Module opshin.rewrite.rewrite_import_typing

Classes

class RewriteImportTyping (*args, **kwargs)

A :class:NodeVisitor subclass that walks the abstract syntax tree and allows modification of nodes.

The NodeTransformer will walk the AST and use the return value of the visitor methods to replace or remove the old node. If the return value of the visitor method is None, the node will be removed from its location, otherwise it is replaced with the return value. The return value may be the original node in which case no replacement takes place.

Here is an example transformer that rewrites all occurrences of name lookups (foo) to data['foo']::

class RewriteName(NodeTransformer):

   def visit_Name(self, node):
       return Subscript(
           value=Name(id='data', ctx=Load()),
           slice=Constant(value=node.id),
           ctx=node.ctx
       )

Keep in mind that if the node you're operating on has child nodes you must either transform the child nodes yourself or call the :meth:generic_visit method for the node first.

For nodes that were part of a collection of statements (that applies to all statement nodes), the visitor may also return a list of nodes rather than just a single node.

Usually you use the transformer like this::

node = YourTransformer().visit(node)

Expand source code

class RewriteImportTyping(CompilingNodeTransformer):
    step = "Checking import and usage of typing"

    imports_typing = False

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.imports_Self = False

    def visit_ImportFrom(self, node: ImportFrom) -> Optional[ImportFrom]:
        if node.module != "typing":
            return node
        if len(node.names) == 1 and node.names[0].name == "Self":
            self.imports_Self = True
            return None
        assert (
            len(node.names) == 3
        ), "The program must contain one 'from typing import Dict, List, Union'"
        for i, n in enumerate(["Dict", "List", "Union"]):
            assert (
                node.names[i].name == n
            ), "The program must contain one 'from typing import Dict, List, Union'"
            assert (
                node.names[i].asname == None
            ), "The program must contain one 'from typing import Dict, List, Union'"
        self.imports_typing = True
        return None

    def visit_ClassDef(self, node: ClassDef) -> ClassDef:
        assert (
            self.imports_typing
        ), "typing must be imported in order to use datum classes"
        if self.imports_Self:
            for i, attribute in enumerate(node.body):
                if isinstance(attribute, FunctionDef):
                    for j, arg in enumerate(attribute.args.args):
                        if (
                            isinstance(arg.annotation, Name)
                            and arg.annotation.id == "Self"
                        ):
                            node.body[i].args.args[j].annotation.idSelf = node.name
                        if (
                            isinstance(arg.annotation, Subscript)
                            and arg.annotation.value.id == "Union"
                        ):
                            for k, s in enumerate(arg.annotation.slice.elts):
                                if isinstance(s, Name) and s.id == "Self":
                                    node.body[i].args.args[j].annotation.slice.elts[
                                        k
                                    ].idSelf = node.name

                    if (
                        isinstance(attribute.returns, Name)
                        and attribute.returns.id == "Self"
                    ):
                        node.body[i].returns.idSelf = node.name

        return node

Ancestors

• CompilingNodeTransformer
• TypedNodeTransformer
• ast.NodeTransformer
• ast.NodeVisitor

Class variables

var imports_typing

var step

Methods

def visit(self, node)

Inherited from: CompilingNodeTransformer.visit

Visit a node.

def visit_ClassDef(self, node: ast.ClassDef) ‑> ast.ClassDef

def visit_ImportFrom(self, node: ast.ImportFrom) ‑> ast.ImportFrom | None