CodeGen: Generate code for Union (1 of N)

Defines an almost empty class.


Bug: 839389
Change-Id: Ide0536992f1247d7e53aa8109083519d41db7892
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1990894
Commit-Queue: Hitoshi Yoshida <peria@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#730093}

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

@@ -34,6 +34,7 @@ from . import clang_format
 from .dictionary import generate_dictionaries
 from .interface import generate_interfaces
 from .path_manager import PathManager
+from .union import generate_unions
 
 
 def _setup_clang_format():

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

@@ -4,6 +4,8 @@
 
 import copy
 
+import web_idl
+
 from . import name_style
 from .codegen_format import NonRenderable
 from .path_manager import PathManager
@@ -169,7 +171,7 @@ class CodeGenContext(object):
     @property
     def idl_location(self):
         idl_def = self.member_like or self.idl_definition
-        if idl_def:
+        if idl_def and not isinstance(idl_def, web_idl.Union):
             location = idl_def.debug_info.location
             text = PathManager.relpath_to_project_root(location.filepath)
             if location.line_number is not None:

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

+# Copyright 2020 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.
+
+import os.path
+
+import web_idl
+
+from . import name_style
+from .code_node import ListNode
+from .code_node import TextNode
+from .code_node_cxx import CxxClassDefNode
+from .code_node_cxx import CxxNamespaceNode
+from .codegen_accumulator import CodeGenAccumulator
+from .codegen_context import CodeGenContext
+from .codegen_utils import collect_include_headers
+from .codegen_utils import component_export
+from .codegen_utils import enclose_with_header_guard
+from .codegen_utils import enclose_with_namespace
+from .codegen_utils import make_copyright_header
+from .codegen_utils import make_forward_declarations
+from .codegen_utils import make_header_include_directives
+from .codegen_utils import write_code_node_to_file
+from .mako_renderer import MakoRenderer
+from .path_manager import PathManager
+
+
+def make_union_class_def(cg_context):
+    assert isinstance(cg_context, CodeGenContext)
+
+    T = TextNode
+
+    union = cg_context.union
+    component = union.components[0]
+
+    class_def = CxxClassDefNode(
+        cg_context.class_name, export=component_export(component))
+    class_def.set_base_template_vars(cg_context.template_bindings())
+
+    class_def.top_section.extend([
+        T("DISALLOW_NEW();"),
+    ])
+
+    class_def.public_section.extend([
+        T("void Trace(Visitor*);"),
+    ])
+
+    return class_def
+
+
+def generate_union(union):
+    path_manager = PathManager(union)
+    class_name = union.identifier
+    cg_context = CodeGenContext(union=union, class_name=class_name)
+
+    filename = "union_example.h"
+    header_path = path_manager.api_path(filename=filename)
+
+    header_node = ListNode(tail="\n")
+    header_node.set_accumulator(CodeGenAccumulator())
+    header_node.set_renderer(MakoRenderer())
+    header_node.accumulator.add_include_headers(collect_include_headers(union))
+
+    header_blink_ns = CxxNamespaceNode(name_style.namespace("blink"))
+
+    class_def = make_union_class_def(cg_context)
+
+    header_node.extend([
+        make_copyright_header(),
+        TextNode(""),
+        enclose_with_header_guard(
+            ListNode([
+                make_header_include_directives(header_node.accumulator),
+                TextNode(""),
+                header_blink_ns,
+            ]), name_style.header_guard(header_path)),
+    ])
+    header_blink_ns.body.extend([
+        make_forward_declarations(header_node.accumulator),
+        TextNode(""),
+    ])
+
+    header_blink_ns.body.append(class_def)
+
+    # Write down to the files.
+    write_code_node_to_file(header_node, path_manager.gen_path_to(header_path))
+
+
+def generate_unions(web_idl_database):
+    union = list(web_idl_database.union_types)[0]
+    generate_union(union)

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

@@ -49,6 +49,7 @@ def main():
     dispatch_table = {
         'dictionary': bind_gen.generate_dictionaries,
         'interface': bind_gen.generate_interfaces,
+        'union': bind_gen.generate_unions,
     }
 
     for task in tasks:

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

@@ -43,6 +43,7 @@ bind_gen/interface.py
 bind_gen/mako_renderer.py
 bind_gen/name_style.py
 bind_gen/path_manager.py
+bind_gen/union.py
 generate_bindings.py
 web_idl/__init__.py
 web_idl/argument.py