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
19namespace absl {
20namespace strings_internal {
21
22int memcasecmp(const char* s1, const char* s2, size_t len) {
23 const unsigned char* us1 = reinterpret_cast<const unsigned char*>(s1);
24 const unsigned char* us2 = reinterpret_cast<const unsigned char*>(s2);
25
26 for (size_t i = 0; i < len; i++) {
27 const int diff =
28 int{static_cast<unsigned char>(absl::ascii_tolower(us1[i]))} -
29 int{static_cast<unsigned char>(absl::ascii_tolower(us2[i]))};
30 if (diff != 0) return diff;
31 }
32 return 0;
33}
34
35char* memdup(const char* s, size_t slen) {
36 void* copy;
37 if ((copy = malloc(slen)) == nullptr) return nullptr;
38 memcpy(copy, s, slen);
39 return reinterpret_cast<char*>(copy);
40}
41
42char* memrchr(const char* s, int c, size_t slen) {
43 for (const char* e = s + slen - 1; e >= s; e--) {
44 if (*e == c) return const_cast<char*>(e);
45 }
46 return nullptr;
47}
48
49size_t memspn(const char* s, size_t slen, const char* accept) {
50 const char* p = s;
51 const char* spanp;
52 char c, sc;
53
54cont:
55 c = *p++;
56 if (slen-- == 0) return p - 1 - s;
57 for (spanp = accept; (sc = *spanp++) != '\0';)
58 if (sc == c) goto cont;
59 return p - 1 - s;
60}
61
62size_t memcspn(const char* s, size_t slen, const char* reject) {
63 const char* p = s;
64 const char* spanp;
65 char c, sc;
66
67 while (slen-- != 0) {
68 c = *p++;
69 for (spanp = reject; (sc = *spanp++) != '\0';)
70 if (sc == c) return p - 1 - s;
71 }
72 return p - s;
73}
74
75char* mempbrk(const char* s, size_t slen, const char* accept) {
76 const char* scanp;
77 int sc;
78
79 for (; slen; ++s, --slen) {
80 for (scanp = accept; (sc = *scanp++) != '\0';)
81 if (sc == *s) return const_cast<char*>(s);
82 }
83 return nullptr;
84}
85
86// This is significantly faster for case-sensitive matches with very
87// few possible matches. See unit test for benchmarks.
88const char* memmatch(const char* phaystack, size_t haylen, const char* pneedle,
89 size_t neelen) {
90 if (0 == neelen) {
91 return phaystack; // even if haylen is 0
92 }
93 if (haylen < neelen) return nullptr;
94
95 const char* match;
96 const char* hayend = phaystack + haylen - neelen + 1;
97 // A static cast is used here to work around the fact that memchr returns
98 // a void* on Posix-compliant systems and const void* on Windows.
99 while ((match = static_cast<const char*>(
100 memchr(phaystack, pneedle[0], hayend - phaystack)))) {
101 if (memcmp(match, pneedle, neelen) == 0)
102 return match;
103 else
104 phaystack = match + 1;
105 }
106 return nullptr;
107}
108
109} // namespace strings_internal
110} // namespace absl
111