GLES2: Use codegen for the entry point header.

This is a first step towards auto-generating more entry point files.

BUG=angleproject:1309

Change-Id: Ic75a627feb91c19b6bb398a6f9f1a37b603dea14
Reviewed-on: https://chromium-review.googlesource.com/483425
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/scripts/generate_entry_points.py b/scripts/generate_entry_points.py
new file mode 100644
index 0000000..ec73d75
--- /dev/null
+++ b/scripts/generate_entry_points.py
@@ -0,0 +1,80 @@
+#!/usr/bin/python
+#
+# Copyright 2017 The ANGLE Project Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+#
+# generate_entry_points.py:
+#   Generates the OpenGL bindings and entry point layers for ANGLE.
+
+import sys, os, pprint
+import xml.etree.ElementTree as etree
+from datetime import date
+
+def script_relative(path):
+    return os.path.join(os.path.dirname(sys.argv[0]), path)
+
+tree = etree.parse(script_relative('gl.xml'))
+root = tree.getroot()
+
+gles2_xpath = ".//feature[@name='GL_ES_VERSION_2_0']//command"
+gles2_commands = [cmd.attrib['name'] for cmd in root.findall(gles2_xpath)]
+
+template_entry_point_header = """// GENERATED FILE - DO NOT EDIT.
+// Generated by {script_name} using data from {data_source_name}.
+//
+// Copyright {year} The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// entry_points_gles_{major_version}_{minor_version}_autogen.h:
+//   Defines the GLES {major_version}.{minor_version} entry points.
+
+#ifndef LIBGLESV2_ENTRYPOINTSGLES{major_version}{minor_version}_AUTOGEN_H_
+#define LIBGLESV2_ENTRYPOINTSGLES{major_version}{minor_version}_AUTOGEN_H_
+
+#include <GLES2/gl{major_version}.h>
+#include <export.h>
+
+namespace gl
+{{
+{entry_points}
+}}  // namespace gl
+
+#endif  // LIBGLESV2_ENTRYPOINTSGLES{major_version}{minor_version}_AUTOGEN_H_
+"""
+
+template_entry_point_decl = """ANGLE_EXPORT {return_type}GL_APIENTRY {name}({params});"""
+
+commands = root.find(".//commands[@namespace='GL']")
+entry_point_decls_gles_2_0 = []
+
+def format_entry_point_decl(cmd_name, proto, params):
+    return template_entry_point_decl.format(
+        name = cmd_name[2:],
+        return_type = proto[:-len(cmd_name)],
+        params = ", ".join(params))
+
+for cmd_name in gles2_commands:
+    command_xpath = "command/proto[name='" + cmd_name + "']/.."
+    command = commands.find(command_xpath)
+    params = ["".join(param.itertext()) for param in command.findall("./param")]
+    proto = "".join(command.find("./proto").itertext())
+    entry_point_decls_gles_2_0 += [format_entry_point_decl(cmd_name, proto, params)]
+
+gles_2_0_header = template_entry_point_header.format(
+    script_name = os.path.basename(sys.argv[0]),
+    data_source_name = "gl.xml",
+    year = date.today().year,
+    major_version = 2,
+    minor_version = 0,
+    entry_points = "\n".join(entry_point_decls_gles_2_0))
+
+def path_to(folder, file):
+    return os.path.join(script_relative(".."), "src", folder, file)
+
+gles_2_0_header_path = path_to("libGLESv2", "entry_points_gles_2_0_autogen.h")
+
+with open(gles_2_0_header_path, "w") as out:
+    out.write(gles_2_0_header)
+    out.close()