Implement version upgrade from 2.4 to 2.5

The version upgrade currently only removes the setting start_layers_at_same_position.

Contributes to issue CURA-3479.

plugins/VersionUpgrade/VersionUpgrade24to25/VersionUpgrade24to25.py

@@ -0,0 +1,77 @@
+# Copyright (c) 2017 Ultimaker B.V.
+# Cura is released under the terms of the AGPLv3 or higher.
+
+import configparser #To parse the files we need to upgrade and write the new files.
+import io #To serialise configparser output to a string.
+
+from UM.VersionUpgrade import VersionUpgrade
+
+_removed_settings = { #Settings that were removed in 2.5.
+    "start_layers_at_same_position"
+}
+
+##  A collection of functions that convert the configuration of the user in Cura
+#   2.4 to a configuration for Cura 2.5.
+#
+#   All of these methods are essentially stateless.
+class VersionUpgrade24to25(VersionUpgrade):
+    ##  Gets the version number from a CFG file in Uranium's 2.4 format.
+    #
+    #   Since the format may change, this is implemented for the 2.4 format only
+    #   and needs to be included in the version upgrade system rather than
+    #   globally in Uranium.
+    #
+    #   \param serialised The serialised form of a CFG file.
+    #   \return The version number stored in the CFG file.
+    #   \raises ValueError The format of the version number in the file is
+    #   incorrect.
+    #   \raises KeyError The format of the file is incorrect.
+    def getCfgVersion(self, serialised):
+        parser = configparser.ConfigParser(interpolation = None)
+        parser.read_string(serialised)
+        return int(parser.get("general", "version")) #Explicitly give an exception when this fails. That means that the file format is not recognised.
+
+    ##  Upgrades the preferences file from version 2.4 to 2.5.
+    #
+    #   \param serialised The serialised form of a preferences file.
+    #   \param filename The name of the file to upgrade.
+    def upgradePreferences(self, serialised, filename):
+        parser = configparser.ConfigParser(interpolation = None)
+        parser.read_string(serialised)
+
+        #Remove settings from the visible_settings.
+        if parser.has_section("general") and "visible_settings" in parser["general"]:
+            visible_settings = parser["general"]["visible_settings"].split(";")
+            visible_settings = filter(lambda setting: setting not in _removed_settings, visible_settings)
+            parser["general"]["visible_settings"] = ";".join(visible_settings)
+
+        #Change the version number in the file.
+        if parser.has_section("general"): #It better have!
+            parser["general"]["version"] = "5"
+
+        #Re-serialise the file.
+        output = io.StringIO()
+        parser.write(output)
+        return [filename], [output.getvalue()]
+
+    ##  Upgrades an instance container from version 2.4 to 2.5.
+    #
+    #   \param serialised The serialised form of a quality profile.
+    #   \param filename The name of the file to upgrade.
+    def upgradeInstanceContainer(self, serialised, filename):
+        parser = configparser.ConfigParser(interpolation = None)
+        parser.read_string(serialised)
+
+        #Remove settings from the [values] section.
+        if parser.has_section("values"):
+            for removed_setting in (_removed_settings & parser["values"].keys()): #Both in keys that need to be removed and in keys present in the file.
+                del parser["values"][removed_setting]
+
+        #Change the version number in the file.
+        if parser.has_section("general"):
+            parser["general"]["version"] = "3"
+
+        #Re-serialise the file.
+        output = io.StringIO()
+        parser.write(output)
+        return [filename], [output.getvalue()]