diff options
Diffstat (limited to 'third_party/abseil-cpp/absl/strings/string_view.h')
| -rw-r--r-- | third_party/abseil-cpp/absl/strings/string_view.h | 198 |
1 files changed, 143 insertions, 55 deletions
diff --git a/third_party/abseil-cpp/absl/strings/string_view.h b/third_party/abseil-cpp/absl/strings/string_view.h index 1861ea62a9..a4c9a6526c 100644 --- a/third_party/abseil-cpp/absl/strings/string_view.h +++ b/third_party/abseil-cpp/absl/strings/string_view.h @@ -36,6 +36,7 @@ #include <limits> #include <string> +#include "absl/base/attributes.h" #include "absl/base/config.h" #include "absl/base/internal/throw_delegate.h" #include "absl/base/macros.h" @@ -48,7 +49,7 @@ namespace absl { ABSL_NAMESPACE_BEGIN -using std::string_view; +using string_view = std::string_view; ABSL_NAMESPACE_END } // namespace absl @@ -61,6 +62,12 @@ ABSL_NAMESPACE_END #define ABSL_INTERNAL_STRING_VIEW_MEMCMP memcmp #endif // ABSL_HAVE_BUILTIN(__builtin_memcmp) +#if defined(__cplusplus) && __cplusplus >= 201402L +#define ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR constexpr +#else +#define ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR +#endif + namespace absl { ABSL_NAMESPACE_BEGIN @@ -111,6 +118,11 @@ ABSL_NAMESPACE_BEGIN // 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 @@ -175,18 +187,20 @@ class string_view { template <typename Allocator> string_view( // NOLINT(runtime/explicit) - const std::basic_string<char, std::char_traits<char>, Allocator>& - str) noexcept + 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. - : string_view(str.data(), str.size()) {} + // 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(const char* str) // NOLINT(runtime/explicit) - : ptr_(str), - length_(str ? CheckLengthInternal(StrlenInternal(str)) : 0) {} + : ptr_(str), length_(str ? StrlenInternal(str) : 0) {} // Implicit constructor of a `string_view` from a `const char*` and length. constexpr string_view(const char* data, size_type len) @@ -259,9 +273,7 @@ class string_view { // string_view::size() // // Returns the number of characters in the `string_view`. - constexpr size_type size() const noexcept { - return length_; - } + constexpr size_type size() const noexcept { return length_; } // string_view::length() // @@ -283,7 +295,7 @@ class string_view { // 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_ASSERT(i < size()), ptr_[i]; + return ABSL_HARDENING_ASSERT(i < size()), ptr_[i]; } // string_view::at() @@ -303,14 +315,14 @@ class string_view { // // Returns the first element of a `string_view`. constexpr const_reference front() const { - return ABSL_ASSERT(!empty()), ptr_[0]; + 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_ASSERT(!empty()), ptr_[size() - 1]; + return ABSL_HARDENING_ASSERT(!empty()), ptr_[size() - 1]; } // string_view::data() @@ -319,7 +331,7 @@ class string_view { // 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 - // std::string. + // string. constexpr const_pointer data() const noexcept { return ptr_; } // Modifiers @@ -327,9 +339,9 @@ class string_view { // string_view::remove_prefix() // // Removes the first `n` characters from the `string_view`. Note that the - // underlying std::string is not changed, only the view. - void remove_prefix(size_type n) { - assert(n <= length_); + // underlying string is not changed, only the view. + ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR void remove_prefix(size_type n) { + ABSL_HARDENING_ASSERT(n <= length_); ptr_ += n; length_ -= n; } @@ -337,16 +349,16 @@ class string_view { // string_view::remove_suffix() // // Removes the last `n` characters from the `string_view`. Note that the - // underlying std::string is not changed, only the view. - void remove_suffix(size_type n) { - assert(n <= length_); + // underlying string is not changed, only the view. + ABSL_INTERNAL_STRING_VIEW_CXX14_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`. - void swap(string_view& s) noexcept { + ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR void swap(string_view& s) noexcept { auto t = *this; *this = s; s = t; @@ -382,21 +394,21 @@ class string_view { // 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`. - string_view substr(size_type pos, size_type n = npos) const { - if (ABSL_PREDICT_FALSE(pos > length_)) - base_internal::ThrowStdOutOfRange("absl::string_view::substr"); - n = (std::min)(n, length_ - pos); - return string_view(ptr_ + pos, n); + // 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 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 std::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. + // 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 @@ -407,31 +419,31 @@ class string_view { // 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 { + 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`. - int compare(size_type pos1, size_type count1, string_view v, size_type pos2, - size_type count2) const { + 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 std::string `s`. - int compare(const char* s) const { return compare(string_view(s)); } + // a different C-style string `s`. + constexpr 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 std::string C-style std::string `s`. - int compare(size_type pos1, size_type count1, const char* s) const { + // `string_view` and a different string C-style string `s`. + constexpr 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 std::string `s`. - int compare(size_type pos1, size_type count1, const char* s, - size_type count2) const { + // `string_view` and a substring of a different C-style string `s`. + constexpr int compare(size_type pos1, size_type count1, const char* s, + size_type count2) const { return substr(pos1, count1).compare(string_view(s, count2)); } @@ -448,48 +460,92 @@ class string_view { // 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(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(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; + 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(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(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; + 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 { + 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(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(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; + 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 { + 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(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(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 @@ -501,25 +557,56 @@ class string_view { // 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(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(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; + 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; + 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(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(const char* s, size_type pos = npos) const { + return find_last_not_of(string_view(s), pos); + } private: + // The constructor from std::string delegates to this constructor. + // See the comment on that constructor for the rationale. + struct SkipCheckLengthTag {}; + string_view(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 (void)ABSL_ASSERT(len <= kMaxSize), len; + return ABSL_HARDENING_ASSERT(len <= kMaxSize), len; } static constexpr size_type StrlenInternal(const char* str) { @@ -590,6 +677,7 @@ std::ostream& operator<<(std::ostream& o, string_view piece); ABSL_NAMESPACE_END } // namespace absl +#undef ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR #undef ABSL_INTERNAL_STRING_VIEW_MEMCMP #endif // ABSL_USES_STD_STRING_VIEW |