1<?php
2
3declare(strict_types=1);
4
5namespace Antlr\Antlr4\Runtime\Tree;
6
7use Antlr\Antlr4\Runtime\Interval;
8
9/**
10 * A tree that knows about an interval in a token stream
11 * is some kind of syntax tree. Subinterfaces distinguish
12 * between parse trees and other kinds of syntax trees we might want to create.
13 */
14interface SyntaxTree extends Tree
15{
16    /**
17     * Return an {@see Interval} indicating the index in the
18     * {@see TokenStream} of the first and last token associated with this
19     * subtree. If this node is a leaf, then the interval represents a single
20     * token and has interval i..i for token index i.
21     *
22     * An interval of i..i-1 indicates an empty interval at position
23     * i in the input stream, where 0 <= i <= the size of the input
24     * token stream. Currently, the code base can only have i=0..n-1 but
25     * in concept one could have an empty interval after EOF.
26     *
27     * If source interval is unknown, this returns {@see Interval::invalid()}.
28     *
29     * As a weird special case, the source interval for rules matched after
30     * EOF is unspecified.
31     */
32    public function getSourceInterval() : Interval;
33}
34