GRIT: Enable variable expansion in filenames during HTML inlining.

grit/format/html_inline.py

Index: grit/format/html_inline.py
===================================================================
--- grit/format/html_inline.py	(revision 124)
+++ grit/format/html_inline.py	(working copy)
@@ -72,7 +72,8 @@
 
 
 def SrcInlineAsDataURL(
-    src_match, base_path, distribution, inlined_files, names_only=False):
+    src_match, base_path, distribution, inlined_files, names_only=False,
+    filename_expansion_function=None):
   """regex replace function.
 
   Takes a regex match for src="filename", attempts to read the file
@@ -93,6 +94,8 @@
     string
   """
   filename = src_match.group('filename')
+  if filename_expansion_function:
+    filename = filename_expansion_function(filename)
   quote = src_match.group('quote')
 
   if filename.find(':') != -1:
@@ -126,7 +129,7 @@
 
 def DoInline(
     input_filename, grd_node, allow_external_script=False, names_only=False,
-    rewrite_function=None):
+    rewrite_function=None, filename_expansion_function=None):
   """Helper function that inlines the resources in a specified file.
 
   Reads input_filename, finds all the src attributes and attempts to
@@ -139,10 +142,14 @@
     names_only: |nil| will be returned for the inlined contents (faster).
     rewrite_function: function(filepath, text, distribution) which will be
         called to rewrite html content before inlining images.
+    filename_expansion_function: function(filename) which will be called to
+        rewrite filenames before attempting to read them.
   Returns:
     a tuple of the inlined data as a string and the set of filenames
     of all the inlined files
   """
+  if filename_expansion_function:
+    input_filename = filename_expansion_function(input_filename)
   input_filepath = os.path.dirname(input_filename)
   distribution = GetDistribution()
 
@@ -153,7 +160,8 @@
                  inlined_files=inlined_files):
     """Helper function to provide SrcInlineAsDataURL with the base file path"""
     return SrcInlineAsDataURL(
-        src_match, filepath, distribution, inlined_files, names_only=names_only)
+        src_match, filepath, distribution, inlined_files, names_only=names_only,
+        filename_expansion_function=filename_expansion_function)
 
   def GetFilepath(src_match, base_path = input_filepath):
     filename = src_match.group('filename')
@@ -163,6 +171,8 @@
       return None
 
     filename = filename.replace('%DISTRIBUTION%', distribution)
+    if filename_expansion_function:
+      filename = filename_expansion_function(filename)
     return os.path.normpath(os.path.join(base_path, filename))
 
   def IsConditionSatisfied(src_match):
@@ -214,12 +224,16 @@
     inlined_files.add(filepath)
 
     if names_only:
-      inlined_files.update(GetResourceFilenames(filepath,
-                                                allow_external_script,
-                                                rewrite_function))
+      inlined_files.update(GetResourceFilenames(
+          filepath,
+          allow_external_script,
+          rewrite_function,
+          filename_expansion_function=filename_expansion_function))
       return ""
 
-    return pattern % InlineToString(filepath, grd_node, allow_external_script)
+    return pattern % InlineToString(
+        filepath, grd_node, allow_external_script,
+        filename_expansion_function=filename_expansion_function)
 
   def InlineIncludeFiles(src_match):
     """Helper function to directly inline generic external files (without
@@ -338,7 +352,7 @@
 
 
 def InlineToString(input_filename, grd_node, allow_external_script=False,
-                   rewrite_function=None):
+                   rewrite_function=None, filename_expansion_function=None):
   """Inlines the resources in a specified file and returns it as a string.
 
   Args:
@@ -348,10 +362,12 @@
     the inlined data as a string
   """
   try:
-    return DoInline(input_filename,
-                    grd_node,
-                    allow_external_script=allow_external_script,
-                    rewrite_function=rewrite_function).inlined_data
+    return DoInline(
+        input_filename,
+        grd_node,
+        allow_external_script=allow_external_script,
+        rewrite_function=rewrite_function,
+        filename_expansion_function=filename_expansion_function).inlined_data
   except IOError, e:
     raise Exception("Failed to open %s while trying to flatten %s. (%s)" %
                     (e.filename, input_filename, e.strerror))
@@ -378,14 +394,17 @@
 
 def GetResourceFilenames(filename,
                          allow_external_script=False,
-                         rewrite_function=None):
+                         rewrite_function=None,
+                         filename_expansion_function=None):
   """For a grd file, returns a set of all the files that would be inline."""
   try:
-    return DoInline(filename,
-                    None,
-                    names_only=True,
-                    allow_external_script=allow_external_script,
-                    rewrite_function=rewrite_function).inlined_files
+    return DoInline(
+        filename,
+        None,
+        names_only=True,
+        allow_external_script=allow_external_script,
+        rewrite_function=rewrite_function,
+        filename_expansion_function=filename_expansion_function).inlined_files
   except IOError, e:
     raise Exception("Failed to open %s while trying to flatten %s. (%s)" %
                     (e.filename, filename, e.strerror))