feat(neovim): add support for C/C++, Lua, Rust, and Java

Add completion support using Neovim's built-in LSP client. Add documentations
for installing language servers. Add highlighting support based on Tree-sitter.
Configure Tree-sitter parsers and language servers.

https://github.com/mfussenegger/nvim-jdtls#configuration-quickstart
LuaLS/lua-language-server#1788 (comment)

README.md

@@ -0,0 +1,25 @@
+# Neovim
+
+Neovim has a built-in LSP client. There are several language servers used in the
+configurations.
+
+Language | Language Server                      | Installation
+-------- | ------------------------------------ | ------------------------------
+C/C++    | [clangd]                             | [Installation][install_clangd]
+Lua      | [lua-language-server][luals]         | [Installation][install_luals]
+Rust     | [rust-analyzer][rls2]                | [Installation][install_rls2]
+Java     | [Eclipse JDT Language Server][jdtls] | [Installation][install_jdtls]
+
+[clangd]: https://github.com/clangd/clangd
+[install_clangd]: https://clangd.llvm.org/installation#installing-clangd
+[luals]: https://github.com/LuaLS/lua-language-server
+[install_luals]: https://luals.github.io/#neovim-install
+[rls2]: https://github.com/rust-lang/rust-analyzer
+[install_rls2]: https://rust-analyzer.github.io/manual.html#installation
+[jdtls]: https://github.com/eclipse-jdtls/eclipse.jdt.ls
+[install_jdtls]: https://github.com/eclipse-jdtls/eclipse.jdt.ls#installation
+
+```console
+$ sudo pacman -S clangd rust-analyzer lua-language-server
+$ paru -S jdtls
+```

neovim/.config/nvim/ftplugin/java.lua

@@ -0,0 +1,5 @@
+local jdtls = require("jdtls")
+jdtls.start_or_attach({
+	cmd = { "jdtls" },
+	root_dir = vim.fs.dirname(vim.fs.find({ "gradlew", ".git", "mvnw", { upward = true }})[1])
+})

neovim/.config/nvim/lua/plugins/cmp.lua

@@ -0,0 +1,9 @@
+local cmp = require("cmp")
+cmp.setup({
+	mapping = cmp.mapping.preset.insert({
+		["<CR>"] = cmp.mapping.confirm({ select = true }),
+	}),
+	sources = cmp.config.sources({
+		{ name = "nvim_lsp" },
+	}),
+})

neovim/.config/nvim/lua/plugins/lspconfig.lua

@@ -0,0 +1,15 @@
+local lspconfig = require("lspconfig")
+lspconfig.clangd.setup({})
+lspconfig.lua_ls.setup({
+	settings = {
+		Lua = {
+			workspace = {
+				library = vim.tbl_extend(
+					"keep",
+					{ "/usr/lib/lua-language-server/meta/template" },
+					vim.api.nvim_get_runtime_file("", true)
+				),
+			},
+		},
+	},
+})

neovim/.config/nvim/rocks.toml

@@ -3,3 +3,18 @@
 "rocks-git.nvim" = "1.1.1"
 "rocks-config.nvim" = "3.1.0"
 "rocks-lazy.nvim" = "1.1.1"
+
+nvim-lspconfig = "1.3.0"
+nvim-cmp = "scm"
+cmp-nvim-lsp = "scm"
+rustaceanvim = "5.22.0"
+nvim-jdtls = "0.2.0"
+
+tree-sitter-c = "0.0.36"
+tree-sitter-cpp = "0.0.35"
+tree-sitter-rust = "0.0.38"
+tree-sitter-java = "0.0.37"
+tree-sitter-lua = "0.0.32"
+
+[plugins.nvim-treesitter]
+git = "nvim-treesitter/nvim-treesitter"