PyQt5 выделение текста

from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from window import Ui_Widget
import sys
 
class SearchHighLight(QSyntaxHighlighter):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.pattern = QRegularExpression()
        self.format = QTextCharFormat()
        self.format.setBackground(Qt.green)
 
    def highlightBlock(self, text):
        match_iterator = self.pattern.globalMatch(text)
        while match_iterator.hasNext():
            match = match_iterator.next();
            self.setFormat(match.capturedStart(), match.capturedLength(), self.format)
 
 
    def searchText(self, text):
        self.pattern = QRegularExpression(text)
        self.rehighlight()
 
 
class MyWindow(QWidget):
    def __init__(self):
        super().__init__()
        self.ui = Ui_Widget()
        self.ui.setupUi(self)
        self.searchHighLight = SearchHighLight(self.ui.textEdit.document())
        self.ui.pushButton.clicked.connect(self.onSearchText)
 
    def onSearchText(self):
        self.searchHighLight.searchText(self.ui.lineEdit.text())
 
if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = MyWindow()
    ex.show()
    sys.exit(app.exec_())

    def on_find(self,rx):
        fmt = QTextCharFormat()
        fmt.setBackground(Qt.green)
        cursor = self.edit.document().find(rx,0)#edit - QTextEdit
        cursor.mergeCharFormat(fmt)
        while not cursor.isNull():
            pos = cursor.position()
            cursor = self.edit.document().find(rx,pos)
            cursor.mergeCharFormat(fmt)