eric6/Preferences/ConfigurationPages/EditorHighlightingStylesPage.py

# -*- coding: utf-8 -*-

# Copyright (c) 2006 - 2020 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing the Editor Highlighting Styles configuration page.
"""


from PyQt5.QtCore import pyqtSlot, Qt, QFileInfo, QFile, QIODevice
from PyQt5.QtGui import QPalette, QFont
from PyQt5.QtWidgets import (
    QColorDialog, QFontDialog, QInputDialog, QMenu, QTreeWidgetItem, QDialog
)

from .ConfigurationPageBase import ConfigurationPageBase
from .Ui_EditorHighlightingStylesPage import Ui_EditorHighlightingStylesPage
from ..SubstyleDefinitionDialog import SubstyleDefinitionDialog

from E5Gui import E5MessageBox, E5FileDialog

import UI.PixmapCache

try:
    MonospacedFontsOption = QFontDialog.MonospacedFonts
except AttributeError:
    MonospacedFontsOption = QFontDialog.FontDialogOptions(0x10)
NoFontsOption = QFontDialog.FontDialogOptions(0)


class EditorHighlightingStylesPage(ConfigurationPageBase,
                                   Ui_EditorHighlightingStylesPage):
    """
    Class implementing the Editor Highlighting Styles configuration page.
    """
    FAMILYONLY = 0
    SIZEONLY = 1
    FAMILYANDSIZE = 2
    FONT = 99
    
    StyleRole = Qt.UserRole + 1
    SubstyleRole = Qt.UserRole + 2
    
    def __init__(self, lexers):
        """
        Constructor
        
        @param lexers reference to the lexers dictionary
        """
        super(EditorHighlightingStylesPage, self).__init__()
        self.setupUi(self)
        self.setObjectName("EditorHighlightingStylesPage")
        
        self.defaultSubstylesButton.setIcon(UI.PixmapCache.getIcon("editUndo"))
        self.addSubstyleButton.setIcon(UI.PixmapCache.getIcon("plus"))
        self.deleteSubstyleButton.setIcon(UI.PixmapCache.getIcon("minus"))
        self.editSubstyleButton.setIcon(UI.PixmapCache.getIcon("edit"))
        self.copySubstyleButton.setIcon(UI.PixmapCache.getIcon("editCopy"))
        
        self.__fontButtonMenu = QMenu()
        act = self.__fontButtonMenu.addAction(self.tr("Font"))
        act.setData(self.FONT)
        self.__fontButtonMenu.addSeparator()
        act = self.__fontButtonMenu.addAction(
            self.tr("Family and Size only"))
        act.setData(self.FAMILYANDSIZE)
        act = self.__fontButtonMenu.addAction(self.tr("Family only"))
        act.setData(self.FAMILYONLY)
        act = self.__fontButtonMenu.addAction(self.tr("Size only"))
        act.setData(self.SIZEONLY)
        self.__fontButtonMenu.triggered.connect(self.__fontButtonMenuTriggered)
        self.fontButton.setMenu(self.__fontButtonMenu)
        
        self.__allFontsButtonMenu = QMenu()
        act = self.__allFontsButtonMenu.addAction(self.tr("Font"))
        act.setData(self.FONT)
        self.__allFontsButtonMenu.addSeparator()
        act = self.__allFontsButtonMenu.addAction(
            self.tr("Family and Size only"))
        act.setData(self.FAMILYANDSIZE)
        act = self.__allFontsButtonMenu.addAction(self.tr("Family only"))
        act.setData(self.FAMILYONLY)
        act = self.__allFontsButtonMenu.addAction(self.tr("Size only"))
        act.setData(self.SIZEONLY)
        self.__allFontsButtonMenu.triggered.connect(
            self.__allFontsButtonMenuTriggered)
        self.allFontsButton.setMenu(self.__allFontsButtonMenu)
        
        self.lexer = None
        self.lexers = lexers
        
        # set initial values
        import QScintilla.Lexers
        languages = sorted([''] + list(self.lexers.keys()))
        for language in languages:
            self.lexerLanguageComboBox.addItem(
                QScintilla.Lexers.getLanguageIcon(language, False),
                language)
        self.on_lexerLanguageComboBox_activated("")
    
    def save(self):
        """
        Public slot to save the Editor Highlighting Styles configuration.
        """
        for lexer in list(self.lexers.values()):
            lexer.writeSettings()
    
    @pyqtSlot(str)
    def on_lexerLanguageComboBox_activated(self, language):
        """
        Private slot to fill the style combo of the source page.
        
        @param language The lexer language (string)
        """
        self.styleElementList.clear()
        self.styleGroup.setEnabled(False)
        self.lexer = None
        
        self.exportCurrentButton.setEnabled(language != "")
        self.importCurrentButton.setEnabled(language != "")
        
        if not language:
            return
        
        try:
            self.lexer = self.lexers[language]
        except KeyError:
            return
        
        self.styleGroup.setEnabled(True)
        for description, styleNo, subStyleNo in self.lexer.getStyles():
            if subStyleNo >= 0:
                parent = self.styleElementList.findItems(
                    self.lexer.description(styleNo), Qt.MatchExactly)[0]
                parent.setExpanded(True)
            else:
                parent = self.styleElementList
            itm = QTreeWidgetItem(parent, [description])
            itm.setData(0, self.StyleRole, styleNo)
            itm.setData(0, self.SubstyleRole, subStyleNo)
        self.__styleAllItems()
        self.styleElementList.setCurrentItem(
            self.styleElementList.topLevelItem(0))
    
    def __stylesForItem(self, itm):
        """
        Private method to get the style and sub-style number of the given item.
        
        @param itm reference to the item to extract the styles from
        @type QTreeWidgetItem
        @return tuple containing the style and sub-style numbers
        @rtype tuple of (int, int)
        """
        style = itm.data(0, self.StyleRole)
        substyle = itm.data(0, self.SubstyleRole)

        return (style, substyle)
    
    def __currentStyles(self):
        """
        Private method to get the styles of the current item.
        
        @return tuple containing the style and sub-style numbers
        @rtype tuple of (int, int)
        """
        itm = self.styleElementList.currentItem()
        if itm is None:
            styles = (0, -1)    # return default style
        else:
            styles = self.__stylesForItem(itm)
        
        return styles
    
    def __styleOneItem(self, item, style, substyle):
        """
        Private method to style one item of the style element list.
        
        @param item reference to the item to be styled
        @type QTreeWidgetItem
        @param style base style number
        @type int
        @param substyle sub-style number
        @type int
        """
        colour = self.lexer.color(style, substyle)
        paper = self.lexer.paper(style, substyle)
        font = self.lexer.font(style, substyle)
        eolfill = self.lexer.eolFill(style, substyle)
        
        item.setFont(0, font)
        item.setBackground(0, paper)
        item.setForeground(0, colour)
        if eolfill:
            item.setCheckState(0, Qt.Checked)
        else:
            item.setCheckState(0, Qt.Unchecked)
    
    def __styleAllItems(self):
        """
        Private method to style all items of the style element list.
        """
        itm = self.styleElementList.topLevelItem(0)
        while itm is not None:
            style, substyle = self.__stylesForItem(itm)
            self.__styleOneItem(itm, style, substyle)
            itm = self.styleElementList.itemBelow(itm)
    
    @pyqtSlot(QTreeWidgetItem, QTreeWidgetItem)
    def on_styleElementList_currentItemChanged(self, current, previous):
        """
        Private method to handle a change of the current row.
        
        @param current reference to the current item
        @type QTreeWidgetItem
        @param previous reference to the previous item
        @type QTreeWidgetItem
        """
        if current is None:
            return
        
        style, substyle = self.__stylesForItem(current)
        colour = self.lexer.color(style, substyle)
        paper = self.lexer.paper(style, substyle)
        eolfill = self.lexer.eolFill(style, substyle)
        font = self.lexer.font(style, substyle)
        
        self.sampleText.setFont(font)
        pl = self.sampleText.palette()
        pl.setColor(QPalette.Text, colour)
        pl.setColor(QPalette.Base, paper)
        self.sampleText.setPalette(pl)
        self.sampleText.repaint()
        self.eolfillCheckBox.setChecked(eolfill)
        
        selectedOne = len(self.styleElementList.selectedItems()) == 1
        self.defaultSubstylesButton.setEnabled(
            selectedOne and substyle < 0 and self.lexer.isBaseStyle(style))
        self.addSubstyleButton.setEnabled(
            selectedOne and substyle < 0 and self.lexer.isBaseStyle(style))
        self.deleteSubstyleButton.setEnabled(selectedOne and substyle >= 0)
        self.editSubstyleButton.setEnabled(selectedOne and substyle >= 0)
        self.copySubstyleButton.setEnabled(selectedOne and substyle >= 0)
    
    @pyqtSlot()
    def on_foregroundButton_clicked(self):
        """
        Private method used to select the foreground colour of the selected
        style and lexer.
        """
        style, substyle = self.__currentStyles()
        colour = QColorDialog.getColor(self.lexer.color(style, substyle))
        if colour.isValid():
            pl = self.sampleText.palette()
            pl.setColor(QPalette.Text, colour)
            self.sampleText.setPalette(pl)
            self.sampleText.repaint()
            for selItem in self.styleElementList.selectedItems():
                style, substyle = self.__stylesForItem(selItem)
                self.lexer.setColor(colour, style, substyle)
                selItem.setForeground(0, colour)
    
    @pyqtSlot()
    def on_backgroundButton_clicked(self):
        """
        Private method used to select the background colour of the selected
        style and lexer.
        """
        style, substyle = self.__currentStyles()
        colour = QColorDialog.getColor(self.lexer.paper(style, substyle))
        if colour.isValid():
            pl = self.sampleText.palette()
            pl.setColor(QPalette.Base, colour)
            self.sampleText.setPalette(pl)
            self.sampleText.repaint()
            for selItem in self.styleElementList.selectedItems():
                style, substyle = self.__stylesForItem(selItem)
                self.lexer.setPaper(colour, style, substyle)
                selItem.setBackground(0, colour)
    
    @pyqtSlot()
    def on_allBackgroundColoursButton_clicked(self):
        """
        Private method used to select the background colour of all styles of a
        selected lexer.
        """
        style, substyle = self.__currentStyles()
        colour = QColorDialog.getColor(self.lexer.paper(style, substyle))
        if colour.isValid():
            pl = self.sampleText.palette()
            pl.setColor(QPalette.Base, colour)
            self.sampleText.setPalette(pl)
            self.sampleText.repaint()
            
            itm = self.styleElementList.topLevelItem(0)
            while itm is not None:
                style, substyle = self.__stylesForItem(itm)
                self.lexer.setPaper(colour, style, substyle)
                itm = self.styleElementList.itemBelow(itm)
            self.__styleAllItems()
    
    def __changeFont(self, doAll, familyOnly, sizeOnly):
        """
        Private slot to change the highlighter font.
        
        @param doAll flag indicating to change the font for all styles
            (boolean)
        @param familyOnly flag indicating to set the font family only (boolean)
        @param sizeOnly flag indicating to set the font size only (boolean
        """
        def setFont(font, style, substyle, familyOnly, sizeOnly):
            """
            Local function to set the font.
            
            @param font font to be set
            @type QFont
            @param style style number
            @type int
            @param substyle sub-style number
            @type int
            @param familyOnly flag indicating to set the font family only
            @type bool
            @param sizeOnly flag indicating to set the font size only
            @type bool
            """
            if familyOnly or sizeOnly:
                newFont = QFont(self.lexer.font(style))
                if familyOnly:
                    newFont.setFamily(font.family())
                if sizeOnly:
                    newFont.setPointSize(font.pointSize())
                self.lexer.setFont(newFont, style, substyle)
            else:
                self.lexer.setFont(font, style, substyle)
        
        def setSampleFont(font, familyOnly, sizeOnly):
            """
            Local function to set the font of the sample text.
            
            @param font font to be set (QFont)
            @param familyOnly flag indicating to set the font family only
                (boolean)
            @param sizeOnly flag indicating to set the font size only (boolean
            """
            if familyOnly or sizeOnly:
                style, substyle = self.__currentStyles()
                newFont = QFont(self.lexer.font(style, substyle))
                if familyOnly:
                    newFont.setFamily(font.family())
                if sizeOnly:
                    newFont.setPointSize(font.pointSize())
                self.sampleText.setFont(newFont)
            else:
                self.sampleText.setFont(font)
        
        style, substyle = self.__currentStyles()
        if self.monospacedButton.isChecked():
            options = MonospacedFontsOption
        else:
            options = NoFontsOption
        font, ok = QFontDialog.getFont(self.lexer.font(style, substyle), self,
                                       "", options)
        if ok:
            setSampleFont(font, familyOnly, sizeOnly)
            if doAll:
                itm = self.styleElementList.topLevelItem(0)
                while itm is not None:
                    style, substyle = self.__stylesForItem(itm)
                    setFont(font, style, substyle, familyOnly, sizeOnly)
                    itm = self.styleElementList.itemBelow(itm)
                self.__styleAllItems()
            else:
                for selItem in self.styleElementList.selectedItems():
                    style, substyle = self.__stylesForItem(selItem)
                    setFont(font, style, substyle, familyOnly, sizeOnly)
                    itmFont = self.lexer.font(style, substyle)
                    selItem.setFont(0, itmFont)
    
    def __fontButtonMenuTriggered(self, act):
        """
        Private slot used to select the font of the selected style and lexer.
        
        @param act reference to the triggering action (QAction)
        """
        if act is None:
            return
        
        familyOnly = act.data() in [self.FAMILYANDSIZE, self.FAMILYONLY]
        sizeOnly = act.data() in [self.FAMILYANDSIZE, self.SIZEONLY]
        self.__changeFont(False, familyOnly, sizeOnly)
    
    def __allFontsButtonMenuTriggered(self, act):
        """
        Private slot used to change the font of all styles of a selected lexer.
        
        @param act reference to the triggering action (QAction)
        """
        if act is None:
            return
        
        familyOnly = act.data() in [self.FAMILYANDSIZE, self.FAMILYONLY]
        sizeOnly = act.data() in [self.FAMILYANDSIZE, self.SIZEONLY]
        self.__changeFont(True, familyOnly, sizeOnly)
    
    @pyqtSlot(bool)
    def on_eolfillCheckBox_clicked(self, on):
        """
        Private method used to set the eolfill for the selected style and
        lexer.
        
        @param on flag indicating enabled or disabled state (boolean)
        """
        style, substyle = self.__currentStyles()
        checkState = Qt.Checked if on else Qt.Unchecked
        for selItem in self.styleElementList.selectedItems():
            style, substyle = self.__stylesForItem(selItem)
            self.lexer.setEolFill(on, style, substyle)
            selItem.setCheckState(0, checkState)
    
    @pyqtSlot()
    def on_allEolFillButton_clicked(self):
        """
        Private method used to set the eolfill for all styles of a selected
        lexer.
        """
        on = self.tr("Enabled")
        off = self.tr("Disabled")
        selection, ok = QInputDialog.getItem(
            self,
            self.tr("Fill to end of line"),
            self.tr("Select fill to end of line for all styles"),
            [on, off],
            0, False)
        if ok:
            enabled = selection == on
            self.eolfillCheckBox.setChecked(enabled)
            
            itm = self.styleElementList.topLevelItem(0)
            while itm is not None:
                style, substyle = self.__stylesForItem(itm)
                self.lexer.setEolFill(enabled, style, substyle)
                itm = self.styleElementList.itemBelow(itm)
            self.__styleAllItems()
    
    @pyqtSlot()
    def on_defaultButton_clicked(self):
        """
        Private method to set the current style to its default values.
        """
        for selItem in self.styleElementList.selectedItems():
            style, substyle = self.__stylesForItem(selItem)
            self.__setToDefault(style, substyle)
        self.on_styleElementList_currentItemChanged(
            self.styleElementList.currentItem(), None)
        self.__styleAllItems()
    
    @pyqtSlot()
    def on_allDefaultButton_clicked(self):
        """
        Private method to set all styles to their default values.
        """
        itm = self.styleElementList.topLevelItem(0)
        while itm is not None:
            style, substyle = self.__stylesForItem(itm)
            self.__setToDefault(style, substyle)
            itm = self.styleElementList.itemBelow(itm)
        self.on_styleElementList_currentItemChanged(
            self.styleElementList.currentItem(), None)
        self.__styleAllItems()
    
    def __setToDefault(self, style, substyle):
        """
        Private method to set a specific style to its default values.
        
        @param style style number
        @type int
        @param substyle sub-style number
        @type int
        """
        self.lexer.setColor(self.lexer.defaultColor(style, substyle),
                            style, substyle)
        self.lexer.setPaper(self.lexer.defaultPaper(style, substyle),
                            style, substyle)
        self.lexer.setFont(self.lexer.defaultFont(style, substyle),
                           style, substyle)
        self.lexer.setEolFill(self.lexer.defaultEolFill(style, substyle),
                              style, substyle)
    
    #######################################################################
    ## Importing and exporting of styles
    #######################################################################
    
    @pyqtSlot()
    def on_importCurrentButton_clicked(self):
        """
        Private slot to import the styles of the current lexer.
        """
        self.__importStyles({self.lexer.language(): self.lexer})
    
    @pyqtSlot()
    def on_exportCurrentButton_clicked(self):
        """
        Private slot to export the styles of the current lexer.
        """
        self.__exportStyles([self.lexer])
    
    @pyqtSlot()
    def on_importAllButton_clicked(self):
        """
        Private slot to import the styles of all lexers.
        """
        self.__importStyles(self.lexers)
    
    @pyqtSlot()
    def on_exportAllButton_clicked(self):
        """
        Private slot to export the styles of all lexers.
        """
        self.__exportStyles(list(self.lexers.values()))
    
    def __exportStyles(self, lexers):
        """
        Private method to export the styles of the given lexers.
        
        @param lexers list of lexer objects for which to export the styles
        """
        from eric6config import getConfig
        stylesDir = getConfig("ericStylesDir")
        
        fn, selectedFilter = E5FileDialog.getSaveFileNameAndFilter(
            self,
            self.tr("Export Highlighting Styles"),
            stylesDir,
            self.tr("Highlighting styles file (*.e6h)"),
            "",
            E5FileDialog.Options(E5FileDialog.DontConfirmOverwrite))
        
        if not fn:
            return
        
        ext = QFileInfo(fn).suffix()
        if not ext:
            ex = selectedFilter.split("(*")[1].split(")")[0]
            if ex:
                fn += ex
        
        f = QFile(fn)
        if f.open(QIODevice.WriteOnly):
            from E5XML.HighlightingStylesWriter import HighlightingStylesWriter
            HighlightingStylesWriter(f, lexers).writeXML()
            f.close()
        else:
            E5MessageBox.critical(
                self,
                self.tr("Export Highlighting Styles"),
                self.tr(
                    """<p>The highlighting styles could not be exported"""
                    """ to file <b>{0}</b>.</p><p>Reason: {1}</p>""")
                .format(fn, f.errorString())
            )
    
    def __importStyles(self, lexers):
        """
        Private method to import the styles of the given lexers.
        
        @param lexers dictionary of lexer objects for which to import the
            styles
        """
        from eric6config import getConfig
        stylesDir = getConfig("ericStylesDir")
        
        fn = E5FileDialog.getOpenFileName(
            self,
            self.tr("Import Highlighting Styles"),
            stylesDir,
            self.tr("Highlighting styles file (*.e6h *.e4h)"))
        
        if not fn:
            return
        
        f = QFile(fn)
        if f.open(QIODevice.ReadOnly):
            from E5XML.HighlightingStylesReader import HighlightingStylesReader
            reader = HighlightingStylesReader(f, lexers)
            reader.readXML()
            f.close()
        else:
            E5MessageBox.critical(
                self,
                self.tr("Import Highlighting Styles"),
                self.tr(
                    """<p>The highlighting styles could not be read"""
                    """ from file <b>{0}</b>.</p><p>Reason: {1}</p>""")
                .format(fn, f.errorString())
            )
            return
        
        self.on_lexerLanguageComboBox_activated(
            self.lexerLanguageComboBox.currentText())
    
    #######################################################################
    ## Methods to save and restore the state
    #######################################################################
    
    def saveState(self):
        """
        Public method to save the current state of the widget.
        
        @return list containing the index of the selected lexer language
            and a tuple containing the index of the parent selected lexer
            entry and the index of the selected entry
        @rtype list of int and tuple of (int, int)
        """
        itm = self.styleElementList.currentItem()
        parent = itm.parent()
        if parent is None:
            currentData = (
                None, self.styleElementList.indexOfTopLevelItem(itm))
        else:
            currentData = (
                self.styleElementList.indexOfTopLevelItem(parent),
                parent.indexOfChild(itm)
            )
        
        savedState = [
            self.lexerLanguageComboBox.currentIndex(),
            currentData,
        ]
        return savedState
    
    def setState(self, state):
        """
        Public method to set the state of the widget.
        
        @param state state data generated by saveState
        """
        self.lexerLanguageComboBox.setCurrentIndex(state[0])
        self.on_lexerLanguageComboBox_activated(
            self.lexerLanguageComboBox.currentText())
        
        parentIndex, index = state[1]
        if parentIndex is None:
            itm = self.styleElementList.topLevelItem(index)
        else:
            parent = self.styleElementList.topLevelItem(parentIndex)
            itm = parent.child(index)
        self.styleElementList.setCurrentItem(itm)
    
    #######################################################################
    ## Methods to add, delete and edit sub-styles and their definitions
    #######################################################################
    
    @pyqtSlot()
    def on_addSubstyleButton_clicked(self):
        """
        Private slot to add a new sub-style.
        """
        style, substyle = self.__currentStyles()
        dlg = SubstyleDefinitionDialog(
            self.lexer, style, substyle, parent=self)
        if dlg.exec_() == QDialog.Accepted:
            description, words = dlg.getData()
            substyle = self.lexer.addSubstyle(style)
            self.lexer.setDescription(description, style, substyle)
            self.lexer.setWords(words, style, substyle)
            
            parent = self.styleElementList.findItems(
                self.lexer.description(style), Qt.MatchExactly)[0]
            parent.setExpanded(True)
            itm = QTreeWidgetItem(parent, [description])
            itm.setData(0, self.StyleRole, style)
            itm.setData(0, self.SubstyleRole, substyle)
            self.__styleOneItem(itm, style, substyle)
    
    @pyqtSlot()
    def on_deleteSubstyleButton_clicked(self):
        """
        Private slot to delete the selected sub-style.
        """
        style, substyle = self.__currentStyles()
        ok = E5MessageBox.yesNo(
            self,
            self.tr("Delete Sub-Style"),
            self.tr("""<p>Shall the sub-style <b>{0}</b> really be"""
                    """ deleted?</p>""").format(
                self.lexer.description(style, substyle))
        )
        if ok:
            self.lexer.delSubstyle(style, substyle)
            
            itm = self.styleElementList.currentItem()
            parent = itm.parent()
            index = parent.indexOfChild(itm)
            parent.takeChild(index)
            del itm
    
    @pyqtSlot()
    def on_editSubstyleButton_clicked(self):
        """
        Private slot to edit the selected sub-style entry.
        """
        style, substyle = self.__currentStyles()
        dlg = SubstyleDefinitionDialog(
            self.lexer, style, substyle, parent=self)
        if dlg.exec_() == QDialog.Accepted:
            description, words = dlg.getData()
            self.lexer.setDescription(description, style, substyle)
            self.lexer.setWords(words, style, substyle)
            
            itm = self.styleElementList.currentItem()
            itm.setText(0, description)
    
    @pyqtSlot()
    def on_copySubstyleButton_clicked(self):
        """
        Private slot to copy the selected sub-style.
        """
        style, substyle = self.__currentStyles()
        newSubstyle = self.lexer.addSubstyle(style)
        
        description = self.tr("{0} - Copy").format(
            self.lexer.description(style, substyle))
        self.lexer.setDescription(description, style, newSubstyle)
        self.lexer.setWords(self.lexer.words(style, substyle),
                            style, newSubstyle)
        self.lexer.setColor(self.lexer.color(style, substyle),
                            style, newSubstyle)
        self.lexer.setPaper(self.lexer.paper(style, substyle),
                            style, newSubstyle)
        self.lexer.setFont(self.lexer.font(style, substyle),
                           style, newSubstyle)
        self.lexer.setEolFill(self.lexer.eolFill(style, substyle),
                              style, newSubstyle)
        
        parent = self.styleElementList.findItems(
            self.lexer.description(style), Qt.MatchExactly)[0]
        parent.setExpanded(True)
        itm = QTreeWidgetItem(parent, [description])
        itm.setData(0, self.StyleRole, style)
        itm.setData(0, self.SubstyleRole, newSubstyle)
        self.__styleOneItem(itm, style, newSubstyle)
    
    @pyqtSlot()
    def on_defaultSubstylesButton_clicked(self):
        """
        Private slot to reset all substyles to default values.
        """
        style, substyle = self.__currentStyles()
        ok = E5MessageBox.yesNo(
            self,
            self.tr("Reset Sub-Styles to Default"),
            self.tr("<p>Do you really want to reset all defined sub-styles of"
                    " <b>{0}</b> to the default values?</p>""")
            .format(self.lexer.description(style, substyle))
        )
        if ok:
            # 1. reset sub-styles
            self.lexer.loadDefaultSubStyles(style)
            
            # 2. delete all existing sub-style items
            parent = self.styleElementList.currentItem()
            while parent.childCount() > 0:
                itm = parent.takeChild(0)     # __IGNORE_WARNING__
                del itm
            
            # 3. create the new list of sub-style items
            for description, _, substyle in self.lexer.getSubStyles(style):
                itm = QTreeWidgetItem(parent, [description])
                itm.setData(0, self.StyleRole, style)
                itm.setData(0, self.SubstyleRole, substyle)
                self.__styleOneItem(itm, style, substyle)


def create(dlg):
    """
    Module function to create the configuration page.
    
    @param dlg reference to the configuration dialog
    @return reference to the instantiated page (ConfigurationPageBase)
    """
    page = EditorHighlightingStylesPage(dlg.getLexers())
    return page