#!/usr/bin/env python
 
 
#############################################################################
##
## Copyright (C) 2013 Riverbank Computing Limited.
## Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
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## This file is part of the examples of PyQt.
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from PyQt5.QtCore import QFile, QRegExp, Qt
from PyQt5.QtGui import QFont, QSyntaxHighlighter, QTextCharFormat
from PyQt5.QtWidgets import (QApplication, QFileDialog, QMainWindow, QMenu,
        QMessageBox, QTextEdit)
 
 
class MainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
 
        self.setupFileMenu()
        self.setupHelpMenu()
        self.setupEditor()
 
        self.setCentralWidget(self.editor)
        self.setWindowTitle("Syntax Highlighter")
 
    def about(self):
        QMessageBox.about(self, "About Syntax Highlighter",
                "<p>The <b>Syntax Highlighter</b> example shows how to " \
                "perform simple syntax highlighting by subclassing the " \
                "QSyntaxHighlighter class and describing highlighting " \
                "rules using regular expressions.</p>")
 
    def newFile(self):
        self.editor.clear()
 
    def openFile(self, path=None):
        if not path:
            path, _ = QFileDialog.getOpenFileName(self, "Open File", '',
                    "C++ Files (*.cpp *.h)")
 
        if path:
            inFile = QFile(path)
            if inFile.open(QFile.ReadOnly | QFile.Text):
                text = inFile.readAll()
 
                try:
                    # Python v3.
                    text = str(text, encoding='ascii')
                except TypeError:
                    # Python v2.
                    text = str(text)
 
                self.editor.setPlainText(text)
 
    def setupEditor(self):
        font = QFont()
        font.setFamily('Courier')
        font.setFixedPitch(True)
        font.setPointSize(10)
 
        self.editor = QTextEdit()
        self.editor.setFont(font)
 
        self.highlighter = Highlighter(self.editor.document())
 
    def setupFileMenu(self):
        fileMenu = QMenu("&File", self)
        self.menuBar().addMenu(fileMenu)
 
        fileMenu.addAction("&New...", self.newFile, "Ctrl+N")
        fileMenu.addAction("&Open...", self.openFile, "Ctrl+O")
        fileMenu.addAction("E&xit", QApplication.instance().quit, "Ctrl+Q")
 
    def setupHelpMenu(self):
        helpMenu = QMenu("&Help", self)
        self.menuBar().addMenu(helpMenu)
 
        helpMenu.addAction("&About", self.about)
        helpMenu.addAction("About &Qt", QApplication.instance().aboutQt)
 
 
class Highlighter(QSyntaxHighlighter):
    def __init__(self, parent=None):
        super(Highlighter, self).__init__(parent)
 
        keywordFormat = QTextCharFormat()
        keywordFormat.setForeground(Qt.darkBlue)
        keywordFormat.setFontWeight(QFont.Bold)
 
        keywordPatterns = ["\\bchar\\b", "\\bclass\\b", "\\bconst\\b",
                "\\bdouble\\b", "\\benum\\b", "\\bexplicit\\b", "\\bfriend\\b",
                "\\binline\\b", "\\bint\\b", "\\blong\\b", "\\bnamespace\\b",
                "\\boperator\\b", "\\bprivate\\b", "\\bprotected\\b",
                "\\bpublic\\b", "\\bshort\\b", "\\bsignals\\b", "\\bsigned\\b",
                "\\bslots\\b", "\\bstatic\\b", "\\bstruct\\b",
                "\\btemplate\\b", "\\btypedef\\b", "\\btypename\\b",
                "\\bunion\\b", "\\bunsigned\\b", "\\bvirtual\\b", "\\bvoid\\b",
                "\\bvolatile\\b"]
 
        self.highlightingRules = [(QRegExp(pattern), keywordFormat)
                for pattern in keywordPatterns]
 
        classFormat = QTextCharFormat()
        classFormat.setFontWeight(QFont.Bold)
        classFormat.setForeground(Qt.darkMagenta)
        self.highlightingRules.append((QRegExp("\\bQ[A-Za-z]+\\b"),
                classFormat))
 
        singleLineCommentFormat = QTextCharFormat()
        singleLineCommentFormat.setForeground(Qt.red)
        self.highlightingRules.append((QRegExp("//[^\n]*"),
                singleLineCommentFormat))
 
        self.multiLineCommentFormat = QTextCharFormat()
        self.multiLineCommentFormat.setForeground(Qt.red)
 
        quotationFormat = QTextCharFormat()
        quotationFormat.setForeground(Qt.darkGreen)
        self.highlightingRules.append((QRegExp("\".*\""), quotationFormat))
 
        functionFormat = QTextCharFormat()
        functionFormat.setFontItalic(True)
        functionFormat.setForeground(Qt.blue)
        self.highlightingRules.append((QRegExp("\\b[A-Za-z0-9_]+(?=\\()"),
                functionFormat))
 
        self.commentStartExpression = QRegExp("/\\*")
        self.commentEndExpression = QRegExp("\\*/")
 
    def highlightBlock(self, text):
        for pattern, format in self.highlightingRules:
            expression = QRegExp(pattern)
            index = expression.indexIn(text)
            while index >= 0:
                length = expression.matchedLength()
                self.setFormat(index, length, format)
                index = expression.indexIn(text, index + length)
 
        self.setCurrentBlockState(0)
 
        startIndex = 0
        if self.previousBlockState() != 1:
            startIndex = self.commentStartExpression.indexIn(text)
 
        while startIndex >= 0:
            endIndex = self.commentEndExpression.indexIn(text, startIndex)
 
            if endIndex == -1:
                self.setCurrentBlockState(1)
                commentLength = len(text) - startIndex
            else:
                commentLength = endIndex - startIndex + self.commentEndExpression.matchedLength()
 
            self.setFormat(startIndex, commentLength,
                    self.multiLineCommentFormat)
            startIndex = self.commentStartExpression.indexIn(text,
                    startIndex + commentLength);
 
 
if __name__ == '__main__':
 
    import sys
 
    app = QApplication(sys.argv)
    window = MainWindow()
    window.resize(640, 512)
    window.show()
    sys.exit(app.exec_())