//
// 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/attributes.h"
#include "absl/base/nullability.h"
#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__)) || \
(
defined(_MSC_VER) && _MSC_VER >= 1928)
#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
// Mozilla added - quiets misused comma warnings resulting from
// frequent use of the pattern:
// return ABSL_HARDENING_ASSERT(i < size()), ptr_[i];
// TODO: https://bugzilla.mozilla.org/show_bug.cgi?id=1796623
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored
"-Wcomma"
#endif
// 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 ABSL_ATTRIBUTE_VIEW string_view {
public:
using traits_type = std::char_traits<
char>;
using value_type =
char;
using pointer = absl::Nullable<
char*>;
using const_pointer = absl::Nullable<
const char*>;
using reference =
char&;
using const_reference =
const char&;
using const_iterator = absl::Nullable<
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;
using absl_internal_is_view = std::true_type;
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
ABSL_ATTRIBUTE_LIFETIME_BOUND) noexcept
// This is implemented in terms of `string_view(p, n)` so `str.size()`
// doesn't need to be reevaluated after `ptr_` is set.
// The length check is also skipped since it is unnecessary and causes
// code bloat.
: string_view(str.data(), str.size(), SkipCheckLengthTag{}) {}
// Implicit constructor of a `string_view` from NUL-terminated `str`. When
// accepting possibly null strings, use `absl::NullSafeStringView(str)`
// instead (see below).
// The length check is skipped since it is unnecessary and causes code bloat.
constexpr string_view(
// NOLINT(runtime/explicit)
absl::Nonnull<
const char*> str)
: ptr_(str), length_(str ? StrlenInternal(str) : 0) {}
// Implicit constructor of a `string_view` from a `const char*` and length.
constexpr string_view(absl::Nullable<
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.
constexpr
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.
constexpr
void remove_suffix(size_type n) {
ABSL_HARDENING_ASSERT(n <= length_);
length_ -= n;
}
// string_view::swap()
//
// Swaps this `string_view` with another `string_view`.
constexpr
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 = 0, 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 this `string_view` and
// another `string_view` `x`, returning a negative value if `*this` is less
// than `x`, 0 if `*this` is equal to `x`, and a positive value if `*this`
// is greater than `x`.
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`.
constexpr
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`.
constexpr
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`.
constexpr
int compare(absl::Nonnull<
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`.
constexpr
int compare(size_type pos1, size_type count1,
absl::Nonnull<
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`.
constexpr
int compare(size_type pos1, size_type count1,
absl::Nonnull<
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;
// Overload of `string_view::find()` for finding a substring of a different
// C-style string `s` within the `string_view`.
size_type find(absl::Nonnull<
const char*> s, size_type pos,
size_type count)
const {
return find(string_view(s, count), pos);
}
// Overload of `string_view::find()` for finding a different C-style string
// `s` within the `string_view`.
size_type find(absl::Nonnull<
const char *> s, size_type pos = 0)
const {
return find(string_view(s), pos);
}
// 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;
// Overload of `string_view::rfind()` for finding a substring of a different
// C-style string `s` within the `string_view`.
size_type rfind(absl::Nonnull<
const char*> s, size_type pos,
size_type count)
const {
return rfind(string_view(s, count), pos);
}
// Overload of `string_view::rfind()` for finding a different C-style string
// `s` within the `string_view`.
size_type rfind(absl::Nonnull<
const char*> s, size_type pos = npos)
const {
return rfind(string_view(s), pos);
}
// 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);
}
// Overload of `string_view::find_first_of()` for finding a substring of a
// different C-style string `s` within the `string_view`.
size_type find_first_of(absl::Nonnull<
const char*> s, size_type pos,
size_type count)
const {
return find_first_of(string_view(s, count), pos);
}
// Overload of `string_view::find_first_of()` for finding a different C-style
// string `s` within the `string_view`.
size_type find_first_of(absl::Nonnull<
const char*> s,
size_type pos = 0)
const {
return find_first_of(string_view(s), 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);
}
// Overload of `string_view::find_last_of()` for finding a substring of a
// different C-style string `s` within the `string_view`.
size_type find_last_of(absl::Nonnull<
const char*> s, size_type pos,
size_type count)
const {
return find_last_of(string_view(s, count), pos);
}
// Overload of `string_view::find_last_of()` for finding a different C-style
// string `s` within the `string_view`.
size_type find_last_of(absl::Nonnull<
const char*> s,
size_type pos = npos)
const {
return find_last_of(string_view(s), 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;
// Overload of `string_view::find_first_not_of()` for finding a substring of a
// different C-style string `s` within the `string_view`.
size_type find_first_not_of(absl::Nonnull<
const char*> s, size_type pos,
size_type count)
const {
return find_first_not_of(string_view(s, count), pos);
}
// Overload of `string_view::find_first_not_of()` for finding a different
// C-style string `s` within the `string_view`.
size_type find_first_not_of(absl::Nonnull<
const char*> s,
size_type pos = 0)
const {
return find_first_not_of(string_view(s), pos);
}
// 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;
// Overload of `string_view::find_last_not_of()` for finding a substring of a
// different C-style string `s` within the `string_view`.
size_type find_last_not_of(absl::Nonnull<
const char*> s, size_type pos,
size_type count)
const {
return find_last_not_of(string_view(s, count), pos);
}
// Overload of `string_view::find_last_not_of()` for finding a different
// C-style string `s` within the `string_view`.
size_type find_last_not_of(absl::Nonnull<
const char*> s,
size_type pos = npos)
const {
return find_last_not_of(string_view(s), pos);
}
#if ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
// string_view::starts_with()
//
// Returns true if the `string_view` starts with the prefix `s`.
//
// This method only exists when targeting at least C++20.
// If support for C++ prior to C++20 is required, use `absl::StartsWith()`
// from `//absl/strings/match.h` for compatibility.
constexpr
bool starts_with(string_view s)
const noexcept {
return s.empty() ||
(size() >= s.size() &&
ABSL_INTERNAL_STRING_VIEW_MEMCMP(data(), s.data(), s.size()) == 0);
}
// Overload of `string_view::starts_with()` that returns true if `c` is the
// first character of the `string_view`.
constexpr
bool starts_with(
char c)
const noexcept {
return !empty() && front() == c;
}
// Overload of `string_view::starts_with()` that returns true if the
// `string_view` starts with the C-style prefix `s`.
constexpr
bool starts_with(
const char* s)
const {
return starts_with(string_view(s));
}
// string_view::ends_with()
//
// Returns true if the `string_view` ends with the suffix `s`.
//
// This method only exists when targeting at least C++20.
// If support for C++ prior to C++20 is required, use `absl::EndsWith()`
// from `//absl/strings/match.h` for compatibility.
constexpr
bool ends_with(string_view s)
const noexcept {
return s.empty() || (size() >= s.size() && ABSL_INTERNAL_STRING_VIEW_MEMCMP(
data() + (size() - s.size()),
s.data(), s.size()) == 0);
}
// Overload of `string_view::ends_with()` that returns true if `c` is the
// last character of the `string_view`.
constexpr
bool ends_with(
char c)
const noexcept {
return !empty() && back() == c;
}
// Overload of `string_view::ends_with()` that returns true if the
// `string_view` ends with the C-style suffix `s`.
constexpr
bool ends_with(
const char* s)
const {
return ends_with(string_view(s));
}
#endif // ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
private:
// The constructor from std::string delegates to this constructor.
// See the comment on that constructor for the rationale.
struct SkipCheckLengthTag {};
string_view(absl::Nullable<
const char*> data, size_type len,
SkipCheckLengthTag) noexcept
: ptr_(data), length_(len) {}
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(absl::Nonnull<
const char*> str) {
#if defined(_MSC_VER) && !
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);
}
absl::Nullable<
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
#if defined(__clang__)
#pragma clang diagnostic pop
#endif
#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(absl::Nullable<
const char*> p) {
return p ? string_view(p) : string_view();
}
ABSL_NAMESPACE_END
}
// namespace absl
#endif // ABSL_STRINGS_STRING_VIEW_H_
