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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Copied from strings/stringpiece.h with modifications
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// A string-like object that points to a sized piece of memory.
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// Functions or methods may use const StringPiece& parameters to accept either
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// a "const char*" or a "string" value that will be implicitly converted to
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// a StringPiece. The implicit conversion means that it is often appropriate
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// to include this .h file in other files rather than forward-declaring
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// StringPiece as would be appropriate for most other Google classes.
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// Systematic usage of StringPiece is encouraged as it will reduce unnecessary
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// conversions from "const char*" to "string" and back again.
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// StringPiece16 is similar to StringPiece but for base::string16 instead of
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// std::string. We do not define as large of a subset of the STL functions
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// from basic_string as in StringPiece, but this can be changed if these
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// functions (find, find_first_of, etc.) are found to be useful in this context.
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#ifndef BASE_STRINGS_STRING_PIECE_H_
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#define BASE_STRINGS_STRING_PIECE_H_
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#include "base/base_export.h"
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#include "base/basictypes.h"
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#include "base/containers/hash_tables.h"
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#include "base/strings/string16.h"
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template <typename STRING_TYPE> class BasicStringPiece;
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typedef BasicStringPiece<std::string> StringPiece;
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typedef BasicStringPiece<string16> StringPiece16;
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// Defines the types, methods, operators, and data members common to both
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// StringPiece and StringPiece16. Do not refer to this class directly, but
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// rather to BasicStringPiece, StringPiece, or StringPiece16.
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template <typename STRING_TYPE> class StringPieceDetail {
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// standard STL container boilerplate
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typedef size_t size_type;
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typedef typename STRING_TYPE::value_type value_type;
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typedef const value_type* pointer;
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typedef const value_type& reference;
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typedef const value_type& const_reference;
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typedef ptrdiff_t difference_type;
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typedef const value_type* const_iterator;
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typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
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static const size_type npos;
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// We provide non-explicit singleton constructors so users can pass
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// in a "const char*" or a "string" wherever a "StringPiece" is
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// expected (likewise for char16, string16, StringPiece16).
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StringPieceDetail() : ptr_(NULL), length_(0) {}
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StringPieceDetail(const value_type* str)
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length_((str == NULL) ? 0 : STRING_TYPE::traits_type::length(str)) {}
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StringPieceDetail(const STRING_TYPE& str)
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: ptr_(str.data()), length_(str.size()) {}
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StringPieceDetail(const value_type* offset, size_type len)
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: ptr_(offset), length_(len) {}
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StringPieceDetail(const typename STRING_TYPE::const_iterator& begin,
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const typename STRING_TYPE::const_iterator& end)
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: ptr_((end > begin) ? &(*begin) : NULL),
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length_((end > begin) ? (size_type)(end - begin) : 0) {}
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// data() may return a pointer to a buffer with embedded NULs, and the
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// returned buffer may or may not be null terminated. Therefore it is
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// typically a mistake to pass data() to a routine that expects a NUL
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const value_type* data() const { return ptr_; }
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size_type size() const { return length_; }
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size_type length() const { return length_; }
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bool empty() const { return length_ == 0; }
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void set(const value_type* data, size_type len) {
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void set(const value_type* str) {
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length_ = str ? STRING_TYPE::traits_type::length(str) : 0;
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value_type operator[](size_type i) const { return ptr_[i]; }
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void remove_prefix(size_type n) {
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void remove_suffix(size_type n) {
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int compare(const BasicStringPiece<STRING_TYPE>& x) const {
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ptr_, x.ptr_, (length_ < x.length_ ? length_ : x.length_));
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if (length_ < x.length_) r = -1;
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else if (length_ > x.length_) r = +1;
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STRING_TYPE as_string() const {
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// std::string doesn't like to take a NULL pointer even with a 0 size.
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return empty() ? STRING_TYPE() : STRING_TYPE(data(), size());
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const_iterator begin() const { return ptr_; }
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const_iterator end() const { return ptr_ + length_; }
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const_reverse_iterator rbegin() const {
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return const_reverse_iterator(ptr_ + length_);
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const_reverse_iterator rend() const {
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return const_reverse_iterator(ptr_);
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size_type max_size() const { return length_; }
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size_type capacity() const { return length_; }
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static int wordmemcmp(const value_type* p,
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const value_type* p2,
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return STRING_TYPE::traits_type::compare(p, p2, N);
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const value_type* ptr_;
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template <typename STRING_TYPE>
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const typename StringPieceDetail<STRING_TYPE>::size_type
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StringPieceDetail<STRING_TYPE>::npos =
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typename StringPieceDetail<STRING_TYPE>::size_type(-1);
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// MSVC doesn't like complex extern templates and DLLs.
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#if !defined(COMPILER_MSVC)
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extern template class BASE_EXPORT StringPieceDetail<std::string>;
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extern template class BASE_EXPORT StringPieceDetail<string16>;
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BASE_EXPORT void CopyToString(const StringPiece& self, std::string* target);
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BASE_EXPORT void AppendToString(const StringPiece& self, std::string* target);
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BASE_EXPORT StringPieceDetail<std::string>::size_type copy(
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const StringPiece& self,
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StringPieceDetail<std::string>::size_type n,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find(
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const StringPiece& self,
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const StringPiece& s,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find(
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const StringPiece& self,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type rfind(
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const StringPiece& self,
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const StringPiece& s,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type rfind(
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const StringPiece& self,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find_first_of(
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const StringPiece& self,
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const StringPiece& s,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find_first_not_of(
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const StringPiece& self,
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const StringPiece& s,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find_first_not_of(
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const StringPiece& self,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find_last_of(
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const StringPiece& self,
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const StringPiece& s,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find_last_of(
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const StringPiece& self,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find_last_not_of(
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const StringPiece& self,
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const StringPiece& s,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPieceDetail<std::string>::size_type find_last_not_of(
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const StringPiece& self,
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StringPieceDetail<std::string>::size_type pos);
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BASE_EXPORT StringPiece substr(const StringPiece& self,
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StringPieceDetail<std::string>::size_type pos,
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StringPieceDetail<std::string>::size_type n);
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} // namespace internal
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// Defines the template type that is instantiated as either StringPiece or
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template <typename STRING_TYPE> class BasicStringPiece :
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public internal::StringPieceDetail<STRING_TYPE> {
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typedef typename internal::StringPieceDetail<STRING_TYPE>::value_type
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typedef typename internal::StringPieceDetail<STRING_TYPE>::size_type
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BasicStringPiece() {}
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BasicStringPiece(const value_type*str)
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: internal::StringPieceDetail<STRING_TYPE>(str) {}
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BasicStringPiece(const STRING_TYPE& str)
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: internal::StringPieceDetail<STRING_TYPE>(str) {}
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BasicStringPiece(const value_type* offset, size_type len)
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: internal::StringPieceDetail<STRING_TYPE>(offset, len) {}
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BasicStringPiece(const typename STRING_TYPE::const_iterator& begin,
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const typename STRING_TYPE::const_iterator& end)
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: internal::StringPieceDetail<STRING_TYPE>(begin, end) {}
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// Specializes BasicStringPiece for std::string to add a few operations that
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// are not needed for string16.
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template <> class BasicStringPiece<std::string> :
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public internal::StringPieceDetail<std::string> {
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BasicStringPiece() {}
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BasicStringPiece(const char* str)
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: internal::StringPieceDetail<std::string>(str) {}
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BasicStringPiece(const std::string& str)
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: internal::StringPieceDetail<std::string>(str) {}
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BasicStringPiece(const char* offset, size_type len)
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: internal::StringPieceDetail<std::string>(offset, len) {}
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BasicStringPiece(const std::string::const_iterator& begin,
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const std::string::const_iterator& end)
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: internal::StringPieceDetail<std::string>(begin, end) {}
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// Prevent the following overload of set() from hiding the definitions in the
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using internal::StringPieceDetail<std::string>::set;
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void set(const void* data, size_type len) {
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ptr_ = reinterpret_cast<const value_type*>(data);
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void CopyToString(std::string* target) const {
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internal::CopyToString(*this, target);
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void AppendToString(std::string* target) const {
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internal::AppendToString(*this, target);
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// Does "this" start with "x"
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bool starts_with(const BasicStringPiece& x) const {
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return ((length_ >= x.length_) &&
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(wordmemcmp(ptr_, x.ptr_, x.length_) == 0));
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// Does "this" end with "x"
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bool ends_with(const BasicStringPiece& x) const {
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return ((length_ >= x.length_) &&
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(wordmemcmp(ptr_ + (length_-x.length_), x.ptr_, x.length_) == 0));
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size_type copy(char* buf, size_type n, size_type pos = 0) const {
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return internal::copy(*this, buf, n, pos);
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size_type find(const BasicStringPiece& s, size_type pos = 0) const {
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return internal::find(*this, s, pos);
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size_type find(char c, size_type pos = 0) const {
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return internal::find(*this, c, pos);
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size_type rfind(const BasicStringPiece& s, size_type pos = npos) const {
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return internal::rfind(*this, s, pos);
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size_type rfind(char c, size_type pos = npos) const {
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return internal::rfind(*this, c, pos);
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size_type find_first_of(const BasicStringPiece& s, size_type pos = 0) const {
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return internal::find_first_of(*this, s, pos);
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size_type find_first_of(char c, size_type pos = 0) const {
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size_type find_first_not_of(const BasicStringPiece& s,
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size_type pos = 0) const {
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return internal::find_first_not_of(*this, s, pos);
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size_type find_first_not_of(char c, size_type pos = 0) const {
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return internal::find_first_not_of(*this, c, pos);
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size_type find_last_of(const BasicStringPiece& s,
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size_type pos = npos) const {
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return internal::find_last_of(*this, s, pos);
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size_type find_last_of(char c, size_type pos = npos) const {
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return rfind(c, pos);
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size_type find_last_not_of(const BasicStringPiece& s,
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size_type pos = npos) const {
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return internal::find_last_not_of(*this, s, pos);
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size_type find_last_not_of(char c, size_type pos = npos) const {
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return internal::find_last_not_of(*this, c, pos);
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BasicStringPiece substr(size_type pos, size_type n = npos) const {
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return internal::substr(*this, pos, n);
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// MSVC doesn't like complex extern templates and DLLs.
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#if !defined(COMPILER_MSVC)
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// We can't explicitly declare the std::string instantiation here because it was
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// already instantiated when specialized, above. Not only is it a no-op, but
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// currently it also crashes Clang (see http://crbug.com/107412).
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extern template class BASE_EXPORT BasicStringPiece<string16>;
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BASE_EXPORT bool operator==(const StringPiece& x, const StringPiece& y);
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inline bool operator!=(const StringPiece& x, const StringPiece& y) {
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inline bool operator<(const StringPiece& x, const StringPiece& y) {
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const int r = StringPiece::wordmemcmp(
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x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));
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return ((r < 0) || ((r == 0) && (x.size() < y.size())));
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inline bool operator>(const StringPiece& x, const StringPiece& y) {
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inline bool operator<=(const StringPiece& x, const StringPiece& y) {
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inline bool operator>=(const StringPiece& x, const StringPiece& y) {
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inline bool operator==(const StringPiece16& x, const StringPiece16& y) {
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if (x.size() != y.size())
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return StringPiece16::wordmemcmp(x.data(), y.data(), x.size()) == 0;
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inline bool operator!=(const StringPiece16& x, const StringPiece16& y) {
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inline bool operator<(const StringPiece16& x, const StringPiece16& y) {
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const int r = StringPiece16::wordmemcmp(
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x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));
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return ((r < 0) || ((r == 0) && (x.size() < y.size())));
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inline bool operator>(const StringPiece16& x, const StringPiece16& y) {
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inline bool operator<=(const StringPiece16& x, const StringPiece16& y) {
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inline bool operator>=(const StringPiece16& x, const StringPiece16& y) {
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BASE_EXPORT std::ostream& operator<<(std::ostream& o,
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const StringPiece& piece);
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// We provide appropriate hash functions so StringPiece and StringPiece16 can
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// be used as keys in hash sets and maps.
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// This hash function is copied from base/containers/hash_tables.h. We don't
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// use the ones already defined for string and string16 directly because it
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// would require the string constructors to be called, which we don't want.
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#define HASH_STRING_PIECE(StringPieceType, string_piece) \
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std::size_t result = 0; \
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for (StringPieceType::const_iterator i = string_piece.begin(); \
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i != string_piece.end(); ++i) \
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result = (result * 131) + *i; \
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namespace BASE_HASH_NAMESPACE {
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#if defined(COMPILER_GCC)
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struct hash<base::StringPiece> {
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std::size_t operator()(const base::StringPiece& sp) const {
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HASH_STRING_PIECE(base::StringPiece, sp);
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struct hash<base::StringPiece16> {
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std::size_t operator()(const base::StringPiece16& sp16) const {
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HASH_STRING_PIECE(base::StringPiece16, sp16);
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#elif defined(COMPILER_MSVC)
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inline size_t hash_value(const base::StringPiece& sp) {
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HASH_STRING_PIECE(base::StringPiece, sp);
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inline size_t hash_value(const base::StringPiece16& sp16) {
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HASH_STRING_PIECE(base::StringPiece16, sp16);
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} // namespace BASE_HASH_NAMESPACE
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#endif // BASE_STRINGS_STRING_PIECE_H_