bind-gen: Implement IDL interface code generation (1 of N)

Splits the contents of example.py into interface.py and
several files.

blink_v8_bridge.py will support Blink-V8 type and value
conversions.

codegen_utils.py is currently a collection of misc util
functions, and should be better organized later.

Bug: 839389
Change-Id: I609be076533106e4e98865add162f40f965398dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1892974Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712554}

third_party/blink/renderer/bindings/scripts/bind_gen/__init__.py

@@ -16,6 +16,9 @@ def _setup_sys_path():
     root_dir = os.path.join(this_dir, *(['..'] * expected_path.count('/')))
 
     sys.path = [
+        # //third_party/blink/renderer/bindings/scripts/web_idl
+        os.path.join(root_dir, 'third_party', 'blink', 'renderer', 'bindings',
+                     'scripts'),
         # //third_party/blink/renderer/build/scripts/blinkbuild
         os.path.join(root_dir, 'third_party', 'blink', 'renderer', 'build',
                      'scripts'),
@@ -47,7 +50,9 @@ def _setup_clang_format():
 _setup_clang_format()
 
 from .example import run_example
+from .interface import generate_interfaces
 
 __all__ = [
+    "generate_interfaces",
     "run_example",
 ]

third_party/blink/renderer/bindings/scripts/bind_gen/blink_v8_bridge.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.
+
+from .code_node import CodeNode
+from .code_node import SymbolDefinitionNode
+from .code_node import SymbolNode
+from .code_node import SymbolScopeNode
+from .code_node import TextNode
+from .code_node import UnlikelyExitNode
+import web_idl
+
+_format = CodeNode.format_template
+
+
+def make_v8_to_blink_value(blink_var_name, v8_value_expr, idl_type):
+    """
+    Returns a SymbolNode whose definition converts a v8::Value to a Blink value.
+    """
+    assert isinstance(blink_var_name, str)
+    assert isinstance(v8_value_expr, str)
+    assert isinstance(idl_type, web_idl.IdlType)
+
+    pattern = "NativeValueTraits<{_1}>::NativeValue({_2})"
+    _1 = "IDL{}".format(idl_type.type_name)
+    _2 = ["${isolate}", v8_value_expr, "${exception_state}"]
+
+    blink_value = _format(pattern, _1=_1, _2=", ".join(_2))
+    idl_type_tag = _1
+
+    pattern = "{_1}& ${{{_2}}} = {_3};"
+    _1 = "NativeValueTraits<{}>::ImplType".format(idl_type_tag)
+    _2 = blink_var_name
+    _3 = blink_value
+    text = _format(pattern, _1=_1, _2=_2, _3=_3)
+
+    def create_definition(symbol_node):
+        return SymbolDefinitionNode(symbol_node, [
+            TextNode(text),
+            UnlikelyExitNode(
+                cond=TextNode("${exception_state}.HadException()"),
+                body=SymbolScopeNode([TextNode("return;")])),
+        ])
+
+    return SymbolNode(blink_var_name, definition_constructor=create_definition)

third_party/blink/renderer/bindings/scripts/bind_gen/code_node_test.py

@@ -12,24 +12,17 @@ from .code_node import SymbolNode
 from .code_node import SymbolScopeNode
 from .code_node import TextNode
 from .code_node import UnlikelyExitNode
+from .codegen_utils import render_code_node
 from .mako_renderer import MakoRenderer
 
 
 class CodeNodeTest(unittest.TestCase):
-    def render(self, node):
-        prev = ""
-        current = str(node)
-        while current != prev:
-            prev = current
-            current = str(node)
-        return current
-
     def assertRenderResult(self, node, expected):
         def simplify(text):
             return "\n".join(
                 [" ".join(line.split()) for line in text.split("\n")])
 
-        actual = simplify(self.render(node))
+        actual = simplify(render_code_node(node))
         expected = simplify(expected)
 
         self.assertEqual(actual, expected)

third_party/blink/renderer/bindings/scripts/bind_gen/codegen_utils.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.
+
+from .clang_format import clang_format
+from .code_node import CodeNode
+from .code_node import LiteralNode
+from .code_node import SymbolScopeNode
+
+
+def make_copyright_header():
+    return LiteralNode("""\
+// 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.\
+""")
+
+
+def enclose_with_header_guard(code_node, header_guard):
+    assert isinstance(code_node, CodeNode)
+    assert isinstance(header_guard, str)
+
+    return SymbolScopeNode([
+        LiteralNode("#ifndef {}".format(header_guard)),
+        LiteralNode("#define {}".format(header_guard)),
+        LiteralNode(""),
+        code_node,
+        LiteralNode(""),
+        LiteralNode("#endif  // {}".format(header_guard)),
+    ])
+
+
+def enclose_with_namespace(code_node, namespace):
+    assert isinstance(code_node, CodeNode)
+    assert isinstance(namespace, str)
+
+    return SymbolScopeNode([
+        LiteralNode("namespace {} {{".format(namespace)),
+        LiteralNode(""),
+        code_node,
+        LiteralNode(""),
+        LiteralNode("}}  // namespace {}".format(namespace)),
+    ])
+
+
+def render_code_node(code_node):
+    """
+    Renders |code_node| and turns it into text letting |code_node| apply all
+    necessary changes (side effects).  Returns the resulting text.
+    """
+    prev = "_"
+    current = ""
+    while current != prev:
+        prev = current
+        current = str(code_node)
+    return current
+
+
+def write_code_node_to_file(code_node, filepath):
+    """Renders |code_node| and then write the result to |filepath|."""
+    assert isinstance(code_node, CodeNode)
+    assert isinstance(filepath, str)
+
+    rendered_text = render_code_node(code_node)
+
+    format_result = clang_format(rendered_text, filename=filepath)
+
+    with open(filepath, "w") as output_file:
+        output_file.write(format_result.contents)

third_party/blink/renderer/bindings/scripts/generate_bindings.py

@@ -40,6 +40,7 @@ def main():
 
     dispatch_table = {
         'example': bind_gen.run_example,
+        'interface': bind_gen.generate_interfaces,
     }
 
     for task in tasks:

third_party/blink/renderer/bindings/scripts/generate_bindings.pydeps

@@ -27,11 +27,15 @@
 ../../build/scripts/blinkbuild/__init__.py
 ../../build/scripts/blinkbuild/name_style_converter.py
 bind_gen/__init__.py
+bind_gen/blink_v8_bridge.py
 bind_gen/clang_format.py
 bind_gen/code_generation_context.py
 bind_gen/code_node.py
+bind_gen/codegen_utils.py
 bind_gen/example.py
+bind_gen/interface.py
 bind_gen/mako_renderer.py
+bind_gen/name_style.py
 generate_bindings.py
 web_idl/__init__.py
 web_idl/argument.py