Recursive behavior trees

[Rockjack00]

This PR addresses Issue #979. It checks for the existence of a subtree in its own prefix while parsing and includes two test cases for recursive trees mentioned in the issue.

[facontidavide]

thanks a lot. I will review it soon

[Copilot]

Pull Request Overview

This PR addresses Issue #979 by adding runtime checks to catch recursive behavior tree definitions and providing test cases to verify these conditions.

• Added two test cases (RecursiveSubtree and RecursiveCycle) to validate that cycles in behavior trees trigger errors.
• Introduced a recursion check in the XML parser to detect subtree cycles during parsing.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
tests/gtest_subtree.cpp	Added tests that ensure recursive trees and cycles are rejected.
src/xml_parsing.cpp	Implemented a recursion check for subtree creation in the XML parser.

[Copilot]

Consider using a delimiter-aware search to verify the presence of subtree_ID within prefix. This ensures that matching does not produce false positives if one subtree ID is a substring of another.

Suggested change

	if(prefix.find(subtree_ID) != std::string::npos)
	std::string subtree_delimited = subtree_ID + "/";
	if(prefix == subtree_ID || prefix.find(subtree_delimited) == 0)

[Rockjack00]

ensures that matching does not produce false positives if one subtree ID is a substring of another.

Good idea, but the provided solution does not achieve this because of the added ::<UID> for subtree paths.
Is there a method used elsewhere in the library for extracting tokens from a path that could be used for this? Otherwise I can add a string splitting routine. I'm not quite as C++ literate, but in python it would look something like this:

import re

ancestors = re.split(r'::[0-9]*/?', prefix)
if subtree_ID in ancestors:
    raise RuntimeError( ... )