gecko/layout/style/nsRuleProcessorData.h

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 * for the specific language governing rights and limitations under the
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 * The Original Code is mozilla.org code.
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 * Contributor(s):
 *   L. David Baron <dbaron@dbaron.org>, Mozilla Corporation
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/*
 * data structures passed to nsIStyleRuleProcessor methods (to pull loop
 * invariant computations out of the loop)
 */

#ifndef nsRuleProcessorData_h_
#define nsRuleProcessorData_h_

#include "nsPresContext.h" // for nsCompatability
#include "nsString.h"
#include "nsChangeHint.h"
#include "nsIContent.h"

class nsIStyleSheet;
class nsPresContext;
class nsIAtom;
class nsICSSPseudoComparator;
class nsRuleWalker;
class nsAttrValue;

// The implementation of the constructor and destructor are currently in
// nsCSSRuleProcessor.cpp.

struct RuleProcessorData {
  RuleProcessorData(nsPresContext* aPresContext,
                    nsIContent* aContent, 
                    nsRuleWalker* aRuleWalker,
                    nsCompatibility* aCompat = nsnull);
  
  // NOTE: not |virtual|
  ~RuleProcessorData();

  // This should be used for all heap-allocation of RuleProcessorData
  static RuleProcessorData* Create(nsPresContext* aPresContext,
                                   nsIContent* aContent, 
                                   nsRuleWalker* aRuleWalker,
                                   nsCompatibility aCompat)
  {
    if (NS_LIKELY(aPresContext)) {
      return new (aPresContext) RuleProcessorData(aPresContext, aContent,
                                                  aRuleWalker, &aCompat);
    }

    return new RuleProcessorData(aPresContext, aContent, aRuleWalker,
                                 &aCompat);
  }
  
  void Destroy() {
    nsPresContext * pc = mPresContext;
    if (NS_LIKELY(pc)) {
      this->~RuleProcessorData();
      pc->FreeToShell(sizeof(RuleProcessorData), this);
      return;
    }
    delete this;
  }

  // For placement new
  void* operator new(size_t sz, RuleProcessorData* aSlot) CPP_THROW_NEW {
    return aSlot;
  }
private:
  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
    return aContext->AllocateFromShell(sz);
  }
  void* operator new(size_t sz) CPP_THROW_NEW {
    return ::operator new(sz);
  }
public:
  const nsString* GetLang();

  // Returns a 1-based index of the child in its parent.  If the child
  // is not in its parent's child list (i.e., it is anonymous content),
  // returns 0.
  // If aCheckEdgeOnly is true, the function will return 1 if the result
  // is 1, and something other than 1 (maybe or maybe not a valid
  // result) otherwise.
  PRInt32 GetNthIndex(PRBool aIsOfType, PRBool aIsFromEnd,
                      PRBool aCheckEdgeOnly);

  nsPresContext*    mPresContext;
  nsIContent*       mContent;       // weak ref
  nsIContent*       mParentContent; // if content, content->GetParent(); weak ref
  nsRuleWalker*     mRuleWalker; // Used to add rules to our results.
  nsIContent*       mScopedRoot;    // Root of scoped stylesheet (set and unset by the supplier of the scoped stylesheet
  
  nsIAtom*          mContentTag;    // if content, then content->GetTag()
  nsIAtom*          mContentID;     // if styled content, then weak reference to styledcontent->GetID()
  PRPackedBool      mIsHTMLContent; // if content, then does QI on HTMLContent, true or false
  PRPackedBool      mIsLink;        // if content, calls nsStyleUtil::IsHTMLLink or nsStyleUtil::IsLink
  PRPackedBool      mHasAttributes; // if content, content->GetAttrCount() > 0
  nsCompatibility   mCompatMode;    // Possibly remove use of this in SelectorMatches?
  nsLinkState       mLinkState;     // if a link, this is the state, otherwise unknown
  PRInt32           mEventState;    // if content, eventStateMgr->GetContentState()
  PRInt32           mNameSpaceID;   // if content, content->GetNameSapce()
  const nsAttrValue* mClasses;      // if styled content, styledcontent->GetClasses()
  // mPreviousSiblingData and mParentData are always RuleProcessorData
  // and never a derived class.  They are allocated lazily, when
  // selectors require matching of prior siblings or ancestors.
  RuleProcessorData* mPreviousSiblingData;
  RuleProcessorData* mParentData;

protected:
  nsString *mLanguage; // NULL means we haven't found out the language yet

  // This node's index for :nth-child(), :nth-last-child(),
  // :nth-of-type(), :nth-last-of-type().  If -2, needs to be computed.
  // If -1, needs to be computed but known not to be 1.
  // If 0, the node is not at any index in its parent.
  // The first subscript is 0 for -child and 1 for -of-type, the second
  // subscript is 0 for nth- and 1 for nth-last-.
  PRInt32 mNthIndices[2][2];
};

struct ElementRuleProcessorData : public RuleProcessorData {
  ElementRuleProcessorData(nsPresContext* aPresContext,
                           nsIContent* aContent, 
                           nsRuleWalker* aRuleWalker)
  : RuleProcessorData(aPresContext,aContent,aRuleWalker)
  {
    NS_PRECONDITION(aPresContext, "null pointer");
    NS_PRECONDITION(aContent, "null pointer");
    NS_PRECONDITION(aRuleWalker, "null pointer");
  }
};

struct PseudoRuleProcessorData : public RuleProcessorData {
  PseudoRuleProcessorData(nsPresContext* aPresContext,
                          nsIContent* aParentContent,
                          nsIAtom* aPseudoTag,
                          nsICSSPseudoComparator* aComparator,
                          nsRuleWalker* aRuleWalker)
  : RuleProcessorData(aPresContext, aParentContent, aRuleWalker)
  {
    NS_PRECONDITION(aPresContext, "null pointer");
    NS_PRECONDITION(aPseudoTag, "null pointer");
    NS_PRECONDITION(aRuleWalker, "null pointer");
    mPseudoTag = aPseudoTag;
    mComparator = aComparator;
  }

  nsIAtom*                 mPseudoTag;
  nsICSSPseudoComparator*  mComparator;
};

struct StateRuleProcessorData : public RuleProcessorData {
  StateRuleProcessorData(nsPresContext* aPresContext,
                         nsIContent* aContent,
                         PRInt32 aStateMask)
    : RuleProcessorData(aPresContext, aContent, nsnull),
      mStateMask(aStateMask)
  {
    NS_PRECONDITION(aPresContext, "null pointer");
    NS_PRECONDITION(aContent, "null pointer");
  }
  const PRInt32 mStateMask; // |HasStateDependentStyle| for which state(s)?
                            //  Constants defined in nsIEventStateManager.h .
};

struct AttributeRuleProcessorData : public RuleProcessorData {
  AttributeRuleProcessorData(nsPresContext* aPresContext,
                             nsIContent* aContent,
                             nsIAtom* aAttribute,
                             PRInt32 aModType,
                             PRUint32 aStateMask)
    : RuleProcessorData(aPresContext, aContent, nsnull),
      mAttribute(aAttribute),
      mModType(aModType),
      mStateMask(aStateMask)
  {
    NS_PRECONDITION(aPresContext, "null pointer");
    NS_PRECONDITION(aContent, "null pointer");
  }
  nsIAtom* mAttribute; // |HasAttributeDependentStyle| for which attribute?
  PRInt32 mModType;    // The type of modification (see nsIDOMMutationEvent).
  PRUint32 mStateMask; // The states that changed with the attr change.
};

#endif /* !defined(nsRuleProcessorData_h_) */