type: add type annotations to render_node.py and output.py

Add complete type annotations to RenderNode class and render_ref_list
function using the new type aliases.

Changes:
- Add types to RenderNode.__init__(), new_child(), to_str()
- Add types to render_ref_list() function
- Use ASTNode and RefDict type aliases from types.py

Author: drmingdrmer

md2zhihu/parser/output.py

@@ -1,6 +1,11 @@
+from typing import List
+
+from ..types import RefDict
+
+
 # TODO: move to renderer module?
-def render_ref_list(refs, platform):
-    ref_lines = ["", "Reference:", ""]
+def render_ref_list(refs: RefDict, platform: str) -> List[str]:
+    ref_lines: List[str] = ["", "Reference:", ""]
     for ref_id in sorted(refs):
         #  url_and_alt is in form "<url> <alt>"
         url_alt = refs[ref_id].split()

md2zhihu/renderer/render_node.py

@@ -1,26 +1,33 @@
+from __future__ import annotations
+
+from typing import Optional
+
+from ..types import ASTNode
+
+
 class RenderNode(object):
     """
     RenderNode is a container of current ast-node and parent
     """
 
-    def __init__(self, n, parent=None):
+    def __init__(self, n: ASTNode, parent: Optional[RenderNode] = None) -> None:
         """
         :param n: ast node: a normal dictionary such as {'type': 'text' ... }
         :param parent: parent RenderNode
         """
-        self.node = n
+        self.node: ASTNode = n
 
-        self.level = 0
+        self.level: int = 0
 
         # parent RenderNode
-        self.parent = parent
+        self.parent: Optional[RenderNode] = parent
 
-    def new_child(self, n):
+    def new_child(self, n: ASTNode) -> RenderNode:
         c = RenderNode(n, parent=self)
         c.level = self.level + 1
         return c
 
-    def to_str(self):
+    def to_str(self) -> str:
         t = "{}".format(self.node.get("type"))
         if self.parent is None:
             return t