A quick auto-indent/smart-indent hack

Hi all,

I've never modified on an open source project before, but Notepad++ was pretty easy to get working with the Visual Studio files. The code is quite easy to read, even with minimal comments. Good job!

Anyway, I loved npp as a text editor, but the only thing missing for me was smart-indentation for programming. So I made a few modifications and it seems to work quite well. It only works with braces (so it won't work for def in Python, if/for/while statements without a {} block in C, html tags, etc), but for Perl and most cases in C/C++, Java, LISP, etc it works quite well.

Now I have a smart-indenting, code-folding, MDI text editor that's perfect for Perl scripts. UltraEdit had a few quirks in the syntax highlighting, and isn't freeware either, let alone open source. Thank you npp!

As you can probably tell, I leveraged the brace-matching code to get this to work. It's not rigourously tested, but for anyone else who's interested, here's what you need to do:

1. Add the private variable "bool _checkIndent;" to the Notepad_plus class

2. Modify the "MaintainIndentation(char ch)" function as follows:

void Notepad_plus::MaintainIndentation(char ch)
{
    int eolMode = int(_pEditView->execute(SCI_GETEOLMODE));
    int curLine = int(_pEditView->getCurrentLineNumber());
    int lastLine = curLine - 1;
    int indentAmount = 0;

    // Flag the line to be checked for smart-indentation if this
    // character closes a block and has no other text on the line
    if (strchr("])}", ch)) {
        int len = _pEditView->getLineLength(curLine) + 1;
        char *line = new char[len];
        _pEditView->execute(SCI_GETLINE, curLine, reinterpret_cast<LPARAM>(line));

        _checkIndent = true;
        for (int a = 0; a < len; a++)
            if (strchr("\0\r\n\t ])}", line[a]) != NULL)
                _checkIndent = false;
    }

    if (((eolMode == SC_EOL_CRLF || eolMode == SC_EOL_LF) && ch == '\n') ||
            (eolMode == SC_EOL_CR && ch == '\r'))
    {
        while (lastLine >= 0 && _pEditView->getLineLength(lastLine) == 0)
            lastLine--;

        if (lastLine >= 0) {
            indentAmount = _pEditView->getLineIndent(lastLine);
        }

        // Find the position of the previous character
        int pos = _pEditView->execute(SCI_GETCURRENTPOS) - ((eolMode == SC_EOL_CRLF) ? 3 : 2);
        // If an opening brace preceded the newline, smart-indent outwards
        if ((pos > 0) && strchr("[({", ch = char(_pEditView->execute(SCI_GETCHARAT, pos))))
            indentAmount += int(_pEditView->execute(SCI_GETTABWIDTH));

        if (indentAmount > 0) {
            _pEditView->setLineIndent(curLine, indentAmount);
        }
    }
}

3. Modify the "braceMatch()" function as follows:

void Notepad_plus::braceMatch()
{
    int braceAtCaret = -1;
    int braceOpposite = -1;
    findMatchingBracePos(braceAtCaret, braceOpposite);

    if ((braceAtCaret != -1) && (braceOpposite == -1))
    {
        _pEditView->execute(SCI_BRACEBADLIGHT, braceAtCaret);
        _pEditView->execute(SCI_SETHIGHLIGHTGUIDE);
    }
    else
    {
        _pEditView->execute(SCI_BRACEHIGHLIGHT, braceAtCaret, braceOpposite);

        // If we're flagged as closing a block, adjust the indentation
        // to match that of where the block opened
        if (_checkIndent && (braceOpposite >= 0)) {
            int curLine = int(_pEditView->getCurrentLineNumber());
            int prevLine = int(_pEditView->execute(SCI_LINEFROMPOSITION, braceOpposite));
            int indentAmount = _pEditView->getLineIndent(prevLine);
            _pEditView->setLineIndent(curLine, indentAmount);
        }
        _checkIndent = false;

        if (_pEditView->isShownIndentGuide())
        {
            int columnAtCaret = int(_pEditView->execute(SCI_GETCOLUMN, braceAtCaret));
            int columnOpposite = int(_pEditView->execute(SCI_GETCOLUMN, braceOpposite));
            _pEditView->execute(SCI_SETHIGHLIGHTGUIDE, (columnAtCaret < columnOpposite)?columnAtCaret:columnOpposite);
        }
    }

    enableCommand(IDM_SEARCH_GOTOMATCHINGBRACE, (braceAtCaret != -1) && (braceOpposite != -1), MENU | TOOLBAR);
}

It might be useful to put a separate "Smart-Indentation" checkbox in the settings dialog, but I couldn't be bothered. Hopefully some of you will find this useful. I'll be happy to send a binary to anyone who wants it.

Enjoy!