How do QTextBlock or QTextFrame iterators work in PyQt

Question

When working with a QTextDocument, Qt provides iterators (such as QTextBlock.iterator) to move through the contents. The documentation here shows the C++ code, but obviously the ++ operator doesn't work and the PyQt version doesn't seem to have anything like a next() function.

So how do you make the iterator iterate?

The documentation for QTextFrame.begin (which returns the iterator) has a broken link to "STL-style-Iterators", but I can't find any details of these being implemented in Python.

Answer 1

The documentation shows that in PyQt, iterator objects support __iadd__ and __isub__. This allows you to use, e.g. it += 1 instead of ++it.

Here's a small demo:

# from PyQt5.QtWidgets import QApplication, QTextEdit
from PyQt4.QtGui import QApplication, QTextEdit

app = QApplication(['test'])

edit = QTextEdit()
edit.setText('one<b>two</b>three<br>')

it = edit.document().firstBlock().begin()
while not it.atEnd():
    fragment = it.fragment()
    if fragment.isValid():
        print(fragment.text())
    it += 1

Output:

one
two
three