nixd: refactor files of nixd implementation

Split nixd implementation into multiple files to make it more readable.

nixd/tools/nixd/meson.build

@@ -1,6 +1,12 @@
 nixd_next = executable('nixd',
-    'src/Controller.cpp',
+    'src/CodeAction.cpp',
+    'src/Convert.cpp',
+    'src/Diagnostics.cpp',
+    'src/Hover.cpp',
+    'src/LifeTime.cpp',
     'src/Main.cpp',
+    'src/Support.cpp',
+    'src/TextDocumentSync.cpp',
     install: true,
     dependencies: [ nixd_lsp_server, nixf, llvm ]
 )

nixd/tools/nixd/src/CodeAction.cpp

@@ -0,0 +1,50 @@
+/// \file
+/// \brief Implementation of [Code Action].
+/// [Code Action]:
+/// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_codeAction
+
+#include "Controller.h"
+
+namespace nixd {
+
+using namespace llvm::json;
+using namespace lspserver;
+
+void Controller::onCodeAction(const lspserver::CodeActionParams &Params,
+                              Callback<std::vector<CodeAction>> Reply) {
+  PathRef File = Params.textDocument.uri.file();
+  Range Range = Params.range;
+  const std::vector<nixf::Diagnostic> &Diagnostics = TUs[File].diagnostics();
+  std::vector<CodeAction> Actions;
+  Actions.reserve(Diagnostics.size());
+  for (const nixf::Diagnostic &D : Diagnostics) {
+    auto DRange = toLSPRange(D.range());
+    if (!Range.overlap(DRange))
+      continue;
+
+    // Add fixes.
+    for (const nixf::Fix &F : D.fixes()) {
+      std::vector<TextEdit> Edits;
+      Edits.reserve(F.edits().size());
+      for (const nixf::TextEdit &TE : F.edits()) {
+        Edits.emplace_back(TextEdit{
+            .range = toLSPRange(TE.oldRange()),
+            .newText = std::string(TE.newText()),
+        });
+      }
+      using Changes = std::map<std::string, std::vector<TextEdit>>;
+      std::string FileURI = URIForFile::canonicalize(File, File).uri();
+      WorkspaceEdit WE{.changes = Changes{
+                           {std::move(FileURI), std::move(Edits)},
+                       }};
+      Actions.emplace_back(CodeAction{
+          .title = F.message(),
+          .kind = std::string(CodeAction::QUICKFIX_KIND),
+          .edit = std::move(WE),
+      });
+    }
+  }
+  Reply(std::move(Actions));
+}
+
+} // namespace nixd