IDL: Support optional argument default value syntax

Source/bindings/scripts/idl_definitions.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 376 matching lines @@
         self.value = value_node.GetName()
 
         if num_children == 3:
             ext_attributes_node = children[2]
             self.extended_attributes = ext_attributes_node_to_extended_attributes(ext_attributes_node)
         else:
             self.extended_attributes = {}
 
 
 ################################################################################
+# Literals
+################################################################################
+
+class IdlLiteral(object):
+    def __init__(self, idl_type, value):
+        self.idl_type = idl_type
+        self.value = value
+        self.is_null = False
+
+    def __str__(self):
+        if self.idl_type == 'DOMString':
+            return 'String("%s")' % self.value
+        if self.idl_type == 'integer':
+            return '%d' % self.value
+        if self.idl_type == 'float':
+            return '%g' % self.value
+        if self.idl_type == 'boolean':
+            return 'true' if self.value else 'false'
+        raise ValueError('Unsupported literal type: %s' % self.idl_type)
+
+
+class IdlLiteralNull(IdlLiteral):
+    def __init__(self):
+        self.idl_type = 'NULL'
+        self.value = None
+        self.is_null = True
+
+    def __str__(self):
+        return 'nullptr'
+
+
+def default_node_to_idl_literal(node):
+    # FIXME: This code is unnecessarily complicated due to the rather
+    # inconsistent way the upstream IDL parser outputs default values.
+    # http://crbug.com/374178
+    idl_type = node.GetProperty('TYPE')
+    if idl_type == 'DOMString':
+        value = node.GetProperty('NAME')

[haraken, 2014/06/13 13:46:52]

Shouldn't this be node.GetProperty('VALUE') ?

[Jens Widell, 2014/06/13 14:14:52]

The use of NAME/VALUE here is entirely dictated by what the IDL parser actually
outputs. See http://crbug.com/374178.

I intend to look into fixing that bug, but wasn't planning to do it before
landing this patch.

+        if '"' in value or '\\' in value:
+            raise ValueError('Unsupported string value: %r' % value)
+        return IdlLiteral(idl_type, value)
+    if idl_type == 'integer':
+        return IdlLiteral(idl_type, int(node.GetProperty('NAME')))

[haraken, 2014/06/13 13:46:52]

Shouldn't this be int(node.GetProperty('VALUE') ?

+    elif idl_type == 'float':

[Nils Barth (inactive), 2014/06/16 09:18:17]

No else after return: these can all be |if|

+        return IdlLiteral(idl_type, float(node.GetProperty('VALUE')))
+    elif idl_type == 'boolean':
+        return IdlLiteral(idl_type, node.GetProperty('VALUE'))
+    elif idl_type == 'NULL':
+        return IdlLiteralNull()
+    raise ValueError('Unrecognized default value type: %s' % idl_type)
+
+
+################################################################################
 # Operations
 ################################################################################
 
 class IdlOperation(TypedObject):
     def __init__(self, node=None):
         self.arguments = []
         self.extended_attributes = {}
         self.specials = []
 
         if not node:
@@ skipping 61 matching lines @@
 # Arguments
 ################################################################################
 
 class IdlArgument(TypedObject):
     def __init__(self, node):
         self.extended_attributes = {}
         self.idl_type = None
         self.is_optional = node.GetProperty('OPTIONAL')  # syntax: (optional T)
         self.is_variadic = False  # syntax: (T...)
         self.name = node.GetName()
+        self.default_value = None
 
         children = node.GetChildren()
         for child in children:
             child_class = child.GetClass()
             if child_class == 'Type':
                 self.idl_type = type_node_to_type(child)
             elif child_class == 'ExtAttributes':
                 self.extended_attributes = ext_attributes_node_to_extended_attributes(child)
             elif child_class == 'Argument':
                 child_name = child.GetName()
                 if child_name != '...':
                     raise ValueError('Unrecognized Argument node; expected "...", got "%s"' % child_name)
                 self.is_variadic = child.GetProperty('ELLIPSIS') or False
+            elif child_class == 'Default':
+                self.default_value = default_node_to_idl_literal(child)
             else:
                 raise ValueError('Unrecognized node class: %s' % child_class)
 
 
 def arguments_node_to_arguments(node):
     # [Constructor] and [CustomConstructor] without arguments (the bare form)
     # have None instead of an arguments node, but have the same meaning as using
     # an empty argument list, [Constructor()], so special-case this.
     # http://www.w3.org/TR/WebIDL/#Constructor
     if node is None:
@@ skipping 188 matching lines @@
     child_class = child.GetClass()
     if child_class != 'Type':
         raise ValueError('Unrecognized node class: %s' % child_class)
     return type_node_to_type(child)
 
 
 def union_type_node_to_idl_union_type(node, is_nullable=False):
     member_types = [type_node_to_type(member_type_node)
                     for member_type_node in node.GetChildren()]
     return IdlUnionType(member_types, is_nullable=is_nullable)