }
 
     Examples examples() override
@@ -117,7 +121,11 @@ struct CmdLsNar : Command, MixLs
 
     CmdLsNar()
     {
-        expectArg("nar", &narPath);
+        expectArgs({
+            .label = "nar",
+            .handler = {&narPath},
+            .completer = completePath
+        });
         expectArg("path", &path);
     }
 
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 3915a4896..fffdeab90 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -68,7 +68,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
         addFlag({
             .longName = "help",
             .description = "show usage information",
-            .handler = {[&]() { showHelpAndExit(); }},
+            .handler = {[&]() { if (!completions) showHelpAndExit(); }},
         });
 
         addFlag({
@@ -96,7 +96,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
         addFlag({
             .longName = "version",
             .description = "show version information",
-            .handler = {[&]() { printVersion(programName); }},
+            .handler = {[&]() { if (!completions) printVersion(programName); }},
         });
 
         addFlag({
@@ -166,7 +166,22 @@ void mainWrapped(int argc, char * * argv)
 
     NixArgs args;
 
-    args.parseCmdline(argvToStrings(argc, argv));
+    Finally printCompletions([&]()
+    {
+        if (completions) {
+            std::cout << (pathCompletions ? "filenames\n" : "no-filenames\n");
+            for (auto & s : *completions)
+                std::cout << s << "\n";
+        }
+    });
+
+    try {
+        args.parseCmdline(argvToStrings(argc, argv));
+    } catch (UsageError &) {
+        if (!completions) throw;
+    }
+
+    if (completions) return;
 
     settings.requireExperimentalFeature("nix-command");
 
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 0a6a7ab19..c936f9cc2 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -767,7 +767,11 @@ struct CmdRepl : StoreCommand, MixEvalArgs
 
     CmdRepl()
     {
-        expectArgs("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 3e2c8b4f3..f9b1298f1 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -149,7 +149,11 @@ struct CmdRun : InstallableCommand, RunCommon
 
     CmdRun()
     {
-        expectArgs("args", &args);
+        expectArgs({
+            .label = "args",
+            .handler = {&args},
+            .completer = completePath
+        });
     }
 
     std::string description() override
diff --git a/src/nix/sigs.cc b/src/nix/sigs.cc
index 6c9b9a792..7821a5432 100644
--- a/src/nix/sigs.cc
+++ b/src/nix/sigs.cc
@@ -105,7 +105,8 @@ struct CmdSignPaths : StorePathsCommand
             .shortName = 'k',
             .description = "file containing the secret signing key",
             .labels = {"file"},
-            .handler = {&secretKeyFile}
+            .handler = {&secretKeyFile},
+            .completer = completePath
         });
     }