diff --git a/tp.el b/tp.el
index 5722751..6657629 100644
--- a/tp.el
+++ b/tp.el
@@ -37,41 +37,18 @@
        (push (cons ',name layer-names) tp-layer-groups))
      (assoc ',name tp-layer-groups)))
 
-;; ;; FIXME:
-;; (defun tp-layer-properties (layer-or-group-or-properties)
-;;   "如果 name 已在 `tp-layer-define' 中定义，忽略 properties;
-;; 否则使用 properties 作为新的层的属性"
-;;   (if-let ((plist (cdr (assoc name tp-layer-alist))))
-;;       (append plist (list 'tp-name name))
-;;     (append properties (list 'tp-name name))))
+(defun tp-layer-properties (layer-name)
+  (when-let ((plist (cdr (assoc layer-name tp-layer-alist))))
+    (append plist (list 'tp-name name))))
 
-(defun tp-layer-properties (name &optional properties)
-  "如果 name 已在 `tp-layer-define' 中定义，忽略 properties;
-否则使用 properties 作为新的层的属性"
-  (if-let ((plist (cdr (assoc name tp-layer-alist))))
-      (append plist (list 'tp-name name))
-    (append properties (list 'tp-name name))))
-
-(defun tp-layer-group-properties (name)
+(defun tp-layer-group-properties (group-name)
   "返回使用 `tp-layer-group-define' 定义的 layer 的属性"
-  (when-let ((layers (cdr (assoc name tp-layer-groups))))
+  (when-let ((layers (cdr (assoc group-name tp-layer-groups))))
     (mapcar (lambda (layer)
               (tp-layer-properties layer))
             layers)))
 
-;;; tp layer
-
-(defun tp--layer-top-props (properties)
-  "获取最上面的属性层，也就是实际要渲染的层"
-  (if-let ((idx (-elem-index 'tp-layers properties)))
-      (-remove-at-indices (list idx (1+ idx)) properties)
-    properties))
-
-(defun tp--layer-below-props (properties)
-  "获取最上层以下的属性层列表"
-  (plist-get properties 'tp-layers))
-
-(defun tp-all (start end &optional object)
+(defun tp-intervals (start end &optional object)
   "获取 OBJECT 的 start 到 end 范围内文本的所有 text properties。
 OBJECT 可以为 buffer 或 string，nil 默认为当前 buffer。
 point 从 0 开始。"
@@ -98,20 +75,24 @@ function 的四个参数分别为:区间开始位置，区间结束位置，顶
       (let* ((interval-start (nth 0 tp)) ;; start from 0
              (interval-end (nth 1 tp))
              (interval-props (nth 2 tp))
-             (top-props (tp--layer-top-props interval-props))
-             (below-props-lst (tp--layer-below-props interval-props)))
+             (top-props
+              (if-let ((idx (-elem-index 'tp-layers properties)))
+                  (-remove-at-indices (list idx (1+ idx)) properties)
+                interval-props))
+             (below-props-lst (plist-get interval-props 'tp-layers)))
         (funcall function
                  interval-start interval-end
                  top-props below-props-lst)))
-    (tp-all start end object))))
+    (tp-intervals start end object))))
 
-(defun tp-region-layer-props (start end name &optional object)
+(defun tp-region-layer-props (start end layer-name &optional object)
   "返回 object 的 start 和 end 之间文本属性层为 name 的属性列表"
   (tp-intervals-map
    (lambda (i-start i-end top belows)
      (when-let ((props (seq-find
                         (lambda (props)
-                          (equal name (plist-get props 'tp-name)))
+                          (equal layer-name
+                                 (plist-get props 'tp-name)))
                         (append (list top) belows))))
        (list (+ start i-start) (+ start i-end) props)))
    start end object))
@@ -131,26 +112,28 @@ function 的四个参数分别为:区间开始位置，区间结束位置，顶
      start end object))
   object)
 
+;; (if (tp-empty-p object)
+;;     (set-text-properties
+;;      start end (append properties (list 'tp-name name))
+;;      object)
+;;   )
+
 ;;;###autoload
-(defun tp-layer-push (start end name &optional properties object)
+(defun tp-layer-push (start end name &optional object)
   "设置 properties 为最上面的 prop 层，name 是 layer 的名字;
 如果 properties 是 nil，则 `tp-layer-define' 定义的名称为 name 的 layer 设置。"
   (declare (indent defun))
   (when (tp-region-layer-props name start end object)
     (error "Already exist layer named %S" name))
-  (if (tp-empty-p object)
-      (set-text-properties
-       start end (append properties (list 'tp-name name))
-       object)
-    (let ((props (tp-layer-properties name properties)))
-      (tp-intervals-map
-       (lambda (i-start i-end top belows)
-         (set-text-properties
-          (+ start i-start) (+ start i-end)
-          (append props
-                  (list 'tp-layers (append (list top) belows)))
-          object))
-       start end object)))
+  (let ((props (tp-layer-properties name)))
+    (tp-intervals-map
+     (lambda (i-start i-end top belows)
+       (set-text-properties
+        (+ start i-start) (+ start i-end)
+        (append props
+                (list 'tp-layers (append (list top) belows)))
+        object))
+     start end object))
   object)
 
 (defun tp-layer-delete (start end name &optional object)