Use jinja2 templating engine for Python code generators

Source/core/scripts/template_expander.py

Index: Source/core/scripts/template_expander.py
diff --git a/Source/core/core.gyp/scripts/supplemental_idl_files.py b/Source/core/scripts/template_expander.py
similarity index 63%
copy from Source/core/core.gyp/scripts/supplemental_idl_files.py
copy to Source/core/scripts/template_expander.py
index eaf0270ac9f6a46637b6196233f09793d855e4b8..945f521261ef96e9d297a76787f279682cff37b7 100644
--- a/Source/core/core.gyp/scripts/supplemental_idl_files.py
+++ b/Source/core/scripts/template_expander.py
@@ -1,5 +1,3 @@
-#!/usr/bin/python
-#
 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -28,18 +26,24 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-"""This file returns a list of all the IDL files that contain a partial interface."""
-
-import re
+import os.path
 import sys
 
-partial_interface_regex = re.compile(r'partial\s+interface\s+(\w+).+\]', re.M | re.S)
+def _setup():
+    autoinstallerpath = "../../../Tools/Scripts/webkitpy/common/system"

[abarth-chromium, 2013/05/06 18:27:32]

Woah, we shouldn't have a dependency across the world like this.

+    sys.path.insert(0, autoinstallerpath)
+    from autoinstall import AutoInstaller
+    installer = AutoInstaller() # This won't re-download if the file already exists
+    installer.install(url="https://pypi.python.org/packages/source/J/Jinja2/Jinja2-2.6.tar.gz#md5=1c49a8825c993bfdcf55bb36897d28a2", url_subpath="Jinja2-2.6/jinja2")

[abarth-chromium, 2013/05/06 18:27:32]

Can we just check jinja into third_party?  We don't want to autoinstall stuff
during compile.  That's what DEPS is for.

+    sys.path.insert(0, os.path.join(autoinstallerpath, "autoinstalled"))
 
-def DoMain(filenames):
-    partial_files = set()
-    for filename in filenames:
-        with open(filename) as f:
-            match = re.search(partial_interface_regex, f.read())
-            if match:
-                partial_files.add(filename)
-    return '\n'.join(partial_files)
+def applytemplate(pathtotemplate, params):
+    try:
+        import jinja2
+    except ImportError:
+        _setup()
+        import jinja2
+    dirname, basename = os.path.split(pathtotemplate)
+    env = jinja2.Environment(loader=jinja2.FileSystemLoader([dirname, "../scripts/templates"]))
+    template = env.get_template(basename)
+    return template.render(params)