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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.

 //

 // Functions or methods may use const StringPiece& parameters to accept either

 // a "const char*" or a "string" value that will be implicitly converted to

 // a StringPiece.  The implicit conversion means that it is often appropriate

 // to include this .h file in other files rather than forward-declaring

 // StringPiece as would be appropriate for most other Google classes.

 //

 // Systematic usage of StringPiece is encouraged as it will reduce unnecessary

 // conversions from "const char*" to "string" and back again.

 //

 // StringPiece16 is similar to StringPiece but for base::string16 instead of

 // std::string. We do not define as large of a subset of the STL functions

 // from basic_string as in StringPiece, but this can be changed if these

 // functions (find, find_first_of, etc.) are found to be useful in this context.

 //

 #ifndef BASE_STRINGS_STRING_PIECE_H_

 #define BASE_STRINGS_STRING_PIECE_H_

 #include <stddef.h>

 #include <iosfwd>

 #include <string>

 #include "base/base_export.h"

 #include "base/basictypes.h"

 #include "base/containers/hash_tables.h"

 #include "base/strings/string16.h"

 namespace base {

 template <typename STRING_TYPE> class BasicStringPiece;

 typedef BasicStringPiece<std::string> StringPiece;

 typedef BasicStringPiece<string16> StringPiece16;

 namespace internal {

 // 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.

 template <typename STRING_TYPE> class StringPieceDetail {

  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).

   StringPieceDetail() : ptr_(NULL), length_(0) {}

   StringPieceDetail(const value_type* str)

       : ptr_(str),

         length_((str == NULL) ? 0 : STRING_TYPE::traits_type::length(str)) {}

   StringPieceDetail(const STRING_TYPE& str)

       : ptr_(str.data()), length_(str.size()) {}

   StringPieceDetail(const value_type* offset, size_type len)

       : ptr_(offset), length_(len) {}

   StringPieceDetail(const typename STRING_TYPE::const_iterator& begin,

                     const typename STRING_TYPE::const_iterator& end)

       : ptr_((end > begin) ? &(*begin) : NULL),

         length_((end > begin) ? (size_type)(end - begin) : 0) {}

   // 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.

   const value_type* data() const { return ptr_; }

   size_type size() const { return length_; }

   size_type length() const { 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;

   }

   value_type operator[](size_type i) const { return ptr_[i]; }

   void remove_prefix(size_type n) {

     ptr_ += n;

     length_ -= n;

   }

   void remove_suffix(size_type n) {

     length_ -= n;

   }

   int compare(const BasicStringPiece<STRING_TYPE>& x) const {

     int r = wordmemcmp(

         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;

   }

   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_; }

   static int wordmemcmp(const value_type* p,

                         const value_type* p2,

                         size_type N) {

     return STRING_TYPE::traits_type::compare(p, p2, N);

   }

  protected:

   const value_type* ptr_;

   size_type     length_;

 };

 template <typename STRING_TYPE>

 const typename StringPieceDetail<STRING_TYPE>::size_type

 StringPieceDetail<STRING_TYPE>::npos =

     typename StringPieceDetail<STRING_TYPE>::size_type(-1);

 // MSVC doesn't like complex extern templates and DLLs.

 #if !defined(COMPILER_MSVC)

 extern template class BASE_EXPORT StringPieceDetail<std::string>;

 extern template class BASE_EXPORT StringPieceDetail<string16>;

 #endif

 BASE_EXPORT void CopyToString(const StringPiece& self, std::string* target);

 BASE_EXPORT void AppendToString(const StringPiece& self, std::string* target);

 BASE_EXPORT StringPieceDetail<std::string>::size_type copy(

     const StringPiece& self,

     char* buf,

     StringPieceDetail<std::string>::size_type n,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find(

     const StringPiece& self,

     const StringPiece& s,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find(

     const StringPiece& self,

     char c,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type rfind(

     const StringPiece& self,

     const StringPiece& s,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type rfind(

     const StringPiece& self,

     char c,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find_first_of(

     const StringPiece& self,

     const StringPiece& s,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find_first_not_of(

     const StringPiece& self,

     const StringPiece& s,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find_first_not_of(

     const StringPiece& self,

     char c,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find_last_of(

     const StringPiece& self,

     const StringPiece& s,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find_last_of(

     const StringPiece& self,

     char c,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find_last_not_of(

     const StringPiece& self,

     const StringPiece& s,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPieceDetail<std::string>::size_type find_last_not_of(

     const StringPiece& self,

     char c,

     StringPieceDetail<std::string>::size_type pos);

 BASE_EXPORT StringPiece substr(const StringPiece& self,

                                StringPieceDetail<std::string>::size_type pos,

                                StringPieceDetail<std::string>::size_type n);

 }  // namespace internal

 // Defines the template type that is instantiated as either StringPiece or

 // StringPiece16.

 template <typename STRING_TYPE> class BasicStringPiece :

     public internal::StringPieceDetail<STRING_TYPE> {

  public:

   typedef typename internal::StringPieceDetail<STRING_TYPE>::value_type

       value_type;

   typedef typename internal::StringPieceDetail<STRING_TYPE>::size_type

       size_type;

   BasicStringPiece() {}

   BasicStringPiece(const value_type*str)

       : internal::StringPieceDetail<STRING_TYPE>(str) {}

   BasicStringPiece(const STRING_TYPE& str)

       : internal::StringPieceDetail<STRING_TYPE>(str) {}

   BasicStringPiece(const value_type* offset, size_type len)

       : internal::StringPieceDetail<STRING_TYPE>(offset, len) {}

   BasicStringPiece(const typename STRING_TYPE::const_iterator& begin,

                    const typename STRING_TYPE::const_iterator& end)

       : internal::StringPieceDetail<STRING_TYPE>(begin, end) {}

 };

 // Specializes BasicStringPiece for std::string to add a few operations that

 // are not needed for string16.

 template <> class BasicStringPiece<std::string> :

     public internal::StringPieceDetail<std::string> {

  public:

   BasicStringPiece() {}

   BasicStringPiece(const char* str)

       : internal::StringPieceDetail<std::string>(str) {}

   BasicStringPiece(const std::string& str)

       : internal::StringPieceDetail<std::string>(str) {}

   BasicStringPiece(const char* offset, size_type len)

       : internal::StringPieceDetail<std::string>(offset, len) {}

   BasicStringPiece(const std::string::const_iterator& begin,

                    const std::string::const_iterator& end)

       : internal::StringPieceDetail<std::string>(begin, end) {}

   // Prevent the following overload of set() from hiding the definitions in the

   // base class.

   using internal::StringPieceDetail<std::string>::set;

   void set(const void* data, size_type len) {

     ptr_ = reinterpret_cast<const value_type*>(data);

     length_ = len;

   }

   void CopyToString(std::string* target) const {

     internal::CopyToString(*this, target);

   }

   void AppendToString(std::string* target) const {

     internal::AppendToString(*this, target);

   }

   // Does "this" start with "x"

   bool starts_with(const BasicStringPiece& x) const {

     return ((length_ >= x.length_) &&

             (wordmemcmp(ptr_, x.ptr_, x.length_) == 0));

   }

   // Does "this" end with "x"

   bool ends_with(const BasicStringPiece& x) const {

     return ((length_ >= x.length_) &&

             (wordmemcmp(ptr_ + (length_-x.length_), x.ptr_, x.length_) == 0));

   }

   size_type copy(char* buf, size_type n, size_type pos = 0) const {

     return internal::copy(*this, buf, n, pos);

   }

   size_type find(const BasicStringPiece& s, size_type pos = 0) const {

     return internal::find(*this, s, pos);

   }

   size_type find(char c, size_type pos = 0) const {

     return internal::find(*this, c, pos);

   }

   size_type rfind(const BasicStringPiece& s, size_type pos = npos) const {

     return internal::rfind(*this, s, pos);

   }

   size_type rfind(char c, size_type pos = npos) const {

     return internal::rfind(*this, c, pos);

   }

   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(char c, size_type pos = 0) const {

     return find(c, pos);

   }

   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(char c, size_type pos = 0) const {

     return internal::find_first_not_of(*this, c, pos);

   }

   size_type find_last_of(const BasicStringPiece& s,

                          size_type pos = npos) const {

     return internal::find_last_of(*this, s, pos);

   }

   size_type find_last_of(char c, size_type pos = npos) const {

     return rfind(c, pos);

   }

   size_type find_last_not_of(const BasicStringPiece& s,

                              size_type pos = npos) const {

     return internal::find_last_not_of(*this, s, pos);

   }

   size_type find_last_not_of(char c, size_type pos = npos) const {

     return internal::find_last_not_of(*this, c, pos);

   }

   BasicStringPiece substr(size_type pos, size_type n = npos) const {

     return internal::substr(*this, pos, n);

   }

 };

 // MSVC doesn't like complex extern templates and DLLs.

 #if !defined(COMPILER_MSVC)

 // We can't explicitly declare the std::string instantiation here because it was

 // already instantiated when specialized, above. Not only is it a no-op, but

 // currently it also crashes Clang (see http://crbug.com/107412).

 extern template class BASE_EXPORT BasicStringPiece<string16>;

 #endif

 BASE_EXPORT bool operator==(const StringPiece& x, const StringPiece& y);

 inline bool operator!=(const StringPiece& x, const StringPiece& y) {

   return !(x == y);

 }

 inline bool operator<(const StringPiece& x, const StringPiece& y) {

   const int r = StringPiece::wordmemcmp(

       x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));

   return ((r < 0) || ((r == 0) && (x.size() < y.size())));

 }

 inline bool operator>(const StringPiece& x, const StringPiece& y) {

   return y < x;

 }

 inline bool operator<=(const StringPiece& x, const StringPiece& y) {

   return !(x > y);

 }

 inline bool operator>=(const StringPiece& x, const StringPiece& y) {

   return !(x < y);

 }

 inline bool operator==(const StringPiece16& x, const StringPiece16& y) {

   if (x.size() != y.size())

     return false;

   return StringPiece16::wordmemcmp(x.data(), y.data(), x.size()) == 0;

 }

 inline bool operator!=(const StringPiece16& x, const StringPiece16& y) {

   return !(x == y);

 }

 inline bool operator<(const StringPiece16& x, const StringPiece16& y) {

   const int r = StringPiece16::wordmemcmp(

       x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));

   return ((r < 0) || ((r == 0) && (x.size() < y.size())));

 }

 inline bool operator>(const StringPiece16& x, const StringPiece16& y) {

   return y < x;

 }

 inline bool operator<=(const StringPiece16& x, const StringPiece16& y) {

   return !(x > y);

 }

 inline bool operator>=(const StringPiece16& x, const StringPiece16& y) {

   return !(x < y);

 }

 BASE_EXPORT std::ostream& operator<<(std::ostream& o,

                                      const StringPiece& piece);

 }  // namespace base

 // 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/containers/hash_tables.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.

 #define HASH_STRING_PIECE(StringPieceType, string_piece)                \

   std::size_t result = 0;                                               \

   for (StringPieceType::const_iterator i = string_piece.begin();        \

        i != string_piece.end(); ++i)                                    \

     result = (result * 131) + *i;                                       \

   return result;                                                        \

 namespace BASE_HASH_NAMESPACE {

 #if defined(COMPILER_GCC)

 template<>

 struct hash<base::StringPiece> {

   std::size_t operator()(const base::StringPiece& sp) const {

     HASH_STRING_PIECE(base::StringPiece, sp);

   }

 };

 template<>

 struct hash<base::StringPiece16> {

   std::size_t operator()(const base::StringPiece16& sp16) const {

     HASH_STRING_PIECE(base::StringPiece16, sp16);

   }

 };

 #elif defined(COMPILER_MSVC)

 inline size_t hash_value(const base::StringPiece& sp) {

   HASH_STRING_PIECE(base::StringPiece, sp);

 }

 inline size_t hash_value(const base::StringPiece16& sp16) {

   HASH_STRING_PIECE(base::StringPiece16, sp16);

 }

 #endif  // COMPILER

 }  // namespace BASE_HASH_NAMESPACE

 #endif  // BASE_STRINGS_STRING_PIECE_H_