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| | | #REDIRECT [[QTextDocument Block Boundary QRegExp]] |
| = QTextDocument Line Endings and Advanced RegExp =
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| == Warning: Experimental Info ==
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| I've picked from QtForum itself. It's progressive article. I will update more when I will achieve something.
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| The find(regex) method of QTextDocument will not attempt to match across a “block” boundary (see answers in this post [developer.qt.nokia.com]). As a result, although the QRegExp doc says that is matched by .* and by , one can never get a match to in a QPlainTextEdit document. The is end of block and the search never spans a block. Thus it seems impossible for a pattern like
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| <code>.*</code>
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| to find a match when the markup begins on one line and ends on another.
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| There is a way around this. The restriction is in QTextDocument; QRegExp does perform as documented when it is applied to a QString. So the following code can apply a general regex to a document. This is using PyQt4; the translation to C++ should be clear. Given is a QPlainTextEdit qpte whose cursor is the starting point for the search. Also given is a QRegExp qrxp that has been prepared with a search pattern such as “<b>.*</b>” and its minimal and case switches set.
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| <code>
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| start_tc = qpte.textCursor() # cursor with starting position
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| range_tc = QTextCursor(start_tc) # make a copy linked to same doc
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| range_tc.movePosition(QTextCursor.End) # point to end of doc
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| # set cursor to select all text from starting point to end
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| range_tc.setPosition(start_tc.selectionStart(),QTextCursor.KeepAnchor)
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| # apply regexp to (part of) the document as a QString
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| hit_pos = qrxp.indexIn(range_tc.selectedText())
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| if hit_pos > –1 : # first occurrence at hit_pos offset
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| find_tc = QTextCursor(start_tc) # another cursor
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| find_tc.setPosition(start_tc.selectionStart()+hit_pos) # point to hit
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| find_tc.movePosition(QTextCursor.Right,
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| QTextCursor.KeepAnchor,
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| qrxp.matchedLength()) # select matched text
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| qpte.setTextCursor(find_tc) # match visible to user<code>
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| </code>
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