Remove static initializers for `RegisterLegacyCommand`

This moves the "legacy"/"nix2" commands under a new `src/legacy/`
directory, instead of being scattered around in a bunch of different
directories.

A new `liblegacy` build target is defined, and the `nix` binary is
linked against it.

Then, `RegisterLegacyCommand` is replaced with `LegacyCommand::add`
calls in functions like `registerNixCollectGarbage()`. These
registration functions are called explicitly in `src/nix/main.cc`.

See: https://git.lix.systems/lix-project/lix/issues/359

Change-Id: Id450ffc3f793374907599cfcc121863b792aac1a

1 files changed, 70 insertions, 0 deletions

diff --git a/src/legacy/dotgraph.cc b/src/legacy/dotgraph.cc
new file mode 100644
index 000000000..2c530999b
--- /dev/null
+++ b/src/legacy/dotgraph.cc
@@ -0,0 +1,70 @@
+#include "dotgraph.hh"
+#include "store-api.hh"
+
+#include <iostream>
+
+
+using std::cout;
+
+namespace nix {
+
+
+static std::string dotQuote(std::string_view s)
+{
+    return "\"" + std::string(s) + "\"";
+}
+
+
+static const std::string & nextColour()
+{
+    static int n = 0;
+    static std::vector<std::string> colours
+        { "black", "red", "green", "blue"
+        , "magenta", "burlywood" };
+    return colours[n++ % colours.size()];
+}
+
+
+static std::string makeEdge(std::string_view src, std::string_view dst)
+{
+    return fmt("%1% -> %2% [color = %3%];\n",
+        dotQuote(src), dotQuote(dst), dotQuote(nextColour()));
+}
+
+
+static std::string makeNode(std::string_view id, std::string_view label,
+    std::string_view colour)
+{
+    return fmt("%1% [label = %2%, shape = box, "
+        "style = filled, fillcolor = %3%];\n",
+        dotQuote(id), dotQuote(label), dotQuote(colour));
+}
+
+
+void printDotGraph(ref<Store> store, StorePathSet && roots)
+{
+    StorePathSet workList(std::move(roots));
+    StorePathSet doneSet;
+
+    cout << "digraph G {\n";
+
+    while (!workList.empty()) {
+        auto path = std::move(workList.extract(workList.begin()).value());
+
+        if (!doneSet.insert(path).second) continue;
+
+        cout << makeNode(std::string(path.to_string()), path.name(), "#ff0000");
+
+        for (auto & p : store->queryPathInfo(path)->references) {
+            if (p != path) {
+                workList.insert(p);
+                cout << makeEdge(std::string(p.to_string()), std::string(path.to_string()));
+            }
+        }
+    }
+
+    cout << "}\n";
+}
+
+
+}