class UnnecessaryFormatString(VisitorBasedCodemodCommand):
DESCRIPTION: str = "Converts f-strings which perform no formatting to regular strings."
@m.leave(m.FormattedString(parts=(m.FormattedStringText(), )))
def _check_formatted_string(
self,
_original_node: libcst.FormattedString,
updated_node: libcst.FormattedString,
) -> libcst.BaseExpression:
old_string_inner = libcst.ensure_type(updated_node.parts[0],
libcst.FormattedStringText).value
if "{{" in old_string_inner or "}}" in old_string_inner:
# there are only two characters we need to worry about escaping.
return updated_node
old_string_literal = updated_node.start + old_string_inner + updated_node.end
new_string_literal = (
updated_node.start.replace("f", "").replace("F", "") +
old_string_inner + updated_node.end)
old_string_evaled = eval(old_string_literal) # noqa
new_string_evaled = eval(new_string_literal) # noqa
if old_string_evaled != new_string_evaled:
warn_message = (
f"Attempted to codemod |{old_string_literal}| to " +
f"|{new_string_literal}| but don't eval to the same! First is |{old_string_evaled}| and "
+ f"second is |{new_string_evaled}|")
self.warn(warn_message)
return updated_node
return libcst.SimpleString(new_string_literal)
def visit_FormattedString(self, node: cst.FormattedString) -> None:
if not m.matches(node, m.FormattedString(parts=(m.FormattedStringText(),))):
return
old_string_inner = cst.ensure_type(node.parts[0], cst.FormattedStringText).value
if "{{" in old_string_inner or "}}" in old_string_inner:
old_string_inner = old_string_inner.replace("{{", "{").replace("}}", "}")
new_string_literal = node.start.replace("f", "").replace("F", "") + old_string_inner + node.end
self.report(node, replacement=cst.SimpleString(new_string_literal))