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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTStringRepr_h
+#define nsTStringRepr_h
+
+#include <limits>
+#include <string_view>
+#include <type_traits> // std::enable_if
+
+#include "mozilla/Char16.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/fallible.h"
+#include "nsStringBuffer.h"
+#include "nsStringFlags.h"
+#include "nsStringFwd.h"
+#include "nsStringIterator.h"
+#include "nsCharTraits.h"
+
+template <typename T>
+class nsTSubstringTuple;
+
+namespace mozilla {
+
+// This is mainly intended to be used in the context of nsTStrings where
+// we want to enable a specific function only for a given character class. In
+// order for this technique to work the member function needs to be templated
+// on something other than `T`. We keep this in the `mozilla` namespace rather
+// than `nsTStringRepr` as it's intentionally not dependent on `T`.
+//
+// The 'T' at the end of `Char[16]OnlyT` is refering to the `::type` portion
+// which will only be defined if the character class is correct. This is similar
+// to `std::enable_if_t` which is available in C++14, but not C++11.
+//
+// `CharType` is generally going to be a shadowed type of `T`.
+//
+// Example usage of a function that will only be defined if `T` == `char`:
+//
+// template <typename T>
+// class nsTSubstring : public nsTStringRepr<T> {
+// template <typename Q = T, typename EnableForChar = typename CharOnlyT<Q>>
+// int Foo() { return 42; }
+// };
+//
+// Please note that we had to use a separate type `Q` for this to work. You
+// will get a semi-decent compiler error if you use `T` directly.
+
+template <typename CharType>
+using CharOnlyT =
+ typename std::enable_if<std::is_same<char, CharType>::value>::type;
+
+template <typename CharType>
+using Char16OnlyT =
+ typename std::enable_if<std::is_same<char16_t, CharType>::value>::type;
+
+namespace detail {
+
+// nsTStringLengthStorage is a helper class which holds the string's length and
+// provides getters and setters for converting to and from `size_t`. This is
+// done to allow the length to be stored in a `uint32_t` using assertions.
+template <typename T>
+class nsTStringLengthStorage {
+ public:
+ // The maximum byte capacity for a `nsTString` must fit within an `int32_t`,
+ // with enough room for a trailing null, as consumers often cast `Length()`
+ // and `Capacity()` to smaller types like `int32_t`.
+ static constexpr size_t kMax =
+ size_t{std::numeric_limits<int32_t>::max()} / sizeof(T) - 1;
+ static_assert(
+ (kMax + 1) * sizeof(T) <= std::numeric_limits<int32_t>::max(),
+ "nsTString's maximum length, including the trailing null, must fit "
+ "within `int32_t`, as callers will cast to `int32_t` occasionally");
+ static_assert(((CheckedInt<uint32_t>{kMax} + 1) * sizeof(T) +
+ sizeof(nsStringBuffer))
+ .isValid(),
+ "Math required to allocate a nsStringBuffer for a "
+ "maximum-capacity string must not overflow uint32_t");
+
+ // Implicit conversion and assignment from `size_t` which assert that the
+ // value is in-range.
+ MOZ_IMPLICIT constexpr nsTStringLengthStorage(size_t aLength)
+ : mLength(static_cast<uint32_t>(aLength)) {
+ MOZ_RELEASE_ASSERT(aLength <= kMax, "string is too large");
+ }
+ constexpr nsTStringLengthStorage& operator=(size_t aLength) {
+ MOZ_RELEASE_ASSERT(aLength <= kMax, "string is too large");
+ mLength = static_cast<uint32_t>(aLength);
+ return *this;
+ }
+ MOZ_IMPLICIT constexpr operator size_t() const { return mLength; }
+
+ private:
+ uint32_t mLength = 0;
+};
+
+// nsTStringRepr defines a string's memory layout and some accessor methods.
+// This class exists so that nsTLiteralString can avoid inheriting
+// nsTSubstring's destructor. All methods on this class must be const because
+// literal strings are not writable.
+//
+// This class is an implementation detail and should not be instantiated
+// directly, nor used in any way outside of the string code itself. It is
+// buried in a namespace to discourage its use in function parameters.
+// If you need to take a parameter, use [const] ns[C]Substring&.
+// If you need to instantiate a string, use ns[C]String or descendents.
+//
+// NAMES:
+// nsStringRepr for wide characters
+// nsCStringRepr for narrow characters
+template <typename T>
+class nsTStringRepr {
+ public:
+ typedef mozilla::fallible_t fallible_t;
+
+ typedef T char_type;
+
+ typedef nsCharTraits<char_type> char_traits;
+ typedef typename char_traits::incompatible_char_type incompatible_char_type;
+
+ typedef nsTStringRepr<T> self_type;
+ typedef self_type base_string_type;
+
+ typedef nsTSubstring<T> substring_type;
+ typedef nsTSubstringTuple<T> substring_tuple_type;
+
+ typedef nsReadingIterator<char_type> const_iterator;
+ typedef char_type* iterator;
+
+ typedef nsTStringComparator<char_type> comparator_type;
+
+ typedef const char_type* const_char_iterator;
+
+ typedef std::basic_string_view<char_type> string_view;
+
+ typedef size_t index_type;
+ typedef size_t size_type;
+
+ // These are only for internal use within the string classes:
+ typedef StringDataFlags DataFlags;
+ typedef StringClassFlags ClassFlags;
+ typedef nsTStringLengthStorage<T> LengthStorage;
+
+ // Reading iterators.
+ constexpr const_char_iterator BeginReading() const { return mData; }
+ constexpr const_char_iterator EndReading() const { return mData + mLength; }
+
+ // Deprecated reading iterators.
+ const_iterator& BeginReading(const_iterator& aIter) const {
+ aIter.mStart = mData;
+ aIter.mEnd = mData + mLength;
+ aIter.mPosition = aIter.mStart;
+ return aIter;
+ }
+
+ const_iterator& EndReading(const_iterator& aIter) const {
+ aIter.mStart = mData;
+ aIter.mEnd = mData + mLength;
+ aIter.mPosition = aIter.mEnd;
+ return aIter;
+ }
+
+ const_char_iterator& BeginReading(const_char_iterator& aIter) const {
+ return aIter = mData;
+ }
+
+ const_char_iterator& EndReading(const_char_iterator& aIter) const {
+ return aIter = mData + mLength;
+ }
+
+ // Accessors.
+ template <typename U, typename Dummy>
+ struct raw_type {
+ typedef const U* type;
+ };
+#if defined(MOZ_USE_CHAR16_WRAPPER)
+ template <typename Dummy>
+ struct raw_type<char16_t, Dummy> {
+ typedef char16ptr_t type;
+ };
+#endif
+
+ // Returns pointer to string data (not necessarily null-terminated)
+ constexpr typename raw_type<T, int>::type Data() const { return mData; }
+
+ constexpr size_type Length() const { return static_cast<size_type>(mLength); }
+
+ constexpr string_view View() const { return string_view(Data(), Length()); }
+
+ constexpr operator string_view() const { return View(); }
+
+ constexpr DataFlags GetDataFlags() const { return mDataFlags; }
+
+ constexpr bool IsEmpty() const { return mLength == 0; }
+
+ constexpr bool IsLiteral() const {
+ return !!(mDataFlags & DataFlags::LITERAL);
+ }
+
+ constexpr bool IsVoid() const { return !!(mDataFlags & DataFlags::VOIDED); }
+
+ constexpr bool IsTerminated() const {
+ return !!(mDataFlags & DataFlags::TERMINATED);
+ }
+
+ constexpr char_type CharAt(index_type aIndex) const {
+ NS_ASSERTION(aIndex < Length(), "index exceeds allowable range");
+ return mData[aIndex];
+ }
+
+ constexpr char_type operator[](index_type aIndex) const {
+ return CharAt(aIndex);
+ }
+
+ char_type First() const;
+
+ char_type Last() const;
+
+ // Equality.
+ bool NS_FASTCALL Equals(const self_type&) const;
+ bool NS_FASTCALL Equals(const self_type&, comparator_type) const;
+
+ bool NS_FASTCALL Equals(const substring_tuple_type& aTuple) const;
+ bool NS_FASTCALL Equals(const substring_tuple_type& aTuple,
+ comparator_type) const;
+
+ bool NS_FASTCALL Equals(const char_type* aData) const;
+ bool NS_FASTCALL Equals(const char_type* aData, comparator_type) const;
+
+ /**
+ * Compare this string and another ASCII-case-insensitively.
+ *
+ * This method is similar to `LowerCaseEqualsASCII` however both strings are
+ * lowercased, meaning that `aString` need not be all lowercase.
+ *
+ * @param aString is the string to check
+ * @return boolean
+ */
+ bool EqualsIgnoreCase(const std::string_view& aString) const;
+
+#ifdef __cpp_char8_t
+ template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
+ bool NS_FASTCALL Equals(const char8_t* aData) const {
+ return Equals(reinterpret_cast<const char*>(aData));
+ }
+
+ template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
+ bool NS_FASTCALL Equals(const char8_t* aData, comparator_type aComp) const {
+ return Equals(reinterpret_cast<const char*>(aData), aComp);
+ }
+#endif
+
+#if defined(MOZ_USE_CHAR16_WRAPPER)
+ template <typename Q = T, typename EnableIfChar16 = Char16OnlyT<Q>>
+ bool NS_FASTCALL Equals(char16ptr_t aData) const {
+ return Equals(static_cast<const char16_t*>(aData));
+ }
+ template <typename Q = T, typename EnableIfChar16 = Char16OnlyT<Q>>
+ bool NS_FASTCALL Equals(char16ptr_t aData, comparator_type aComp) const {
+ return Equals(static_cast<const char16_t*>(aData), aComp);
+ }
+#endif
+
+ // An efficient comparison with ASCII that can be used even
+ // for wide strings. Call this version when you know the
+ // length of 'data'.
+ bool NS_FASTCALL EqualsASCII(const char* aData, size_type aLen) const;
+ // An efficient comparison with ASCII that can be used even
+ // for wide strings. Call this version when 'data' is
+ // null-terminated.
+ bool NS_FASTCALL EqualsASCII(const char* aData) const;
+
+ // An efficient comparison with Latin1 characters that can be used even for
+ // wide strings.
+ bool EqualsLatin1(const char* aData, size_type aLength) const;
+
+ // EqualsLiteral must ONLY be called with an actual literal string, or
+ // a char array *constant* declared without an explicit size and with an
+ // initializer that is a string literal or is otherwise null-terminated.
+ // Use EqualsASCII for other char array variables.
+ // (Although this method may happen to produce expected results for other
+ // char arrays that have bound one greater than the sequence of interest,
+ // such use is discouraged for reasons of readability and maintainability.)
+ // The template trick to acquire the array bound at compile time without
+ // using a macro is due to Corey Kosak, with much thanks.
+ template <int N>
+ inline bool EqualsLiteral(const char (&aStr)[N]) const {
+ return EqualsASCII(aStr, N - 1);
+ }
+
+ // EqualsLiteral must ONLY be called with an actual literal string, or
+ // a char array *constant* declared without an explicit size and with an
+ // initializer that is a string literal or is otherwise null-terminated.
+ // Use EqualsASCII for other char array variables.
+ // (Although this method may happen to produce expected results for other
+ // char arrays that have bound one greater than the sequence of interest,
+ // such use is discouraged for reasons of readability and maintainability.)
+ // The template trick to acquire the array bound at compile time without
+ // using a macro is due to Corey Kosak, with much thanks.
+ template <size_t N, typename = std::enable_if_t<!std::is_same_v<
+ const char (&)[N], const char_type (&)[N]>>>
+ inline bool EqualsLiteral(const char_type (&aStr)[N]) const {
+ return *this == nsTLiteralString<char_type>(aStr);
+ }
+
+ // The LowerCaseEquals methods compare the ASCII-lowercase version of
+ // this string (lowercasing only ASCII uppercase characters) to some
+ // ASCII/Literal string. The ASCII string is *not* lowercased for
+ // you. If you compare to an ASCII or literal string that contains an
+ // uppercase character, it is guaranteed to return false. We will
+ // throw assertions too.
+ bool NS_FASTCALL LowerCaseEqualsASCII(const char* aData,
+ size_type aLen) const;
+ bool NS_FASTCALL LowerCaseEqualsASCII(const char* aData) const;
+
+ // LowerCaseEqualsLiteral must ONLY be called with an actual literal string,
+ // or a char array *constant* declared without an explicit size and with an
+ // initializer that is a string literal or is otherwise null-terminated.
+ // Use LowerCaseEqualsASCII for other char array variables.
+ // (Although this method may happen to produce expected results for other
+ // char arrays that have bound one greater than the sequence of interest,
+ // such use is discouraged for reasons of readability and maintainability.)
+ template <int N>
+ bool LowerCaseEqualsLiteral(const char (&aStr)[N]) const {
+ return LowerCaseEqualsASCII(aStr, N - 1);
+ }
+
+ // Returns true if this string overlaps with the given string fragment.
+ bool IsDependentOn(const char_type* aStart, const char_type* aEnd) const {
+ // If it _isn't_ the case that one fragment starts after the other ends,
+ // or ends before the other starts, then, they conflict:
+ //
+ // !(f2.begin >= f1.aEnd || f2.aEnd <= f1.begin)
+ //
+ // Simplified, that gives us (To avoid relying on Undefined Behavior
+ // from comparing pointers from different allocations (which in
+ // principle gives the optimizer the permission to assume elsewhere
+ // that the pointers are from the same allocation), the comparisons
+ // are done on integers, which merely relies on implementation-defined
+ // behavior of converting pointers to integers. std::less and
+ // std::greater implementations don't actually provide the guarantees
+ // that they should.):
+ return (reinterpret_cast<uintptr_t>(aStart) <
+ reinterpret_cast<uintptr_t>(mData + mLength) &&
+ reinterpret_cast<uintptr_t>(aEnd) >
+ reinterpret_cast<uintptr_t>(mData));
+ }
+
+ /**
+ * Search for the given substring within this string.
+ *
+ * @param aString is substring to be sought in this
+ * @param aOffset tells us where in this string to start searching
+ * @return offset in string, or kNotFound
+ */
+ int32_t Find(const string_view& aString, index_type aOffset = 0) const;
+
+ // Previously there was an overload of `Find()` which took a bool second
+ // argument. Avoid issues by explicitly preventing that overload.
+ // TODO: Remove this at some point.
+ template <typename I,
+ typename = std::enable_if_t<!std::is_same_v<I, index_type> &&
+ std::is_convertible_v<I, index_type>>>
+ int32_t Find(const string_view& aString, I aOffset) const {
+ static_assert(!std::is_same_v<I, bool>, "offset must not be `bool`");
+ return Find(aString, static_cast<index_type>(aOffset));
+ }
+
+ /**
+ * Search for the given ASCII substring within this string, ignoring case.
+ *
+ * @param aString is substring to be sought in this
+ * @param aOffset tells us where in this string to start searching
+ * @return offset in string, or kNotFound
+ */
+ int32_t LowerCaseFindASCII(const std::string_view& aString,
+ index_type aOffset = 0) const;
+
+ /**
+ * Scan the string backwards, looking for the given substring.
+ *
+ * @param aString is substring to be sought in this
+ * @return offset in string, or kNotFound
+ */
+ int32_t RFind(const string_view& aString) const;
+
+ size_type CountChar(char_type) const;
+
+ bool Contains(char_type aChar) const { return FindChar(aChar) != kNotFound; }
+
+ /**
+ * Search for the first instance of a given char within this string
+ *
+ * @param aChar is the character to search for
+ * @param aOffset tells us where in this string to start searching
+ * @return offset in string, or kNotFound
+ */
+ int32_t FindChar(char_type aChar, index_type aOffset = 0) const;
+
+ /**
+ * Search for the last instance of a given char within this string
+ *
+ * @param aChar is the character to search for
+ * @param aOffset tells us where in this string to start searching
+ * @return offset in string, or kNotFound
+ */
+ int32_t RFindChar(char_type aChar, int32_t aOffset = -1) const;
+
+ /**
+ * This method searches this string for the first character found in
+ * the given string.
+ *
+ * @param aSet contains set of chars to be found
+ * @param aOffset tells us where in this string to start searching
+ * (counting from left)
+ * @return offset in string, or kNotFound
+ */
+
+ int32_t FindCharInSet(const string_view& aSet, index_type aOffset = 0) const;
+
+ /**
+ * This method searches this string for the last character found in
+ * the given string.
+ *
+ * @param aSet contains set of chars to be found
+ * @param aOffset tells us where in this string to start searching
+ * (counting from left)
+ * @return offset in string, or kNotFound
+ */
+
+ int32_t RFindCharInSet(const string_view& aSet, int32_t aOffset = -1) const;
+
+ /**
+ * Perform locale-independent string to double-precision float conversion.
+ *
+ * Leading spaces in the string will be ignored. The returned value will be
+ * finite unless aErrorCode is set to a failed status.
+ *
+ * @param aErrorCode will contain error if one occurs
+ * @return double-precision float rep of string value
+ */
+ double ToDouble(nsresult* aErrorCode) const;
+
+ /**
+ * Perform locale-independent string to single-precision float conversion.
+ *
+ * Leading spaces in the string will be ignored. The returned value will be
+ * finite unless aErrorCode is set to a failed status.
+ *
+ * @param aErrorCode will contain error if one occurs
+ * @return single-precision float rep of string value
+ */
+ float ToFloat(nsresult* aErrorCode) const;
+
+ /**
+ * Similar to above ToDouble and ToFloat but allows trailing characters that
+ * are not converted.
+ */
+ double ToDoubleAllowTrailingChars(nsresult* aErrorCode) const;
+ float ToFloatAllowTrailingChars(nsresult* aErrorCode) const;
+
+ protected:
+ nsTStringRepr() = delete; // Never instantiate directly
+
+ constexpr nsTStringRepr(char_type* aData, size_type aLength,
+ DataFlags aDataFlags, ClassFlags aClassFlags)
+ : mData(aData),
+ mLength(aLength),
+ mDataFlags(aDataFlags),
+ mClassFlags(aClassFlags) {}
+
+ static constexpr size_type kMaxCapacity = LengthStorage::kMax;
+
+ /**
+ * Checks if the given capacity is valid for this string type.
+ */
+ [[nodiscard]] static constexpr bool CheckCapacity(size_type aCapacity) {
+ return aCapacity <= kMaxCapacity;
+ }
+
+ char_type* mData;
+ LengthStorage mLength;
+ DataFlags mDataFlags;
+ ClassFlags const mClassFlags;
+};
+
+extern template class nsTStringRepr<char>;
+extern template class nsTStringRepr<char16_t>;
+
+} // namespace detail
+} // namespace mozilla
+
+template <typename T>
+int NS_FASTCALL Compare(const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const mozilla::detail::nsTStringRepr<T>& aRhs,
+ nsTStringComparator<T> = nsTDefaultStringComparator<T>);
+
+extern template int NS_FASTCALL Compare<char>(
+ const mozilla::detail::nsTStringRepr<char>&,
+ const mozilla::detail::nsTStringRepr<char>&, nsTStringComparator<char>);
+
+extern template int NS_FASTCALL
+Compare<char16_t>(const mozilla::detail::nsTStringRepr<char16_t>&,
+ const mozilla::detail::nsTStringRepr<char16_t>&,
+ nsTStringComparator<char16_t>);
+
+template <typename T>
+inline constexpr bool operator!=(
+ const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const mozilla::detail::nsTStringRepr<T>& aRhs) {
+ return !aLhs.Equals(aRhs);
+}
+
+template <typename T>
+inline constexpr bool operator!=(const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const T* aRhs) {
+ return !aLhs.Equals(aRhs);
+}
+
+template <typename T>
+inline bool operator<(const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const mozilla::detail::nsTStringRepr<T>& aRhs) {
+ return Compare(aLhs, aRhs) < 0;
+}
+
+template <typename T>
+inline bool operator<=(const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const mozilla::detail::nsTStringRepr<T>& aRhs) {
+ return Compare(aLhs, aRhs) <= 0;
+}
+
+template <typename T>
+inline bool operator==(const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const mozilla::detail::nsTStringRepr<T>& aRhs) {
+ return aLhs.Equals(aRhs);
+}
+
+template <typename T>
+inline bool operator==(const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const T* aRhs) {
+ return aLhs.Equals(aRhs);
+}
+
+template <typename T>
+inline bool operator>=(const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const mozilla::detail::nsTStringRepr<T>& aRhs) {
+ return Compare(aLhs, aRhs) >= 0;
+}
+
+template <typename T>
+inline bool operator>(const mozilla::detail::nsTStringRepr<T>& aLhs,
+ const mozilla::detail::nsTStringRepr<T>& aRhs) {
+ return Compare(aLhs, aRhs) > 0;
+}
+
+#endif