Refactor previewers (#345)

lua/telescope/previewers/utils.lua

@@ -0,0 +1,17 @@
+local context_manager = require('plenary.context_manager')
+
+local utils = {}
+
+utils.with_preview_window = function(status, bufnr, callable)
+  if bufnr and vim.api.nvim_buf_call and false then
+    vim.api.nvim_buf_call(bufnr, callable)
+  else
+    return context_manager.with(function()
+      vim.cmd(string.format("noautocmd call nvim_set_current_win(%s)", status.preview_win))
+      coroutine.yield()
+      vim.cmd(string.format("noautocmd call nvim_set_current_win(%s)", status.prompt_win))
+    end, callable)
+  end
+end
+
+return utils