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ASTWalker

A walker visiting an abstract syntax tree in preorder.

The following methods get called:

  • enter_ on entering a node, where class name is the class of the node in lower case.
  • leave_ on leaving a node, where class name is the class of the node in lower case.
Source code in src/library_analyzer/utils/_ast_walker.py 
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class ASTWalker:
    """A walker visiting an abstract syntax tree in preorder.

    The following methods get called:

    * enter_<class_name> on entering a node, where class name is the class of the node in lower case.
    * leave_<class_name> on leaving a node, where class name is the class of the node in lower case.
    """

    def __init__(self, handler: Any) -> None:
        self._handler = handler
        self._cache: dict[type, _EnterAndLeaveFunctions] = {}

    def walk(self, node: astroid.NodeNG) -> None:
        self.__walk(node, set())

    def __walk(self, node: astroid.NodeNG, visited_nodes: set[astroid.NodeNG]) -> None:
        if node in visited_nodes:
            raise AssertionError("Node visited twice")
        visited_nodes.add(node)

        self.__enter(node)
        for child_node in node.get_children():
            self.__walk(child_node, visited_nodes)
        self.__leave(node)

    def __enter(self, node: astroid.NodeNG) -> None:
        method = self.__get_callbacks(node)[0]
        if method is not None:
            method(node)

    def __leave(self, node: astroid.NodeNG) -> None:
        method = self.__get_callbacks(node)[1]
        if method is not None:
            method(node)

    def __get_callbacks(self, node: astroid.NodeNG) -> _EnterAndLeaveFunctions:
        klass = node.__class__
        methods = self._cache.get(klass)

        if methods is None:
            handler = self._handler
            class_name = klass.__name__.lower()
            enter_method = getattr(handler, f"enter_{class_name}", getattr(handler, "enter_default", None))
            leave_method = getattr(handler, f"leave_{class_name}", getattr(handler, "leave_default", None))
            self._cache[klass] = (enter_method, leave_method)
        else:
            enter_method, leave_method = methods

        return enter_method, leave_method

__enter(node)

Source code in src/library_analyzer/utils/_ast_walker.py 
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def __enter(self, node: astroid.NodeNG) -> None:
    method = self.__get_callbacks(node)[0]
    if method is not None:
        method(node)

__get_callbacks(node)

Source code in src/library_analyzer/utils/_ast_walker.py 
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def __get_callbacks(self, node: astroid.NodeNG) -> _EnterAndLeaveFunctions:
    klass = node.__class__
    methods = self._cache.get(klass)

    if methods is None:
        handler = self._handler
        class_name = klass.__name__.lower()
        enter_method = getattr(handler, f"enter_{class_name}", getattr(handler, "enter_default", None))
        leave_method = getattr(handler, f"leave_{class_name}", getattr(handler, "leave_default", None))
        self._cache[klass] = (enter_method, leave_method)
    else:
        enter_method, leave_method = methods

    return enter_method, leave_method

__init__(handler)

Source code in src/library_analyzer/utils/_ast_walker.py 
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def __init__(self, handler: Any) -> None:
    self._handler = handler
    self._cache: dict[type, _EnterAndLeaveFunctions] = {}

__leave(node)

Source code in src/library_analyzer/utils/_ast_walker.py 
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def __leave(self, node: astroid.NodeNG) -> None:
    method = self.__get_callbacks(node)[1]
    if method is not None:
        method(node)

__walk(node, visited_nodes)

Source code in src/library_analyzer/utils/_ast_walker.py 
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def __walk(self, node: astroid.NodeNG, visited_nodes: set[astroid.NodeNG]) -> None:
    if node in visited_nodes:
        raise AssertionError("Node visited twice")
    visited_nodes.add(node)

    self.__enter(node)
    for child_node in node.get_children():
        self.__walk(child_node, visited_nodes)
    self.__leave(node)

walk(node)

Source code in src/library_analyzer/utils/_ast_walker.py 
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def walk(self, node: astroid.NodeNG) -> None:
    self.__walk(node, set())