diff options
Diffstat (limited to 'absl/strings/string_view.h')
| -rw-r--r-- | absl/strings/string_view.h | 164 |
1 files changed, 123 insertions, 41 deletions
diff --git a/absl/strings/string_view.h b/absl/strings/string_view.h index 5260b5b7..e3239f57 100644 --- a/absl/strings/string_view.h +++ b/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" @@ -54,13 +55,20 @@ ABSL_NAMESPACE_END #else // ABSL_USES_STD_STRING_VIEW -#if ABSL_HAVE_BUILTIN(__builtin_memcmp) || \ - (defined(__GNUC__) && !defined(__clang__)) +#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) +#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 @@ -180,18 +188,20 @@ 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) @@ -264,9 +274,7 @@ 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() // @@ -333,7 +341,7 @@ class string_view { // // 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_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR void remove_prefix(size_type n) { ABSL_HARDENING_ASSERT(n <= length_); ptr_ += n; length_ -= n; @@ -343,7 +351,7 @@ class string_view { // // 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_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR void remove_suffix(size_type n) { ABSL_HARDENING_ASSERT(n <= length_); length_ -= n; } @@ -351,7 +359,7 @@ class string_view { // 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; @@ -388,7 +396,7 @@ class string_view { // `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 { + 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"), @@ -398,12 +406,10 @@ class string_view { // 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. + // 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 @@ -414,31 +420,31 @@ 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 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 string C-style string `s`. - int compare(size_type pos1, size_type count1, const char* s) const { + 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 string `s`. - int compare(size_type pos1, size_type count1, const char* s, - size_type count2) const { + 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)); } @@ -455,48 +461,92 @@ 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 @@ -508,20 +558,51 @@ 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)(); @@ -597,6 +678,7 @@ 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 |