/**
* Assembles some number of elements from the top of the global stack into a new Tree, and
* replaces those elements with the new Tree.
*
* <p><b>Caution:</b> The arguments must be consecutive integers 1..N, in any order, but with no
* gaps; for example, makeTree(2,4,1,5) would cause problems (3 was omitted).
*
* @param rootIndex Which stack element (counting from 1) to use as the root of the new Tree.
* @param childIndices Which stack elements to use as the children of the root.
*/
void makeTree(int rootIndex, int... childIndices) {
// Get root from stack
Tree<Token> root = getStackItem(rootIndex);
// Get other trees from stack and add them as children of root
for (int i = 0; i < childIndices.length; i++) {
root.addChild(getStackItem(childIndices[i]));
}
// Pop root and all children from stack
for (int i = 0; i <= childIndices.length; i++) {
stack.pop();
}
// Put the root back on the stack
stack.push(root);
}
