The following does not work correctly in QML. The problem seems to be occurring early – AST::RegExpLiteral node only keeps a single SourceLocation, and that location has a length of 1. The script parser uses that to turn the regexp /[a-zA-z]{2,4}/ into the QString expression "/". After passing through the rewriter we end up with a binding with an empty expression.

import Qt 4.7

Rectangle {
    id: container
    width: 400
    height: 400

    TextInput { id: strInput;
        validator: QRegExpValidator {
            regExp: /[a-zA-z]{2,4}/
        }
    }
}