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Diffstat (limited to 'third_party/abseil_cpp/absl/strings/string_view.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/strings/string_view.h | 629 |
1 files changed, 0 insertions, 629 deletions
diff --git a/third_party/abseil_cpp/absl/strings/string_view.h b/third_party/abseil_cpp/absl/strings/string_view.h deleted file mode 100644 index 5260b5b73f47..000000000000 --- a/third_party/abseil_cpp/absl/strings/string_view.h +++ /dev/null @@ -1,629 +0,0 @@ -// -// Copyright 2017 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. -// -// ----------------------------------------------------------------------------- -// File: string_view.h -// ----------------------------------------------------------------------------- -// -// This file contains the definition of the `absl::string_view` class. A -// `string_view` points to a contiguous span of characters, often part or all of -// another `std::string`, double-quoted string literal, character array, or even -// another `string_view`. -// -// This `absl::string_view` abstraction is designed to be a drop-in -// replacement for the C++17 `std::string_view` abstraction. -#ifndef ABSL_STRINGS_STRING_VIEW_H_ -#define ABSL_STRINGS_STRING_VIEW_H_ - -#include <algorithm> -#include <cassert> -#include <cstddef> -#include <cstring> -#include <iosfwd> -#include <iterator> -#include <limits> -#include <string> - -#include "absl/base/config.h" -#include "absl/base/internal/throw_delegate.h" -#include "absl/base/macros.h" -#include "absl/base/optimization.h" -#include "absl/base/port.h" - -#ifdef ABSL_USES_STD_STRING_VIEW - -#include <string_view> // IWYU pragma: export - -namespace absl { -ABSL_NAMESPACE_BEGIN -using string_view = std::string_view; -ABSL_NAMESPACE_END -} // namespace absl - -#else // ABSL_USES_STD_STRING_VIEW - -#if ABSL_HAVE_BUILTIN(__builtin_memcmp) || \ - (defined(__GNUC__) && !defined(__clang__)) -#define ABSL_INTERNAL_STRING_VIEW_MEMCMP __builtin_memcmp -#else // ABSL_HAVE_BUILTIN(__builtin_memcmp) -#define ABSL_INTERNAL_STRING_VIEW_MEMCMP memcmp -#endif // ABSL_HAVE_BUILTIN(__builtin_memcmp) - -namespace absl { -ABSL_NAMESPACE_BEGIN - -// absl::string_view -// -// A `string_view` provides a lightweight view into the string data provided by -// a `std::string`, double-quoted string literal, character array, or even -// another `string_view`. A `string_view` does *not* own the string to which it -// points, and that data cannot be modified through the view. -// -// You can use `string_view` as a function or method parameter anywhere a -// parameter can receive a double-quoted string literal, `const char*`, -// `std::string`, or another `absl::string_view` argument with no need to copy -// the string data. Systematic use of `string_view` within function arguments -// reduces data copies and `strlen()` calls. -// -// Because of its small size, prefer passing `string_view` by value: -// -// void MyFunction(absl::string_view arg); -// -// If circumstances require, you may also pass one by const reference: -// -// void MyFunction(const absl::string_view& arg); // not preferred -// -// Passing by value generates slightly smaller code for many architectures. -// -// In either case, the source data of the `string_view` must outlive the -// `string_view` itself. -// -// A `string_view` is also suitable for local variables if you know that the -// lifetime of the underlying object is longer than the lifetime of your -// `string_view` variable. However, beware of binding a `string_view` to a -// temporary value: -// -// // BAD use of string_view: lifetime problem -// absl::string_view sv = obj.ReturnAString(); -// -// // GOOD use of string_view: str outlives sv -// std::string str = obj.ReturnAString(); -// absl::string_view sv = str; -// -// Due to lifetime issues, a `string_view` is sometimes a poor choice for a -// return value and usually a poor choice for a data member. If you do use a -// `string_view` this way, it is your responsibility to ensure that the object -// pointed to by the `string_view` outlives the `string_view`. -// -// A `string_view` may represent a whole string or just part of a string. For -// example, when splitting a string, `std::vector<absl::string_view>` is a -// natural data type for the output. -// -// For another example, a Cord is a non-contiguous, potentially very -// long string-like object. The Cord class has an interface that iteratively -// provides string_view objects that point to the successive pieces of a Cord -// object. -// -// When constructed from a source which is NUL-terminated, the `string_view` -// itself will not include the NUL-terminator unless a specific size (including -// the NUL) is passed to the constructor. As a result, common idioms that work -// on NUL-terminated strings do not work on `string_view` objects. If you write -// code that scans a `string_view`, you must check its length rather than test -// for nul, for example. Note, however, that nuls may still be embedded within -// a `string_view` explicitly. -// -// You may create a null `string_view` in two ways: -// -// absl::string_view sv; -// absl::string_view sv(nullptr, 0); -// -// For the above, `sv.data() == nullptr`, `sv.length() == 0`, and -// `sv.empty() == true`. Also, if you create a `string_view` with a non-null -// pointer then `sv.data() != nullptr`. Thus, you can use `string_view()` to -// signal an undefined value that is different from other `string_view` values -// in a similar fashion to how `const char* p1 = nullptr;` is different from -// `const char* p2 = "";`. However, in practice, it is not recommended to rely -// on this behavior. -// -// Be careful not to confuse a null `string_view` with an empty one. A null -// `string_view` is an empty `string_view`, but some empty `string_view`s are -// not null. Prefer checking for emptiness over checking for null. -// -// There are many ways to create an empty string_view: -// -// const char* nullcp = nullptr; -// // string_view.size() will return 0 in all cases. -// absl::string_view(); -// absl::string_view(nullcp, 0); -// absl::string_view(""); -// absl::string_view("", 0); -// absl::string_view("abcdef", 0); -// absl::string_view("abcdef" + 6, 0); -// -// All empty `string_view` objects whether null or not, are equal: -// -// absl::string_view() == absl::string_view("", 0) -// absl::string_view(nullptr, 0) == absl::string_view("abcdef"+6, 0) -class string_view { - public: - using traits_type = std::char_traits<char>; - using value_type = char; - using pointer = char*; - using const_pointer = const char*; - using reference = char&; - using const_reference = const char&; - using const_iterator = const char*; - using iterator = const_iterator; - using const_reverse_iterator = std::reverse_iterator<const_iterator>; - using reverse_iterator = const_reverse_iterator; - using size_type = size_t; - using difference_type = std::ptrdiff_t; - - static constexpr size_type npos = static_cast<size_type>(-1); - - // Null `string_view` constructor - constexpr string_view() noexcept : ptr_(nullptr), length_(0) {} - - // Implicit constructors - - template <typename Allocator> - string_view( // NOLINT(runtime/explicit) - const std::basic_string<char, std::char_traits<char>, Allocator>& - str) noexcept - // This is implemented in terms of `string_view(p, n)` so `str.size()` - // doesn't need to be reevaluated after `ptr_` is set. - : string_view(str.data(), str.size()) {} - - // Implicit constructor of a `string_view` from NUL-terminated `str`. When - // accepting possibly null strings, use `absl::NullSafeStringView(str)` - // instead (see below). - constexpr string_view(const char* str) // NOLINT(runtime/explicit) - : ptr_(str), - length_(str ? CheckLengthInternal(StrlenInternal(str)) : 0) {} - - // Implicit constructor of a `string_view` from a `const char*` and length. - constexpr string_view(const char* data, size_type len) - : ptr_(data), length_(CheckLengthInternal(len)) {} - - // NOTE: Harmlessly omitted to work around gdb bug. - // constexpr string_view(const string_view&) noexcept = default; - // string_view& operator=(const string_view&) noexcept = default; - - // Iterators - - // string_view::begin() - // - // Returns an iterator pointing to the first character at the beginning of the - // `string_view`, or `end()` if the `string_view` is empty. - constexpr const_iterator begin() const noexcept { return ptr_; } - - // string_view::end() - // - // Returns an iterator pointing just beyond the last character at the end of - // the `string_view`. This iterator acts as a placeholder; attempting to - // access it results in undefined behavior. - constexpr const_iterator end() const noexcept { return ptr_ + length_; } - - // string_view::cbegin() - // - // Returns a const iterator pointing to the first character at the beginning - // of the `string_view`, or `end()` if the `string_view` is empty. - constexpr const_iterator cbegin() const noexcept { return begin(); } - - // string_view::cend() - // - // Returns a const iterator pointing just beyond the last character at the end - // of the `string_view`. This pointer acts as a placeholder; attempting to - // access its element results in undefined behavior. - constexpr const_iterator cend() const noexcept { return end(); } - - // string_view::rbegin() - // - // Returns a reverse iterator pointing to the last character at the end of the - // `string_view`, or `rend()` if the `string_view` is empty. - const_reverse_iterator rbegin() const noexcept { - return const_reverse_iterator(end()); - } - - // string_view::rend() - // - // Returns a reverse iterator pointing just before the first character at the - // beginning of the `string_view`. This pointer acts as a placeholder; - // attempting to access its element results in undefined behavior. - const_reverse_iterator rend() const noexcept { - return const_reverse_iterator(begin()); - } - - // string_view::crbegin() - // - // Returns a const reverse iterator pointing to the last character at the end - // of the `string_view`, or `crend()` if the `string_view` is empty. - const_reverse_iterator crbegin() const noexcept { return rbegin(); } - - // string_view::crend() - // - // Returns a const reverse iterator pointing just before the first character - // at the beginning of the `string_view`. This pointer acts as a placeholder; - // attempting to access its element results in undefined behavior. - const_reverse_iterator crend() const noexcept { return rend(); } - - // Capacity Utilities - - // string_view::size() - // - // Returns the number of characters in the `string_view`. - constexpr size_type size() const noexcept { - return length_; - } - - // string_view::length() - // - // Returns the number of characters in the `string_view`. Alias for `size()`. - constexpr size_type length() const noexcept { return size(); } - - // string_view::max_size() - // - // Returns the maximum number of characters the `string_view` can hold. - constexpr size_type max_size() const noexcept { return kMaxSize; } - - // string_view::empty() - // - // Checks if the `string_view` is empty (refers to no characters). - constexpr bool empty() const noexcept { return length_ == 0; } - - // string_view::operator[] - // - // Returns the ith element of the `string_view` using the array operator. - // Note that this operator does not perform any bounds checking. - constexpr const_reference operator[](size_type i) const { - return ABSL_HARDENING_ASSERT(i < size()), ptr_[i]; - } - - // string_view::at() - // - // Returns the ith element of the `string_view`. Bounds checking is performed, - // and an exception of type `std::out_of_range` will be thrown on invalid - // access. - constexpr const_reference at(size_type i) const { - return ABSL_PREDICT_TRUE(i < size()) - ? ptr_[i] - : ((void)base_internal::ThrowStdOutOfRange( - "absl::string_view::at"), - ptr_[i]); - } - - // string_view::front() - // - // Returns the first element of a `string_view`. - constexpr const_reference front() const { - return ABSL_HARDENING_ASSERT(!empty()), ptr_[0]; - } - - // string_view::back() - // - // Returns the last element of a `string_view`. - constexpr const_reference back() const { - return ABSL_HARDENING_ASSERT(!empty()), ptr_[size() - 1]; - } - - // string_view::data() - // - // Returns a pointer to the underlying character array (which is of course - // stored elsewhere). Note that `string_view::data()` may contain embedded nul - // characters, but the returned buffer may or may not be NUL-terminated; - // therefore, do not pass `data()` to a routine that expects a NUL-terminated - // string. - constexpr const_pointer data() const noexcept { return ptr_; } - - // Modifiers - - // string_view::remove_prefix() - // - // Removes the first `n` characters from the `string_view`. Note that the - // underlying string is not changed, only the view. - void remove_prefix(size_type n) { - ABSL_HARDENING_ASSERT(n <= length_); - ptr_ += n; - length_ -= n; - } - - // string_view::remove_suffix() - // - // Removes the last `n` characters from the `string_view`. Note that the - // underlying string is not changed, only the view. - void remove_suffix(size_type n) { - ABSL_HARDENING_ASSERT(n <= length_); - length_ -= n; - } - - // string_view::swap() - // - // Swaps this `string_view` with another `string_view`. - void swap(string_view& s) noexcept { - auto t = *this; - *this = s; - s = t; - } - - // Explicit conversion operators - - // Converts to `std::basic_string`. - template <typename A> - explicit operator std::basic_string<char, traits_type, A>() const { - if (!data()) return {}; - return std::basic_string<char, traits_type, A>(data(), size()); - } - - // string_view::copy() - // - // Copies the contents of the `string_view` at offset `pos` and length `n` - // into `buf`. - size_type copy(char* buf, size_type n, size_type pos = 0) const { - if (ABSL_PREDICT_FALSE(pos > length_)) { - base_internal::ThrowStdOutOfRange("absl::string_view::copy"); - } - size_type rlen = (std::min)(length_ - pos, n); - if (rlen > 0) { - const char* start = ptr_ + pos; - traits_type::copy(buf, start, rlen); - } - return rlen; - } - - // string_view::substr() - // - // Returns a "substring" of the `string_view` (at offset `pos` and length - // `n`) as another string_view. This function throws `std::out_of_bounds` if - // `pos > size`. - // Use absl::ClippedSubstr if you need a truncating substr operation. - constexpr string_view substr(size_type pos, size_type n = npos) const { - return ABSL_PREDICT_FALSE(pos > length_) - ? (base_internal::ThrowStdOutOfRange( - "absl::string_view::substr"), - string_view()) - : string_view(ptr_ + pos, Min(n, length_ - pos)); - } - - // string_view::compare() - // - // Performs a lexicographical comparison between the `string_view` and - // another `absl::string_view`, returning -1 if `this` is less than, 0 if - // `this` is equal to, and 1 if `this` is greater than the passed string - // view. Note that in the case of data equality, a further comparison is made - // on the respective sizes of the two `string_view`s to determine which is - // smaller, equal, or greater. - constexpr int compare(string_view x) const noexcept { - return CompareImpl(length_, x.length_, - Min(length_, x.length_) == 0 - ? 0 - : ABSL_INTERNAL_STRING_VIEW_MEMCMP( - ptr_, x.ptr_, Min(length_, x.length_))); - } - - // Overload of `string_view::compare()` for comparing a substring of the - // 'string_view` and another `absl::string_view`. - int compare(size_type pos1, size_type count1, string_view v) const { - return substr(pos1, count1).compare(v); - } - - // Overload of `string_view::compare()` for comparing a substring of the - // `string_view` and a substring of another `absl::string_view`. - int compare(size_type pos1, size_type count1, string_view v, size_type pos2, - size_type count2) const { - return substr(pos1, count1).compare(v.substr(pos2, count2)); - } - - // Overload of `string_view::compare()` for comparing a `string_view` and a - // a different C-style string `s`. - int compare(const char* s) const { return compare(string_view(s)); } - - // Overload of `string_view::compare()` for comparing a substring of the - // `string_view` and a different string C-style string `s`. - int compare(size_type pos1, size_type count1, const char* s) const { - return substr(pos1, count1).compare(string_view(s)); - } - - // Overload of `string_view::compare()` for comparing a substring of the - // `string_view` and a substring of a different C-style string `s`. - int compare(size_type pos1, size_type count1, const char* s, - size_type count2) const { - return substr(pos1, count1).compare(string_view(s, count2)); - } - - // Find Utilities - - // string_view::find() - // - // Finds the first occurrence of the substring `s` within the `string_view`, - // returning the position of the first character's match, or `npos` if no - // match was found. - size_type find(string_view s, size_type pos = 0) const noexcept; - - // Overload of `string_view::find()` for finding the given character `c` - // within the `string_view`. - size_type find(char c, size_type pos = 0) const noexcept; - - // string_view::rfind() - // - // Finds the last occurrence of a substring `s` within the `string_view`, - // returning the position of the first character's match, or `npos` if no - // match was found. - size_type rfind(string_view s, size_type pos = npos) const - noexcept; - - // Overload of `string_view::rfind()` for finding the last given character `c` - // within the `string_view`. - size_type rfind(char c, size_type pos = npos) const noexcept; - - // string_view::find_first_of() - // - // Finds the first occurrence of any of the characters in `s` within the - // `string_view`, returning the start position of the match, or `npos` if no - // match was found. - size_type find_first_of(string_view s, size_type pos = 0) const - noexcept; - - // Overload of `string_view::find_first_of()` for finding a character `c` - // within the `string_view`. - size_type find_first_of(char c, size_type pos = 0) const - noexcept { - return find(c, pos); - } - - // string_view::find_last_of() - // - // Finds the last occurrence of any of the characters in `s` within the - // `string_view`, returning the start position of the match, or `npos` if no - // match was found. - size_type find_last_of(string_view s, size_type pos = npos) const - noexcept; - - // Overload of `string_view::find_last_of()` for finding a character `c` - // within the `string_view`. - size_type find_last_of(char c, size_type pos = npos) const - noexcept { - return rfind(c, pos); - } - - // string_view::find_first_not_of() - // - // Finds the first occurrence of any of the characters not in `s` within the - // `string_view`, returning the start position of the first non-match, or - // `npos` if no non-match was found. - size_type find_first_not_of(string_view s, size_type pos = 0) const noexcept; - - // Overload of `string_view::find_first_not_of()` for finding a character - // that is not `c` within the `string_view`. - size_type find_first_not_of(char c, size_type pos = 0) const noexcept; - - // string_view::find_last_not_of() - // - // Finds the last occurrence of any of the characters not in `s` within the - // `string_view`, returning the start position of the last non-match, or - // `npos` if no non-match was found. - size_type find_last_not_of(string_view s, - size_type pos = npos) const noexcept; - - // Overload of `string_view::find_last_not_of()` for finding a character - // that is not `c` within the `string_view`. - size_type find_last_not_of(char c, size_type pos = npos) const - noexcept; - - private: - static constexpr size_type kMaxSize = - (std::numeric_limits<difference_type>::max)(); - - static constexpr size_type CheckLengthInternal(size_type len) { - return ABSL_HARDENING_ASSERT(len <= kMaxSize), len; - } - - static constexpr size_type StrlenInternal(const char* str) { -#if defined(_MSC_VER) && _MSC_VER >= 1910 && !defined(__clang__) - // MSVC 2017+ can evaluate this at compile-time. - const char* begin = str; - while (*str != '\0') ++str; - return str - begin; -#elif ABSL_HAVE_BUILTIN(__builtin_strlen) || \ - (defined(__GNUC__) && !defined(__clang__)) - // GCC has __builtin_strlen according to - // https://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Other-Builtins.html, but - // ABSL_HAVE_BUILTIN doesn't detect that, so we use the extra checks above. - // __builtin_strlen is constexpr. - return __builtin_strlen(str); -#else - return str ? strlen(str) : 0; -#endif - } - - static constexpr size_t Min(size_type length_a, size_type length_b) { - return length_a < length_b ? length_a : length_b; - } - - static constexpr int CompareImpl(size_type length_a, size_type length_b, - int compare_result) { - return compare_result == 0 ? static_cast<int>(length_a > length_b) - - static_cast<int>(length_a < length_b) - : (compare_result < 0 ? -1 : 1); - } - - const char* ptr_; - size_type length_; -}; - -// This large function is defined inline so that in a fairly common case where -// one of the arguments is a literal, the compiler can elide a lot of the -// following comparisons. -constexpr bool operator==(string_view x, string_view y) noexcept { - return x.size() == y.size() && - (x.empty() || - ABSL_INTERNAL_STRING_VIEW_MEMCMP(x.data(), y.data(), x.size()) == 0); -} - -constexpr bool operator!=(string_view x, string_view y) noexcept { - return !(x == y); -} - -constexpr bool operator<(string_view x, string_view y) noexcept { - return x.compare(y) < 0; -} - -constexpr bool operator>(string_view x, string_view y) noexcept { - return y < x; -} - -constexpr bool operator<=(string_view x, string_view y) noexcept { - return !(y < x); -} - -constexpr bool operator>=(string_view x, string_view y) noexcept { - return !(x < y); -} - -// IO Insertion Operator -std::ostream& operator<<(std::ostream& o, string_view piece); - -ABSL_NAMESPACE_END -} // namespace absl - -#undef ABSL_INTERNAL_STRING_VIEW_MEMCMP - -#endif // ABSL_USES_STD_STRING_VIEW - -namespace absl { -ABSL_NAMESPACE_BEGIN - -// ClippedSubstr() -// -// Like `s.substr(pos, n)`, but clips `pos` to an upper bound of `s.size()`. -// Provided because std::string_view::substr throws if `pos > size()` -inline string_view ClippedSubstr(string_view s, size_t pos, - size_t n = string_view::npos) { - pos = (std::min)(pos, static_cast<size_t>(s.size())); - return s.substr(pos, n); -} - -// NullSafeStringView() -// -// Creates an `absl::string_view` from a pointer `p` even if it's null-valued. -// This function should be used where an `absl::string_view` can be created from -// a possibly-null pointer. -constexpr string_view NullSafeStringView(const char* p) { - return p ? string_view(p) : string_view(); -} - -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_STRINGS_STRING_VIEW_H_ |