fix luasnip complete and move it to reasonable place (#235)

Co-authored-by: curtain <kaleidoscope@163.com>

lua/plugins/luasnip.lua

@@ -3,6 +3,67 @@ 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,