nvim-lsp: create nvim LSP plugin

flake.nix

@@ -49,6 +49,11 @@
             };
 
             plugins.gitgutter.enable = true;
+
+            plugins.lsp = {
+              enable = true;
+              servers.clangd.enable = true;
+            };
           };
         })
       ];

plugins/default.nix

@@ -6,5 +6,7 @@
     ./statuslines/airline.nix
 
     ./git/gitgutter.nix
+
+    ./nvim-lsp
   ];
 }

plugins/nvim-lsp/clangd.nix

@@ -0,0 +1,18 @@
+{ pkgs, config, lib, ... }:
+with lib;
+let
+  cfg = config.programs.nixvim.plugins.lsp.servers.clangd;
+in
+{
+  options = {
+    programs.nixvim.plugins.lsp.servers.clangd = {
+      enable = mkEnableOption "Enable clangd LSP, for C/C++.";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    programs.nixvim.extraPackages = [ pkgs.clang-tools ];
+
+    programs.nixvim.plugins.lsp.enabledServers = [ "clangd" ];
+  };
+}

plugins/nvim-lsp/default.nix

@@ -0,0 +1,69 @@
+{ config, pkgs, lib, ... }:
+with lib;
+let
+  cfg = config.programs.nixvim.plugins.lsp;
+  helpers = (import ../helpers.nix { inherit lib; });
+in
+{
+  imports = [
+    ./clangd.nix
+    ./rust-analyzer.nix
+    ./rnix-lsp.nix
+  ];
+
+  options = {
+    programs.nixvim.plugins.lsp = {
+      enable = mkEnableOption "Enable neovim's built-in LSP";
+
+      enabledServers = mkOption {
+        type = with types; listOf (oneOf [str (submodule {
+          options = {
+            name = mkOption {
+              type = str;
+              description = "The server's name";
+            };
+
+            extraOptions = mkOption {
+              type = attrs;
+              description = "Extra options for the server";
+            };
+          };
+        })]);
+        description = "A list of enabled LSP servers. Don't use this directly.";
+        default = [];
+      };
+
+      onAttach = mkOption {
+        type = types.lines;
+        description = "A lua function to be run when a new LSP buffer is attached. The argument `client` is provided.";
+        default = "";
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    programs.nixvim = {
+      extraPlugins = [ pkgs.vimPlugins.nvim-lspconfig ];
+
+      # Enable all LSP servers
+      extraConfigLua = ''
+        -- LSP {{{
+        local __lspServers = ${helpers.toLuaObject cfg.enabledServers}
+        local __lspOnAttach = function(client)
+          ${cfg.onAttach}
+        end
+
+        for i,server in ipairs(__lspServers) do
+          if type(server) == "string" then
+            require('lspconfig')[server].setup {
+              on_attach = __lspOnAttach
+            }
+          else
+            require('lspconfig')[server.name].setup(server.extraOptions)
+          end
+        end
+        -- }}}
+      '';
+    };
+  };
+}

plugins/nvim-lsp/rnix-lsp.nix

@@ -0,0 +1,18 @@
+{ pkgs, config, lib, ... }:
+with lib;
+let
+  cfg = config.programs.nixvim.plugins.lsp.servers.rnix-lsp;
+in
+{
+  options = {
+    programs.nixvim.plugins.lsp.servers.rnix-lsp = {
+      enable = mkEnableOption "Enable rnix LSP, for Nix";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    programs.nixvim.extraPackages = [ pkgs.rnix-lsp ];
+
+    programs.nixvim.lsp.plugins.enabledServers = [ "rnix" ];
+  };
+}

plugins/nvim-lsp/rust-analyzer.nix

@@ -0,0 +1,18 @@
+{ pkgs, config, lib, ... }:
+with lib;
+let
+  cfg = config.programs.nixvim.plugins.lsp.servers.rust-analyzer;
+in
+{
+  options = {
+    programs.nixvim.plugins.lsp.servers.rust-analyzer = {
+      enable = mkEnableOption "Enable rust-analyzer, for Rust.";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    programs.nixvim.extraPackages = [ pkgs.rust-analyzer ];
+
+    programs.nixvim.plugins.lsp.enabledServers = [ "rust_analyzer" ];
+  };
+}