Refactor previewers (#345)

lua/telescope/previewers/previewer.lua

@@ -0,0 +1,55 @@
+local Previewer = {}
+Previewer.__index = Previewer
+
+function Previewer:new(opts)
+  opts = opts or {}
+
+  return setmetatable({
+    state = nil,
+    _setup_func = opts.setup,
+    _teardown_func = opts.teardown,
+    _send_input = opts.send_input,
+    _scroll_fn = opts.scroll_fn,
+    preview_fn = opts.preview_fn,
+  }, Previewer)
+end
+
+function Previewer:preview(entry, status)
+  if not entry then
+    return
+  end
+
+  if not self.state then
+    if self._setup_func then
+      self.state = self:_setup_func()
+    else
+      self.state = {}
+    end
+  end
+
+  return self:preview_fn(entry, status)
+end
+
+function Previewer:teardown()
+  if self._teardown_func then
+    self:_teardown_func()
+  end
+end
+
+function Previewer:send_input(input)
+  if self._send_input then
+    self:_send_input(input)
+  else
+    vim.api.nvim_err_writeln("send_input is not defined for this previewer")
+  end
+end
+
+function Previewer:scroll_fn(direction)
+  if self._scroll_fn then
+    self:_scroll_fn(direction)
+  else
+    vim.api.nvim_err_writeln("scroll_fn is not defined for this previewer")
+  end
+end
+
+return Previewer