Implement interface for __showtree__.

Some cleanup and import fixes.

mwparserfromhell/nodes/__init__.py

@@ -31,6 +31,10 @@ class Node(StringMixIn):
     def __strip__(self, normalize, collapse):
         return None
 
+    def __showtree__(self, write, get, mark):
+        write(unicode(self))
+
+
 from mwparserfromhell.nodes import extras
 from mwparserfromhell.nodes.text import Text
 from mwparserfromhell.nodes.heading import Heading

mwparserfromhell/nodes/heading.py

@@ -40,6 +40,11 @@ class Heading(Node):
     def __strip__(self, normalize, collapse):
         return self.title
 
+    def __showtree__(self, write, get, mark):
+        write("=" * self.level)
+        get(self.title)
+        write("=" * self.level)
+
     @property
     def title(self):
         return self._title

mwparserfromhell/nodes/tag.py

@@ -20,8 +20,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-from mwparserfromhell.nodes import Node
-from mwparserfromhell.nodes.extras import Attribute
+from mwparserfromhell.nodes import Node, Text
 
 __all__ = ["Tag"]
 
@@ -86,7 +85,7 @@ class Tag(Node):
         if not self.showtag:
             open_, close = self._translate()
             if self.self_closing:
-                return _open
+                return open_
             else:
                 return open_ + unicode(self.contents) + close
 
@@ -104,7 +103,7 @@ class Tag(Node):
         yield None, self
         if self.showtag:
             for child in getter(self.tag):
-                yield self.tag, tag
+                yield self.tag, child
             for attr in self.attrs:
                 for child in getter(attr.name):
                     yield attr.name, child
@@ -119,7 +118,31 @@ class Tag(Node):
             return self.contents.strip_code(normalize, collapse)
         return None
 
-    def translate(self):
+    def __showtree__(self, write, get, mark):
+        tagnodes = self.tag.nodes
+        if (not self.attrs and len(tagnodes) == 1 and
+                                        isinstance(tagnodes[0], Text)):
+            write("<" + unicode(tagnodes[0]) + ">")
+        else:
+            write("<")
+            get(self.tag)
+            for attr in self.attrs:
+                get(attr.name)
+                if not attr.value:
+                    continue
+                write("    = ")
+                mark()
+                get(attr.value)
+            write(">")
+        get(self.contents)
+        if len(tagnodes) == 1 and isinstance(tagnodes[0], Text):
+            write("</" + unicode(tagnodes[0]) + ">")
+        else:
+            write("</")
+            get(self.tag)
+            write(">")
+
+    def _translate(self):
         translations = {
             self.TAG_ITALIC: ("''", "''"),
             self.TAG_BOLD: ("'''", "'''"),

mwparserfromhell/nodes/template.py

@@ -57,6 +57,18 @@ class Template(Node):
             for child in getter(param.value):
                 yield param.value, child
 
+    def __showtree__(self, write, get, mark):
+        write("{{")
+        get(self.name)
+        for param in self.params:
+            write("    | ")
+            mark()
+            get(param.name)
+            write("    = ")
+            mark()
+            get(param.value)
+        write("}}")
+
     def _surface_escape(self, code, char):
         replacement = HTMLEntity(value=ord(char))
         for node in code.filter_text(recursive=False):

mwparserfromhell/wikicode.py

@@ -22,9 +22,7 @@
 
 import re
 
-from mwparserfromhell.nodes import (
-    Heading, HTMLEntity, Node, Tag, Template, Text
-)
+from mwparserfromhell.nodes import Node, Template, Text
 from mwparserfromhell.string_mixin import StringMixIn
 from mwparserfromhell.utils import parse_anything
 
@@ -95,47 +93,10 @@ class Wikicode(StringMixIn):
             else:
                 lines.append(" " * 6 * indent + " ".join(args))
 
+        get = lambda code: self._get_tree(code, lines, marker, indent + 1)
+        mark = lambda: lines.append(marker)
         for node in code.nodes:
-            if isinstance(node, Heading):
-                write("=" * node.level)
-                self._get_tree(node.title, lines, marker, indent + 1)
-                write("=" * node.level)
-            elif isinstance(node, Tag):
-                tagnodes = node.tag.nodes
-                if (not node.attrs and len(tagnodes) == 1 and
-                        isinstance(tagnodes[0], Text)):
-                    write("<" + unicode(tagnodes[0]) + ">")
-                else:
-                    write("<")
-                    self._get_tree(node.tag, lines, marker, indent + 1)
-                    for attr in node.attrs:
-                        self._get_tree(attr.name, lines, marker, indent + 1)
-                        if not attr.value:
-                            continue
-                        write("    = ")
-                        lines.append(marker)  # Continue from this line
-                        self._get_tree(attr.value, lines, marker, indent + 1)
-                    write(">")
-                self._get_tree(node.contents, lines, marker, indent + 1)
-                if len(tagnodes) == 1 and isinstance(tagnodes[0], Text):
-                    write("</" + unicode(tagnodes[0]) + ">")
-                else:
-                    write("</")
-                    self._get_tree(node.tag, lines, marker, indent + 1)
-                    write(">")
-            elif isinstance(node, Template):
-                write("{{")
-                self._get_tree(node.name, lines, marker, indent + 1)
-                for param in node.params:
-                    write("    | ")
-                    lines.append(marker)  # Continue from this line
-                    self._get_tree(param.name, lines, marker, indent + 1)
-                    write("    = ")
-                    lines.append(marker)  # Continue from this line
-                    self._get_tree(param.value, lines, marker, indent + 1)
-                write("}}")
-            else:
-                write(unicode(node))
+            node.__showtree__(write, get, mark)
         return lines
 
     @property