1 //===-- String utils --------------------------------------------*- C++ -*-===//
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 #ifndef LIBC_SRC_STRING_STRING_UTILS_H
10 #define LIBC_SRC_STRING_STRING_UTILS_H
11 
12 #include "utils/CPP/Bitset.h"
13 #include <stddef.h> // size_t
14 
15 namespace __llvm_libc {
16 namespace internal {
17 
18 // Returns the maximum length span that contains only characters not found in
19 // 'segment'. If no characters are found, returns the length of 'src'.
20 static inline size_t complementary_span(const char *src, const char *segment) {
21   const char *initial = src;
22   cpp::Bitset<256> bitset;
23 
24   for (; *segment; ++segment)
25     bitset.set(*segment);
26   for (; *src && !bitset.test(*src); ++src)
27     ;
28   return src - initial;
29 }
30 
31 // Given the similarities between strtok and strtok_r, we can implement both
32 // using a utility function. On the first call, 'src' is scanned for the
33 // first character not found in 'delimiter_string'. Once found, it scans until
34 // the first character in the 'delimiter_string' or the null terminator is
35 // found. We define this span as a token. The end of the token is appended with
36 // a null terminator, and the token is returned. The point where the last token
37 // is found is then stored within 'context' for subsequent calls. Subsequent
38 // calls will use 'context' when a nullptr is passed in for 'src'. Once the null
39 // terminating character is reached, returns a nullptr.
40 static inline char *string_token(char *__restrict src,
41                                  const char *__restrict delimiter_string,
42                                  char **__restrict saveptr) {
43   cpp::Bitset<256> delimiter_set;
44   for (; *delimiter_string; ++delimiter_string)
45     delimiter_set.set(*delimiter_string);
46 
47   src = src ? src : *saveptr;
48   for (; *src && delimiter_set.test(*src); ++src)
49     ;
50   if (!*src) {
51     *saveptr = src;
52     return nullptr;
53   }
54   char *token = src;
55   for (; *src && !delimiter_set.test(*src); ++src)
56     ;
57   if (*src) {
58     *src = '\0';
59     ++src;
60   }
61   *saveptr = src;
62   return token;
63 }
64 
65 } // namespace internal
66 } // namespace __llvm_libc
67 
68 #endif //  LIBC_SRC_STRING_STRING_UTILS_H
69