(** Shared string utility functions.

    Centralizes whitespace handling to avoid duplication across prescan, lexer,
    and normalization modules. *)

(** Strip leading whitespace (spaces and tabs). *)
let lstrip s =
  let len = String.length s in
  let i = ref 0 in
  while !i < len && (s.[!i] = ' ' || s.[!i] = '\t') do
    incr i
  done;
  if !i = 0 then s else String.sub s !i (len - !i)

(** Strip trailing whitespace (spaces, tabs, and carriage returns). *)
let rstrip s =
  let len = String.length s in
  let i = ref (len - 1) in
  while !i >= 0 && (s.[!i] = ' ' || s.[!i] = '\t' || s.[!i] = '\r') do
    decr i
  done;
  if !i = len - 1 then s else String.sub s 0 (!i + 1)

(** Strip both leading and trailing whitespace. *)
let strip s = lstrip (rstrip s)