package antlr;
/* ANTLR Translator Generator
* Project led by Terence Parr at http://www.cs.usfca.edu
* Software rights: http://www.antlr.org/license.html
*
* $Id: //depot/code/org.antlr/release/antlr-2.7.7/antlr/TreeBlockContext.java#2 $
*/
/**The context needed to add root,child elements to a Tree. There
* is only one alternative (i.e., a list of children). We subclass to
* specialize. MakeGrammar.addElementToCurrentAlt will work correctly
* now for either a block of alts or a Tree child list.
*
* The first time addAlternativeElement is called, it sets the root element
* rather than adding it to one of the alternative lists. Rather than have
* the grammar duplicate the rules for grammar atoms etc... we use the same
* grammar and same refToken behavior etc... We have to special case somewhere
* and here is where we do it.
*/
class
TreeBlockContext extends
BlockContext {
protected boolean
nextElementIsRoot = true;
public void
addAlternativeElement(
AlternativeElement e) {
TreeElement tree = (
TreeElement)
block;
if (
nextElementIsRoot) {
tree.
root = (
GrammarAtom)
e;
nextElementIsRoot = false;
}
else {
super.addAlternativeElement(
e);
}
}
}