Start position and End position

[jose]

In order to get the end line number of a node element, I've been using the following piece of code (also described in here):

def find_end_line_number(node):
    """Finds end line of a node."""
    max_line = node.position.line

    def traverse(node):
        for child in node.children:
            if isinstance(child, list) and (len(child) > 0):
                for item in child:
                    traverse(item)
            else:
                if hasattr(child, '_position'):
                    nonlocal max_line
                    if child._position.line > max_line:
                        max_line = child._position.line
                        return

    traverse(node)
    return max_line

which does not work for some cases, e.g., classes or methods with empty bodies. This pull request adds support to collect the end position (line number and column) of a node out-of-the-box.

[Yanivmd]

Hey @jose, thanks for this contribution! Saved me a lot of time.
Until this is merged I switched to using your fork.

One thing to note (for anyone else considering this) - in the main repo node.position will always exist, but sometimes be None. In the fork start_position (and I guess end_poisition) might not exist for these cases (so check with hasattr).

[emsi]

@jose I'm having following error while parsing code using javalang with your patch:

File /usr/local/lib/python3.9/site-packages/javalang/ast.py:54, in Node.filter(self, pattern)
     53 def filter(self, pattern):
---> 54     for path, node in self:
     55         if ((isinstance(pattern, type) and isinstance(node, pattern)) or
     56             (node == pattern)):
     57             yield path, node

File /usr/local/lib/python3.9/site-packages/javalang/ast.py:72, in walk_tree(root)
     69 else:
     70     children = root
---> 72 for child in children:
     73     if isinstance(child, (Node, list, tuple)):
     74         for path, node in walk_tree(child):

File /usr/local/lib/python3.9/site-packages/javalang/ast.py:72, in walk_tree(root)
     69 else:
     70     children = root
---> 72 for child in children:
     73     if isinstance(child, (Node, list, tuple)):
     74         for path, node in walk_tree(child):

    [... skipping similar frames: walk_tree at line 72 (2966 times)]

File /usr/local/lib/python3.9/site-packages/javalang/ast.py:72, in walk_tree(root)
     69 else:
     70     children = root
---> 72 for child in children:
     73     if isinstance(child, (Node, list, tuple)):
     74         for path, node in walk_tree(child):

File /usr/local/lib/python3.9/site-packages/javalang/ast.py:66, in walk_tree(root)
     63 def walk_tree(root):
     64     children = None
---> 66     if isinstance(root, Node):
     67         yield (), root
     68         children = root.children

RecursionError: maximum recursion depth exceeded while calling a Python object

[emsi]

I've provided alternative implementation of end position just for methods in pr #120