Add functions to restore previous script editors

Workbench will now note file paths of scripts that are open when
mantid is closed (saved in QSettings). It will restore these on
startup.

qt/applications/workbench/workbench/app/mainwindow.py

@@ -220,6 +220,8 @@ class MainWindow(QMainWindow):
         # uses default configuration as necessary
         self.readSettings(CONF)
 
+        self.editor.restore_session_tabs()
+
         self.setup_layout()
         self.create_actions()
         self.populate_menus()
@@ -422,10 +424,9 @@ class MainWindow(QMainWindow):
                 event.ignore()
                 return
 
+        self.writeSettings(CONF)  # write current window information to global settings object
         # Close editors
         if self.editor.app_closing():
-            self.writeSettings(CONF)  # write current window information to global settings object
-
             # Close all open plots
             # We don't want this at module scope here
             import matplotlib.pyplot as plt  # noqa

qt/applications/workbench/workbench/plugins/editor.py

@@ -97,6 +97,9 @@ class MultiFileEditor(PluginWidget):
         '''This is used by MainWindow to execute a file after opening it'''
         return self.editors.execute_current()
 
+    def restore_session_tabs(self):
+        self.editors.restore_session_tabs()
+
     # ----------- Plugin API --------------------
 
     def app_closing(self):
@@ -128,11 +131,14 @@ class MultiFileEditor(PluginWidget):
     def get_plugin_title(self):
         return "Editor"
 
-    def readSettings(self, _):
-        pass
+    def readSettings(self, settings):
+        try:
+            self.editors.prev_session_tabs = settings.get('Editor/SessionTabs')
+        except KeyError:
+            pass
 
-    def writeSettings(self, _):
-        pass
+    def writeSettings(self, settings):
+        settings.set('Editor/SessionTabs', self.editors.tab_filepaths)
 
     def register_plugin(self):
         self.main.add_dockwidget(self)

qt/python/mantidqt/widgets/codeeditor/multifileinterpreter.py

@@ -39,6 +39,7 @@ class MultiPythonFileInterpreter(QWidget):
 
         # attributes
         self.default_content = default_content
+        self.prev_session_tabs = None
         self.whitespace_visible = False
 
         # widget setup
@@ -55,6 +56,15 @@ class MultiPythonFileInterpreter(QWidget):
     def editor_count(self):
         return self._tabs.count()
 
+    @property
+    def tab_filepaths(self):
+        file_paths = []
+        for idx in range(self.editor_count):
+            file_path = self._tabs.widget(idx).filename
+            if file_path:
+                file_paths.append(file_path)
+        return file_paths
+
     def append_new_editor(self, content=None, filename=None):
         if content is None:
             content = self.default_content
@@ -171,22 +181,31 @@ class MultiPythonFileInterpreter(QWidget):
             content = code_file.read()
         self.append_new_editor(content=content, filename=filepath)
 
+    def open_files_in_new_tabs(self, filepaths):
+        for filepath in filepaths:
+            self.open_file_in_new_tab(filepath)
+
     def plus_button_clicked(self, _):
         """Add a new tab when the plus button is clicked"""
         self.append_new_editor()
 
+    def restore_session_tabs(self):
+        if self.prev_session_tabs is not None:
+            self.open_files_in_new_tabs(self.prev_session_tabs)
+            self.close_tab(0)  # close default empty script
+
     def save_current_file(self):
         """Save the current file"""
         self.current_editor().save()
 
-    def toggle_comment_current(self):
-        self.current_editor().toggle_comment()
+    def spaces_to_tabs_current(self):
+        self.current_editor().replace_spaces_with_tabs()
 
     def tabs_to_spaces_current(self):
         self.current_editor().replace_tabs_with_spaces()
 
-    def spaces_to_tabs_current(self):
-        self.current_editor().replace_spaces_with_tabs()
+    def toggle_comment_current(self):
+        self.current_editor().toggle_comment()
 
     def toggle_whitespace_visible_all(self):
         if self.whitespace_visible:

qt/python/mantidqt/widgets/codeeditor/test/test_multifileinterpreter.py

@@ -10,6 +10,7 @@
 from __future__ import (absolute_import, unicode_literals)
 
 # system imports
+import os
 import unittest
 
 # third-party library imports
@@ -31,6 +32,20 @@ class MultiPythonFileInterpreterTest(GuiTest):
         widget.append_new_editor()
         self.assertEqual(2, widget.editor_count)
 
+    def test_tab_session_restore(self):
+        widget = MultiPythonFileInterpreter()
+        widget.prev_session_tabs = [
+            os.path.join(os.path.dirname(__file__), u'__init__.py'),
+            __file__]
+        widget.restore_session_tabs()
+        self.assertEqual(2, widget.editor_count)
+
+    def test_tab_session_restore_nothing_to_restore(self):
+        widget = MultiPythonFileInterpreter()
+        widget.prev_session_tabs = None
+        widget.restore_session_tabs()
+        self.assertEqual(1, widget.editor_count)  # default empty tab should be open
+
 
 if __name__ == '__main__':
     unittest.main()