зеркало из https://github.com/mozilla/gecko-dev.git
398 строки
15 KiB
C++
398 строки
15 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsTStringRepr_h
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#define nsTStringRepr_h
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#include <type_traits> // std::enable_if
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#include "mozilla/Char16.h"
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#include "mozilla/fallible.h"
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#include "nsStringFlags.h"
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#include "nsStringIterator.h"
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#include "nsCharTraits.h"
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template <typename T>
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class nsTSubstringTuple;
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namespace mozilla {
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// This is mainly intended to be used in the context of nsTStrings where
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// we want to enable a specific function only for a given character class. In
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// order for this technique to work the member function needs to be templated
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// on something other than `T`. We keep this in the `mozilla` namespace rather
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// than `nsTStringRepr` as it's intentionally not dependent on `T`.
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//
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// The 'T' at the end of `Char[16]OnlyT` is refering to the `::type` portion
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// which will only be defined if the character class is correct. This is similar
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// to `std::enable_if_t` which is available in C++14, but not C++11.
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//
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// `CharType` is generally going to be a shadowed type of `T`.
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//
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// Example usage of a function that will only be defined if `T` == `char`:
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//
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// template <typename T>
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// class nsTSubstring : public nsTStringRepr<T> {
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// template <typename Q = T, typename EnableForChar = typename CharOnlyT<Q>>
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// int Foo() { return 42; }
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// };
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//
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// Please note that we had to use a separate type `Q` for this to work. You
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// will get a semi-decent compiler error if you use `T` directly.
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template <typename CharType>
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using CharOnlyT =
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typename std::enable_if<std::is_same<char, CharType>::value>::type;
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template <typename CharType>
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using Char16OnlyT =
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typename std::enable_if<std::is_same<char16_t, CharType>::value>::type;
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namespace detail {
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// nsTStringRepr defines a string's memory layout and some accessor methods.
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// This class exists so that nsTLiteralString can avoid inheriting
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// nsTSubstring's destructor. All methods on this class must be const because
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// literal strings are not writable.
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//
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// This class is an implementation detail and should not be instantiated
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// directly, nor used in any way outside of the string code itself. It is
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// buried in a namespace to discourage its use in function parameters.
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// If you need to take a parameter, use [const] ns[C]Substring&.
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// If you need to instantiate a string, use ns[C]String or descendents.
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//
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// NAMES:
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// nsStringRepr for wide characters
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// nsCStringRepr for narrow characters
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template <typename T>
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class nsTStringRepr {
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public:
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typedef mozilla::fallible_t fallible_t;
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typedef T char_type;
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typedef nsCharTraits<char_type> char_traits;
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typedef typename char_traits::incompatible_char_type incompatible_char_type;
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typedef nsTStringRepr<T> self_type;
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typedef self_type base_string_type;
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typedef nsTSubstring<T> substring_type;
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typedef nsTSubstringTuple<T> substring_tuple_type;
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typedef nsReadingIterator<char_type> const_iterator;
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typedef char_type* iterator;
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typedef nsTStringComparator<char_type> comparator_type;
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typedef const char_type* const_char_iterator;
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typedef uint32_t index_type;
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typedef uint32_t size_type;
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// These are only for internal use within the string classes:
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typedef StringDataFlags DataFlags;
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typedef StringClassFlags ClassFlags;
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// Reading iterators.
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constexpr const_char_iterator BeginReading() const { return mData; }
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constexpr const_char_iterator EndReading() const { return mData + mLength; }
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// Deprecated reading iterators.
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const_iterator& BeginReading(const_iterator& aIter) const {
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aIter.mStart = mData;
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aIter.mEnd = mData + mLength;
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aIter.mPosition = aIter.mStart;
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return aIter;
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}
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const_iterator& EndReading(const_iterator& aIter) const {
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aIter.mStart = mData;
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aIter.mEnd = mData + mLength;
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aIter.mPosition = aIter.mEnd;
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return aIter;
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}
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const_char_iterator& BeginReading(const_char_iterator& aIter) const {
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return aIter = mData;
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}
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const_char_iterator& EndReading(const_char_iterator& aIter) const {
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return aIter = mData + mLength;
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}
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// Accessors.
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template <typename U, typename Dummy>
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struct raw_type {
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typedef const U* type;
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};
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#if defined(MOZ_USE_CHAR16_WRAPPER)
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template <typename Dummy>
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struct raw_type<char16_t, Dummy> {
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typedef char16ptr_t type;
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};
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#endif
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// Returns pointer to string data (not necessarily null-terminated)
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constexpr const typename raw_type<T, int>::type Data() const { return mData; }
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constexpr size_type Length() const { return mLength; }
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constexpr DataFlags GetDataFlags() const { return mDataFlags; }
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constexpr bool IsEmpty() const { return mLength == 0; }
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constexpr bool IsLiteral() const {
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return !!(mDataFlags & DataFlags::LITERAL);
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}
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constexpr bool IsVoid() const { return !!(mDataFlags & DataFlags::VOIDED); }
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constexpr bool IsTerminated() const {
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return !!(mDataFlags & DataFlags::TERMINATED);
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}
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constexpr char_type CharAt(index_type aIndex) const {
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NS_ASSERTION(aIndex < mLength, "index exceeds allowable range");
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return mData[aIndex];
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}
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constexpr char_type operator[](index_type aIndex) const {
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return CharAt(aIndex);
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}
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char_type First() const;
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char_type Last() const;
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size_type NS_FASTCALL CountChar(char_type) const;
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int32_t NS_FASTCALL FindChar(char_type, index_type aOffset = 0) const;
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bool Contains(char_type aChar) const;
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// Equality.
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bool NS_FASTCALL Equals(const self_type&) const;
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bool NS_FASTCALL Equals(const self_type&, comparator_type) const;
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bool NS_FASTCALL Equals(const substring_tuple_type& aTuple) const;
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bool NS_FASTCALL Equals(const substring_tuple_type& aTuple,
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comparator_type) const;
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bool NS_FASTCALL Equals(const char_type* aData) const;
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bool NS_FASTCALL Equals(const char_type* aData, comparator_type) const;
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/**
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* Compares a given string to this string.
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*
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* @param aString is the string to be compared
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* @param aIgnoreCase tells us how to treat case
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* @param aCount tells us how many chars to compare
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* @return -1,0,1
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*/
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template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
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int32_t Compare(const char_type* aString, bool aIgnoreCase = false,
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int32_t aCount = -1) const;
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/**
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* Equality check between given string and this string.
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*
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* @param aString is the string to check
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* @param aIgnoreCase tells us how to treat case
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* @param aCount tells us how many chars to compare
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* @return boolean
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*/
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template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
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bool EqualsIgnoreCase(const char_type* aString, int32_t aCount = -1) const {
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return Compare(aString, true, aCount) == 0;
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}
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template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
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bool EqualsIgnoreCase(const incompatible_char_type* aString,
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int32_t aCount = -1) const;
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#if defined(MOZ_USE_CHAR16_WRAPPER)
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template <typename Q = T, typename EnableIfChar16 = Char16OnlyT<Q>>
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bool NS_FASTCALL Equals(char16ptr_t aData) const {
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return Equals(static_cast<const char16_t*>(aData));
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}
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template <typename Q = T, typename EnableIfChar16 = Char16OnlyT<Q>>
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bool NS_FASTCALL Equals(char16ptr_t aData, comparator_type aComp) const {
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return Equals(static_cast<const char16_t*>(aData), aComp);
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}
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#endif
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// An efficient comparison with ASCII that can be used even
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// for wide strings. Call this version when you know the
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// length of 'data'.
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bool NS_FASTCALL EqualsASCII(const char* aData, size_type aLen) const;
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// An efficient comparison with ASCII that can be used even
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// for wide strings. Call this version when 'data' is
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// null-terminated.
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bool NS_FASTCALL EqualsASCII(const char* aData) const;
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// An efficient comparison with Latin1 characters that can be used even for
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// wide strings.
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bool EqualsLatin1(const char* aData, size_type aLength) const;
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// EqualsLiteral must ONLY be called with an actual literal string, or
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// a char array *constant* declared without an explicit size and with an
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// initializer that is a string literal or is otherwise null-terminated.
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// Use EqualsASCII for other char array variables.
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// (Although this method may happen to produce expected results for other
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// char arrays that have bound one greater than the sequence of interest,
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// such use is discouraged for reasons of readability and maintainability.)
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// The template trick to acquire the array bound at compile time without
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// using a macro is due to Corey Kosak, with much thanks.
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template <int N>
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inline bool EqualsLiteral(const char (&aStr)[N]) const {
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return EqualsASCII(aStr, N - 1);
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}
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// EqualsLiteral must ONLY be called with an actual literal string, or
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// a char array *constant* declared without an explicit size and with an
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// initializer that is a string literal or is otherwise null-terminated.
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// Use EqualsASCII for other char array variables.
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// (Although this method may happen to produce expected results for other
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// char arrays that have bound one greater than the sequence of interest,
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// such use is discouraged for reasons of readability and maintainability.)
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// The template trick to acquire the array bound at compile time without
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// using a macro is due to Corey Kosak, with much thanks.
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template <size_t N, typename = std::enable_if_t<!std::is_same_v<
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const char (&)[N], const char_type (&)[N]>>>
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inline bool EqualsLiteral(const char_type (&aStr)[N]) const {
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return *this == nsTLiteralString<char_type>(aStr);
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}
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// The LowerCaseEquals methods compare the ASCII-lowercase version of
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// this string (lowercasing only ASCII uppercase characters) to some
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// ASCII/Literal string. The ASCII string is *not* lowercased for
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// you. If you compare to an ASCII or literal string that contains an
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// uppercase character, it is guaranteed to return false. We will
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// throw assertions too.
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bool NS_FASTCALL LowerCaseEqualsASCII(const char* aData,
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size_type aLen) const;
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bool NS_FASTCALL LowerCaseEqualsASCII(const char* aData) const;
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// LowerCaseEqualsLiteral must ONLY be called with an actual literal string,
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// or a char array *constant* declared without an explicit size and with an
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// initializer that is a string literal or is otherwise null-terminated.
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// Use LowerCaseEqualsASCII for other char array variables.
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// (Although this method may happen to produce expected results for other
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// char arrays that have bound one greater than the sequence of interest,
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// such use is discouraged for reasons of readability and maintainability.)
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template <int N>
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bool LowerCaseEqualsLiteral(const char (&aStr)[N]) const {
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return LowerCaseEqualsASCII(aStr, N - 1);
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}
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// Returns true if this string overlaps with the given string fragment.
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bool IsDependentOn(const char_type* aStart, const char_type* aEnd) const {
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// If it _isn't_ the case that one fragment starts after the other ends,
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// or ends before the other starts, then, they conflict:
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//
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// !(f2.begin >= f1.aEnd || f2.aEnd <= f1.begin)
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//
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// Simplified, that gives us (To avoid relying on Undefined Behavior
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// from comparing pointers from different allocations (which in
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// principle gives the optimizer the permission to assume elsewhere
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// that the pointers are from the same allocation), the comparisons
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// are done on integers, which merely relies on implementation-defined
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// behavior of converting pointers to integers. std::less and
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// std::greater implementations don't actually provide the guarantees
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// that they should.):
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return (reinterpret_cast<uintptr_t>(aStart) <
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reinterpret_cast<uintptr_t>(mData + mLength) &&
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reinterpret_cast<uintptr_t>(aEnd) >
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reinterpret_cast<uintptr_t>(mData));
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}
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protected:
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nsTStringRepr() = delete; // Never instantiate directly
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constexpr nsTStringRepr(char_type* aData, size_type aLength,
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DataFlags aDataFlags, ClassFlags aClassFlags)
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: mData(aData),
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mLength(aLength),
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mDataFlags(aDataFlags),
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mClassFlags(aClassFlags) {}
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char_type* mData;
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size_type mLength;
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DataFlags mDataFlags;
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ClassFlags const mClassFlags;
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};
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extern template class nsTStringRepr<char>;
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extern template class nsTStringRepr<char16_t>;
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} // namespace detail
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} // namespace mozilla
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template <typename T>
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int NS_FASTCALL Compare(const mozilla::detail::nsTStringRepr<T>& aLhs,
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const mozilla::detail::nsTStringRepr<T>& aRhs,
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nsTStringComparator<T> = nsTDefaultStringComparator<T>);
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extern template int NS_FASTCALL Compare<char>(
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const mozilla::detail::nsTStringRepr<char>&,
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const mozilla::detail::nsTStringRepr<char>&, nsTStringComparator<char>);
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extern template int NS_FASTCALL
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Compare<char16_t>(const mozilla::detail::nsTStringRepr<char16_t>&,
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const mozilla::detail::nsTStringRepr<char16_t>&,
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nsTStringComparator<char16_t>);
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template <typename T>
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inline constexpr bool operator!=(
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const mozilla::detail::nsTStringRepr<T>& aLhs,
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const mozilla::detail::nsTStringRepr<T>& aRhs) {
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return !aLhs.Equals(aRhs);
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}
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template <typename T>
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inline constexpr bool operator!=(const mozilla::detail::nsTStringRepr<T>& aLhs,
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const T* aRhs) {
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return !aLhs.Equals(aRhs);
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}
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template <typename T>
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inline bool operator<(const mozilla::detail::nsTStringRepr<T>& aLhs,
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const mozilla::detail::nsTStringRepr<T>& aRhs) {
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return Compare(aLhs, aRhs) < 0;
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}
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template <typename T>
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inline bool operator<=(const mozilla::detail::nsTStringRepr<T>& aLhs,
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const mozilla::detail::nsTStringRepr<T>& aRhs) {
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return Compare(aLhs, aRhs) <= 0;
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}
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template <typename T>
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inline bool operator==(const mozilla::detail::nsTStringRepr<T>& aLhs,
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const mozilla::detail::nsTStringRepr<T>& aRhs) {
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return aLhs.Equals(aRhs);
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}
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template <typename T>
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inline bool operator==(const mozilla::detail::nsTStringRepr<T>& aLhs,
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const T* aRhs) {
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return aLhs.Equals(aRhs);
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}
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template <typename T>
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inline bool operator>=(const mozilla::detail::nsTStringRepr<T>& aLhs,
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const mozilla::detail::nsTStringRepr<T>& aRhs) {
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return Compare(aLhs, aRhs) >= 0;
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}
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template <typename T>
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inline bool operator>(const mozilla::detail::nsTStringRepr<T>& aLhs,
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const mozilla::detail::nsTStringRepr<T>& aRhs) {
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return Compare(aLhs, aRhs) > 0;
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}
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#endif
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