Insert_possibly_matching_paren.bsh

insert(textArea, sc, ec, init) {
	if (textArea.getSelectionCount() == 0) {
		sel = new Selection.Range(textArea.getCaretPosition(), textArea.getCaretPosition());
	} else if (init && textArea.getSelectionCount() == 1 && textArea.getSelection()[0] instanceof Selection.Range) {
		sel = textArea.getSelection()[0];
	} else {
		// TODO?
		selections = textArea.getSelection();
		for (int i = 0; i < selections.length; i++) {
			textArea.setSelectedText(selections[i], init ? sc : ec);
		}
		return;
	}
	
	if (init) {
		position = textArea.getCaretPosition();
		prior = new Selection.Range(sel.getStart(), sel.getStart());
		post = new Selection.Range(sel.getEnd() + 1, sel.getEnd() + 1);
		textArea.setSelectedText(prior, sc);
		textArea.setSelectedText(post, ec);
		
		if (position >= prior.getStart()) {
			position++;
		}
		if (position > post.getEnd()) {
			position++;
		}
		
		textArea.moveCaretPosition(position);
		textArea.setSelection(new Selection.Range(sel.getStart(), Math.max(sel.getStart(), sel.getEnd() - 1)));
	} else {
		target = new Selection.Range(sel.getEnd(), sel.getEnd() + 1);
		if (target.getEnd() <= textArea.getBufferLength()) {
			if (!textArea.getSelectedText(target).equals(ec)) {
				textArea.setSelectedText(new Selection.Range(sel.getEnd(), sel.getEnd()), ec);
			}
			textArea.setCaretPosition(sel.getEnd() + 1);
		} else {
			textArea.setSelectedText(ec, true);
		}
	}
}

insert(textArea, "(", ")", false);