Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 546 insertions, 0 deletions

diff --git a/xpcom/string/nsTStringRepr.h b/xpcom/string/nsTStringRepr.h
new file mode 100644
index 0000000000..7e7fa53384
--- /dev/null
+++ b/xpcom/string/nsTStringRepr.h
@@ -0,0 +1,546 @@
+/* -*- 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;
+
+#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