text: // Copyright 2015 The Chromium Authors. All rights reserved.
  // Copyright (C) 2016 Apple Inc. All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //    * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //    * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //    * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include "config.h"
  #include "CSSVariableData.h"
  
  #include "CSSCustomPropertyValue.h"
  #include "CSSParserTokenRange.h"
  #include <wtf/text/AtomicStringHash.h>
  #include <wtf/text/StringBuilder.h>
  #include <wtf/text/StringView.h>
  
  namespace WebCore {
  
  template<typename CharacterType> void CSSVariableData::updateTokens(const CSSParserTokenRange& range)
  {
      const CharacterType* currentOffset = m_backingString.characters<CharacterType>();
      for (const CSSParserToken& token : range) {
          if (token.hasStringBacking()) {
              unsigned length = token.value().length();
              StringView string(currentOffset, length);
              m_tokens.append(token.copyWithUpdatedString(string));
              currentOffset += length;
          } else
              m_tokens.append(token);
      }
      ASSERT(currentOffset == m_backingString.characters<CharacterType>() + m_backingString.length());
  }
  
  bool CSSVariableData::operator==(const CSSVariableData& other) const
  {
      return tokens() == other.tokens();
  }
  
  void CSSVariableData::consumeAndUpdateTokens(const CSSParserTokenRange& range)
  {
      StringBuilder stringBuilder;
      CSSParserTokenRange localRange = range;
  
      while (!localRange.atEnd()) {
          CSSParserToken token = localRange.consume();
          if (token.hasStringBacking())
              stringBuilder.append(token.value());
      }
      m_backingString = stringBuilder.toString();
      if (m_backingString.is8Bit())
          updateTokens<LChar>(range);
      else
          updateTokens<UChar>(range);
  }
  
  CSSVariableData::CSSVariableData(const CSSParserTokenRange& range, bool needsVariableResolution)
      : m_needsVariableResolution(needsVariableResolution)
  {
      ASSERT(!range.atEnd());
      consumeAndUpdateTokens(range);
  }
  
  bool CSSVariableData::checkVariablesForCycles(const AtomicString& name, CustomPropertyValueMap& customProperties, HashSet<AtomicString>& seenProperties, HashSet<AtomicString>& invalidProperties) const
  {
      if (invalidProperties.contains(name))
          return false;
      
      HashSet<AtomicString> newSeenProperties = seenProperties;
      newSeenProperties.add(name);
      
      bool valid = checkVariablesForCyclesWithRange(m_tokens, customProperties, newSeenProperties, invalidProperties);
      if (!valid)
          invalidProperties.add(name);
      
      return valid;
  }
      
  bool CSSVariableData::checkVariablesForCyclesWithRange(CSSParserTokenRange range, CustomPropertyValueMap& customProperties, HashSet<AtomicString>& seenProperties, HashSet<AtomicString>& invalidProperties) const
  {
      while (!range.atEnd()) {
          if (range.peek().functionId() == CSSValueVar || range.peek().functionId() == CSSValueConstant) {
              CSSParserTokenRange block = range.consumeBlock();
              
              block.consumeWhitespace();
              ASSERT(block.peek().type() == IdentToken);
              AtomicString variableName = block.consumeIncludingWhitespace().value().toAtomicString();
              ASSERT(block.atEnd() || block.peek().type() == CommaToken);
              if (seenProperties.contains(variableName))
                  return false;
  
              RefPtr<CSSCustomPropertyValue> value = customProperties.get(variableName);
              if (value && value->containsVariables() && !value->checkVariablesForCycles(variableName, customProperties, seenProperties, invalidProperties))
                  return false;
  
              if (range.peek().type() == CommaToken) {
                  // Fallback.
                  range.consume();
                  return checkVariablesForCyclesWithRange(block, customProperties, seenProperties, invalidProperties);
              }
          } else
              range.consume();
      }
      return true;
  }
  
  bool CSSVariableData::resolveVariableFallback(const CustomPropertyValueMap& customProperties, CSSParserTokenRange range, Vector<CSSParserToken>& result) const
  {
      if (range.atEnd())
          return false;
      ASSERT(range.peek().type() == CommaToken);
      range.consume();
      return resolveTokenRange(customProperties, range, result);
  }
      
  bool CSSVariableData::resolveVariableReference(const CustomPropertyValueMap& customProperties, CSSParserTokenRange range, Vector<CSSParserToken>& result) const
  {
      range.consumeWhitespace();
      ASSERT(range.peek().type() == IdentToken);
      AtomicString variableName = range.consumeIncludingWhitespace().value().toAtomicString();
      ASSERT(range.atEnd() || (range.peek().type() == CommaToken));
      
      RefPtr<CSSCustomPropertyValue> property = customProperties.get(variableName);
      if (!property || !property->value())
          return resolveVariableFallback(customProperties, range, result);
      
      if (property->containsVariables()) {
          // FIXME: Avoid doing this work more than once.
          RefPtr<CSSVariableData> resolvedData = property->value()->resolveVariableReferences(customProperties);
          if (!resolvedData)
              return false;
          result.appendVector(resolvedData->tokens());
      } else
          result.appendVector(property->value()->tokens());
      
      return true;
  }
  
  RefPtr<CSSVariableData> CSSVariableData::resolveVariableReferences(const CustomPropertyValueMap& customProperties) const
  {
      Vector<CSSParserToken> resolvedTokens;
      CSSParserTokenRange range = m_tokens;
      if (!resolveTokenRange(customProperties, range, resolvedTokens))
          return nullptr;
      return CSSVariableData::createResolved(resolvedTokens, *this);
  }
      
  bool CSSVariableData::resolveTokenRange(const CustomPropertyValueMap& customProperties, CSSParserTokenRange range, Vector<CSSParserToken>& result) const
  {
      bool success = true;
      while (!range.atEnd()) {
          if (range.peek().functionId() == CSSValueVar || range.peek().functionId() == CSSValueConstant)
              success &= resolveVariableReference(customProperties, range.consumeBlock(), result);
          else
              result.append(range.consume());
      }
      return success;
  }
  
  } // namespace WebCore
  