third_party/WebKit/Source/wtf/text/StringView.cpp

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "wtf/text/StringView.h"

#include "wtf/text/AtomicString.h"
#include "wtf/text/StringImpl.h"
#include "wtf/text/WTFString.h"

namespace WTF {

StringView::StringView(const UChar* chars)
    : StringView(chars, chars ? lengthOfNullTerminatedString(chars) : 0) {}

#if DCHECK_IS_ON()
StringView::~StringView() {
  DCHECK(m_impl);
  DCHECK(!m_impl->hasOneRef()) << "StringView does not own the StringImpl, it "
                                  "must not have the last ref.";
}
#endif

String StringView::toString() const {
  if (isNull())
    return String();
  if (isEmpty())
    return emptyString();
  if (StringImpl* impl = sharedImpl())
    return impl;
  if (is8Bit())
    return String(characters8(), m_length);
  return StringImpl::create8BitIfPossible(characters16(), m_length);
}

AtomicString StringView::toAtomicString() const {
  if (isNull())
    return nullAtom;
  if (isEmpty())
    return emptyAtom;
  if (StringImpl* impl = sharedImpl())
    return AtomicString(impl);
  if (is8Bit())
    return AtomicString(characters8(), m_length);
  return AtomicString(characters16(), m_length);
}

bool equalStringView(const StringView& a, const StringView& b) {
  if (a.isNull() || b.isNull())
    return a.isNull() == b.isNull();
  if (a.length() != b.length())
    return false;
  if (a.is8Bit()) {
    if (b.is8Bit())
      return equal(a.characters8(), b.characters8(), a.length());
    return equal(a.characters8(), b.characters16(), a.length());
  }
  if (b.is8Bit())
    return equal(a.characters16(), b.characters8(), a.length());
  return equal(a.characters16(), b.characters16(), a.length());
}

bool equalIgnoringCaseAndNullity(const StringView& a, const StringView& b) {
  if (a.length() != b.length())
    return false;
  if (a.is8Bit()) {
    if (b.is8Bit())
      return equalIgnoringCase(a.characters8(), b.characters8(), a.length());
    return equalIgnoringCase(a.characters8(), b.characters16(), a.length());
  }
  if (b.is8Bit())
    return equalIgnoringCase(a.characters16(), b.characters8(), a.length());
  return equalIgnoringCase(a.characters16(), b.characters16(), a.length());
}

bool equalIgnoringCase(const StringView& a, const StringView& b) {
  if (a.isNull() || b.isNull())
    return a.isNull() == b.isNull();
  return equalIgnoringCaseAndNullity(a, b);
}

bool equalIgnoringASCIICase(const StringView& a, const StringView& b) {
  if (a.isNull() || b.isNull())
    return a.isNull() == b.isNull();
  if (a.length() != b.length())
    return false;
  if (a.is8Bit()) {
    if (b.is8Bit())
      return equalIgnoringASCIICase(a.characters8(), b.characters8(),
                                    a.length());
    return equalIgnoringASCIICase(a.characters8(), b.characters16(),
                                  a.length());
  }
  if (b.is8Bit())
    return equalIgnoringASCIICase(a.characters16(), b.characters8(),
                                  a.length());
  return equalIgnoringASCIICase(a.characters16(), b.characters16(), a.length());
}

}  // namespace WTF