Compile the list of spans of every match.

def compileMatchList(self):
        """
        Compile the list of spans of every match.
        """
        # Get the new sub-string to search for.
        self.matchList = []

        # Return immediately if the input field is empty.
        numChar = len(self.toReplace)
        if numChar == 0:
            return

        # Compile a list of all sub-string spans.
        stop = 0
        text = self.qteWidget.text()
        while True:
            start = text.find(self.toReplace, stop)
            if start == -1:
                break
            else:
                stop = start + numChar
                self.matchList.append((start, stop))