147 lines
5.6 KiB
C++
147 lines
5.6 KiB
C++
//
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// These routines provide mem versions of standard C string routines,
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// such as strpbrk. They function exactly the same as the str versions,
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// so if you wonder what they are, replace the word "mem" by
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// "str" and check out the man page. I could return void*, as the
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// strutil.h mem*() routines tend to do, but I return char* instead
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// since this is by far the most common way these functions are called.
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//
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// The difference between the mem and str versions is the mem version
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// takes a pointer and a length, rather than a '\0'-terminated string.
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// The memcase* routines defined here assume the locale is "C"
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// (they use absl::ascii_tolower instead of tolower).
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//
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// These routines are based on the BSD library.
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//
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// Here's a list of routines from string.h, and their mem analogues.
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// Functions in lowercase are defined in string.h; those in UPPERCASE
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// are defined here:
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//
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// strlen --
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// strcat strncat MEMCAT
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// strcpy strncpy memcpy
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// -- memccpy (very cool function, btw)
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// -- memmove
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// -- memset
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// strcmp strncmp memcmp
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// strcasecmp strncasecmp MEMCASECMP
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// strchr memchr
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// strcoll --
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// strxfrm --
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// strdup strndup MEMDUP
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// strrchr MEMRCHR
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// strspn MEMSPN
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// strcspn MEMCSPN
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// strpbrk MEMPBRK
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// strstr MEMSTR MEMMEM
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// (g)strcasestr MEMCASESTR MEMCASEMEM
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// strtok --
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// strprefix MEMPREFIX (strprefix is from strutil.h)
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// strcaseprefix MEMCASEPREFIX (strcaseprefix is from strutil.h)
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// strsuffix MEMSUFFIX (strsuffix is from strutil.h)
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// strcasesuffix MEMCASESUFFIX (strcasesuffix is from strutil.h)
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// -- MEMIS
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// -- MEMCASEIS
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// strcount MEMCOUNT (strcount is from strutil.h)
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#ifndef ABSL_STRINGS_INTERNAL_MEMUTIL_H_
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#define ABSL_STRINGS_INTERNAL_MEMUTIL_H_
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#include <cstddef>
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#include <cstring>
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#include "absl/base/port.h" // disable some warnings on Windows
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#include "absl/strings/ascii.h" // for absl::ascii_tolower
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namespace absl {
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namespace strings_internal {
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inline char* memcat(char* dest, size_t destlen, const char* src,
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size_t srclen) {
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return reinterpret_cast<char*>(memcpy(dest + destlen, src, srclen));
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}
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int memcasecmp(const char* s1, const char* s2, size_t len);
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char* memdup(const char* s, size_t slen);
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char* memrchr(const char* s, int c, size_t slen);
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size_t memspn(const char* s, size_t slen, const char* accept);
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size_t memcspn(const char* s, size_t slen, const char* reject);
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char* mempbrk(const char* s, size_t slen, const char* accept);
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// This is for internal use only. Don't call this directly
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template <bool case_sensitive>
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const char* int_memmatch(const char* haystack, size_t haylen,
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const char* needle, size_t neelen) {
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if (0 == neelen) {
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return haystack; // even if haylen is 0
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}
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const char* hayend = haystack + haylen;
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const char* needlestart = needle;
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const char* needleend = needlestart + neelen;
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for (; haystack < hayend; ++haystack) {
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char hay = case_sensitive
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? *haystack
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: absl::ascii_tolower(static_cast<unsigned char>(*haystack));
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char nee = case_sensitive
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? *needle
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: absl::ascii_tolower(static_cast<unsigned char>(*needle));
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if (hay == nee) {
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if (++needle == needleend) {
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return haystack + 1 - neelen;
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}
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} else if (needle != needlestart) {
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// must back up haystack in case a prefix matched (find "aab" in "aaab")
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haystack -= needle - needlestart; // for loop will advance one more
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needle = needlestart;
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}
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}
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return nullptr;
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}
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// These are the guys you can call directly
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inline const char* memstr(const char* phaystack, size_t haylen,
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const char* pneedle) {
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return int_memmatch<true>(phaystack, haylen, pneedle, strlen(pneedle));
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}
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inline const char* memcasestr(const char* phaystack, size_t haylen,
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const char* pneedle) {
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return int_memmatch<false>(phaystack, haylen, pneedle, strlen(pneedle));
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}
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inline const char* memmem(const char* phaystack, size_t haylen,
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const char* pneedle, size_t needlelen) {
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return int_memmatch<true>(phaystack, haylen, pneedle, needlelen);
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}
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inline const char* memcasemem(const char* phaystack, size_t haylen,
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const char* pneedle, size_t needlelen) {
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return int_memmatch<false>(phaystack, haylen, pneedle, needlelen);
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}
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// This is significantly faster for case-sensitive matches with very
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// few possible matches. See unit test for benchmarks.
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const char* memmatch(const char* phaystack, size_t haylen, const char* pneedle,
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size_t neelen);
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} // namespace strings_internal
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} // namespace absl
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#endif // ABSL_STRINGS_INTERNAL_MEMUTIL_H_
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