/jEdit/tags/jedit-4-2-pre14/macros/Editing/Greedy_Backspace.bsh

/*
 * Greedy_Backspace.bsh - If buffer is using soft tabs,
 * this macro will backspace to the previous tab stop,
 * if all characters between the caret and the tab stop
 * are spaces.  In all other cases a single character is
 * removed.
 *
 * Copyright (C) 2002-2004 Ollie Rutherfurd <oliver@jedit.org>
 *
 * $Id: Greedy_Backspace.bsh 5032 2004-05-06 19:53:37Z orutherfurd $
 */

/**
 * @param onlyFullTabs if true, multiple spaces are only
 *                     removed if they would constitute
 *                     a 'complete' tab.
 */
void greedyBackspace(View view, boolean onlyFullTabs)
{
	JEditTextArea textArea = view.getTextArea();
	Buffer buffer = textArea.getBuffer();
	int caret = textArea.getCaretPosition();
	int caretLine = textArea.getCaretLine();
	int lineStart = textArea.getLineStartOffset(caretLine);

	if(buffer.getBooleanProperty("noTabs") == true)
	{
		// if anything is selected, use standard 
		if(textArea.getSelection().length != 0)
		{
			textArea.backspace();
		}
		// if at the start of the line, use standard
		else if(caret == lineStart)
		{
			textArea.backspace();
		}
		else
		{
			int col = caret - lineStart;
			int tabSize = buffer.getIntegerProperty("tabSize",8);

			// unlikely, but just in case
			if(tabSize <= 0)
			{
				buffer.remove(caret-1,1);
			}
			else
			{
				int toTabStop = ((col-1) % tabSize) + 1;
				int count = 1;
				for(int i=1; i < toTabStop; i++)
				{
					// only backspace over spaces
					if(!" ".equals(buffer.getText(caret-(i+1),1)))
						break;
					count += 1;
				}

				// if onlyFullTabs must be only spaces to
				// the tabStop and must have tabSize number 
				// of spaces to remove them all.
				if(onlyFullTabs == false || count == tabSize){
					buffer.remove(caret-count,count);
				}
				else{
					buffer.remove(caret-1,1);
				}
			}
		}
	}
	else
		textArea.backspace();
}

if(buffer.isReadOnly())
	getToolkit().beep();
else
	greedyBackspace(view,true);