css: Overhaul value parsing

Value parsing only sometimes emitted errors. Sometimes it didn't emit
errors but ignored the value, sometimes it took a default, sometimes it
converted it to something it deemed suitable.

While refactoring, I moved the whole GValue <=> char * conversion
routines to a separate file, to make navigating the core css provider
easier.

gtk/Makefile.am

@@ -387,6 +387,7 @@ gtk_private_h_sources =		\
 	gtkbuttonprivate.h	\
 	gtkcellareaboxcontextprivate.h	\
 	gtkcssproviderprivate.h	\
+	gtkcssstringfuncsprivate.h	\
 	gtkcustompaperunixdialog.h \
 	gtkdndcursors.h		\
 	gtkentryprivate.h	\
@@ -512,6 +513,7 @@ gtk_base_c_sources = 		\
 	gtkcomboboxtext.c	\
 	gtkcontainer.c		\
 	gtkcssprovider.c	\
+	gtkcssstringfuncs.c	\
 	gtkdialog.c		\
 	gtkdrawingarea.c	\
 	gtkeditable.c		\

gtk/gtkcssstringfuncsprivate.h

@@ -0,0 +1,43 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2010 Carlos Garnacho <carlosg@gnome.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GTK_CSS_STRINGFUNCS_PRIVATE_H__
+#define __GTK_CSS_STRINGFUNCS_PRIVATE_H__
+
+#include <gtk/gtksymboliccolor.h>
+
+G_BEGIN_DECLS
+
+gboolean                _gtk_css_value_from_string        (GValue        *value,
+                                                           GFile         *base,
+                                                           const char    *string,
+                                                           GError       **error);
+char *                  _gtk_css_value_to_string          (const GValue  *value);
+
+GtkSymbolicColor *      _gtk_css_parse_symbolic_color     (const char    *str,
+                                                           GError       **error);
+
+GFile *                 _gtk_css_parse_url                (GFile         *base,
+                                                           const char    *str,
+                                                           char         **end,
+                                                           GError       **error);
+
+G_END_DECLS
+
+#endif /* __GTK_CSS_STRINGFUNCS_PRIVATE_H__ */