DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Mercurial (a81015259a98)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Boris Zbarsky <bzbarsky@mit.edu>.
 * Portions created by the Initial Developer are Copyright (C) 2001
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   L. David Baron <dbaron@dbaron.org>, Mozilla Corporation
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * representation of media lists used when linking to style sheets or by
 * @media rules
 */

#ifndef nsIMediaList_h_
#define nsIMediaList_h_

#include "nsIDOMMediaList.h"
#include "nsTArray.h"
#include "nsIAtom.h"
#include "nsCSSValue.h"

class nsPresContext;
class nsCSSStyleSheet;
class nsAString;
struct nsMediaFeature;

struct nsMediaExpression {
  enum Range { eMin, eMax, eEqual };

  const nsMediaFeature *mFeature;
  Range mRange;
  nsCSSValue mValue;

  // aActualValue must be obtained from mFeature->mGetter
  bool Matches(nsPresContext* aPresContext,
                 const nsCSSValue& aActualValue) const;
};

/**
 * An nsMediaQueryResultCacheKey records what feature/value combinations
 * a set of media query results are valid for.  This allows the caller
 * to quickly learn whether a prior result of media query evaluation is
 * still valid (e.g., due to a window size change) without rerunning all
 * of the evaluation and rebuilding the list of rules.
 *
 * This object may not be used after any media rules in any of the
 * sheets it was given to have been modified.  However, this is
 * generally not a problem since ClearRuleCascades is called on the
 * sheet whenever this happens, and these objects are stored inside the
 * rule cascades.  (FIXME: We're not actually doing this all the time.)
 *
 * The implementation could be further optimized in the future to store
 * ranges (combinations of less-than, less-than-or-equal, greater-than,
 * greater-than-or-equal, equal, not-equal, present, not-present) for
 * each feature rather than simply storing the list of expressions.
 * However, this requires combining any such ranges.
 */
class nsMediaQueryResultCacheKey {
public:
  nsMediaQueryResultCacheKey(nsIAtom* aMedium)
    : mMedium(aMedium)
  {}

  /**
   * Record that aExpression was tested while building the cached set
   * that this cache key is for, and that aExpressionMatches was whether
   * it matched.
   */
  void AddExpression(const nsMediaExpression* aExpression,
                     bool aExpressionMatches);
  bool Matches(nsPresContext* aPresContext) const;
private:
  struct ExpressionEntry {
    // FIXME: if we were better at maintaining invariants about clearing
    // rule cascades when media lists change, this could be a |const
    // nsMediaExpression*| instead.
    nsMediaExpression mExpression;
    bool mExpressionMatches;
  };
  struct FeatureEntry {
    const nsMediaFeature *mFeature;
    InfallibleTArray<ExpressionEntry> mExpressions;
  };
  nsCOMPtr<nsIAtom> mMedium;
  nsTArray<FeatureEntry> mFeatureCache;
};

class nsMediaQuery {
public:
  nsMediaQuery()
    : mNegated(false)
    , mHasOnly(false)
    , mTypeOmitted(false)
    , mHadUnknownExpression(false)
  {
  }

private:
  // for Clone only
  nsMediaQuery(const nsMediaQuery& aOther)
    : mNegated(aOther.mNegated)
    , mHasOnly(aOther.mHasOnly)
    , mTypeOmitted(aOther.mTypeOmitted)
    , mHadUnknownExpression(aOther.mHadUnknownExpression)
    , mMediaType(aOther.mMediaType)
    // Clone checks the result of this deep copy for allocation failure
    , mExpressions(aOther.mExpressions)
  {
  }

public:

  void SetNegated()                     { mNegated = true; }
  void SetHasOnly()                     { mHasOnly = true; }
  void SetTypeOmitted()                 { mTypeOmitted = true; }
  void SetHadUnknownExpression()        { mHadUnknownExpression = true; }
  void SetType(nsIAtom* aMediaType)     { 
                                          NS_ASSERTION(aMediaType,
                                                       "expected non-null");
                                          mMediaType = aMediaType;
                                        }

  // Return a new nsMediaExpression in the array for the caller to fill
  // in.  The caller must either fill it in completely, or call
  // SetHadUnknownExpression on this nsMediaQuery.
  // Returns null on out-of-memory.
  nsMediaExpression* NewExpression()    { return mExpressions.AppendElement(); }

  void AppendToString(nsAString& aString) const;

  nsMediaQuery* Clone() const;

  // Does this query apply to the presentation?
  // If |aKey| is non-null, add cache information to it.
  bool Matches(nsPresContext* aPresContext,
                 nsMediaQueryResultCacheKey* aKey) const;

private:
  bool mNegated;
  bool mHasOnly; // only needed for serialization
  bool mTypeOmitted; // only needed for serialization
  bool mHadUnknownExpression;
  nsCOMPtr<nsIAtom> mMediaType;
  nsTArray<nsMediaExpression> mExpressions;
};

class nsMediaList : public nsIDOMMediaList {
public:
  nsMediaList();

  NS_DECL_ISUPPORTS

  NS_DECL_NSIDOMMEDIALIST

  nsresult GetText(nsAString& aMediaText);
  nsresult SetText(const nsAString& aMediaText);

  // Does this query apply to the presentation?
  // If |aKey| is non-null, add cache information to it.
  bool Matches(nsPresContext* aPresContext,
                 nsMediaQueryResultCacheKey* aKey);

  nsresult SetStyleSheet(nsCSSStyleSheet* aSheet);
  void AppendQuery(nsAutoPtr<nsMediaQuery>& aQuery) {
    // Takes ownership of aQuery
    mArray.AppendElement(aQuery.forget());
  }

  nsresult Clone(nsMediaList** aResult);

  PRInt32 Count() { return mArray.Length(); }
  nsMediaQuery* MediumAt(PRInt32 aIndex) { return mArray[aIndex]; }
  void Clear() { mArray.Clear(); }

protected:
  ~nsMediaList();

  nsresult Delete(const nsAString & aOldMedium);
  nsresult Append(const nsAString & aOldMedium);

  InfallibleTArray<nsAutoPtr<nsMediaQuery> > mArray;
  // not refcounted; sheet will let us know when it goes away
  // mStyleSheet is the sheet that needs to be dirtied when this medialist
  // changes
  nsCSSStyleSheet*         mStyleSheet;
};
#endif /* !defined(nsIMediaList_h_) */