nixos-config/home-manager/neovim/nvim-cmp.lua

local has_words_before = function()
    local line, col = unpack(vim.api.nvim_win_get_cursor(0))
    return col ~= 0 and
        vim.api.nvim_buf_get_lines(0, line - 1, line, true)[1]:sub(
            col, col):match("%s") == nil
end

local cmp = require("cmp")
local luasnip = require("luasnip")

cmp.setup({
    snippet = {
        expand = function(args)
            luasnip.lsp_expand(args.body)
        end
    },
    sources = cmp.config.sources({
        { name = "nvim_lsp" },
        { name = "nvim_lsp_signature_help" },
        { name = "luasnip" },
        { name = "path" },
        { name = "buffer" },
        { name = "nvim-lua" },
        { name = "calc" },
    }),
    mapping = cmp.mapping.preset.insert({
        ["<C-b>"] = cmp.mapping.scroll_docs(-4),
        ["<C-f>"] = cmp.mapping.scroll_docs(4),
        ["<C-Space>"] = cmp.mapping.complete({}),
        ["<C-e>"] = cmp.mapping.abort(),
        ["<CR>"] = cmp.mapping.confirm({ select = true }), -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
        ["<Tab>"] = cmp.mapping(function(fallback)
            if cmp.visible() then
                cmp.select_next_item()
            elseif luasnip.expand_or_jumpable() then
                luasnip.expand_or_jump()
            elseif has_words_before() then
                cmp.complete()
            else
                fallback()
            end
        end, { "i", "s" }),
        ["<S-Tab>"] = cmp.mapping(function(fallback)
            if cmp.visible() then
                cmp.select_prev_item()
            elseif luasnip.jumpable(-1) then
                luasnip.jump(-1)
            else
                fallback()
            end
        end, { "i", "s" }),
    }),
    experimental = { ghost_text = true }
})

-- `/` cmdline setup.
cmp.setup.cmdline("/", {
    sources = cmp.config.sources(
        { name = "buffer" }
    )
})

-- `:` cmdline setup.
cmp.setup.cmdline(":", {
    sources = cmp.config.sources(
        { name = "path" },
        { name = "cmdline" }
    )
})