520 lines
19 KiB
C
520 lines
19 KiB
C
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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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//
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// A string-like object that points to a sized piece of memory.
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//
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// You can use StringPiece as a function or method parameter. A StringPiece
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// parameter can receive a double-quoted string literal argument, a "const
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// char*" argument, a string argument, or a StringPiece argument with no data
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// copying. Systematic use of StringPiece for arguments reduces data
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// copies and strlen() calls.
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//
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// Prefer passing StringPieces by value:
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// void MyFunction(StringPiece arg);
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// If circumstances require, you may also pass by const reference:
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// void MyFunction(const StringPiece& arg); // not preferred
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// Both of these have the same lifetime semantics. Passing by value
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// generates slightly smaller code. For more discussion, Googlers can see
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// the thread go/stringpiecebyvalue on c-users.
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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 <stddef.h>
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#include <iosfwd>
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#include <string>
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#include <type_traits>
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#include "base/base_export.h"
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#include "base/logging.h"
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#include "base/strings/char_traits.h"
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#include "base/strings/string16.h"
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#include "base/strings/string_piece_forward.h"
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namespace base {
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// internal --------------------------------------------------------------------
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// Many of the StringPiece functions use different implementations for the
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// 8-bit and 16-bit versions, and we don't want lots of template expansions in
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// this (very common) header that will slow down compilation.
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//
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// So here we define overloaded functions called by the StringPiece template.
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// For those that share an implementation, the two versions will expand to a
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// template internal to the .cc file.
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namespace internal {
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BASE_EXPORT size_t copy(const StringPiece& self,
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char* buf,
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size_t n,
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size_t pos);
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BASE_EXPORT size_t copy(const StringPiece16& self,
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char16* buf,
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size_t n,
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size_t pos);
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BASE_EXPORT size_t find(const StringPiece& self,
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const StringPiece& s,
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size_t pos);
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BASE_EXPORT size_t find(const StringPiece16& self,
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const StringPiece16& s,
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size_t pos);
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BASE_EXPORT size_t find(const StringPiece& self,
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char c,
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size_t pos);
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BASE_EXPORT size_t find(const StringPiece16& self,
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char16 c,
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size_t pos);
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BASE_EXPORT size_t rfind(const StringPiece& self,
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const StringPiece& s,
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size_t pos);
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BASE_EXPORT size_t rfind(const StringPiece16& self,
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const StringPiece16& s,
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size_t pos);
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BASE_EXPORT size_t rfind(const StringPiece& self,
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char c,
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size_t pos);
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BASE_EXPORT size_t rfind(const StringPiece16& self,
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char16 c,
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size_t pos);
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BASE_EXPORT size_t find_first_of(const StringPiece& self,
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const StringPiece& s,
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size_t pos);
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BASE_EXPORT size_t find_first_of(const StringPiece16& self,
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const StringPiece16& s,
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size_t pos);
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BASE_EXPORT size_t find_first_not_of(const StringPiece& self,
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const StringPiece& s,
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size_t pos);
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BASE_EXPORT size_t find_first_not_of(const StringPiece16& self,
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const StringPiece16& s,
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size_t pos);
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BASE_EXPORT size_t find_first_not_of(const StringPiece& self,
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char c,
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size_t pos);
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BASE_EXPORT size_t find_first_not_of(const StringPiece16& self,
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char16 c,
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size_t pos);
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BASE_EXPORT size_t find_last_of(const StringPiece& self,
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const StringPiece& s,
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size_t pos);
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BASE_EXPORT size_t find_last_of(const StringPiece16& self,
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const StringPiece16& s,
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size_t pos);
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BASE_EXPORT size_t find_last_of(const StringPiece& self,
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char c,
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size_t pos);
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BASE_EXPORT size_t find_last_of(const StringPiece16& self,
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char16 c,
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size_t pos);
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BASE_EXPORT size_t find_last_not_of(const StringPiece& self,
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const StringPiece& s,
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size_t pos);
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BASE_EXPORT size_t find_last_not_of(const StringPiece16& self,
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const StringPiece16& s,
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size_t pos);
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BASE_EXPORT size_t find_last_not_of(const StringPiece16& self,
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char16 c,
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size_t pos);
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BASE_EXPORT size_t find_last_not_of(const StringPiece& self,
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char c,
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size_t pos);
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BASE_EXPORT StringPiece substr(const StringPiece& self,
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size_t pos,
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size_t n);
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BASE_EXPORT StringPiece16 substr(const StringPiece16& self,
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size_t pos,
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size_t n);
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} // namespace internal
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// BasicStringPiece ------------------------------------------------------------
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// Defines the types, methods, operators, and data members common to both
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// StringPiece and StringPiece16.
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//
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// This is templatized by string class type rather than character type, so
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// BasicStringPiece<std::string> or BasicStringPiece<base::string16>.
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template <typename STRING_TYPE> class BasicStringPiece {
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public:
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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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public:
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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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constexpr BasicStringPiece() : ptr_(NULL), length_(0) {}
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// TODO(crbug.com/1049498): Construction from nullptr is not allowed for
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// std::basic_string_view, so remove the special handling for it.
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// Note: This doesn't just use STRING_TYPE::traits_type::length(), since that
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// isn't constexpr until C++17.
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constexpr BasicStringPiece(const value_type* str)
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: ptr_(str), length_(!str ? 0 : CharTraits<value_type>::length(str)) {}
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// Explicitly disallow construction from nullptr. Note that this does not
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// catch construction from runtime strings that might be null.
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// Note: The following is just a more elaborate way of spelling
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// `BasicStringPiece(nullptr_t) = delete`, but unfortunately the terse form is
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// not supported by the PNaCl toolchain.
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// TODO(crbug.com/1049498): Remove once we CHECK(str) in the constructor
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// above.
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template <class T, class = std::enable_if_t<std::is_null_pointer<T>::value>>
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BasicStringPiece(T) {
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static_assert(sizeof(T) == 0, // Always false.
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"StringPiece does not support construction from nullptr, use "
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"the default constructor instead.");
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}
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BasicStringPiece(const STRING_TYPE& str)
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: ptr_(str.data()), length_(str.size()) {}
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constexpr BasicStringPiece(const value_type* offset, size_type len)
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: ptr_(offset), length_(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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DCHECK(begin <= end) << "StringPiece iterators swapped or invalid.";
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length_ = static_cast<size_t>(std::distance(begin, end));
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// The length test before assignment is to avoid dereferencing an iterator
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// that may point to the end() of a string.
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ptr_ = length_ > 0 ? &*begin : nullptr;
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}
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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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// terminated string.
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constexpr const value_type* data() const { return ptr_; }
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constexpr size_type size() const noexcept { return length_; }
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constexpr size_type length() const noexcept { return length_; }
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bool empty() const { return length_ == 0; }
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constexpr value_type operator[](size_type i) const {
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CHECK(i < length_);
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return ptr_[i];
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}
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value_type front() const {
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CHECK_NE(0UL, length_);
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return ptr_[0];
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}
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value_type back() const {
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CHECK_NE(0UL, length_);
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return ptr_[length_ - 1];
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}
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constexpr void remove_prefix(size_type n) {
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CHECK(n <= length_);
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ptr_ += n;
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length_ -= n;
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}
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constexpr void remove_suffix(size_type n) {
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CHECK(n <= length_);
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length_ -= n;
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}
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constexpr int compare(BasicStringPiece x) const noexcept {
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int r = CharTraits<value_type>::compare(
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ptr_, x.ptr_, (length_ < x.length_ ? length_ : x.length_));
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if (r == 0) {
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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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}
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return r;
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}
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// This is the style of conversion preferred by std::string_view in C++17.
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explicit operator STRING_TYPE() const { return as_string(); }
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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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}
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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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}
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const_reverse_iterator rend() const {
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return const_reverse_iterator(ptr_);
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}
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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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size_type copy(value_type* buf, size_type n, size_type pos = 0) const {
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return internal::copy(*this, buf, n, pos);
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}
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// Does "this" start with "x"
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constexpr bool starts_with(BasicStringPiece x) const noexcept {
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return (
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(this->length_ >= x.length_) &&
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(CharTraits<value_type>::compare(this->ptr_, x.ptr_, x.length_) == 0));
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}
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// Does "this" end with "x"
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constexpr bool ends_with(BasicStringPiece x) const noexcept {
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return ((this->length_ >= x.length_) &&
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(CharTraits<value_type>::compare(
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this->ptr_ + (this->length_ - x.length_), x.ptr_, x.length_) ==
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0));
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}
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// find: Search for a character or substring at a given offset.
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size_type find(const BasicStringPiece<STRING_TYPE>& s,
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size_type pos = 0) const {
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return internal::find(*this, s, pos);
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}
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size_type find(value_type c, size_type pos = 0) const {
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return internal::find(*this, c, pos);
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}
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// rfind: Reverse find.
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size_type rfind(const BasicStringPiece& s,
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size_type pos = BasicStringPiece::npos) const {
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return internal::rfind(*this, s, pos);
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}
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size_type rfind(value_type c, size_type pos = BasicStringPiece::npos) const {
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return internal::rfind(*this, c, pos);
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}
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// find_first_of: Find the first occurence of one of a set of characters.
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size_type find_first_of(const BasicStringPiece& s,
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size_type pos = 0) const {
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return internal::find_first_of(*this, s, pos);
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}
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size_type find_first_of(value_type c, size_type pos = 0) const {
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return find(c, pos);
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}
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// find_first_not_of: Find the first occurence not of a set of characters.
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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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}
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size_type find_first_not_of(value_type c, size_type pos = 0) const {
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return internal::find_first_not_of(*this, c, pos);
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}
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// find_last_of: Find the last occurence of one of a set of characters.
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size_type find_last_of(const BasicStringPiece& s,
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size_type pos = BasicStringPiece::npos) const {
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return internal::find_last_of(*this, s, pos);
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}
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size_type find_last_of(value_type c,
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size_type pos = BasicStringPiece::npos) const {
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return rfind(c, pos);
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}
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// find_last_not_of: Find the last occurence not of a set of characters.
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size_type find_last_not_of(const BasicStringPiece& s,
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size_type pos = BasicStringPiece::npos) const {
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return internal::find_last_not_of(*this, s, pos);
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}
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size_type find_last_not_of(value_type c,
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size_type pos = BasicStringPiece::npos) const {
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return internal::find_last_not_of(*this, c, pos);
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}
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// substr.
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BasicStringPiece substr(size_type pos,
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size_type n = BasicStringPiece::npos) const {
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return internal::substr(*this, pos, n);
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}
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protected:
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const value_type* ptr_;
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size_type length_;
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};
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template <typename STRING_TYPE>
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const typename BasicStringPiece<STRING_TYPE>::size_type
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BasicStringPiece<STRING_TYPE>::npos =
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typename BasicStringPiece<STRING_TYPE>::size_type(-1);
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|
|
|
||
|
|
// 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_
|