在lazyvim中用nvim-cmp管理自动补全

用lazyvim管理nvim-cmp 时设置tab键和shift-tab键上下选择补全项，enter键选中补全项

将下属代码填到~/.config/nvim/lua/plugins/nvim-cmp.lua

return {
  "hrsh7th/nvim-cmp",
  dependencies = {
    "L3MON4D3/LuaSnip", -- 关键修正：必须显式声明依赖 LuaSnip
    "hrsh7th/cmp-emoji",
  },
  ---@param opts cmp.ConfigSchema
  opts = function(_, opts)
    local cmp = require("cmp")
    local luasnip = require("luasnip") -- 有了上面的依赖，这里就不会报错了
 
    -- 辅助函数：检查光标前是否有文字
    local has_words_before = function()
      unpack = unpack or table.unpack
      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
 
    opts.mapping = vim.tbl_extend("force", opts.mapping, {
      -- TAB 键逻辑
      ["<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" }),
 
      -- SHIFT+TAB 键逻辑
      ["<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" }),
 
      -- ENTER 键逻辑
      ["<CR>"] = cmp.mapping.confirm({ select = true }),
    })
  end,
}