opengeode.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# pylint: disable=C0302
"""
    OpenGEODE - A tiny, free SDL Editor for TASTE

    SDL is the Specification and Description Language (Z100 standard from ITU)

    Copyright (c) 2012-2013 European Space Agency

    Designed and implemented by Maxime Perrotin

    Contact: maxime.perrotin@esa.int
"""

import signal
import sys
import os
import argparse
import logging
import traceback
import re
import code
import pprint
from functools import partial
from itertools import chain

# Added to please py2exe - NOQA makes flake8 ignore the following lines:
# pylint: disable=W0611
import enum  # NOQA
import string  # NOQA
import fnmatch  # NOQA
import operator  # NOQA
import subprocess  # NOQA
import distutils  # NOQA
import tempfile  # NOQA
import uuid  # NOQA
import importlib  # NOQA
import antlr3  # NOQA
import antlr3.tree  # NOQA
import importlib  # NOQA
import PySide  # NOQA
import PySide.QtCore  # NOQA
import PySide.QtGui  # NOQA
import PySide.QtUiTools  # NOQA
import undoCommands  # NOQA
import sdl92Lexer  # NOQA
import sdl92Parser  # NOQA
import genericSymbols  # NOQA
import sdlSymbols
import PySide.QtXml  # NOQA
import singledispatch  # NOQA
import Asn1scc  # NOQA
import Connectors  # NOQA
import TextInteraction  # NOQA
try:
    import stringtemplate3  # NOQA
except ImportError:
    pass

#from PySide import phonon

from PySide import QtGui, QtCore
from PySide.QtCore import Qt, QSize, QFile, QIODevice, QRectF, QTimer, QPoint

from PySide.QtUiTools import QUiLoader
from PySide import QtSvg

from genericSymbols import(Symbol, Comment, Cornergrabber, Connection)
from sdlSymbols import(Input, Output, Decision, DecisionAnswer, Task,
        ProcedureCall, TextSymbol, State, Start, Join, Label, Procedure,
        ProcedureStart, ProcedureStop, StateStart, Connect, Process)
from TextInteraction import EditableText

# Icons and png files generated from the resource file:
import icons  # NOQA

LOG = logging.getLogger(__name__)

import AdaGenerator
import ogParser
import ogAST
import Renderer
import Clipboard
import Statechart
import Lander
import Helper
import Pr


# Try importing graphviz for the SDL to Statechart converter
# This is optional, as graphviz installation can not be easily
# automated on some platforms by opengeode installation scripts.
try:
    import pygraphviz  # NOQA
    graphviz = True
except ImportError:
    graphviz = False

try:
    import LlvmGenerator
except ImportError:
    LlvmGenerator = None

try:
    import StgBackend
except ImportError:
    StgBackend = False


__all__ = ['opengeode', 'SDL_Scene', 'SDL_View', 'parse']
__version__ = '1.0RC2'

if hasattr(sys, 'frozen'):
    # Detect if we are running on Windows (py2exe-generated)
    try:
        CUR_DIR = os.path.dirname(unicode
                (sys.executable, sys.getfilesystemencoding()))
    except TypeError:
        CUR_DIR = os.path.dirname(os.path.realpath(__file__))
    else:
        # Redirect stderr to a log file - to avoid py2exe error message
        # that pops up at application closure when app logs errors
        sys.stdout = open('opengeode_stdout.log', 'w')
        sys.stderr = open('opengeode_stderr.log', 'w')
else:
    CUR_DIR = os.path.dirname(os.path.realpath(__file__))


# Global handling all top-level elements
# It seems that if we don't keep a global list of these elements
# (START, STATE, and Text symbols)
# they sometimes get destroyed and disappear from the scene.
# As if a GC was deleting these object *even if they belong to the scene*
# (but have no parentItem). Most likely a Qt/Pyside bug.
G_SYMBOLS = set()


# Other Qt bug:
# QGraphicsTextItem don't stand that their parent item (usually an
# SDL symbol) is removed from the scene (scene.removeItem()). It
# provokes segfault when application exits.
# Workaround is to use hide()/show() to make items disappear
# from the scene (when deleted). Seems OK (MP 2013-03-26)

# Lookup table used to configure the context-dependent toolbars
ACTIONS = {
    'block': [Process, Comment, TextSymbol],
    'process': [Start, State, Input, Connect, Task, Decision, DecisionAnswer,
                Output, ProcedureCall, TextSymbol, Comment, Label,
                Join, Procedure],
    'procedure': [ProcedureStart, Task, Decision,
                  DecisionAnswer, Output, ProcedureCall, TextSymbol,
                  Comment, Label, Join, ProcedureStop],
    'statechart': [],
    'state': [StateStart, State, Input, Connect, Task, Decision,
              DecisionAnswer, Output, ProcedureCall, TextSymbol, Comment,
              Label, Join, ProcedureStop, Procedure],
    'clipboard': [Start, State, Input, Connect, Task, Decision, DecisionAnswer,
                  Output, ProcedureCall, TextSymbol, Comment, Label,
                  Join, Procedure, Process, StateStart, ProcedureStop],
    'lander': [],
    'asn1': []
}


class Vi_bar(QtGui.QLineEdit, object):
    ''' Line editor for the Vi-like command mode '''
    def __init__(self):
        ''' Create the bar - no need for parent '''
        super(Vi_bar, self).__init__()

    def keyPressEvent(self, key_event):
        ''' Handle key press - in particular Escape '''
        super(Vi_bar, self).keyPressEvent(key_event)
        if key_event.key() == Qt.Key_Escape:
            self.clearFocus()


class File_toolbar(QtGui.QToolBar, object):
    ''' Toolbar with file open, save, etc '''
    def __init__(self, parent):
        ''' Create the toolbar using standard icons '''
        super(File_toolbar, self).__init__(parent)
        self.setMovable(False)
        self.setFloatable(False)
        self.new_button = self.addAction(self.style().standardIcon(
            QtGui.QStyle.SP_FileIcon), 'New model')
        self.open_button = self.addAction(self.style().standardIcon(
            QtGui.QStyle.SP_DialogOpenButton), 'Open model')
        self.save_button = self.addAction(self.style().standardIcon(
            QtGui.QStyle.SP_DialogSaveButton), 'Save model')
        self.check_button = self.addAction(self.style().standardIcon(
            QtGui.QStyle.SP_DialogApplyButton), 'Check model')
        self.addSeparator()
        # Up arrow to come back from a subscene (e.g. procedure)
        self.up_button = self.addAction(self.style().standardIcon(
            QtGui.QStyle.SP_ArrowUp), 'Go one level above')
        self.up_button.setEnabled(False)


class Sdl_toolbar(QtGui.QToolBar, object):
    '''
        Toolbar with SDL symbols
        The list of symbols is passed as paramters at creation time ; the class
        looks for icons for the name of the symbols and .png extension.
        The buttons activation is context dependent. Configuration is done
        directly at symbol leval (using the "allowed_followers" property)
    '''
    def __init__(self, parent):
        ''' Create the toolbar, get icons and link actions '''
        super(Sdl_toolbar, self).__init__(parent)
        self.setMovable(False)
        self.setFloatable(False)
        self.setIconSize(QSize(35, 35))
        self.actions = {}

    def set_actions(self, bar_items):
        ''' Set the acons and actions on the toolbar '''
        self.actions = {}
        self.clear()
        for item in bar_items:
            item_name = item.__name__
            self.actions[item_name] = self.addAction(
                           QtGui.QIcon(':icons/{icon}'.format(
                           icon=item_name.lower() + '.png')), item_name)
        self.update_menu()

    def enable_action(self, action):
        ''' Used as a slot to allow a scene to enable a menu action,
            e.g. if the Start symbol is deleted, the Start button
            shall be activated '''
        self.actions[action].setEnabled(True)

    def disable_action(self, action):
        ''' See description in enable_action '''
        self.actions[action].setEnabled(False)

    def update_menu(self, scene=None):
        ''' Context-dependent enabling/disabling of menu buttons '''
        try:
            selection = list(scene.selected_symbols())
        except AttributeError:
            selection = []
        if not selection:
            # Second chance, check if an item has focus (editable text)
            try:
                selection.append(scene.focusItem().parentItem())
            except AttributeError:
                pass
        if len(selection) > 1:
            # When several items are selected, disable all menu entries
            for _, action in self.actions.viewitems():
                action.setEnabled(False)
        elif not selection:
            # When nothing is selected:
            # activate everything, and when user selects an icon,
            # keep the action on hold until he clicks on the scene
            for action in self.actions.viewkeys():
                self.actions[action].setEnabled(True)

            # Check for singletons (e.g. START symbol)
            try:
                for item in scene.visible_symb:
                    try:
                        if item.is_singleton:
                            self.actions[
                                    item.__class__.__name__].setEnabled(False)
                    except (AttributeError, KeyError) as error:
                        LOG.debug(str(error))
            except AttributeError:
                pass
        else:
            # Only one selected item
            selection, = selection
            for action in self.actions.viewkeys():
                self.actions[action].setEnabled(False)
            for action in getattr(selection, 'allowed_followers', []):
                try:
                    self.actions[action].setEnabled(True)
                except KeyError:
                    LOG.debug('No menu item for symbol "' + action + '"')


class SDL_Scene(QtGui.QGraphicsScene, object):
    ''' Main graphic scene (canvas) where the user can place SDL symbols '''
    # Signal to be emitted when the scene is left (e.g. UP button)
    scene_left = QtCore.Signal()

    def __init__(self, context='process'):
        '''
            Create an SDL Scene for a given context:
            process, procedure or composite state
        '''
        super(SDL_Scene, self).__init__()
        # Reference to the parent scene
        self.parent_scene = None
        self.mode = 'idle'
        self.context = context
        self.allowed_symbols = ACTIONS[context]
        # Configure the action menu
        all_possible_actions = set()
        for action in ACTIONS.viewvalues():
            all_possible_actions |= set(action)
        self.actions = {action.__name__: partial(self.add_symbol, action)
                for action in all_possible_actions}

        # Create a stack for handling undo/redo commands
        # (defined in undoCommands.py)
        self.undo_stack = QtGui.QUndoStack(self)
        # buttonSelected is used to set which symbol to draw
        # on next scene click (see mousePressEvent)
        self.button_selected = None
        self.setBackgroundBrush(QtGui.QBrush(
                                           QtGui.QImage(':icons/texture.png')))
        self.messages_window = None
        self.click_coordinates = None
        self.orig_pos = None
        self.process_name = 'opengeode'
        # Scene name is used to update the tab window name when scene changes
        self.name = ''
        # search_item/search_pattern are used for search/replace function
        self.search_item = None
        self.search_pattern = None
        # Selection rectangle when user clicks on the scene and moves mouse
        self.select_rect = None
        # Keep a list of composite states: {'stateName': SDL_Scene}
        self._composite_states = {}
        # Keep a track of highlighted symbols: { symbol: brush }
        self.highlighted = {}

    @property
    def visible_symb(self):
        ''' Return the visible items of a scene '''
        return (it for it in self.items() if it.isVisible() and
                isinstance(it, Symbol))

    @property
    def editable_texts(self):
        ''' Return all EditableText areas of a scene '''
        return (it for it in self.items() if it.isVisible() and
                isinstance(it, EditableText))

    @property
    def floating_symb(self):
        ''' Return the top level floating items of a scene '''
        return (it for it in self.visible_symb if not it.hasParent)

    @property
    def processes(self):
        ''' Return visible processes components of the scene '''
        return (it for it in self.visible_symb if isinstance(it, Process) and
                not isinstance(it, Procedure))

    @property
    def procedures(self):
        ''' Return visible procedures components of the scene '''
        return (it for it in self.visible_symb if isinstance(it, Procedure))

    @property
    def states(self):
        ''' Return visible state components of the scene '''
        return (it for it in self.visible_symb if isinstance(it, State))

    @property
    def texts(self):
        ''' Return visible text areas components of the scene '''
        return (it for it in self.visible_symb if isinstance(it, TextSymbol))

    @property
    def procs(self):
        ''' Return visible procedure declaration components of the scene '''
        return (it for it in self.visible_symb if isinstance(it, Procedure))

    @property
    def start(self):
        ''' Return visible start components of the scene '''
        return (it for it in self.visible_symb if isinstance(it, Start))

    @property
    def floating_labels(self):
        ''' Return visible floating label components of the scene '''
        return (it for it in self.floating_symb if isinstance(it, Label))

    @property
    def returns(self):
        ''' Return visible return components of the scene '''
        return (it for it in self.visible_symb if isinstance(it,
                                                              ProcedureStop))

    @property
    def composite_states(self):
        ''' Return states that contain a composite part '''
        # Update the list first
        for each in self.states:
            if each.is_composite() and \
                  each.nested_scene not in self._composite_states.viewvalues():
                self._composite_states[unicode(each).split()[0].lower()] = \
                                                            each.nested_scene
        return self._composite_states

    @composite_states.setter
    def composite_states(self, value):
        ''' Attribute setter '''
        self._composite_states = value

    @property
    def all_nested_scenes(self):
        ''' Return all nested scenes, recursively '''
        for each in self.visible_symb:
            if each.nested_scene and isinstance(each.nested_scene, SDL_Scene):
                yield each.nested_scene
                for sub in each.nested_scene.all_nested_scenes:
                    yield sub

    def quit_scene(self):
        ''' Called in case of scene switch (e.g. UP button) '''
        pass

    def render_everything(self, ast):
        ''' Render a process and its children scenes, recursively '''
        already_created = []

        def recursive_render(content, dest_scene):
            ''' Process the rendering in scenes and nested scenes '''
            if isinstance(content, ogAST.Process):
                # XXX - should be set when entering the process
                self.process_name = ast.processName

            try:
                # Render top-level items and their children:
                for each in Renderer.render(content, dest_scene):
                    G_SYMBOLS.add(each)
                # Refreshing the scene may result in resizing some symbols
                dest_scene.refresh()
                for each in dest_scene.floating_symb:
                    # Once everything is rendered, adjust position of each
                    # symbol to the value from the AST (positions may be
                    # slightly altered by the reshaping functions)
                    def fix_pos_from_ast(symbol):
                        try:
                            if symbol.ast.pos_x and symbol.ast.pos_y:
                                relpos = symbol.mapFromScene(symbol.ast.pos_x,
                                                           symbol.ast.pos_y)
                                symbol.pos_x += relpos.x()
                                symbol.pos_y += relpos.y()
                                symbol.update_connections()
                                # Update_position is called here because it
                                # is not possible to be sure that the
                                # positionning stored in the file will be
                                # rendered correctly on the host plaform.
                                # Font rendering may cause slight differences
                                # between Linux and Windows for example.
                                symbol.update_position()
                            else:
                                # No CIF coordinates: (1) fix COMMENT position
                                # and (2) if floating, call CAM
                                if isinstance(symbol, genericSymbols.Comment):
                                    symbol.pos_x = \
                                      symbol.parent.boundingRect().width() + 15
                                    symbol.pos_y = 0
                                if not symbol.hasParent:
                                    symbol.cam(symbol.position,
                                               symbol.position)
                        except AttributeError:
                            # no AST, ignore (e.g. Connections, Cornergrabbers)
                            pass
                        else:
                            # Recursively fix pos of sub branches and followers
                            for branch in (elm for elm in symbol.childSymbols()
                                       if isinstance(elm,
                                             genericSymbols.HorizontalSymbol)):
                                fix_pos_from_ast(branch)
                            fix_pos_from_ast(symbol.next_aligned_symbol())
                            fix_pos_from_ast(symbol.comment)
                    fix_pos_from_ast(each)
            except TypeError:
                LOG.error(traceback.format_exc())

            # Render nested scenes, recursively:
            for each in (item for item in dest_scene.visible_symb
                         if item.nested_scene):
                if isinstance(each.nested_scene, ogAST.CompositeState) \
                        and (not each.nested_scene.statename
                             or each.nested_scene in already_created):
                    # Ignore nested state scenes that already exist
                    continue
                subscene = \
                        self.create_subscene(each.__class__.__name__.lower())
                already_created.append(each.nested_scene)
                subscene.name = unicode(each)
                LOG.debug('Created scene: {}'.format(subscene.name))
                recursive_render(each.nested_scene.content, subscene)
                each.nested_scene = subscene

            # Make sure all composite states are initially up to date
            # (Needed for the symbol shape to have dashed lines)
            for each in dest_scene.states:
                if unicode(each).lower() in \
                        dest_scene.composite_states.viewkeys():
                    each.nested_scene = dest_scene.composite_states[
                                                         unicode(each).lower()]

        recursive_render(ast, self)

    def refresh(self):
        ''' Refresh the symbols and connections in the scene '''
        for symbol in self.visible_symb:
            symbol.updateConnectionPointPosition()
            symbol.updateConnectionPoints()
        for symbol in self.editable_texts:
            # EditableText refreshing - design explanation:
            # The first one is tricky: at symbol initialization,
            # the bounding rect of the text is computed from the raw
            # text value, without any formatting. However, it can
            # happen that text (especially when a model is loaded)
            # contains highlighted data (bold), which has the effect
            # of making the width of the text in fact wider than
            # the bounding rect. The set_text_alignment function,
            # that is applying the aligment of the text within its
            # bounding rect, can work only if the text width is fixed.
            # It has to set it according to the bounding rect, which,
            # therefore can be too small, and this has the effect of
            # pushing the exceeding character to the next line.
            # The only way to avoid this is to call setTextWidth
            # with the value -1 before the aligment is computed.
            # This has the effect of re-computing the bounding rect
            # and fixing the width issue.
            symbol.setTextWidth(-1)
            symbol.set_textbox_position()
            symbol.try_resize()
            symbol.set_text_alignment()
        for symbol in self.visible_symb:
            symbol.update_connections()

    def set_cursor(self, follower):
        ''' Set the cursor shape depending on the selected menu item '''
        for item in self.items():
            try:
                if follower.__name__ not in item.allowed_followers:
                    item.setCursor(Qt.ForbiddenCursor)
                else:
                    item.setCursor(Qt.PointingHandCursor)
            except AttributeError:
                # if there are items not having allowed_followers
                pass

    def reset_cursor(self):
        ''' Reset the default cursor of an item '''
        for item in self.items():
            try:
                item.setCursor(item.default_cursor)
            except AttributeError:
                pass

    def translate_to_origin(self):
        '''
            Translate all items to coordinate system starting at (0,0),
            in order to avoid negative coordinates
        '''
        try:
            min_x = min(item.x() for item in self.floating_symb)
            min_y = min(item.y() for item in self.floating_symb)
        except ValueError:
            # No item in the scene
            return 0, 0
        delta_x = -min_x if min_x < 0 else 0
        delta_y = -min_y if min_y < 0 else 0
        for item in self.floating_symb:
            item.pos_x += delta_x
            item.pos_y += delta_y
        return delta_x, delta_y

    def selected_symbols(self):
        ''' Generate the list of selected symbols (excluding grabbers) '''
        for selection in self.selectedItems():
            if isinstance(selection, Symbol):
                yield selection
            elif isinstance(selection, Cornergrabber):
                yield selection.parent

    def set_selection(self, toolbar):
        ''' When the selection has changed, update menu, etc '''
        toolbar.update_menu(self)
        for item in self.selected_symbols():
            item.grabber.display()

    def raise_syntax_errors(self, errors=None):
        ''' Display an syntax error pop-up message '''
        if not errors:
            return
        for view in self.views():
            errs = []
            for error in errors:
                split = error.split()
                if split[0] == 'line' and len(split) > 1:
                    line_col = split[1].split(':')
                    if len(line_col) == 2:
                        # Get line number and column..to locate error
                        # line_nb, col = line_col
                        errs.append(' '.join(split[2:]))
                    else:
                        errs.append(error)
                else:
                    errs.append(error)
            self.clear_focus()
            msg_box = QtGui.QMessageBox(view)
            msg_box.setIcon(QtGui.QMessageBox.Warning)
            msg_box.setWindowTitle('OpenGEODE - Syntax Error')
            msg_box.setInformativeText('\n'.join(errs))
            msg_box.setText("Syntax error!")
            msg_box.setStandardButtons(QtGui.QMessageBox.Discard)
            msg_box.setDefaultButton(QtGui.QMessageBox.Discard)
            msg_box.exec_()

    def check_syntax(self, symbol):
        ''' Create PR representation for a symbol and check its syntax '''
        pr_text = '\n'.join(Pr.generate(symbol, recursive=False))
        errors = symbol.check_syntax(pr_text)
        self.raise_syntax_errors(errors)

    def update_completion_list(self, symbol):
        ''' When text has changed on a symbol, update the data dictionnary '''
        pr_text = '\n'.join(Pr.generate(symbol,
                                        recursive=False,
                                        nextstate=False, cpy=True))
        symbol.update_completion_list(pr_text=pr_text)

    def highlight(self, item):
        ''' Highlight a symbol '''
        if item in self.highlighted:
            return
        bound = item.boundingRect()
        center = bound.center().x()
        gradient = QtGui.QLinearGradient(center, 0, center, bound.height())
        gradient.setColorAt(0, Qt.cyan)
        gradient.setColorAt(1, Qt.white)
        self.highlighted[item] = item.brush()
        item.setBrush(QtGui.QBrush(gradient))

    def clear_highlight(self, item=None, reset=True):
        ''' Remove the highlighting of one item or all items on the scene '''
        if item in self.highlighted:
            self.setBrush(self.highlighted.pop(item))
        if reset:
            for item, brush in self.highlighted.viewitems():
                item.setBrush(brush)
            self.highlighted = {}

    def find_text(self, pattern):
        ''' Return all symbols with matching text '''
        for item in (symbol for symbol in self.items()
                     if isinstance(symbol, EditableText)
                     and symbol.isVisible()):
            if re.search(pattern, unicode(item), flags=re.IGNORECASE):
                yield item.parentItem()

    def search(self, pattern, replace_with=None):
        ''' Search and replace function ; get next search result with key n '''
        self.clearSelection()
        self.clear_focus()
        if pattern.endswith('\\'):
            # Avoid buggy pattern ending with a single backslash
            pattern += '\\'
        self.search_item = self.find_text(pattern)
        self.search_pattern = pattern
        if replace_with:
            with undoCommands.UndoMacro(self.undo_stack, 'Search and Replace'):
                for item in self.search_item:
                    new_string = re.sub(pattern,
                                        replace_with,
                                        unicode(item.text),
                                        flags=re.IGNORECASE)
                    undo_cmd = undoCommands.ReplaceText(
                                     item.text, unicode(item.text), new_string)
                    self.undo_stack.push(undo_cmd)
                    item.select()
            self.refresh()
        else:
            try:
                item = self.search_item.next()
                item.select()
                item.ensureVisible()
            except StopIteration:
                LOG.info('Pattern not found')

    def delete_selected_symbols(self):
        '''
            Remove selected symbols from the scene, with proper re-connections
        '''
        self.undo_stack.beginMacro('Delete items')
        for item in self.selected_symbols():
            if not item.scene():
                # Ignore if item has already been deleted
                # (in case of multiple selection)
                continue
            undo_cmd = undoCommands.DeleteSymbol(item)
            self.undo_stack.push(undo_cmd)
            try:
                item.branchEntryPoint.parent.updateConnectionPointPosition()
                item.branchEntryPoint.parent.updateConnectionPoints()
            except AttributeError:
                pass
        self.undo_stack.endMacro()

    def copy_selected_symbols(self):
        '''
            Create a copy of selected symbols to a buffer (in AST form)
            Called when user presses Ctrl-C
        '''
        self.click_coordinates = None
        try:
            Clipboard.copy(self.selected_symbols())
        except TypeError as error_msg:
            try:
                self.messages_window.addItem(unicode(error_msg))
            except AttributeError:
                LOG.error(unicode(error_msg))
            raise

    def cut_selected_symbols(self):
        '''
            Create a copy of selected symbols, then delete them
        '''
        try:
            self.copy_selected_symbols()
        except TypeError:
            LOG.error('Copy error - Cannot cut')
        else:
            self.delete_selected_symbols()

    def paste_symbols(self):
        '''
            Paste previously copied symbols at selection point
        '''
        parent = list(self.selected_symbols())
        if len(parent) > 1:
            self.messages_window.addItem(
                    'Cannot paste when several items are selected')
        else:
            parent_item, = parent or [None]
            try:
                new_items = Clipboard.paste(parent_item, self)
            except TypeError as error_msg:
                LOG.error(str(error_msg))
                try:
                    self.messages_window.addItem(str(error_msg))
                except AttributeError:
                    pass
            else:
                self.undo_stack.beginMacro('Paste')
                for item in new_items:
                    # Allow pasting inputs when input is selected
                    # Same for decision answers and connections
                    if(isinstance(parent_item, genericSymbols.HorizontalSymbol)
                            and type(parent_item) == type(item)):
                        parent_item = parent_item.parentItem()

                    undo_cmd = undoCommands.InsertSymbol(item, parent_item,
                            pos=None if parent_item
                                     else self.click_coordinates or item.pos())

                    self.undo_stack.push(undo_cmd)
                    if parent_item:
                        parent_item = item
                    else:
                        G_SYMBOLS.add(item)
                    item.cam(item.pos(), item.pos())
                self.undo_stack.endMacro()
                self.refresh()

    def sdl_to_statechart(self):
        ''' Create a graphviz representation of the SDL model '''
        pr_raw = Pr.parse_scene(self)
        pr_data = unicode('\n'.join(pr_raw))
        ast, _, _ = ogParser.parse_pr(string=pr_data)
        try:
            process_ast, = ast.processes
        except ValueError:
            LOG.error('No statechart to render')
            return None
        # Flatten nested states
        Helper.flatten(process_ast)
        return Statechart.create_dot_graph(process_ast)

    def export_branch_to_picture(self, symbol, filename, doc_format):
        ''' Save a symbol and its followers to a file '''
        temp_scene = SDL_Scene(context=self.context)
        temp_scene.messages_window = self.messages_window
        self.clearSelection()
        symbol.select()
        try:
            self.copy_selected_symbols()
            temp_scene.paste_symbols()
            temp_scene.export_img(filename, doc_format)
        except AttributeError:
            pass

    def export_img(self, filename=None, doc_format='png', split=False):
        ''' Save the scene as a PNG/SVG or PDF document
            If specified, split the diagram in multiple files, one
            per top-level floating item
        '''
        if not filename:
            return

        if split:
            # Save in multiple files
            index = 0
            for item in self.floating_symb:
                name = '{}-{}'.format(filename, str(index))
                LOG.info('Saving {ext} file: {name}.{ext}'
                         .format(ext=doc_format, name=name))
                self.export_branch_to_picture(item, name, doc_format)
                index += 1

        if filename.split('.')[-1] != doc_format:
            filename += '.' + doc_format

        self.clearSelection()
        self.clear_focus()
        # Copy in a different scene to get the smallest rectangle
        other_scene = SDL_Scene(context=self.context)
        other_scene.messages_window = self.messages_window
        other_scene.setBackgroundBrush(QtGui.QBrush())
        for each in self.floating_symb:
            each.select()
            try:
                self.copy_selected_symbols()
            except AttributeError as err:
                LOG.debug(str(traceback.format_exc()))
                LOG.error(str(err))
            other_scene.paste_symbols()
            each.select(False)
        rect = other_scene.sceneRect()

        # enlarge the rect to fit extra pixels due to antialiasing
        rect.adjust(-5, -5, 5, 5)
        if doc_format == 'png':
            device = QtGui.QImage(rect.size().toSize(),
                                  QtGui.QImage.Format_ARGB32)
            device.fill(Qt.transparent)
        elif doc_format == 'svg':
            device = QtSvg.QSvgGenerator()
            device.setFileName(filename)
            device.setTitle('OpenGEODE SDL Diagram')
            device.setSize(rect.size().toSize())
        elif doc_format == 'pdf':
            device = QtGui.QPrinter()
            device.setOutputFormat(QtGui.QPrinter.PdfFormat)
            device.setPaperSize(
                    rect.size().toSize(), QtGui.QPrinter.Point)
            device.setFullPage(True)
            device.setOutputFileName(filename)
        else:
            LOG.error('Output format not supported: ' + doc_format)
        painter = QtGui.QPainter(device)
        other_scene.render(painter, source=rect)
        try:
            device.save(filename)
        except AttributeError:
            # Due to inconsistencies in Qt API - only QtGui.QImage has the save
            pass
        if painter.isActive():
            painter.end()

    def clear_focus(self):
        ''' Clear focus from any item on the scene '''
        try:
            self.focusItem().clearFocus()
        except AttributeError:
            # if no focus item
            pass

    def symbol_near(self, pos, dist=5, selectable_only=True):
        ''' If any, returns symbol around pos '''
        items = self.items(
                QRectF(pos.x() - dist, pos.y() - dist, 2 * dist, 2 * dist))
        for item in items:
            if((selectable_only and item.flags() &
                    QtGui.QGraphicsItem.ItemIsSelectable)
                    or not selectable_only):
                return item.parent if isinstance(item, Cornergrabber) else item

    def can_insert(self, pos, item_type):
        ''' Check if we can add an item type at a given position '''
        parent_item = self.symbol_near(pos)
        if not parent_item:
            # No symbol at the given position
            if item_type.needs_parent:
                raise TypeError(str(item_type.__name__) + ' needs a parent')
            else:
                return None
        else:
            # Check if item as pos accepts item type as follower
            if item_type.__name__ in parent_item.allowed_followers:
                return parent_item
            else:
                raise TypeError(parent_item.__class__.__name__ +
                                ' symbol cannot be followed by ' +
                                item_type.__name__)

    # pylint: disable=C0103
    def mousePressEvent(self, event):
        '''
            Handle mouse click on the scene:
            If a symbol was selected in the menu, check if it can be inserted
            Otherwise store the coordinates, in which case if the user does
            a paste action with floating items, they will be placed there.
        '''
        self.reset_cursor()
        # First propagate event to symbols for specific treatment
        super(SDL_Scene, self).mousePressEvent(event)
        # Store mouse coordinates as possible paste position
        self.click_coordinates = event.scenePos()
        # Enter state machine
        if self.mode == 'idle' and event.button() == Qt.LeftButton:
            # Idle mode: click triggers selection square
            nearby_connection = self.symbol_near(event.scenePos(),
                                                 selectable_only=False)
            connection_selected = False
            if isinstance(nearby_connection, Connection):
                # Click near a connection - forward the event to it
                # (some connections like statechart Edges can react)
                nearby_connection.mousePressEvent(event)
                connection_selected = True
            if not self.symbol_near(event.scenePos(), dist=1):
                self.mode = 'select_items'
                self.orig_pos = event.scenePos()
                self.select_rect = self.addRect(
                        QRectF(self.orig_pos, self.orig_pos))
                if self.context == 'statechart' and not connection_selected:
                    # Specific treatment for statecharts - should subclass
                    for item in self.items():
                        # Remove all Edges control points from the scene
                        try:
                            item.bezier_set_visible(False)
                        except AttributeError:
                            pass

        elif self.mode == 'wait_placement':
            try:
                parent = \
                        self.can_insert(event.scenePos(), self.button_selected)
            except TypeError as err:
                self.messages_window.addItem(str(err))
            else:
                with undoCommands.UndoMacro(self.undo_stack, 'Place Symbol'):
                    item = self.place_symbol(
                            item_type=self.button_selected,
                            parent=parent,
                            pos=event.scenePos() if not parent else None)
            # self.button_selected = None
            self.mode = 'idle'
        elif self.mode == 'wait_connection_source':
            # Check location, and if ok:
            self.mode = 'wait_next_connection_point'
            # if not OK, reset and:
            self.mode = 'idle'

    # pylint: disable=C0103
    def mouseMoveEvent(self, event):
        ''' Handle Click + Mouse move, based on the mode '''
        if event.buttons() == Qt.NoButton or self.mode == 'idle':
            return super(SDL_Scene, self).mouseMoveEvent(event)
        elif self.mode == 'select_items':
            rect = QRectF(self.orig_pos, event.scenePos())
            self.select_rect.setRect(rect.normalized())
        elif self.mode == 'wait_next_connection_point':
            # Update the line
            pass

    # pylint: disable=C0103
    def mouseReleaseEvent(self, event):
        if self.mode == 'select_items':
            for item in self.items(self.select_rect.rect().toRect(),
                    mode=Qt.ContainsItemBoundingRect):
                try:
                    item.select()
                except AttributeError:
                    pass
            #self.removeItem(self.select_rect)
            # XXX stop with removeItem, it provokes segfault
            self.select_rect.hide()
        self.mode = 'idle'
        super(SDL_Scene, self).mouseReleaseEvent(event)

    # pylint: disable=C0103
    def keyPressEvent(self, event):
        ''' Handle keyboard: Delete, Undo/Redo '''
        super(SDL_Scene, self).keyPressEvent(event)
        if event.matches(QtGui.QKeySequence.Delete) and self.selectedItems():
            self.delete_selected_symbols()
            self.clearSelection()
            self.clear_focus()
        elif event.matches(QtGui.QKeySequence.Undo):
            if not isinstance(self.focusItem(), EditableText):
                LOG.debug('UNDO ' + self.undo_stack.undoText())
                self.undo_stack.undo()
                self.clearSelection()
                self.refresh()
                # Emit a selection change to make sure the toolbar is updated
                # (e.g. when Undoing a Place START symbol)
                self.selectionChanged.emit()
                self.clear_focus()
        elif event.matches(QtGui.QKeySequence.Redo):
            if not isinstance(self.focusItem(), EditableText):
                LOG.debug('REDO ' + self.undo_stack.redoText())
                self.undo_stack.redo()
                self.clearSelection()
                self.refresh()
                self.clear_focus()
                # Emit a selection change to make sure the toolbar is updated
                self.selectionChanged.emit()
        elif event.matches(QtGui.QKeySequence.Copy):
            if not isinstance(self.focusItem(), EditableText):
                try:
                    self.copy_selected_symbols()
                except TypeError:
                    LOG.error('Cannot copy')
        elif event.matches(QtGui.QKeySequence.Cut):
            self.cut_selected_symbols()
        elif event.matches(QtGui.QKeySequence.Paste):
            if not isinstance(self.focusItem(), EditableText):
                self.paste_symbols()
                self.refresh()
                self.clear_focus()
        elif event.key() == Qt.Key_N:
            # n to select the next item in a search (vim mode)
            if self.focusItem():
                # Only active when no item has keyboard focus
                return
            try:
                self.clearSelection()
                item = self.search_item.next()
                item.select()
                item.ensureVisible()
            except StopIteration:
                LOG.info('No more matches')
                self.search(self.search_pattern)
            except AttributeError:
                LOG.info('No search pattern set. Use "/<pattern>"')
        elif (event.key() == Qt.Key_J and
                event.modifiers() == Qt.ControlModifier):
            # Debug mode
            for selection in self.selected_symbols():
                LOG.info(unicode(selection))
                LOG.info('Position: ' + str(selection.pos()))
                LOG.info('ScenePos: ' + str(selection.scenePos()))
                LOG.info('BoundingRect: ' + str(selection.boundingRect()))
                #LOG.info('ChildrenList: ' + str(selection.childItems()))
                LOG.info('ChildrenBoundingRect: ' +
                        str(selection.childrenBoundingRect()))
                pprint.pprint(selection.__dict__, None, 2, 1)
            code.interact('type your command:', local=locals())

    def create_subscene(self, context):
        ''' Create a new SDL scene, e.g. for nested symbols '''
        subscene = SDL_Scene(context=context)
        subscene.messages_window = self.messages_window
        subscene.parent_scene = self
        return subscene

    def place_symbol(self, item_type, parent, pos=None):
        ''' Draw a symbol on the scene '''
        item = item_type()
        # Add the item to the scene
        if item not in self.items():
            self.addItem(item)
        # Create Undo command (makes the call to the insertSymbol function):
        undo_cmd = undoCommands.InsertSymbol(item=item, parent=parent, pos=pos)
        self.undo_stack.push(undo_cmd)
        # If no item is selected (e.g. new STATE), add it to the scene
        if not parent:
            G_SYMBOLS.add(item)

        if item_type == Decision:
            # When creating a new decision, add two default answers
            self.place_symbol(item_type=DecisionAnswer, parent=item)
            self.place_symbol(item_type=DecisionAnswer, parent=item)
        elif item_type in (Procedure, State, Process):
            # Create a sub-scene for clickable symbols
            item.nested_scene = \
                    self.create_subscene(item_type.__name__.lower())

        self.clearSelection()
        self.clear_focus()
        item.select()
        item.cam(item.pos(), item.pos())
        # When item is placed, immediately set focus to input text
        item.edit_text()

        for view in self.views():
            view.refresh()
            view.ensureVisible(item)
        return item

    def add_symbol(self, item_type):
        ''' Add a symbol, or postpone until a parent symbol is selected  '''
        try:
            # If an item is selected or if its text has focus,
            # use it as parent item for the newly inserted item
            selection, = (list(self.selected_symbols()) or
                          [self.focusItem().parentItem()])
            with undoCommands.UndoMacro(self.undo_stack, 'Place Symbol'):
                self.place_symbol(item_type=item_type, parent=selection)
        except (ValueError, AttributeError):
            # Menu item clicked but no symbol selected
            # -> store until user clicks on the scene
            self.messages_window.clear()
            self.messages_window.addItem(
                    'Click on the scene to place the symbol')
            self.button_selected = item_type
            if item_type == Connection:
                self.mode = 'wait_connection_source'
            else:
                self.mode = 'wait_placement'
            self.set_cursor(item_type)
            return None


class SDL_View(QtGui.QGraphicsView, object):
    ''' Main graphic view used to display the SDL scene and handle zoom '''
    # signal to ask the main application that a new scene is needed
    need_new_scene = QtCore.Signal()
    update_asn1_dock = QtCore.Signal(ogAST.AST)

    def __init__(self, scene):
        ''' Create the SDL view holding the scene '''
        super(SDL_View, self).__init__(scene)
        self.wrapping_window = None
        self.messages_window = None
        self.mode = ''
        self.phantom_rect = None
        self.filename = ''
        self.orig_pos = None
        # mouse_pos is used to handle screen scrolling with middle mouse button
        self.mouse_pos = None
        # Up button allows to move from one scene to another
        self.up_button = None
        # Toolbar with the icons of the SDL symbols
        self.toolbar = None
        # Scene stack (used for nested symbols)
        self.parent_scene = []
        # Set of PR files that are not saved back (e.g. system structure)
        self.readonly_pr = None
        # Context history referencing the AST entry corresponding to the scene
        # Used when navigating between scene with up/down button to update
        # the CONTEXT parameter in sdlSymbols - used for autocompletion
        self.context_history = []
        # Special scene for the Lander module
        self.lander_scene = SDL_Scene(context='lander')
        # Do not initialize the lander now - only if needed
        self.lander = None

    def set_toolbar(self):
        ''' Define the toolbar depending on the context '''
        self.toolbar.set_actions(
                bar_items=ACTIONS.get(self.scene().context, []))

        # Connect toolbar actions
        self.scene().selectionChanged.connect(partial(
                                    self.scene().set_selection, self.toolbar))
        for item in self.toolbar.actions.viewkeys():
            self.toolbar.actions[item].triggered.connect(
                                                   self.scene().actions[item])
        self.toolbar.update_menu(self.scene())

    # pylint: disable=C0103
    def keyPressEvent(self, event):
        ''' Handle keyboard: Zoom, open/save diagram, etc. '''
        if event.matches(QtGui.QKeySequence.ZoomOut):
            self.scale(0.8, 0.8)
        elif event.matches(QtGui.QKeySequence.ZoomIn):
            self.scale(1.2, 1.2)
        elif event.matches(QtGui.QKeySequence.Save):
            self.save_diagram()
        elif (event.key() == Qt.Key_G and
                event.modifiers() == Qt.ControlModifier):
            self.generate_ada()
        elif event.key() == Qt.Key_F7:
            self.check_model()
        elif event.key() == Qt.Key_F5:
            self.refresh()
            # Refresh statechart
            if graphviz:
                Statechart.update(self.scene())
        elif event.matches(QtGui.QKeySequence.Open):
            self.open_diagram()
        elif event.matches(QtGui.QKeySequence.New):
            self.new_diagram()
        elif (event.key() == Qt.Key_F12 and
                event.modifiers() == Qt.ControlModifier and
                self.scene() != self.lander_scene):
            self.lander_scene.setSceneRect(0, 0, self.width(), self.height())
            if not self.lander:
                self.lander = Lander.Lander(self.lander_scene)
            horpos = self.horizontalScrollBar().value()
            verpos = self.verticalScrollBar().value()
            self.parent_scene.append((self.scene(), horpos, verpos))
            self.scene().clear_focus()
            self.setScene(self.lander_scene)
            self.up_button.setEnabled(True)
            self.set_toolbar()
            self.lander.play()
        super(SDL_View, self).keyPressEvent(event)

    def refresh(self):
        ''' Refresh the complete view '''
        self.scene().refresh()
        self.setSceneRect(self.scene().sceneRect())
        self.viewport().update()

    # pylint: disable=C0103
    def resizeEvent(self, event):
        '''
           Called by Qt when window is resized
           Make sure that the scene that is displayed is at least
           of the size of the view, by drawing a transparent rectangle
           Otherwise, the scene is centered on the view, with the size
           of its bounding rect. This is nice in theory, except when
           the user wants to place a symbol at an exact position - in
           that case, the automatic centering is not appropriate.
        '''
        LOG.debug('resizing view')
        scene_rect = self.scene().itemsBoundingRect()
        view_size = self.size()
        scene_rect.setWidth(max(scene_rect.width(), view_size.width()))
        scene_rect.setHeight(max(scene_rect.height(), view_size.height()))
        if self.phantom_rect and self.phantom_rect in self.scene().items():
            #self.scene().removeItem(self.phantom_rect)
            # XXX stop with removeItem, it provokes segfault
            self.phantom_rect.hide()
        self.phantom_rect = self.scene().addRect(scene_rect,
                pen=QtGui.QPen(QtGui.QColor(0, 0, 0, 0)))
        # Hide the rectangle so that it does not collide with the symbols
        self.phantom_rect.hide()
        self.refresh()
        super(SDL_View, self).resizeEvent(event)

    def about_og(self):
        ''' Display the About dialog '''
        QtGui.QMessageBox.about(self, 'About OpenGEODE',
                'OpenGEODE - a tiny SDL editor for TASTE\n\n'
                'Author: \nMaxime Perrotin'
                '\n\nContact: maxime.perrotin@esa.int\n\n'
                'Coded with Pyside (Python + Qt)\n'
                'and ANTLR 3.1.3 for Python (parser)')

    # pylint: disable=C0103
    def wheelEvent(self, wheelEvent):
        '''
            Catch the mouse Wheel event
        '''
        if wheelEvent.modifiers() == Qt.ControlModifier:
            # Google-Earth zoom mode (Zoom with center on the mouse position)
            self.setTransformationAnchor(QtGui.QGraphicsView.AnchorUnderMouse)
            if wheelEvent.delta() < 0:
                self.scale(0.9, 0.9)
            else:
                self.scale(1.1, 1.1)
            self.setTransformationAnchor(QtGui.QGraphicsView.AnchorViewCenter)
        else:
            return super(SDL_View, self).wheelEvent(wheelEvent)

    # pylint: disable=C0103
    def mousePressEvent(self, evt):
        '''
            Catch mouse press event to move (when middle button is clicked)
            or to select multiple items
        '''
        # First propagate the click (then scene will receive it first):
        super(SDL_View, self).mousePressEvent(evt)
        try:
            self.toolbar.update_menu(self.scene())
        except AttributeError:
            # If scene has no menu connected (eg. ASN.1 dock..)
            pass
        self.mouse_pos = evt.pos()
        if evt.button() == Qt.MidButton:
            self.mode = 'moveScreen'

    def go_up(self):
        '''
            When Up button is clicked, go up one nested scene level
        '''
        LOG.debug('GO_UP')
        self.scene().clear_focus()
        # Scene may need to be informed when it is left:
        self.scene().scene_left.emit()
        scene, horpos, verpos = self.parent_scene.pop()
        self.setScene(scene)
        self.wrapping_window.setWindowTitle(self.scene().name)
        self.horizontalScrollBar().setSliderPosition(horpos)
        self.verticalScrollBar().setSliderPosition(verpos)
        self.set_toolbar()
        if not self.parent_scene:
            self.up_button.setEnabled(False)
        self.refresh()
        self.horizontalScrollBar().setSliderPosition(horpos)
        self.verticalScrollBar().setSliderPosition(verpos)
        sdlSymbols.CONTEXT = self.context_history.pop()

    def go_down(self, scene, name=''):
        ''' Enter a nested diagram (procedure, composite state) '''
        # Save context history
        self.context_history.append(sdlSymbols.CONTEXT)
        subtype, subname = name.split()
        # Get AST of the element that is entered
        if subtype == 'procedure':
            for each in sdlSymbols.CONTEXT.procedures:
                if subname.lower() == each.inputString.lower():
                    sdlSymbols.CONTEXT = each
                    break
            else:
                # Not existing yet - creating the AST context
                new_context = ogAST.Procedure()
                new_context.inputString = subname.lower()
                sdlSymbols.CONTEXT.procedures.append(new_context)
                sdlSymbols.CONTEXT = new_context
        elif subtype == 'state':
            for each in sdlSymbols.CONTEXT.composite_states:
                if subname.lower() == each.statename.lower():
                    sdlSymbols.CONTEXT = each
                    break
            else:
                # Not existing yet - creating the AST context
                new_context = ogAST.CompositeState()
                new_context.statename = subname.lower()
                sdlSymbols.CONTEXT.composite_states.append(new_context)
                sdlSymbols.CONTEXT = new_context
        elif subtype == 'process':
            for each in sdlSymbols.CONTEXT.processes:
                if subname.lower() == each.processName.lower():
                    sdlSymbols.CONTEXT = each
                    break
            else:
                # Not existing yet - creating the AST context
                new_context = ogAST.Process()
                new_context.processName = subname.lower()
                sdlSymbols.CONTEXT.processes.append(new_context)
                sdlSymbols.CONTEXT = new_context

        horpos = self.horizontalScrollBar().value()
        verpos = self.verticalScrollBar().value()
        self.scene().name = self.wrapping_window.windowTitle()
        self.parent_scene.append((self.scene(), horpos, verpos))
        self.scene().clear_focus()
        self.setScene(scene)
        self.scene().name = name + '[*]'
        self.wrapping_window.setWindowTitle(self.scene().name)
        self.up_button.setEnabled(True)
        self.set_toolbar()
        self.scene().scene_left.emit()
        self.refresh()

    # pylint: disable=C0103
    def mouseDoubleClickEvent(self, evt):
        ''' Catch a double click - possibly change the scene '''
        super(SDL_View, self).mouseDoubleClickEvent(evt)
        if evt.button() == Qt.LeftButton:
            item = self.scene().symbol_near(self.mapToScene(evt.pos()))
            try:
                if item.allow_nesting:
                    item.double_click()
                    ctx = unicode(item.__class__.__name__.lower())
                    if not isinstance(item.nested_scene, SDL_Scene):
                        item.nested_scene = \
                                self.scene().create_subscene(context=ctx)
                    self.go_down(item.nested_scene,
                                 name=ctx + u' ' + unicode(item))
                else:
                    # Otherwise, double-click edits the item text
                    item.edit_text(self.mapToScene(evt.pos()))
            except AttributeError as err:
                LOG.debug('Ignoring double click:' + str(err))

    # pylint: disable=C0103
    def mouseMoveEvent(self, evt):
        ''' Handle the screen move when user clicks '''
        if evt.buttons() == Qt.NoButton:
            return super(SDL_View, self).mouseMoveEvent(evt)
        new_pos = evt.pos()
        if self.mode == 'moveScreen':
            diff_x = self.mouse_pos.x() - new_pos.x()
            diff_y = self.mouse_pos.y() - new_pos.y()
            h_scroll = self.horizontalScrollBar()
            v_scroll = self.verticalScrollBar()
            h_scroll.setValue(h_scroll.value() + diff_x)
            v_scroll.setValue(v_scroll.value() + diff_y)
            self.mouse_pos = new_pos
        else:
            return super(SDL_View, self).mouseMoveEvent(evt)

    # pylint: disable=C0103
    def mouseReleaseEvent(self, evt):
        self.mode = ''
        # Adjust scrollbars if diagram got bigger due to a move
        if self.scene().context != 'statechart':
            # Make sure scene size remains OK when adding/moving symbols
            # Avoid doing it when editing texts - it would prevent text
            # selection or cursor move
            if not isinstance(self.scene().focusItem(), EditableText):
                self.refresh()
        super(SDL_View, self).mouseReleaseEvent(evt)

    def save_as(self):
        ''' Save As function '''
        self.save_diagram(save_as=True)

    def save_diagram(self, save_as=False, autosave=False):
        ''' Save the diagram to a .pr file '''
        if (not self.filename or save_as) and not autosave:
            self.filename = QtGui.QFileDialog.getSaveFileName(
                    self, "Save model", ".", "SDL Model (*.pr)")[0]
        if self.filename and self.filename.split('.')[-1] != 'pr':
            self.filename += ".pr"
        filename = (
                (self.filename or '_opengeode')
                + '.autosave') if autosave else self.filename
        if not filename and not autosave:
            return False
        else:
            pr_file = QFile(filename)
            pr_file.open(QIODevice.WriteOnly | QIODevice.Text)
            if not autosave:
                self.scene().process_name = ''.join(filename
                        .split(os.path.extsep)[0:-1]).split(os.path.sep)[-1]
                self.wrapping_window.setWindowTitle(
                        'process ' + self.scene().process_name + '[*]')
        # If the current scene is a nested one, save the top parent
        if self.parent_scene:
            scene = self.parent_scene[0][0]
        else:
            scene = self.scene()

        if not scene:
            LOG.info('No scene - nothing to save')
            return False

        # Translate scenes to avoid negative coordinates
        for each in scene.all_nested_scenes:
            each.translate_to_origin()
        delta_x, delta_y = scene.translate_to_origin()

        pr_raw = Pr.parse_scene(scene, full_model=True
                                       if not self.readonly_pr else False)

        # Move items back to original place to avoid scrollbar jumps
        for item in scene.floating_symb:
            item.moveBy(-delta_x, -delta_y)

        pr_data = unicode('\n'.join(pr_raw))
        try:
            pr_file.write(pr_data.encode('utf-8'))
            pr_file.close()
            if not autosave:
                self.scene().clear_focus()
                self.scene().undo_stack.setClean()
            else:
                LOG.debug('Auto-saving backup file completed:' + filename)
            return True
        except AttributeError:
            LOG.error('Impossible to save the file')
            return False

    def save_png(self):
        ''' Save the current view as a PNG image '''
        filename = QtGui.QFileDialog.getSaveFileName(
                self, "Save picture", ".", "Image (*.png)")[0]
        self.scene().export_img(filename, doc_format='png')

    def load_file(self, files):
        ''' Parse a PR file and render it on the scene '''
        dir_pool = set(os.path.dirname(each) for each in files)
        if len(dir_pool) != 1:
            LOG.warning('Files are spread in several directories - '
                        'ASN.1 files may not be found')
        else:
            files = [os.path.abspath(each) for each in files]
            os.chdir(dir_pool.pop() or '.')
        try:
            ast, warnings, errors = ogParser.parse_pr(files=files)
        except IOError:
            LOG.error('Aborting: could not open or parse input file')
            sdlSymbols.CONTEXT = ogAST.Block()
            return
        try:
            process, = ast.processes
            self.filename = process.filename
            self.readonly_pr = ast.pr_files - {self.filename}
        except ValueError:
            LOG.error('Cannot load more than one process at a time')
            return
        try:
            syst, = ast.systems
            block, = syst.blocks
            if block.processes[0].referenced:
                LOG.debug('Process is referenced, fixing')
                block.processes = [process]
        except ValueError:
            # No System/Block hierarchy, creating single block
            block = ogAST.Block()
            block.processes = [process]
        LOG.debug('Parsing complete. Summary, found ' + str(len(warnings)) +
                ' warnings and ' + str(len(errors)) + ' errors')
        self.log_errors(errors, warnings)
        self.scene().render_everything(block)
        self.toolbar.update_menu(self.scene())
        self.wrapping_window.setWindowTitle('block ' +
                                            process.processName + '[*]')
        self.refresh()
        self.centerOn(self.sceneRect().topLeft())
        self.scene().undo_stack.clear()
        # Emit a signal for the application to update the ASN.1 scene
        self.update_asn1_dock.emit(ast)
        # Set AST to be used as data dictionnary and updated on the fly
        sdlSymbols.AST = ast
        sdlSymbols.CONTEXT = block

    def open_diagram(self):
        ''' Load one or several .pr file and display the state machine '''
        if not self.new_diagram():
            return
        filenames, _ = QtGui.QFileDialog.getOpenFileNames(self,
                "Open model(s)", ".", "SDL model (*.pr)")
        if not filenames:
            return
        else:
            self.load_file(filenames)
            self.up_button.setEnabled(False)

    def is_model_clean(self):
        ''' Check recursively if anything has changed in any scene '''
        if self.parent_scene:
            scene = self.parent_scene[0][0]
        else:
            scene = self.scene()
        for each in chain([scene], scene.all_nested_scenes):
            if not each.undo_stack.isClean():
                return False
        return True

    def propose_to_save(self):
        ''' Display a dialog to let the user save his diagram '''
        msg_box = QtGui.QMessageBox(self)
        msg_box.setWindowTitle('OpenGEODE')
        msg_box.setText("The model has been modified.")
        msg_box.setInformativeText("Do you want to save your changes?")
        msg_box.setStandardButtons(QtGui.QMessageBox.Save |
                QtGui.QMessageBox.Discard |
                QtGui.QMessageBox.Cancel)
        msg_box.setDefaultButton(QtGui.QMessageBox.Save)
        ret = msg_box.exec_()
        if ret == QtGui.QMessageBox.Save:
            if not self.save_diagram():
                return False
        elif ret == QtGui.QMessageBox.Cancel:
            return False
        return True

    def new_diagram(self):
        ''' If model state is clean, reset current diagram '''
        if not self.is_model_clean():
            # If changes occured since last save, pop up a window
            if not self.propose_to_save():
                return False
        self.need_new_scene.emit()
        self.parent_scene = []
        self.scene().undo_stack.clear()
        #self.scene().clear()
        G_SYMBOLS.clear()
        self.scene().process_name = ''
        self.filename = None
        self.readonly_pr = None
        self.wrapping_window.setWindowTitle('process[*]')
        self.set_toolbar()
        return True

    def log_errors(self, errors, warnings):
        ''' Report Error and Warnings on the console and in the log window '''
        if self.messages_window:
            self.messages_window.clear()
        for error in errors:
            if type(error[0]) == list:
                # should be fixed now, CHECKME - NO, NOT FULLY FIXED
                # problem is in decision answers branches
                error[0] = 'Internal error - ' + str(error[0])
            LOG.error(error[0])
            item = QtGui.QListWidgetItem(u'[ERROR] ' + error[0])
            if len(error) == 3:
                item.setData(Qt.UserRole, error[1])
                #found = self.scene().symbol_near(QPoint(*error[1]), 1)
                # Pyside bug: setData cannot store 'found' directly
                #item.setData(Qt.UserRole + 1, id(found))
                item.setData(Qt.UserRole + 1, error[2])
            if self.messages_window:
                self.messages_window.addItem(item)
        for warning in warnings:
            LOG.warning(warning[0])
            item = QtGui.QListWidgetItem(u'[WARNING] ' + str(warning[0]))
            if len(warning)