Added ast pretty printer

hy/util.py

@@ -18,6 +18,8 @@
 # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 # DEALINGS IN THE SOFTWARE.
 
+import ast
+
 
 def flatten_literal_list(entry):
     for e in entry:
@@ -26,3 +28,42 @@ def flatten_literal_list(entry):
                 yield x  # needs more yield-from
         else:
             yield e
+
+
+def dump(node, annotate_fields=True, include_attributes=False, indent='  '):
+    """
+    Return a formatted dump of the tree in *node*.  This is mainly useful for
+    debugging purposes.  The returned string will show the names and the values
+    for fields.  This makes the code impossible to evaluate, so if evaluation is
+    wanted *annotate_fields* must be set to False.  Attributes such as line
+    numbers and column offsets are not dumped by default.  If this is wanted,
+    *include_attributes* can be set to True.
+
+    Original author: Alex Leone (acleone ~AT~ gmail.com), 2010-01-30
+    """
+    def _format(node, level=0):
+        if isinstance(node, ast.AST):
+            fields = [(a, _format(b, level)) for a, b in ast.iter_fields(node)]
+            if include_attributes and node._attributes:
+                fields.extend([(a, _format(getattr(node, a), level))
+                               for a in node._attributes])
+            return ''.join([
+                node.__class__.__name__,
+                '(',
+                ', '.join(('%s=%s' % field for field in fields)
+                           if annotate_fields else
+                           (b for a, b in fields)),
+                ')'])
+        elif isinstance(node, list):
+            lines = ['[']
+            lines.extend((indent * (level + 2) + _format(x, level + 2) + ','
+                         for x in node))
+            if len(lines) > 1:
+                lines.append(indent * (level + 1) + ']')
+            else:
+                lines[-1] += ']'
+            return '\n'.join(lines)
+        return repr(node)
+    if not isinstance(node, ast.AST):
+        raise TypeError('expected AST, got %r' % node.__class__.__name__)
+    return _format(node)