layout/style/nsRuleWalker.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 /*
   7  * a class that walks the lexicographic tree of rule nodes as style
   8  * rules are matched
   9  */
  10
  11 #ifndef nsRuleWalker_h_
  12 #define nsRuleWalker_h_
  13
  14 #include "nsRuleNode.h"
  15 #include "nsIStyleRule.h"
  16 #include "StyleRule.h"
  17
  18 class nsRuleWalker {
  19 public:
  20   nsRuleNode* CurrentNode() { return mCurrent; }
  21   void SetCurrentNode(nsRuleNode* aNode) {
  22     NS_ASSERTION(aNode, "Must have node here!");
  23     mCurrent = aNode;
  24   }
  25
  26 protected:
  27   void DoForward(nsIStyleRule* aRule) {
  28     mCurrent = mCurrent->Transition(aRule, mLevel, mImportance);
  29     NS_POSTCONDITION(mCurrent, "Transition messed up");
  30   }
  31
  32 public:
  33   void Forward(nsIStyleRule* aRule) {
  34     NS_PRECONDITION(!nsRefPtr<mozilla::css::StyleRule>(do_QueryObject(aRule)),
  35                     "Calling the wrong Forward() overload");
  36     DoForward(aRule);
  37   }
  38   void Forward(mozilla::css::StyleRule* aRule) {
  39     DoForward(aRule);
  40     mCheckForImportantRules =
  41       mCheckForImportantRules && !aRule->GetImportantRule();
  42   }
  43   // ForwardOnPossiblyCSSRule should only be used by callers that have
  44   // an explicit list of rules they need to walk, with the list
  45   // already containing any important rules they care about.
  46   void ForwardOnPossiblyCSSRule(nsIStyleRule* aRule) {
  47     DoForward(aRule);
  48   }
  49
  50   void Reset() { mCurrent = mRoot; }
  51
  52   bool AtRoot() { return mCurrent == mRoot; }
  53
  54   void SetLevel(uint8_t aLevel, bool aImportance,
  55                 bool aCheckForImportantRules) {
  56     NS_ASSERTION(!aCheckForImportantRules || !aImportance,
  57                  "Shouldn't be checking for important rules while walking "
  58                  "important rules");
  59     mLevel = aLevel;
  60     mImportance = aImportance;
  61     mCheckForImportantRules = aCheckForImportantRules;
  62   }
  63   uint8_t GetLevel() const { return mLevel; }
  64   bool GetImportance() const { return mImportance; }
  65   bool GetCheckForImportantRules() const { return mCheckForImportantRules; }
  66
  67   bool AuthorStyleDisabled() const { return mAuthorStyleDisabled; }
  68
  69   // We define the visited-relevant link to be the link that is the
  70   // nearest self-or-ancestor to the node being matched.
  71   enum VisitedHandlingType {
  72     // Do rule matching as though all links are unvisited.
  73     eRelevantLinkUnvisited,
  74     // Do rule matching as though the relevant link is visited and all
  75     // other links are unvisited.
  76     eRelevantLinkVisited,
  77     // Do rule matching as though a rule should match if it would match
  78     // given any set of visitedness states.  (used by users other than
  79     // nsRuleWalker)
  80     eLinksVisitedOrUnvisited
  81   };
  82
  83 private:
  84   nsRuleNode* mCurrent; // Our current position.  Never null.
  85   nsRuleNode* mRoot; // The root of the tree we're walking.
  86   uint8_t mLevel; // an nsStyleSet::sheetType
  87   bool mImportance;
  88   bool mCheckForImportantRules; // If true, check for important rules as
  89                                 // we walk and set to false if we find
  90                                 // one.
  91   bool mAuthorStyleDisabled;
  92
  93 public:
  94   nsRuleWalker(nsRuleNode* aRoot, bool aAuthorStyleDisabled)
  95     : mCurrent(aRoot)
  96     , mRoot(aRoot)
  97     , mAuthorStyleDisabled(aAuthorStyleDisabled)
  98   {
  99     NS_ASSERTION(mCurrent, "Caller screwed up and gave us null node");
 100     MOZ_COUNT_CTOR(nsRuleWalker);
 101   }
 102   ~nsRuleWalker() { MOZ_COUNT_DTOR(nsRuleWalker); }
 103 };
 104
 105 #endif /* !defined(nsRuleWalker_h_) */