Mojo: bindings generator: Add an AST type for parameter lists.

mojo/public/tools/bindings/pylib/mojom/parse/ast.py

Index: mojo/public/tools/bindings/pylib/mojom/parse/ast.py
diff --git a/mojo/public/tools/bindings/pylib/mojom/parse/ast.py b/mojo/public/tools/bindings/pylib/mojom/parse/ast.py
index be8d20e634dd9987a57a41c23ae9a406c1c0545b..78017e56a645aecc25fae1e960942f9796981269 100644
--- a/mojo/public/tools/bindings/pylib/mojom/parse/ast.py
+++ b/mojo/public/tools/bindings/pylib/mojom/parse/ast.py
@@ -9,7 +9,7 @@
 # and lineno).
 
 
-class BaseNode(object):
+class NodeBase(object):
   """Base class for nodes in the AST."""
 
   def __init__(self, filename=None, lineno=None):
@@ -17,23 +17,23 @@ class BaseNode(object):
     self.lineno = lineno
 
 
-class Ordinal(BaseNode):
+class Ordinal(NodeBase):
   """Represents an ordinal value labeling, e.g., a struct field."""
 
   def __init__(self, value, **kwargs):
-    BaseNode.__init__(self, **kwargs)
+    NodeBase.__init__(self, **kwargs)
     self.value = value
 
   def __eq__(self, other):
     return self.value == other.value
 
 
-class Parameter(BaseNode):
+class Parameter(NodeBase):
   """Represents a method request or response parameter."""
 
   def __init__(self, typename, name, ordinal, **kwargs):
     assert isinstance(ordinal, Ordinal)
-    BaseNode.__init__(self, **kwargs)
+    NodeBase.__init__(self, **kwargs)
     self.typename = typename
     self.name = name
     self.ordinal = ordinal
@@ -42,3 +42,53 @@ class Parameter(BaseNode):
     return self.typename == other.typename and \
            self.name == other.name and \
            self.ordinal == other.ordinal
+
+
+class NodeListBase(NodeBase):
+  """Represents a list of other nodes, all having the same type. (This is meant
+  to be subclassed, with subclasses defining _list_item_type to be the class of
+  the members of the list; _list_item_type should also be a NodeBase.)"""
+
+  def __init__(self, item_or_items=None, **kwargs):
+    assert issubclass(self._list_item_type, NodeBase)
+    NodeBase.__init__(self, **kwargs)
+    if item_or_items is None:
+      self.elements = []
+    elif isinstance(item_or_items, list):
+      # TODO(vtl): Possibly we should assert that each element of the list is a
+      # |_list_item_type|.
+      self.elements = list(item_or_items)
+    else:
+      assert isinstance(item_or_items, self._list_item_type)
+      self.elements = [item_or_items]
+    self._UpdateFilenameAndLineno()
+
+  # Support iteration. For everything else, users should just access |elements|
+  # directly. (We intentionally do NOT supply |__len__()| or |__nonzero__()|, so
+  # |bool(NodeListBase())| is true.)
+  def __iter__(self):
+    return self.elements.__iter__()
+
+  def __eq__(self, other):
+    if type(self) != type(other):
+      return False
+    for element in self.elements:
+      if self.elements != other.elements:
+        return False
+    return True
+
+  def Append(self, item):
+    assert isinstance(item, self._list_item_type)
+    self.elements.append(item)
+    self._UpdateFilenameAndLineno()
+
+  def _UpdateFilenameAndLineno(self):
+    if self.elements:
+      self.filename = self.elements[0].filename
+      self.lineno = self.elements[0].lineno
+
+
+class ParameterList(NodeListBase):
+  """Represents a list of (method request or response) parameters."""
+
+  _list_item_type = Parameter