OCamlLex 不区分大小写

Question

有没有办法在 Ocamllex 规范中使用区分大小写的 token ？
我已经尝试以这种方式制作不区分大小写的 token :

let token = parser
    ...
   | ['C''c']['A''a']['S''s']['E''e'] { CASE }
    ...

但我正在寻找其他东西，如果存在的话。

Answer 1

使用接受小写和大写的普通标记词法分析器，并在表中查找关键字，忽略大小写:

{
type token = Case | Test | Ident of string

let keyword_tbl = Hashtbl.create 64

let _ = List.iter (fun (name, keyword) ->
    Hashtbl.add keyword_tbl name keyword) [
    "case", Case;
    "test", Test;
  ]
}

let ident_char = ['a'-'z' 'A'-'Z' '_']

rule next_token = parse
  | ident_char+ as s {
      let canon = String.lowercase s in
      try Hashtbl.find keyword_tbl canon
      with Not_found ->
        (* `Ident canon` if you want case-insensitive vars as well
         * as keywords *)
        Ident s
    }