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TMessagesProj/jni/voip/webrtc/base/strings/string_piece.h

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+// 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 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);
+
+}  // namespace internal
+
+// BasicStringPiece ------------------------------------------------------------
+
+// Defines the types, methods, operators, and data members common to both
+// StringPiece and 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(crbug.com/1049498): 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)) {}
+  // Explicitly disallow construction from nullptr. Note that this does not
+  // catch construction from runtime strings that might be null.
+  // Note: The following is just a more elaborate way of spelling
+  // `BasicStringPiece(nullptr_t) = delete`, but unfortunately the terse form is
+  // not supported by the PNaCl toolchain.
+  // TODO(crbug.com/1049498): Remove once we CHECK(str) in the constructor
+  // above.
+  template <class T, class = std::enable_if_t<std::is_null_pointer<T>::value>>
+  BasicStringPiece(T) {
+    static_assert(sizeof(T) == 0,  // Always false.
+                  "StringPiece does not support construction from nullptr, use "
+                  "the default constructor instead.");
+  }
+  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) {
+    DCHECK(begin <= end) << "StringPiece iterators swapped or invalid.";
+    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; }
+
+  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_; }
+
+  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_