helm/software/matita/contribs/assembly/string/string.ma

   1 (**************************************************************************)
   2 (*       ___                                                              *)
   3 (*      ||M||                                                             *)
   4 (*      ||A||       A project by Andrea Asperti                           *)
   5 (*      ||T||                                                             *)
   6 (*      ||I||       Developers:                                           *)
   7 (*      ||T||         The HELM team.                                      *)
   8 (*      ||A||         http://helm.cs.unibo.it                             *)
   9 (*      \   /                                                             *)
  10 (*       \ /        This file is distributed under the terms of the       *)
  11 (*        v         GNU General Public License Version 2                  *)
  12 (*                                                                        *)
  13 (**************************************************************************)
  14
  15 (* ********************************************************************** *)
  16 (*                                                                        *)
  17 (* Sviluppato da:                                                         *)
  18 (*   Cosimo Oliboni, oliboni@cs.unibo.it                                  *)
  19 (*                                                                        *)
  20 (* ********************************************************************** *)
  21
  22 include "string/ascii_min.ma".
  23 include "compiler/utility.ma".
  24
  25 (* ************************ *)
  26 (* MANIPOLAZIONE DI STRINGA *)
  27 (* ************************ *)
  28
  29 (* tipo pubblico *)
  30 definition aux_str_type ≝ list ascii_min.
  31
  32 (* empty string *)
  33 definition empty_str ≝ nil ascii_min.
  34
  35 (* is empty ? *)
  36 definition isNull_str ≝
  37 λstr:aux_str_type.match str with
  38  [ nil ⇒ true | cons _ _ ⇒ false ].
  39
  40 (* strcmp *)
  41 let rec strCmp_str (str,str':aux_str_type) ≝
  42  match str with
  43   [ nil ⇒ match str' with
  44    [ nil ⇒ true | cons _ _ ⇒ false ]
  45   | cons h t ⇒ match str' with
  46    [ nil ⇒ false
  47    | cons h' t' ⇒ match eqAsciiMin h h' with
  48     [ true ⇒ strCmp_str t t' | false ⇒ false ]
  49   ]].
  50
  51 (* strcat *)
  52 definition strCat_str ≝
  53 λstr,str':aux_str_type.str@str'.
  54
  55 (* strlen *)
  56 definition strLen_str ≝ λstr:aux_str_type.len_list ? str.