libc/src/string/strcasestr.cpp

   1 //===-- Implementation of strcasestr --------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/string/strcasestr.h"
  10
  11 #include "src/__support/common.h"
  12 #include "src/__support/ctype_utils.h"
  13 #include "src/__support/macros/config.h"
  14 #include "src/string/memory_utils/inline_strstr.h"
  15
  16 namespace LIBC_NAMESPACE_DECL {
  17
  18 // TODO: This is a simple brute force implementation. This can be
  19 // improved upon using well known string matching algorithms.
  20 LLVM_LIBC_FUNCTION(char *, strcasestr,
  21                    (const char *haystack, const char *needle)) {
  22   auto case_cmp = [](char a, char b) {
  23     return LIBC_NAMESPACE::internal::tolower(a) -
  24            LIBC_NAMESPACE::internal::tolower(b);
  25   };
  26   return inline_strstr(haystack, needle, case_cmp);
  27 }
  28
  29 } // namespace LIBC_NAMESPACE_DECL