my-nvim-setup/lua/plugins/luasnip.lua

local present, luasnip = pcall(require, "luasnip")
if not present then
    return
end

local t = function(str)
    return vim.api.nvim_replace_termcodes(str, true, true, true)
end

local check_back_space = function()
    local col = vim.fn.col(".") - 1
    if col == 0 or vim.fn.getline("."):sub(col, col):match("%s") then
        return true
    else
        return false
    end
end

_G.tab_complete = function()
    if vim.fn.pumvisible() == 1 then
        return t "<C-n>"
    elseif luasnip and luasnip.expand_or_jumpable() then
        return t "<Plug>luasnip-expand-or-jump"
    elseif check_back_space() then
        return t "<Tab>"
    else
        return vim.fn["compe#complete"]()
    end
end
_G.s_tab_complete = function()
    if vim.fn.pumvisible() == 1 then
        return t "<C-p>"
    elseif luasnip and luasnip.jumpable(-1) then
        return t "<Plug>luasnip-jump-prev"
    else
        return t "<S-Tab>"
    end
end

_G.completions = function()
    local npairs
    if
        not pcall(
            function()
                npairs = require "nvim-autopairs"
            end
        )
     then
        return
    end

    if vim.fn.pumvisible() == 1 then
        if vim.fn.complete_info()["selected"] ~= -1 then
            return vim.fn["compe#confirm"]("<CR>")
        end
    end
    return npairs.check_break_line_char()
end

vim.api.nvim_set_keymap("i", "<Tab>", "v:lua.tab_complete()", {expr = true})
vim.api.nvim_set_keymap("s", "<Tab>", "v:lua.tab_complete()", {expr = true})
vim.api.nvim_set_keymap("i", "<S-Tab>", "v:lua.s_tab_complete()", {expr = true})
vim.api.nvim_set_keymap("s", "<S-Tab>", "v:lua.s_tab_complete()", {expr = true})
vim.api.nvim_set_keymap("i", "<CR>", "v:lua.completions()", {expr = true})

luasnip.config.set_config(
    {
        history = true,
        updateevents = "TextChanged,TextChangedI"
    }
)
require("luasnip/loaders/from_vscode").load()