tor-browser

The Tor Browser
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NodeInfo.h (9775B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 /*
      8 * Class that represents a prefix/namespace/localName triple; a single
      9 * nodeinfo is shared by all elements in a document that have that
     10 * prefix, namespace, and localName.
     11 *
     12 * nsNodeInfoManagers are internal objects that manage a list of
     13 * NodeInfos, every document object should hold a strong reference to
     14 * a nsNodeInfoManager and every NodeInfo also holds a strong reference
     15 * to their owning manager. When a NodeInfo is no longer used it will
     16 * automatically remove itself from its owner manager, and when all
     17 * NodeInfos have been removed from a nsNodeInfoManager and all external
     18 * references are released the nsNodeInfoManager deletes itself.
     19 */
     20 
     21 #ifndef mozilla_dom_NodeInfo_h___
     22 #define mozilla_dom_NodeInfo_h___
     23 
     24 #include "mozilla/Attributes.h"
     25 #include "mozilla/Maybe.h"
     26 #include "mozilla/dom/NameSpaceConstants.h"
     27 #include "nsAtom.h"
     28 #include "nsCycleCollectionParticipant.h"
     29 #include "nsHashKeys.h"
     30 #include "nsString.h"
     31 
     32 class nsNodeInfoManager;
     33 
     34 namespace mozilla::dom {
     35 
     36 class Document;
     37 
     38 class NodeInfo final {
     39 public:
     40  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(NodeInfo)
     41  NS_DECL_CYCLE_COLLECTION_SKIPPABLE_NATIVE_CLASS_WITH_CUSTOM_DELETE(NodeInfo)
     42 
     43  /*
     44   * Get the name from this node as a string, this does not include the prefix.
     45   *
     46   * For the HTML element "<body>" this will return "body" and for the XML
     47   * element "<html:body>" this will return "body".
     48   */
     49  void GetName(nsAString& aName) const;
     50 
     51  /*
     52   * Get the name from this node as an atom, this does not include the prefix.
     53   * This function never returns a null atom.
     54   *
     55   * For the HTML element "<body>" this will return the "body" atom and for
     56   * the XML element "<html:body>" this will return the "body" atom.
     57   */
     58  nsAtom* NameAtom() const { return mInner.mName; }
     59 
     60  /*
     61   * Get the qualified name from this node as a string, the qualified name
     62   * includes the prefix, if one exists.
     63   *
     64   * For the HTML element "<body>" this will return "body" and for the XML
     65   * element "<html:body>" this will return "html:body".
     66   */
     67  const nsString& QualifiedName() const { return mQualifiedName; }
     68 
     69  /*
     70   * Returns the node's nodeName as defined in DOM Core
     71   */
     72  const nsString& NodeName() const { return mNodeName; }
     73 
     74  /*
     75   * Returns the node's localName as defined in DOM Core
     76   */
     77  const nsString& LocalName() const { return mLocalName; }
     78 
     79  /*
     80   * Get the prefix from this node as a string.
     81   *
     82   * For the HTML element "<body>" this will return a null string and for
     83   * the XML element "<html:body>" this will return the string "html".
     84   */
     85  void GetPrefix(nsAString& aPrefix) const;
     86 
     87  /*
     88   * Get the prefix from this node as an atom.
     89   *
     90   * For the HTML element "<body>" this will return a null atom and for
     91   * the XML element "<html:body>" this will return the "html" atom.
     92   */
     93  nsAtom* GetPrefixAtom() const { return mInner.mPrefix; }
     94 
     95  /*
     96   * Get the namespace URI for a node, if the node has a namespace URI.
     97   */
     98  void GetNamespaceURI(nsAString& aNameSpaceURI) const;
     99 
    100  /*
    101   * Get the namespace ID for a node if the node has a namespace, if not this
    102   * returns kNameSpaceID_None.
    103   */
    104  int32_t NamespaceID() const { return mInner.mNamespaceID; }
    105 
    106  /*
    107   * Get the nodetype for the node. Returns the values specified in Node
    108   * for Node.nodeType
    109   */
    110  uint16_t NodeType() const { return mInner.mNodeType; }
    111 
    112  /*
    113   * Get the extra name, used by PIs and DocTypes, for the node.
    114   */
    115  nsAtom* GetExtraName() const { return mInner.mExtraName; }
    116 
    117  /**
    118   * Get the owning node info manager. Only to be used inside Gecko, you can't
    119   * really do anything with the pointer outside Gecko anyway.
    120   */
    121  nsNodeInfoManager* NodeInfoManager() const { return mOwnerManager; }
    122 
    123  /*
    124   * Utility functions that can be used to check if a nodeinfo holds a specific
    125   * name, name and prefix, name and prefix and namespace ID, or just
    126   * namespace ID.
    127   */
    128  inline bool Equals(NodeInfo* aNodeInfo) const;
    129 
    130  bool NameAndNamespaceEquals(NodeInfo* aNodeInfo) const;
    131 
    132  bool Equals(const nsAtom* aNameAtom) const {
    133    return mInner.mName == aNameAtom;
    134  }
    135 
    136  bool Equals(const nsAtom* aNameAtom, const nsAtom* aPrefixAtom) const {
    137    return (mInner.mName == aNameAtom) && (mInner.mPrefix == aPrefixAtom);
    138  }
    139 
    140  bool Equals(const nsAtom* aNameAtom, int32_t aNamespaceID) const {
    141    return ((mInner.mName == aNameAtom) &&
    142            (mInner.mNamespaceID == aNamespaceID));
    143  }
    144 
    145  bool Equals(const nsAtom* aNameAtom, const nsAtom* aPrefixAtom,
    146              int32_t aNamespaceID) const {
    147    return ((mInner.mName == aNameAtom) && (mInner.mPrefix == aPrefixAtom) &&
    148            (mInner.mNamespaceID == aNamespaceID));
    149  }
    150 
    151  bool NamespaceEquals(int32_t aNamespaceID) const {
    152    return mInner.mNamespaceID == aNamespaceID;
    153  }
    154 
    155  inline bool Equals(const nsAString& aName) const;
    156 
    157  inline bool Equals(const nsAString& aName, const nsAString& aPrefix) const;
    158 
    159  inline bool Equals(const nsAString& aName, int32_t aNamespaceID) const;
    160 
    161  inline bool Equals(const nsAString& aName, const nsAString& aPrefix,
    162                     int32_t aNamespaceID) const;
    163 
    164  bool NamespaceEquals(const nsAString& aNamespaceURI) const;
    165 
    166  inline bool QualifiedNameEquals(const nsAtom* aNameAtom) const;
    167 
    168  bool QualifiedNameEquals(const nsAString& aQualifiedName) const {
    169    return mQualifiedName == aQualifiedName;
    170  }
    171 
    172  /*
    173   * Retrieve a pointer to the document that owns this node info.
    174   */
    175  Document* GetDocument() const { return mDocument; }
    176 
    177 private:
    178  NodeInfo() = delete;
    179  NodeInfo(const NodeInfo& aOther) = delete;
    180 
    181  // NodeInfo is only constructed by nsNodeInfoManager which is a friend class.
    182  // aName and aOwnerManager may not be null.
    183  NodeInfo(nsAtom* aName, nsAtom* aPrefix, int32_t aNamespaceID,
    184           uint16_t aNodeType, nsAtom* aExtraName,
    185           nsNodeInfoManager* aOwnerManager);
    186 
    187  ~NodeInfo();
    188 
    189 public:
    190  bool CanSkip();
    191 
    192  /**
    193   * This method gets called by the cycle collector when it's time to delete
    194   * this object.
    195   */
    196  void DeleteCycleCollectable();
    197 
    198 protected:
    199  /*
    200   * NodeInfoInner is used for two things:
    201   *
    202   *   1. as a member in nsNodeInfo for holding the name, prefix and
    203   *      namespace ID
    204   *   2. as the hash key in the hash table in nsNodeInfoManager
    205   *
    206   * NodeInfoInner does not do any kind of reference counting,
    207   * that's up to the user of this class. Since NodeInfoInner is
    208   * typically used as a member of NodeInfo, the hash table doesn't
    209   * need to delete the keys. When the value (NodeInfo) is deleted
    210   * the key is automatically deleted.
    211   */
    212 
    213  class NodeInfoInner {
    214   public:
    215    NodeInfoInner()
    216        : mName(nullptr),
    217          mPrefix(nullptr),
    218          mNamespaceID(kNameSpaceID_Unknown),
    219          mNodeType(0),
    220          mNameString(nullptr),
    221          mExtraName(nullptr),
    222          mHash() {}
    223    NodeInfoInner(nsAtom* aName, nsAtom* aPrefix, int32_t aNamespaceID,
    224                  uint16_t aNodeType, nsAtom* aExtraName)
    225        : mName(aName),
    226          mPrefix(aPrefix),
    227          mNamespaceID(aNamespaceID),
    228          mNodeType(aNodeType),
    229          mNameString(nullptr),
    230          mExtraName(aExtraName),
    231          mHash() {}
    232    NodeInfoInner(const nsAString& aTmpName, nsAtom* aPrefix,
    233                  int32_t aNamespaceID, uint16_t aNodeType)
    234        : mName(nullptr),
    235          mPrefix(aPrefix),
    236          mNamespaceID(aNamespaceID),
    237          mNodeType(aNodeType),
    238          mNameString(&aTmpName),
    239          mExtraName(nullptr),
    240          mHash() {}
    241 
    242    bool operator==(const NodeInfoInner& aOther) const {
    243      if (mPrefix != aOther.mPrefix || mNamespaceID != aOther.mNamespaceID ||
    244          mNodeType != aOther.mNodeType || mExtraName != aOther.mExtraName) {
    245        return false;
    246      }
    247 
    248      if (mName) {
    249        if (aOther.mName) {
    250          return mName == aOther.mName;
    251        }
    252        return mName->Equals(*(aOther.mNameString));
    253      }
    254 
    255      if (aOther.mName) {
    256        return aOther.mName->Equals(*(mNameString));
    257      }
    258 
    259      return mNameString->Equals(*(aOther.mNameString));
    260    }
    261 
    262    uint32_t Hash() const {
    263      if (!mHash) {
    264        mHash.emplace(mName ? mName->hash()
    265                            : mozilla::HashString(*mNameString));
    266      }
    267      return mHash.value();
    268    }
    269 
    270    nsAtom* const MOZ_OWNING_REF mName;
    271    nsAtom* MOZ_OWNING_REF mPrefix;
    272    int32_t mNamespaceID;
    273    uint16_t mNodeType;  // As defined by Node.nodeType
    274    const nsAString* const mNameString;
    275    nsAtom* MOZ_OWNING_REF mExtraName;  // Only used by PIs and DocTypes
    276    mutable mozilla::Maybe<const uint32_t> mHash;
    277  };
    278 
    279  // nsNodeInfoManager needs to pass mInner to the hash table.
    280  friend class ::nsNodeInfoManager;
    281 
    282  // This is a non-owning reference, but it's safe since it's set to nullptr
    283  // by nsNodeInfoManager::DropDocumentReference when the document is destroyed.
    284  Document* MOZ_NON_OWNING_REF mDocument;  // Cache of mOwnerManager->mDocument
    285 
    286  NodeInfoInner mInner;
    287 
    288  RefPtr<nsNodeInfoManager> mOwnerManager;
    289 
    290  /*
    291   * Members for various functions of mName+mPrefix that we can be
    292   * asked to compute.
    293   */
    294 
    295  // Qualified name
    296  nsString mQualifiedName;
    297 
    298  // nodeName for the node.
    299  nsString mNodeName;
    300 
    301  // localName for the node. This is either equal to mInner.mName, or a
    302  // void string, depending on mInner.mNodeType.
    303  nsString mLocalName;
    304 };
    305 
    306 }  // namespace mozilla::dom
    307 
    308 #endif /* mozilla_dom_NodeInfo_h___ */