| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| // Copied from strings/stringpiece.h with modifications |
| // |
| // A string-like object that points to a sized piece of memory. |
| // |
| // You can use StringPiece as a function or method parameter. A StringPiece |
| // parameter can receive a double-quoted string literal argument, a "const |
| // char*" argument, a string argument, or a StringPiece argument with no data |
| // copying. Systematic use of StringPiece for arguments reduces data |
| // copies and strlen() calls. |
| // |
| // Prefer passing StringPieces by value: |
| // void MyFunction(StringPiece arg); |
| // If circumstances require, you may also pass by const reference: |
| // void MyFunction(const StringPiece& arg); // not preferred |
| // Both of these have the same lifetime semantics. Passing by value |
| // generates slightly smaller code. For more discussion, Googlers can see |
| // the thread go/stringpiecebyvalue on c-users. |
| |
| #ifndef BASE_STRINGS_STRING_PIECE_H_ |
| #define BASE_STRINGS_STRING_PIECE_H_ |
| |
| #include <stddef.h> |
| |
| #include <iosfwd> |
| #include <string> |
| #include <type_traits> |
| |
| #include "base/base_export.h" |
| #include "base/logging.h" |
| #include "base/strings/char_traits.h" |
| #include "base/strings/string16.h" |
| #include "base/strings/string_piece_forward.h" |
| |
| namespace base { |
| |
| // internal -------------------------------------------------------------------- |
| |
| // Many of the StringPiece functions use different implementations for the |
| // 8-bit and 16-bit versions, and we don't want lots of template expansions in |
| // this (very common) header that will slow down compilation. |
| // |
| // So here we define overloaded functions called by the StringPiece template. |
| // For those that share an implementation, the two versions will expand to a |
| // template internal to the .cc file. |
| namespace internal { |
| |
| BASE_EXPORT void CopyToString(const StringPiece& self, std::string* target); |
| BASE_EXPORT void CopyToString(const StringPiece16& self, string16* target); |
| |
| BASE_EXPORT void AppendToString(const StringPiece& self, std::string* target); |
| BASE_EXPORT void AppendToString(const StringPiece16& self, string16* target); |
| |
| BASE_EXPORT size_t copy(const StringPiece& self, |
| char* buf, |
| size_t n, |
| size_t pos); |
| BASE_EXPORT size_t copy(const StringPiece16& self, |
| char16* buf, |
| size_t n, |
| size_t pos); |
| |
| BASE_EXPORT size_t find(const StringPiece& self, |
| const StringPiece& s, |
| size_t pos); |
| BASE_EXPORT size_t find(const StringPiece16& self, |
| const StringPiece16& s, |
| size_t pos); |
| BASE_EXPORT size_t find(const StringPiece& self, |
| char c, |
| size_t pos); |
| BASE_EXPORT size_t find(const StringPiece16& self, |
| char16 c, |
| size_t pos); |
| |
| BASE_EXPORT size_t rfind(const StringPiece& self, |
| const StringPiece& s, |
| size_t pos); |
| BASE_EXPORT size_t rfind(const StringPiece16& self, |
| const StringPiece16& s, |
| size_t pos); |
| BASE_EXPORT size_t rfind(const StringPiece& self, |
| char c, |
| size_t pos); |
| BASE_EXPORT size_t rfind(const StringPiece16& self, |
| char16 c, |
| size_t pos); |
| |
| BASE_EXPORT size_t find_first_of(const StringPiece& self, |
| const StringPiece& s, |
| size_t pos); |
| BASE_EXPORT size_t find_first_of(const StringPiece16& self, |
| const StringPiece16& s, |
| size_t pos); |
| |
| BASE_EXPORT size_t find_first_not_of(const StringPiece& self, |
| const StringPiece& s, |
| size_t pos); |
| BASE_EXPORT size_t find_first_not_of(const StringPiece16& self, |
| const StringPiece16& s, |
| size_t pos); |
| BASE_EXPORT size_t find_first_not_of(const StringPiece& self, |
| char c, |
| size_t pos); |
| BASE_EXPORT size_t find_first_not_of(const StringPiece16& self, |
| char16 c, |
| size_t pos); |
| |
| BASE_EXPORT size_t find_last_of(const StringPiece& self, |
| const StringPiece& s, |
| size_t pos); |
| BASE_EXPORT size_t find_last_of(const StringPiece16& self, |
| const StringPiece16& s, |
| size_t pos); |
| BASE_EXPORT size_t find_last_of(const StringPiece& self, |
| char c, |
| size_t pos); |
| BASE_EXPORT size_t find_last_of(const StringPiece16& self, |
| char16 c, |
| size_t pos); |
| |
| BASE_EXPORT size_t find_last_not_of(const StringPiece& self, |
| const StringPiece& s, |
| size_t pos); |
| BASE_EXPORT size_t find_last_not_of(const StringPiece16& self, |
| const StringPiece16& s, |
| size_t pos); |
| BASE_EXPORT size_t find_last_not_of(const StringPiece16& self, |
| char16 c, |
| size_t pos); |
| BASE_EXPORT size_t find_last_not_of(const StringPiece& self, |
| char c, |
| size_t pos); |
| |
| BASE_EXPORT StringPiece substr(const StringPiece& self, |
| size_t pos, |
| size_t n); |
| BASE_EXPORT StringPiece16 substr(const StringPiece16& self, |
| size_t pos, |
| size_t n); |
| |
| #if DCHECK_IS_ON() |
| // Asserts that begin <= end to catch some errors with iterator usage. |
| BASE_EXPORT void AssertIteratorsInOrder(std::string::const_iterator begin, |
| std::string::const_iterator end); |
| BASE_EXPORT void AssertIteratorsInOrder(string16::const_iterator begin, |
| string16::const_iterator end); |
| #endif |
| |
| } // namespace internal |
| |
| // BasicStringPiece ------------------------------------------------------------ |
| |
| // Defines the types, methods, operators, and data members common to both |
| // StringPiece and StringPiece16. Do not refer to this class directly, but |
| // rather to BasicStringPiece, StringPiece, or StringPiece16. |
| // |
| // This is templatized by string class type rather than character type, so |
| // BasicStringPiece<std::string> or BasicStringPiece<base::string16>. |
| template <typename STRING_TYPE> class BasicStringPiece { |
| public: |
| // Standard STL container boilerplate. |
| typedef size_t size_type; |
| typedef typename STRING_TYPE::value_type value_type; |
| typedef const value_type* pointer; |
| typedef const value_type& reference; |
| typedef const value_type& const_reference; |
| typedef ptrdiff_t difference_type; |
| typedef const value_type* const_iterator; |
| typedef std::reverse_iterator<const_iterator> const_reverse_iterator; |
| |
| static const size_type npos; |
| |
| public: |
| // We provide non-explicit singleton constructors so users can pass |
| // in a "const char*" or a "string" wherever a "StringPiece" is |
| // expected (likewise for char16, string16, StringPiece16). |
| constexpr BasicStringPiece() : ptr_(NULL), length_(0) {} |
| // TODO(dcheng): Construction from nullptr is not allowed for |
| // std::basic_string_view, so remove the special handling for it. |
| // Note: This doesn't just use STRING_TYPE::traits_type::length(), since that |
| // isn't constexpr until C++17. |
| constexpr BasicStringPiece(const value_type* str) |
| : ptr_(str), length_(!str ? 0 : CharTraits<value_type>::length(str)) {} |
| BasicStringPiece(const STRING_TYPE& str) |
| : ptr_(str.data()), length_(str.size()) {} |
| constexpr BasicStringPiece(const value_type* offset, size_type len) |
| : ptr_(offset), length_(len) {} |
| BasicStringPiece(const typename STRING_TYPE::const_iterator& begin, |
| const typename STRING_TYPE::const_iterator& end) { |
| #if DCHECK_IS_ON() |
| // This assertion is done out-of-line to avoid bringing in logging.h and |
| // instantiating logging macros for every instantiation. |
| internal::AssertIteratorsInOrder(begin, end); |
| #endif |
| length_ = static_cast<size_t>(std::distance(begin, end)); |
| |
| // The length test before assignment is to avoid dereferencing an iterator |
| // that may point to the end() of a string. |
| ptr_ = length_ > 0 ? &*begin : nullptr; |
| } |
| |
| // data() may return a pointer to a buffer with embedded NULs, and the |
| // returned buffer may or may not be null terminated. Therefore it is |
| // typically a mistake to pass data() to a routine that expects a NUL |
| // terminated string. |
| constexpr const value_type* data() const { return ptr_; } |
| constexpr size_type size() const noexcept { return length_; } |
| constexpr size_type length() const noexcept { return length_; } |
| bool empty() const { return length_ == 0; } |
| |
| void clear() { |
| ptr_ = NULL; |
| length_ = 0; |
| } |
| void set(const value_type* data, size_type len) { |
| ptr_ = data; |
| length_ = len; |
| } |
| void set(const value_type* str) { |
| ptr_ = str; |
| length_ = str ? STRING_TYPE::traits_type::length(str) : 0; |
| } |
| |
| constexpr value_type operator[](size_type i) const { |
| CHECK(i < length_); |
| return ptr_[i]; |
| } |
| |
| value_type front() const { |
| CHECK_NE(0UL, length_); |
| return ptr_[0]; |
| } |
| |
| value_type back() const { |
| CHECK_NE(0UL, length_); |
| return ptr_[length_ - 1]; |
| } |
| |
| constexpr void remove_prefix(size_type n) { |
| CHECK(n <= length_); |
| ptr_ += n; |
| length_ -= n; |
| } |
| |
| constexpr void remove_suffix(size_type n) { |
| CHECK(n <= length_); |
| length_ -= n; |
| } |
| |
| constexpr int compare(BasicStringPiece x) const noexcept { |
| int r = CharTraits<value_type>::compare( |
| ptr_, x.ptr_, (length_ < x.length_ ? length_ : x.length_)); |
| if (r == 0) { |
| if (length_ < x.length_) r = -1; |
| else if (length_ > x.length_) r = +1; |
| } |
| return r; |
| } |
| |
| // This is the style of conversion preferred by std::string_view in C++17. |
| explicit operator STRING_TYPE() const { return as_string(); } |
| |
| STRING_TYPE as_string() const { |
| // std::string doesn't like to take a NULL pointer even with a 0 size. |
| return empty() ? STRING_TYPE() : STRING_TYPE(data(), size()); |
| } |
| |
| const_iterator begin() const { return ptr_; } |
| const_iterator end() const { return ptr_ + length_; } |
| const_reverse_iterator rbegin() const { |
| return const_reverse_iterator(ptr_ + length_); |
| } |
| const_reverse_iterator rend() const { |
| return const_reverse_iterator(ptr_); |
| } |
| |
| size_type max_size() const { return length_; } |
| size_type capacity() const { return length_; } |
| |
| // Sets the value of the given string target type to be the current string. |
| // This saves a temporary over doing |a = b.as_string()| |
| void CopyToString(STRING_TYPE* target) const { |
| internal::CopyToString(*this, target); |
| } |
| |
| void AppendToString(STRING_TYPE* target) const { |
| internal::AppendToString(*this, target); |
| } |
| |
| size_type copy(value_type* buf, size_type n, size_type pos = 0) const { |
| return internal::copy(*this, buf, n, pos); |
| } |
| |
| // Does "this" start with "x" |
| constexpr bool starts_with(BasicStringPiece x) const noexcept { |
| return ( |
| (this->length_ >= x.length_) && |
| (CharTraits<value_type>::compare(this->ptr_, x.ptr_, x.length_) == 0)); |
| } |
| |
| // Does "this" end with "x" |
| constexpr bool ends_with(BasicStringPiece x) const noexcept { |
| return ((this->length_ >= x.length_) && |
| (CharTraits<value_type>::compare( |
| this->ptr_ + (this->length_ - x.length_), x.ptr_, x.length_) == |
| 0)); |
| } |
| |
| // find: Search for a character or substring at a given offset. |
| size_type find(const BasicStringPiece<STRING_TYPE>& s, |
| size_type pos = 0) const { |
| return internal::find(*this, s, pos); |
| } |
| size_type find(value_type c, size_type pos = 0) const { |
| return internal::find(*this, c, pos); |
| } |
| |
| // rfind: Reverse find. |
| size_type rfind(const BasicStringPiece& s, |
| size_type pos = BasicStringPiece::npos) const { |
| return internal::rfind(*this, s, pos); |
| } |
| size_type rfind(value_type c, size_type pos = BasicStringPiece::npos) const { |
| return internal::rfind(*this, c, pos); |
| } |
| |
| // find_first_of: Find the first occurence of one of a set of characters. |
| size_type find_first_of(const BasicStringPiece& s, |
| size_type pos = 0) const { |
| return internal::find_first_of(*this, s, pos); |
| } |
| size_type find_first_of(value_type c, size_type pos = 0) const { |
| return find(c, pos); |
| } |
| |
| // find_first_not_of: Find the first occurence not of a set of characters. |
| size_type find_first_not_of(const BasicStringPiece& s, |
| size_type pos = 0) const { |
| return internal::find_first_not_of(*this, s, pos); |
| } |
| size_type find_first_not_of(value_type c, size_type pos = 0) const { |
| return internal::find_first_not_of(*this, c, pos); |
| } |
| |
| // find_last_of: Find the last occurence of one of a set of characters. |
| size_type find_last_of(const BasicStringPiece& s, |
| size_type pos = BasicStringPiece::npos) const { |
| return internal::find_last_of(*this, s, pos); |
| } |
| size_type find_last_of(value_type c, |
| size_type pos = BasicStringPiece::npos) const { |
| return rfind(c, pos); |
| } |
| |
| // find_last_not_of: Find the last occurence not of a set of characters. |
| size_type find_last_not_of(const BasicStringPiece& s, |
| size_type pos = BasicStringPiece::npos) const { |
| return internal::find_last_not_of(*this, s, pos); |
| } |
| size_type find_last_not_of(value_type c, |
| size_type pos = BasicStringPiece::npos) const { |
| return internal::find_last_not_of(*this, c, pos); |
| } |
| |
| // substr. |
| BasicStringPiece substr(size_type pos, |
| size_type n = BasicStringPiece::npos) const { |
| return internal::substr(*this, pos, n); |
| } |
| |
| protected: |
| const value_type* ptr_; |
| size_type length_; |
| }; |
| |
| template <typename STRING_TYPE> |
| const typename BasicStringPiece<STRING_TYPE>::size_type |
| BasicStringPiece<STRING_TYPE>::npos = |
| typename BasicStringPiece<STRING_TYPE>::size_type(-1); |
| |
| // MSVC doesn't like complex extern templates and DLLs. |
| #if !defined(COMPILER_MSVC) |
| extern template class BASE_EXPORT BasicStringPiece<std::string>; |
| extern template class BASE_EXPORT BasicStringPiece<string16>; |
| #endif |
| |
| // Comparison operators -------------------------------------------------------- |
| // operator == |
| template <typename StringT> |
| constexpr bool operator==(BasicStringPiece<StringT> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return lhs.size() == rhs.size() && lhs.compare(rhs) == 0; |
| } |
| |
| // Here and below we make use of std::common_type_t to emulate an identity type |
| // transformation. This creates a non-deduced context, so that we can compare |
| // StringPieces with types that implicitly convert to StringPieces. See |
| // https://wg21.link/n3766 for details. |
| // Furthermore, we require dummy template parameters for these overloads to work |
| // around a name mangling issue on Windows. |
| template <typename StringT, int = 1> |
| constexpr bool operator==( |
| BasicStringPiece<StringT> lhs, |
| std::common_type_t<BasicStringPiece<StringT>> rhs) noexcept { |
| return lhs.size() == rhs.size() && lhs.compare(rhs) == 0; |
| } |
| |
| template <typename StringT, int = 2> |
| constexpr bool operator==(std::common_type_t<BasicStringPiece<StringT>> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return lhs.size() == rhs.size() && lhs.compare(rhs) == 0; |
| } |
| |
| // operator != |
| template <typename StringT> |
| constexpr bool operator!=(BasicStringPiece<StringT> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return !(lhs == rhs); |
| } |
| |
| template <typename StringT, int = 1> |
| constexpr bool operator!=( |
| BasicStringPiece<StringT> lhs, |
| std::common_type_t<BasicStringPiece<StringT>> rhs) noexcept { |
| return !(lhs == rhs); |
| } |
| |
| template <typename StringT, int = 2> |
| constexpr bool operator!=(std::common_type_t<BasicStringPiece<StringT>> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return !(lhs == rhs); |
| } |
| |
| // operator < |
| template <typename StringT> |
| constexpr bool operator<(BasicStringPiece<StringT> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return lhs.compare(rhs) < 0; |
| } |
| |
| template <typename StringT, int = 1> |
| constexpr bool operator<( |
| BasicStringPiece<StringT> lhs, |
| std::common_type_t<BasicStringPiece<StringT>> rhs) noexcept { |
| return lhs.compare(rhs) < 0; |
| } |
| |
| template <typename StringT, int = 2> |
| constexpr bool operator<(std::common_type_t<BasicStringPiece<StringT>> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return lhs.compare(rhs) < 0; |
| } |
| |
| // operator > |
| template <typename StringT> |
| constexpr bool operator>(BasicStringPiece<StringT> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return rhs < lhs; |
| } |
| |
| template <typename StringT, int = 1> |
| constexpr bool operator>( |
| BasicStringPiece<StringT> lhs, |
| std::common_type_t<BasicStringPiece<StringT>> rhs) noexcept { |
| return rhs < lhs; |
| } |
| |
| template <typename StringT, int = 2> |
| constexpr bool operator>(std::common_type_t<BasicStringPiece<StringT>> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return rhs < lhs; |
| } |
| |
| // operator <= |
| template <typename StringT> |
| constexpr bool operator<=(BasicStringPiece<StringT> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return !(rhs < lhs); |
| } |
| |
| template <typename StringT, int = 1> |
| constexpr bool operator<=( |
| BasicStringPiece<StringT> lhs, |
| std::common_type_t<BasicStringPiece<StringT>> rhs) noexcept { |
| return !(rhs < lhs); |
| } |
| |
| template <typename StringT, int = 2> |
| constexpr bool operator<=(std::common_type_t<BasicStringPiece<StringT>> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return !(rhs < lhs); |
| } |
| |
| // operator >= |
| template <typename StringT> |
| constexpr bool operator>=(BasicStringPiece<StringT> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return !(lhs < rhs); |
| } |
| |
| template <typename StringT, int = 1> |
| constexpr bool operator>=( |
| BasicStringPiece<StringT> lhs, |
| std::common_type_t<BasicStringPiece<StringT>> rhs) noexcept { |
| return !(lhs < rhs); |
| } |
| |
| template <typename StringT, int = 2> |
| constexpr bool operator>=(std::common_type_t<BasicStringPiece<StringT>> lhs, |
| BasicStringPiece<StringT> rhs) noexcept { |
| return !(lhs < rhs); |
| } |
| |
| BASE_EXPORT std::ostream& operator<<(std::ostream& o, |
| const StringPiece& piece); |
| |
| BASE_EXPORT std::ostream& operator<<(std::ostream& o, |
| const StringPiece16& piece); |
| |
| // Hashing --------------------------------------------------------------------- |
| |
| // We provide appropriate hash functions so StringPiece and StringPiece16 can |
| // be used as keys in hash sets and maps. |
| |
| // This hash function is copied from base/strings/string16.h. We don't use the |
| // ones already defined for string and string16 directly because it would |
| // require the string constructors to be called, which we don't want. |
| |
| template <typename StringPieceType> |
| struct StringPieceHashImpl { |
| std::size_t operator()(StringPieceType sp) const { |
| std::size_t result = 0; |
| for (auto c : sp) |
| result = (result * 131) + c; |
| return result; |
| } |
| }; |
| |
| using StringPieceHash = StringPieceHashImpl<StringPiece>; |
| using StringPiece16Hash = StringPieceHashImpl<StringPiece16>; |
| using WStringPieceHash = StringPieceHashImpl<WStringPiece>; |
| |
| } // namespace base |
| |
| #endif // BASE_STRINGS_STRING_PIECE_H_ |