ch17: update from book draft

17-it-generator/tree/extra/pretty_tree.py

@@ -0,0 +1,31 @@
+from tree import tree
+
+SPACES = ' ' * 4
+HLINE = '\u2500'            # ─ BOX DRAWINGS LIGHT HORIZONTAL
+HLINE2 = HLINE * 2
+ELBOW = f'\u2514{HLINE2} '  # └ BOX DRAWINGS LIGHT UP AND RIGHT
+TEE   = f'\u251C{HLINE2} '  # ├ BOX DRAWINGS LIGHT VERTICAL AND RIGHT
+PIPE  = f'\u2502   '        # │ BOX DRAWINGS LIGHT VERTICAL
+
+
+def render_lines(tree_iter):
+    name, _, _ = next(tree_iter)
+    yield name
+    prefix = ''
+
+    for name, level, last in tree_iter:
+        if last:
+            connector = ELBOW
+        else:
+            connector = TEE
+
+        prefix = prefix[:4 * (level-1)]
+        prefix = prefix.replace(TEE, PIPE).replace(ELBOW, SPACES)
+        prefix += connector
+
+        yield prefix + name
+
+
+if __name__ == '__main__':
+    for line in render_lines(tree(BaseException)):
+        print(line)