--- /dev/null
+"""
+Formatting numeric literals.
+"""
+from blib2to3.pytree import Leaf
+
+
+def format_hex(text: str) -> str:
+ """
+ Formats a hexadecimal string like "0x12B3"
+ """
+ before, after = text[:2], text[2:]
+ return f"{before}{after.upper()}"
+
+
+def format_scientific_notation(text: str) -> str:
+ """Formats a numeric string utilizing scentific notation"""
+ before, after = text.split("e")
+ sign = ""
+ if after.startswith("-"):
+ after = after[1:]
+ sign = "-"
+ elif after.startswith("+"):
+ after = after[1:]
+ before = format_float_or_int_string(before)
+ return f"{before}e{sign}{after}"
+
+
+def format_long_or_complex_number(text: str) -> str:
+ """Formats a long or complex string like `10L` or `10j`"""
+ number = text[:-1]
+ suffix = text[-1]
+ # Capitalize in "2L" because "l" looks too similar to "1".
+ if suffix == "l":
+ suffix = "L"
+ return f"{format_float_or_int_string(number)}{suffix}"
+
+
+def format_float_or_int_string(text: str) -> str:
+ """Formats a float string like "1.0"."""
+ if "." not in text:
+ return text
+
+ before, after = text.split(".")
+ return f"{before or 0}.{after or 0}"
+
+
+def normalize_numeric_literal(leaf: Leaf) -> None:
+ """Normalizes numeric (float, int, and complex) literals.
+
+ All letters used in the representation are normalized to lowercase (except
+ in Python 2 long literals).
+ """
+ text = leaf.value.lower()
+ if text.startswith(("0o", "0b")):
+ # Leave octal and binary literals alone.
+ pass
+ elif text.startswith("0x"):
+ text = format_hex(text)
+ elif "e" in text:
+ text = format_scientific_notation(text)
+ elif text.endswith(("j", "l")):
+ text = format_long_or_complex_number(text)
+ else:
+ text = format_float_or_int_string(text)
+ leaf.value = text