1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/strings/internal/memutil.h"
16
17 #include <cstdlib>
18
19 namespace absl {
20 ABSL_NAMESPACE_BEGIN
21 namespace strings_internal {
22
memcasecmp(const char * s1,const char * s2,size_t len)23 int memcasecmp(const char* s1, const char* s2, size_t len) {
24 const unsigned char* us1 = reinterpret_cast<const unsigned char*>(s1);
25 const unsigned char* us2 = reinterpret_cast<const unsigned char*>(s2);
26
27 for (size_t i = 0; i < len; i++) {
28 const int diff =
29 int{static_cast<unsigned char>(absl::ascii_tolower(us1[i]))} -
30 int{static_cast<unsigned char>(absl::ascii_tolower(us2[i]))};
31 if (diff != 0) return diff;
32 }
33 return 0;
34 }
35
memdup(const char * s,size_t slen)36 char* memdup(const char* s, size_t slen) {
37 void* copy;
38 if ((copy = malloc(slen)) == nullptr) return nullptr;
39 memcpy(copy, s, slen);
40 return reinterpret_cast<char*>(copy);
41 }
42
memrchr(const char * s,int c,size_t slen)43 char* memrchr(const char* s, int c, size_t slen) {
44 for (const char* e = s + slen - 1; e >= s; e--) {
45 if (*e == c) return const_cast<char*>(e);
46 }
47 return nullptr;
48 }
49
memspn(const char * s,size_t slen,const char * accept)50 size_t memspn(const char* s, size_t slen, const char* accept) {
51 const char* p = s;
52 const char* spanp;
53 char c, sc;
54
55 cont:
56 c = *p++;
57 if (slen-- == 0)
58 return static_cast<size_t>(p - 1 - s);
59 for (spanp = accept; (sc = *spanp++) != '\0';)
60 if (sc == c) goto cont;
61 return static_cast<size_t>(p - 1 - s);
62 }
63
memcspn(const char * s,size_t slen,const char * reject)64 size_t memcspn(const char* s, size_t slen, const char* reject) {
65 const char* p = s;
66 const char* spanp;
67 char c, sc;
68
69 while (slen-- != 0) {
70 c = *p++;
71 for (spanp = reject; (sc = *spanp++) != '\0';)
72 if (sc == c)
73 return static_cast<size_t>(p - 1 - s);
74 }
75 return static_cast<size_t>(p - s);
76 }
77
mempbrk(const char * s,size_t slen,const char * accept)78 char* mempbrk(const char* s, size_t slen, const char* accept) {
79 const char* scanp;
80 int sc;
81
82 for (; slen; ++s, --slen) {
83 for (scanp = accept; (sc = *scanp++) != '\0';)
84 if (sc == *s) return const_cast<char*>(s);
85 }
86 return nullptr;
87 }
88
89 // This is significantly faster for case-sensitive matches with very
90 // few possible matches. See unit test for benchmarks.
memmatch(const char * phaystack,size_t haylen,const char * pneedle,size_t neelen)91 const char* memmatch(const char* phaystack, size_t haylen, const char* pneedle,
92 size_t neelen) {
93 if (0 == neelen) {
94 return phaystack; // even if haylen is 0
95 }
96 if (haylen < neelen) return nullptr;
97
98 const char* match;
99 const char* hayend = phaystack + haylen - neelen + 1;
100 // A static cast is used here to work around the fact that memchr returns
101 // a void* on Posix-compliant systems and const void* on Windows.
102 while (
103 (match = static_cast<const char*>(memchr(
104 phaystack, pneedle[0], static_cast<size_t>(hayend - phaystack))))) {
105 if (memcmp(match, pneedle, neelen) == 0)
106 return match;
107 else
108 phaystack = match + 1;
109 }
110 return nullptr;
111 }
112
113 } // namespace strings_internal
114 ABSL_NAMESPACE_END
115 } // namespace absl
116