gecko-dev/xpcom/string/nsTStringRepr.cpp

/* -*- 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/. */

#include "nsTStringRepr.h"

#include "double-conversion/string-to-double.h"
#include "mozilla/FloatingPoint.h"
#include "nsError.h"
#include "nsString.h"

namespace mozilla::detail {

template <typename T>
typename nsTStringRepr<T>::char_type nsTStringRepr<T>::First() const {
  MOZ_RELEASE_ASSERT(this->mLength > 0, "|First()| called on an empty string");
  return this->mData[0];
}

template <typename T>
typename nsTStringRepr<T>::char_type nsTStringRepr<T>::Last() const {
  MOZ_RELEASE_ASSERT(this->mLength > 0, "|Last()| called on an empty string");
  return this->mData[this->mLength - 1];
}

template <typename T>
bool nsTStringRepr<T>::Equals(const self_type& aStr) const {
  return this->mLength == aStr.mLength &&
         char_traits::compare(this->mData, aStr.mData, this->mLength) == 0;
}

template <typename T>
bool nsTStringRepr<T>::Equals(const self_type& aStr,
                              comparator_type aComp) const {
  return this->mLength == aStr.mLength &&
         aComp(this->mData, aStr.mData, this->mLength, aStr.mLength) == 0;
}

template <typename T>
bool nsTStringRepr<T>::Equals(const substring_tuple_type& aTuple) const {
  return Equals(substring_type(aTuple));
}

template <typename T>
bool nsTStringRepr<T>::Equals(const substring_tuple_type& aTuple,
                              comparator_type aComp) const {
  return Equals(substring_type(aTuple), aComp);
}

template <typename T>
bool nsTStringRepr<T>::Equals(const char_type* aData) const {
  // unfortunately, some callers pass null :-(
  if (!aData) {
    MOZ_ASSERT_UNREACHABLE("null data pointer");
    return this->mLength == 0;
  }

  // XXX avoid length calculation?
  size_type length = char_traits::length(aData);
  return this->mLength == length &&
         char_traits::compare(this->mData, aData, this->mLength) == 0;
}

template <typename T>
bool nsTStringRepr<T>::Equals(const char_type* aData,
                              comparator_type aComp) const {
  // unfortunately, some callers pass null :-(
  if (!aData) {
    MOZ_ASSERT_UNREACHABLE("null data pointer");
    return this->mLength == 0;
  }

  // XXX avoid length calculation?
  size_type length = char_traits::length(aData);
  return this->mLength == length &&
         aComp(this->mData, aData, this->mLength, length) == 0;
}

template <typename T>
bool nsTStringRepr<T>::EqualsASCII(const char* aData, size_type aLen) const {
  return this->mLength == aLen &&
         char_traits::compareASCII(this->mData, aData, aLen) == 0;
}

template <typename T>
bool nsTStringRepr<T>::EqualsASCII(const char* aData) const {
  return char_traits::compareASCIINullTerminated(this->mData, this->mLength,
                                                 aData) == 0;
}

template <typename T>
bool nsTStringRepr<T>::EqualsLatin1(const char* aData,
                                    const size_type aLength) const {
  return (this->mLength == aLength) &&
         char_traits::equalsLatin1(this->mData, aData, aLength);
}

template <typename T>
bool nsTStringRepr<T>::LowerCaseEqualsASCII(const char* aData,
                                            size_type aLen) const {
  return this->mLength == aLen &&
         char_traits::compareLowerCaseToASCII(this->mData, aData, aLen) == 0;
}

template <typename T>
bool nsTStringRepr<T>::LowerCaseEqualsASCII(const char* aData) const {
  return char_traits::compareLowerCaseToASCIINullTerminated(
             this->mData, this->mLength, aData) == 0;
}

template <typename T>
int32_t nsTStringRepr<T>::Find(const string_view& aString,
                               index_type aOffset) const {
  auto idx = View().find(aString, aOffset);
  return idx == string_view::npos ? kNotFound : idx;
}

template <typename T>
int32_t nsTStringRepr<T>::LowerCaseFindASCII(const std::string_view& aString,
                                             index_type aOffset) const {
  if (aOffset > Length()) {
    return kNotFound;
  }
  auto begin = BeginReading();
  auto end = EndReading();
  auto it =
      std::search(begin + aOffset, end, aString.begin(), aString.end(),
                  [](char_type l, char r) {
                    MOZ_ASSERT(!(r & ~0x7F), "Unexpected non-ASCII character");
                    MOZ_ASSERT(char_traits::ASCIIToLower(r) == char_type(r),
                               "Search string must be ASCII lowercase");
                    return char_traits::ASCIIToLower(l) == char_type(r);
                  });
  return it == end ? kNotFound : std::distance(begin, it);
}

template <typename T>
int32_t nsTStringRepr<T>::RFind(const string_view& aString) const {
  auto idx = View().rfind(aString);
  return idx == string_view::npos ? kNotFound : idx;
}

template <typename T>
typename nsTStringRepr<T>::size_type nsTStringRepr<T>::CountChar(
    char_type aChar) const {
  return std::count(BeginReading(), EndReading(), aChar);
}

template <typename T>
int32_t nsTStringRepr<T>::FindChar(char_type aChar, index_type aOffset) const {
  auto idx = View().find(aChar, aOffset);
  return idx == string_view::npos ? kNotFound : idx;
}

template <typename T>
int32_t nsTStringRepr<T>::RFindChar(char_type aChar, int32_t aOffset) const {
  auto idx = View().rfind(aChar, aOffset != -1 ? aOffset : string_view::npos);
  return idx == string_view::npos ? kNotFound : idx;
}

template <typename T>
int32_t nsTStringRepr<T>::FindCharInSet(const string_view& aSet,
                                        index_type aOffset) const {
  auto idx = View().find_first_of(aSet, aOffset);
  return idx == string_view::npos ? kNotFound : idx;
}

template <typename T>
int32_t nsTStringRepr<T>::RFindCharInSet(const string_view& aSet,
                                         int32_t aOffset) const {
  auto idx =
      View().find_last_of(aSet, aOffset != -1 ? aOffset : string_view::npos);
  return idx == string_view::npos ? kNotFound : idx;
}

template <typename T>
bool nsTStringRepr<T>::EqualsIgnoreCase(const std::string_view& aString) const {
  return std::equal(BeginReading(), EndReading(), aString.begin(),
                    aString.end(), [](char_type l, char r) {
                      return char_traits::ASCIIToLower(l) ==
                             char_traits::ASCIIToLower(char_type(r));
                    });
}

// We can't use the method `StringToDoubleConverter::ToDouble` due to linking
// issues on Windows as it's in mozglue. Instead, implement the selection logic
// using an overload set.
//
// StringToFloat is used instead of StringToDouble for floats due to differences
// in rounding behaviour.
static void StringToFP(
    const double_conversion::StringToDoubleConverter& aConverter,
    const char* aData, size_t aLength, int* aProcessed, float* aResult) {
  *aResult = aConverter.StringToFloat(aData, aLength, aProcessed);
}

static void StringToFP(
    const double_conversion::StringToDoubleConverter& aConverter,
    const char* aData, size_t aLength, int* aProcessed, double* aResult) {
  *aResult = aConverter.StringToDouble(aData, aLength, aProcessed);
}

static void StringToFP(
    const double_conversion::StringToDoubleConverter& aConverter,
    const char16_t* aData, size_t aLength, int* aProcessed, float* aResult) {
  *aResult = aConverter.StringToFloat(reinterpret_cast<const uc16*>(aData),
                                      aLength, aProcessed);
}

static void StringToFP(
    const double_conversion::StringToDoubleConverter& aConverter,
    const char16_t* aData, size_t aLength, int* aProcessed, double* aResult) {
  *aResult = aConverter.StringToDouble(reinterpret_cast<const uc16*>(aData),
                                       aLength, aProcessed);
}

template <typename FloatT, typename CharT>
static FloatT ParseFloatingPoint(const nsTStringRepr<CharT>& aString,
                                 bool aAllowTrailingChars,
                                 nsresult* aErrorCode) {
  // Performs conversion to double following the "rules for parsing
  // floating-point number values" from the HTML standard.
  // https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#rules-for-parsing-floating-point-number-values
  //
  // This behaviour allows for leading spaces, and will not generate infinity or
  // NaN values except in error conditions.
  int flags = double_conversion::StringToDoubleConverter::ALLOW_LEADING_SPACES;
  if (aAllowTrailingChars) {
    flags |= double_conversion::StringToDoubleConverter::ALLOW_TRAILING_JUNK;
  }
  double_conversion::StringToDoubleConverter converter(
      flags, mozilla::UnspecifiedNaN<double>(),
      mozilla::UnspecifiedNaN<double>(), nullptr, nullptr);

  FloatT result;
  int processed;
  StringToFP(converter, aString.Data(), aString.Length(), &processed, &result);

  *aErrorCode = mozilla::IsFinite(result) ? NS_OK : NS_ERROR_ILLEGAL_VALUE;
  return result;
}

template <typename T>
double nsTStringRepr<T>::ToDouble(nsresult* aErrorCode) const {
  return ParseFloatingPoint<double, T>(*this, /* aAllowTrailingChars */ false,
                                       aErrorCode);
}

template <typename T>
double nsTStringRepr<T>::ToDoubleAllowTrailingChars(
    nsresult* aErrorCode) const {
  return ParseFloatingPoint<double, T>(*this, /* aAllowTrailingChars */ true,
                                       aErrorCode);
}

template <typename T>
float nsTStringRepr<T>::ToFloat(nsresult* aErrorCode) const {
  return ParseFloatingPoint<float, T>(*this, /* aAllowTrailingChars */ false,
                                      aErrorCode);
}

template <typename T>
float nsTStringRepr<T>::ToFloatAllowTrailingChars(nsresult* aErrorCode) const {
  return ParseFloatingPoint<float, T>(*this, /* aAllowTrailingChars */ true,
                                      aErrorCode);
}

}  // namespace mozilla::detail

template class mozilla::detail::nsTStringRepr<char>;
template class mozilla::detail::nsTStringRepr<char16_t>;