def joined_string(fmt_call: ast.Call) -> ast.JoinedStr:
""" Transform a "...".format() call node into a f-string node. """
string = fmt_call.func.value.s
var_map = {kw.arg: kw.value for kw in fmt_call.keywords}
for i, val in enumerate(fmt_call.args):
var_map[i] = val
splits = deque(stdlib_parse(string))
seq_ctr = 0
new_segments = []
manual_field_ordering = False
for raw, var_name, fmt_str, conversion in splits:
if raw:
new_segments.append(ast_string_node(raw))
if var_name is None:
continue
if "[" in var_name:
raise FlyntException(
f"Skipping f-stringify of a fmt call with indexed name {var_name}"
)
suffix = ""
if "." in var_name:
idx = var_name.find(".")
var_name, suffix = var_name[:idx], var_name[idx + 1 :]
if var_name.isdigit():
manual_field_ordering = True
identifier = int(var_name)
elif len(var_name) == 0:
assert not manual_field_ordering
identifier = seq_ctr
seq_ctr += 1
else:
identifier = var_name
try:
ast_name = var_map.pop(identifier)
except KeyError as e:
raise ConversionRefused(
f"A variable {identifier} is used multiple times - better not to replace it."
) from e
if suffix:
ast_name = ast.Attribute(value=ast_name, attr=suffix)
new_segments.append(ast_formatted_value(ast_name, fmt_str, conversion))
if var_map:
raise FlyntException(
f"Some variables were never used: {var_map} - skipping conversion, it's a risk of bug."
)
def is_literal_string(node):
if sys.version_info < (3, 8):
return isinstance(node, ast.Str)
else:
return (isinstance(node, ast.Constant) and
isinstance(node.value, str))
def literal_string_value(node):
if sys.version_info < (3, 8):
return node.s
else:
return node.value
def fix_literals(segment):
if (isinstance(segment, ast.FormattedValue) and
segment.format_spec is None and
is_literal_string(segment.value)):
return segment.value
return segment
new_segments = [fix_literals(e) for e in new_segments]
if all(is_literal_string(segment)
for segment in new_segments):
return ast.Str(''.join(literal_string_value(segment) for segment in new_segments))
return ast.JoinedStr(new_segments)