Replace Uint(len(...)) with ulen(...)

[SamWilsn]

Prompt

Using libcst (you can find some examples in src/ethereum_spec_tools/new_fork if you need them), write a
codemod to transform Uint(len(...)) into ulen(...) from ethereum/ethereum-types, and then apply the codemod to the whole repository.

Codemod

from pathlib import Path

import libcst as cst
import libcst.matchers as m
from libcst.codemod import CodemodContext, VisitorBasedCodemodCommand
from libcst.codemod.visitors import AddImportsVisitor, RemoveImportsVisitor
from typing_extensions import override


class UintLenToUlen(VisitorBasedCodemodCommand):
    """
    Replace `Uint(len(...))` with `ulen(...)`.
    """

    DESCRIPTION: str = "Replace Uint(len(...)) with ulen(...)."

    _transformed: bool

    def __init__(self, context: CodemodContext) -> None:
        super().__init__(context)
        self._transformed = False

    @override
    def leave_Call(
        self, original_node: cst.Call, updated_node: cst.Call
    ) -> cst.BaseExpression:
        # Match Uint(len(...))
        if not m.matches(
            updated_node,
            m.Call(
                func=m.Name("Uint"),
                args=[
                    m.Arg(
                        value=m.Call(func=m.Name("len")),
                        keyword=None,
                        star="",
                    )
                ],
            ),
        ):
            return updated_node

        if not self._transformed:
            self._transformed = True
            AddImportsVisitor.add_needed_import(
                self.context, "ethereum_types.numeric", "ulen"
            )
            RemoveImportsVisitor.remove_unused_import(
                self.context, "ethereum_types.numeric", "Uint"
            )

        # Extract the inner len() call's arguments
        inner_call = updated_node.args[0].value
        assert isinstance(inner_call, cst.Call)

        # Build ulen(...) preserving the inner arguments
        return updated_node.with_changes(
            func=cst.Name("ulen"),
            args=inner_call.args,
        )


def main() -> None:
    src_dir = Path("src/ethereum")
    files = sorted(src_dir.rglob("*.py"))

    for path in files:
        source = path.read_text()

        context = CodemodContext()
        tree = cst.parse_module(source)
        new_tree = UintLenToUlen(context).transform_module(tree)
        new_source = new_tree.code

        if new_source != source:
            path.write_text(new_source)
            print(f"  Modified: {path}")


if __name__ == "__main__":
    main()

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[codecov]

Codecov Report

❌ Patch coverage is 95.83333% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.35%. Comparing base (c1d8f42) to head (58a1584).

Files with missing lines	Patch %	Lines
src/ethereum/forks/amsterdam/block_access_lists.py	50.00%	1 Missing ⚠️
...orks/frontier/vm/precompiled_contracts/identity.py	50.00%	1 Missing ⚠️
.../forks/frontier/vm/precompiled_contracts/sha256.py	50.00%	1 Missing ⚠️
...rks/homestead/vm/precompiled_contracts/identity.py	50.00%	1 Missing ⚠️
...forks/homestead/vm/precompiled_contracts/sha256.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff                @@
##           forks/amsterdam    #2580   +/-   ##
================================================
  Coverage            86.35%   86.35%           
================================================
  Files                  599      599           
  Lines                36904    36904           
  Branches              3771     3771           
================================================
  Hits                 31868    31868           
  Misses                4485     4485           
  Partials               551      551           

Flag	Coverage Δ
unittests	86.35% <95.83%> (ø)

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