protected void pushOnAstStack(ASTNode node) {
	/*add a new obj on top of the ast stack
	astPtr points on the top*/

	int stackLength = this.astStack.length;
	if (++this.astPtr >= stackLength) {
		System.arraycopy(
			this.astStack, 0,
			this.astStack = new ASTNode[stackLength + AstStackIncrement], 0,
			stackLength);
		this.astPtr = stackLength;
	}
	this.astStack[this.astPtr] = node;

	stackLength = this.astLengthStack.length;
	if (++this.astLengthPtr >= stackLength) {
		System.arraycopy(
			this.astLengthStack, 0,
			this.astLengthStack = new int[stackLength + AstStackIncrement], 0,
			stackLength);
	}
	this.astLengthStack[this.astLengthPtr] = 1;
}