IDL Compiler: Implement ExtendedAttribute(s)

Implement ExtendedAttribute and ExtendedAttributes class
to follow the designed APIs.
https://docs.google.com/document/d/1ZPuPWjBSQVfVeJYptk7dYg1OAxx89-kwHz6oJlZGA5o/edit?usp=sharing

Bug: 839389
Change-Id: I21e2f4dd02433d52c14b362bd9f2cafd4eee3667
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1520518
Commit-Queue: Hitoshi Yoshida <peria@chromium.org>
Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642390}

third_party/blink/renderer/bindings/scripts/web_idl/extended_attribute.py

@@ -5,20 +5,73 @@
 # This file defines some classes to implement extended attributes
 # https://heycam.github.io/webidl/#idl-extended-attributes
 
-import exceptions
+from itertools import groupby
 
 
 class ExtendedAttribute(object):
-    """ExtendedAttribute represents an exnteded attribute, except for attributes
-    that have their own classes.
-    i.e. [Constructor], [CustomConstructor], [NamedConstructor], and [Exposed].
-    ExtendedAttribute assumes following formats as spec defines.
+    """ExtendedAttribute represents an exnteded attribute that
+    is described in either of following formats as spec defines.
     a. [Key]
     b. [Key=Value]
     c. [Key=(Value1,Value2,...)]
-    d. [Key(Type1 Value1, Type2 Value2,...)]
-    e. [Key=Name(Type1 Value1, Type2 Value2,...)]
+    d. [Key(ValueL1 ValueR1, ValueL2 ValueR2,...)]
+    e. [Key=Name(ValueL1 ValueR1, ValueL2 ValueR2,...)]
     """
+    _FORM_NO_ARGS = 'NoArgs'  # for (a)
+    _FORM_IDENT = 'Ident'  # for (b)
+    _FORM_IDENT_LIST = 'IdentList'  # for (c)
+    _FORM_ARG_LIST = 'ArgList'  # for (d)
+    _FORM_NAMED_ARG_LIST = 'NamedArgList'  # for (e)
+
+    def __init__(self, key, values=None, arguments=None, name=None):
+        # |values| can be either of None, a single string, or a list.
+        assert values is None or isinstance(values, (str, tuple, list))
+        # |arguments| can be either of None or a list of pairs of strings.
+        assert arguments is None or isinstance(arguments, (tuple, list))
+
+        self._format = None
+        self._key = key
+        self._values = values
+        self._arguments = arguments
+        self._name = name
+
+        if name is not None:
+            self._format = self._FORM_NAMED_ARG_LIST
+            if values is not None or arguments is None:
+                raise ValueError('Unknown format for ExtendedAttribute')
+        elif arguments is not None:
+            assert all(
+                isinstance(arg, (tuple, list)) and len(arg) == 2
+                and isinstance(arg[0], str) and isinstance(arg[1], str)
+                for arg in arguments)
+            self._format = self._FORM_ARG_LIST
+            if values is not None:
+                raise ValueError('Unknown format for ExtendedAttribute')
+        elif values is None:
+            self._format = self._FORM_NO_ARGS
+        elif isinstance(values, (tuple, list)):
+            self._format = self._FORM_IDENT_LIST
+            self._values = tuple(values)
+        elif isinstance(values, str):
+            self._format = self._FORM_IDENT
+        else:
+            raise ValueError('Unknown format for ExtendedAttribute')
+
+    def __str__(self):
+        if self._format == self._FORM_NO_ARGS:
+            return self._key
+        if self._format == self._FORM_IDENT:
+            return '{}={}'.format(self._key, self._values)
+        if self._format == self._FORM_IDENT_LIST:
+            return '{}=({})'.format(self._key, ', '.join(self._values))
+        args_str = '({})'.format(', '.join(
+            [' '.join(arg) for arg in self._arguments]))
+        if self._format == self._FORM_ARG_LIST:
+            return '{}{}'.format(self._key, args_str)
+        if self._format == self._FORM_NAMED_ARG_LIST:
+            return '{}={}{}'.format(self._key, self._name, args_str)
+        # Should not reach here.
+        assert False, 'Unknown format: {}'.format(self._format)
 
     @property
     def key(self):
@@ -26,54 +79,91 @@ class ExtendedAttribute(object):
         Returns the key.
         @return str
         """
-        raise exceptions.NotImplementedError()
+        return self._key
 
     @property
     def value(self):
         """
-        Returns the value for (b). Returns None for (a). Crashes otherwise.
+        Returns the value for the format Ident. Returns None for the format
+        NoArgs. Raises an error otherwise.
         @return str
         """
-        raise exceptions.NotImplementedError()
+        if self._format in (self._FORM_NO_ARGS, self._FORM_IDENT):
+            return self._values
+        raise ValueError('"{}" does not have a single value.'.format(
+            str(self)))
 
     @property
     def values(self):
         """
-        Returns a list of values for (b) and (c). Returns an empty list
-        for (a). Crashes otherwise.
+        Returns a list of values for formats Ident and IdentList. Returns an
+        empty list for the format NorArgs. Raises an error otherwise.
         @return tuple(str)
         """
-        raise exceptions.NotImplementedError()
+        if self._format == self._FORM_NO_ARGS:
+            return ()
+        if self._format == self._FORM_IDENT:
+            return (self._values, )
+        if self._format == self._FORM_IDENT_LIST:
+            return self._values
+        raise ValueError('"{}" does not have values.'.format(str(self)))
 
     @property
     def arguments(self):
         """
-        Returns a tuple of arguments for (d) and (e). Crashes otherwise.
+        Returns a tuple of value pairs for formats ArgList and NamedArgList.
+        Raises an error otherwise.
         @return tuple(Argument)
         """
-        raise exceptions.NotImplementedError()
+        if self._format in (self._FORM_ARG_LIST, self._FORM_NAMED_ARG_LIST):
+            return self._arguments
+        raise ValueError('"{}" does not have arguments.'.format(str(self)))
 
     @property
     def name(self):
         """
-        Returns |Name| for (e). Crashes otherwise.
+        Returns |Name| for the format NamedArgList. Raises an error otherwise.
         @return str
         """
-        raise exceptions.NotImplementedError()
+        if self._format == self._FORM_NAMED_ARG_LIST:
+            return self._name
+        raise ValueError('"{}" does not have a name.'.format(str(self)))
 
 
 class ExtendedAttributes(object):
-    """ExtendedAttributes is a dict-like container for ExtendedAttribute instances."""
+    """
+    ExtendedAttributes is a dict-like container for ExtendedAttribute instances.
+    With a key string, you can get an ExtendedAttribute or a list of them.
 
-    def has_key(self, _):
+    For an IDL fragment
+      [A, A=(foo, bar), B=baz]
+    the generated ExtendedAttributes instance will be like
+      {
+        'A': (ExtendedAttribute('A'), ExtendedAttribute('A', values=('foo', 'bar'))),
+        'B': (ExtendedAttribute('B', value='baz')),
+      }
+    """
+
+    def __init__(self, attributes=None):
+        assert attributes is None or (isinstance(attributes, (list, tuple))
+                                      and all(
+                                          isinstance(attr, ExtendedAttribute)
+                                          for attr in attributes))
+        attributes = sorted(attributes or [], key=lambda x: x.key)
+        self._attributes = {
+            k: tuple(v)
+            for k, v in groupby(attributes, key=lambda x: x.key)
+        }
+
+    def __contains__(self, key):
         """
         Returns True if this has an extended attribute with the |key|.
         @param  str key
         @return bool
         """
-        raise exceptions.NotImplementedError()
+        return key in self._attributes
 
-    def get(self, _):
+    def get(self, key):
         """
         Returns an exnteded attribute whose key is |key|.
         If |self| has no such elements, returns None,
@@ -81,12 +171,24 @@ class ExtendedAttributes(object):
         @param  str key
         @return ExtendedAttriute?
         """
-        raise exceptions.NotImplementedError()
+        values = self.get_list_of(key)
+        if len(values) == 0:
+            return None
+        if len(values) == 1:
+            return values[0]
+        raise ValueError(
+            'There are multiple extended attributes for the key "{}"'.format(
+                key))
 
-    def get_list_of(self, _):
+    def get_list_of(self, key):
         """
         Returns a list of extended attributes whose keys are |identifier|.
         @param  str key
         @return tuple(ExtendedAttribute)
         """
-        raise exceptions.NotImplementedError()
+        return self._attributes.get(key, ())
+
+    def append(self, extended_attribute):
+        assert isinstance(extended_attribute, ExtendedAttribute)
+        key = extended_attribute.key
+        self._attributes[key] = self.get_list_of(key) + (extended_attribute, )

third_party/blink/renderer/bindings/scripts/web_idl/extended_attribute_test.py

+# Copyright 2019 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# pylint: disable=import-error,print-statement,relative-import
+"""Unit tests for extended_attributes.py."""
+
+import unittest
+
+from .extended_attribute import ExtendedAttribute
+from .extended_attribute import ExtendedAttributes
+
+
+class TestableExtendedAttribute(ExtendedAttribute):
+    FORM_NO_ARGS = ExtendedAttribute._FORM_NO_ARGS
+    FORM_IDENT = ExtendedAttribute._FORM_IDENT
+    FORM_IDENT_LIST = ExtendedAttribute._FORM_IDENT_LIST
+    FORM_ARG_LIST = ExtendedAttribute._FORM_ARG_LIST
+    FORM_NAMED_ARG_LIST = ExtendedAttribute._FORM_NAMED_ARG_LIST
+
+    def __init__(self, key, values=None, arguments=None, name=None):
+        super(TestableExtendedAttribute, self).__init__(
+            key=key, values=values, arguments=arguments, name=name)
+
+    @property
+    def format(self):
+        return self._format
+
+
+class ExtendedAttributeTest(unittest.TestCase):
+    def test_attribute_create(self):
+        # NoArgs
+        attr = TestableExtendedAttribute(key='Foo')
+        self.assertEqual(attr.format, TestableExtendedAttribute.FORM_NO_ARGS)
+        self.assertEqual(attr.key, 'Foo')
+        self.assertEqual(attr.value, None)
+        self.assertEqual(attr.values, ())
+        with self.assertRaises(ValueError):
+            _ = attr.arguments
+        with self.assertRaises(ValueError):
+            _ = attr.name
+
+        # Ident
+        attr = TestableExtendedAttribute(key='Bar', values='Val')
+        self.assertEqual(attr.format, TestableExtendedAttribute.FORM_IDENT)
+        self.assertEqual(attr.key, 'Bar')
+        self.assertEqual(attr.value, 'Val')
+        self.assertEqual(attr.values, ('Val', ))
+        with self.assertRaises(ValueError):
+            _ = attr.arguments
+        with self.assertRaises(ValueError):
+            _ = attr.name
+
+        # IdentList
+        attr = TestableExtendedAttribute(key='Buz', values=('Val', 'ue'))
+        self.assertEqual(attr.format,
+                         TestableExtendedAttribute.FORM_IDENT_LIST)
+        self.assertEqual(attr.key, 'Buz')
+        self.assertEqual(attr.values, ('Val', 'ue'))
+        attr = TestableExtendedAttribute(
+            key='IdentList', values=['Val', 'ue', 'List'])
+        self.assertEqual(attr.values, ('Val', 'ue', 'List'))
+        with self.assertRaises(ValueError):
+            _ = attr.arguments
+        with self.assertRaises(ValueError):
+            _ = attr.name
+
+        # ArgList
+        attr = TestableExtendedAttribute(
+            key='Foo', arguments=(('Left', 'Right'), ('foo', 'bar')))
+        self.assertEqual(attr.format, TestableExtendedAttribute.FORM_ARG_LIST)
+        self.assertEqual(attr.key, 'Foo')
+        with self.assertRaises(ValueError):
+            _ = attr.values
+        self.assertEqual(attr.arguments, (('Left', 'Right'), ('foo', 'bar')))
+        with self.assertRaises(ValueError):
+            _ = attr.name
+
+        # NamedArgList
+        attr = TestableExtendedAttribute(
+            key='Bar', arguments=(('Left', 'Right'), ), name='Buz')
+        self.assertEqual(attr.format,
+                         TestableExtendedAttribute.FORM_NAMED_ARG_LIST)
+        self.assertEqual(attr.key, 'Bar')
+        with self.assertRaises(ValueError):
+            _ = attr.values
+        self.assertEqual(attr.arguments, (('Left', 'Right'), ))
+        self.assertEqual(attr.name, 'Buz')
+
+    def test_attributes(self):
+        attrs = [
+            ExtendedAttribute(key='A', values='val'),
+            ExtendedAttribute(key='B'),
+            ExtendedAttribute(key='C', values=('Val', 'ue')),
+            ExtendedAttribute(key='B', values=('Val', 'ue', 'B'))
+        ]
+        attributes = ExtendedAttributes(attrs)
+        self.assertTrue('A' in attributes)
+        self.assertFalse('D' in attributes)
+        self.assertEqual(attributes.get('A').value, 'val')
+        b_values = attributes.get_list_of('B')
+        self.assertEqual(b_values[0].values, ())
+        self.assertEqual(b_values[1].values, ('Val', 'ue', 'B'))