# node_visitor URL: /kida/api/analysis/node_visitor/ Section: analysis Description: Unified AST Visitor and Transformer base classes. Provides ``NodeVisitor`` and ``NodeTransformer`` with automatic ``visit_`` dispatch, eliminating the need for every analysis module to implement its own traversal logic. Adding a new AST node type requires zero changes to visitor code — ``generic_visit`` uses ``Node.iter_child_nodes()`` (backed by ``__dataclass_fields__`` introspection) to discover children automatically. Usage:: class MyAnalyzer(NodeVisitor): def visit_Name(self, node: Name) -> None: print(f"Found name: {node.name}") def visit_Filter(self, node: Filter) -> None: print(f"Found filter: {node.name}") self.generic_visit(node) # visit children too class MyOptimizer(NodeTransformer): def visit_Const(self, node: Const) -> Node: if isinstance(node.value, str): return Const(lineno=node.lineno, col_offset=node.col_offset, value=node.value.upper()) return node --- > For a complete page index, fetch /kida/llms.txt. Open LLM text (/kida/api/analysis/node_visitor/index.txt) Share with AI Ask Claude (https://claude.ai/new?q=Please%20help%20me%20understand%20this%20documentation%3A%20%2Fkida%2Fapi%2Fanalysis%2Fnode_visitor%2Findex.txt) Ask ChatGPT (https://chatgpt.com/?q=Please%20help%20me%20understand%20this%20documentation%3A%20%2Fkida%2Fapi%2Fanalysis%2Fnode_visitor%2Findex.txt) Ask Gemini (https://gemini.google.com/app?q=Please%20help%20me%20understand%20this%20documentation%3A%20%2Fkida%2Fapi%2Fanalysis%2Fnode_visitor%2Findex.txt) Ask Copilot (https://copilot.microsoft.com/?q=Please%20help%20me%20understand%20this%20documentation%3A%20%2Fkida%2Fapi%2Fanalysis%2Fnode_visitor%2Findex.txt) Module # `analysis.node_visitor` Unified AST Visitor and Transformer base classes. Provides`NodeVisitor` and `NodeTransformer`with automatic `visit_`dispatch, eliminating the need for every analysis module to implement its own traversal logic. Adding a new AST node type requires zero changes to visitor code — `generic_visit` uses `Node.iter_child_nodes()`(backed by `__dataclass_fields__`introspection) to discover children automatically. Usage:: ``` class MyAnalyzer(NodeVisitor): def visit_Name(self, node: Name) -> None: print(f"Found name: {node.name}") def visit_Filter(self, node: Filter) -> None: print(f"Found filter: {node.name}") self.generic_visit(node) # visit children too class MyOptimizer(NodeTransformer): def visit_Const(self, node: Const) -> Node: if isinstance(node.value, str): return Const(lineno=node.lineno, col_offset=node.col_offset, value=node.value.upper()) return node ``` 2Classes ## Classes `NodeVisitor` 4 ▼ Walk a Kida AST calling ``visit_`` methods on each node. For every node encountered, ``visit… Walk a Kida AST calling`visit_`methods on each node. For every node encountered,`visit()` checks for a `visit_` method (where`` is `type(node).__name__`) and calls it. If no specific method exists,`generic_visit()`is called, which visits all child nodes. Subclasses override`visit_`to handle specific node types. Call`self.generic_visit(node)`inside a handler to also visit children. #### Attributes Name Type Description `_dispatch_cache` `ClassVar[dict[type, Any]]` — #### Methods `visit` 1 `Any` ▼ Dispatch to ``visit_`` or ``generic_visit``. `def visit(self, node: Node) -> Any` ##### Parameters Name Type Description `node` `—` ##### Returns `Any` `generic_visit` 1 ▼ Visit all child nodes (default handler). `def generic_visit(self, node: Node) -> None` ##### Parameters Name Type Description `node` `—` Internal Methods 1 ▼ `__init_subclass__` 1 ▼ `def __init_subclass__(cls, **kwargs: Any) -> None` ##### Parameters Name Type Description `**kwargs` `—` `NodeTransformer` 7 ▼ Walk a Kida AST and rebuild nodes when ``visit_`` returns a replacement. Similar to ``NodeVi… Walk a Kida AST and rebuild nodes when`visit_`returns a replacement. Similar to`NodeVisitor`but each handler returns a (possibly new) node. `generic_visit()`visits all child fields; if any child changes, the parent node is reconstructed via`dataclasses.replace()`. Subclasses override`visit_`to transform specific node types. Returning`None`from a handler removes the node from its parent's body. #### Attributes Name Type Description `_dispatch_cache` `ClassVar[dict[type, Any]]` — #### Methods `visit` 1 `Node | None` ▼ Dispatch to ``visit_`` or ``generic_visit``. `def visit(self, node: Node) -> Node | None` ##### Parameters Name Type Description `node` `—` ##### Returns `Node | None` `generic_visit` 1 `Node` ▼ Rebuild *node* if any child field changed after visiting. `def generic_visit(self, node: Node) -> Node` ##### Parameters Name Type Description `node` `—` ##### Returns `Node` Internal Methods 4 ▼ `__init_subclass__` 1 ▼ `def __init_subclass__(cls, **kwargs: Any) -> None` ##### Parameters Name Type Description `**kwargs` `—` `_visit_field` 1 `Any` ▼ Visit a single field value, returning updated value if changed. `def _visit_field(self, value: Any) -> Any` ##### Parameters Name Type Description `value` `—` ##### Returns `Any` `_visit_sequence` 1 `Sequence[Any]` ▼ Visit a sequence, handling nested tuples (elif_, cases, etc.). `def _visit_sequence(self, seq: Sequence[Any]) -> Sequence[Any]` ##### Parameters Name Type Description `seq` `—` ##### Returns `Sequence[Any]` `_visit_dict` 1 `dict[str, Any]` ▼ Visit dict values (kwargs, slots, embed blocks, etc.). `def _visit_dict(self, mapping: dict[str, Any]) -> dict[str, Any]` ##### Parameters Name Type Description `mapping` `—` ##### Returns `dict[str, Any]`