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      1 /*
      2  * Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef Position_h
     27 #define Position_h
     28 
     29 #include "core/dom/ContainerNode.h"
     30 #include "core/editing/EditingBoundary.h"
     31 #include "core/editing/TextAffinity.h"
     32 #include "core/platform/text/TextDirection.h"
     33 #include "wtf/Assertions.h"
     34 #include "wtf/PassRefPtr.h"
     35 #include "wtf/RefPtr.h"
     36 
     37 namespace WebCore {
     38 
     39 class CSSComputedStyleDeclaration;
     40 class Element;
     41 class InlineBox;
     42 class Node;
     43 class Range;
     44 class RenderObject;
     45 class Text;
     46 
     47 enum PositionMoveType {
     48     CodePoint,       // Move by a single code point.
     49     Character,       // Move to the next Unicode character break.
     50     BackwardDeletion // Subject to platform conventions.
     51 };
     52 
     53 class Position {
     54 public:
     55     enum AnchorType {
     56         PositionIsOffsetInAnchor,
     57         PositionIsBeforeAnchor,
     58         PositionIsAfterAnchor,
     59         PositionIsBeforeChildren,
     60         PositionIsAfterChildren,
     61     };
     62 
     63     Position()
     64         : m_offset(0)
     65         , m_anchorType(PositionIsOffsetInAnchor)
     66         , m_isLegacyEditingPosition(false)
     67     {
     68     }
     69 
     70     // For creating legacy editing positions: (Anchor type will be determined from editingIgnoresContent(node))
     71     class LegacyEditingOffset {
     72     public:
     73         int value() const { return m_offset; }
     74 
     75     private:
     76         explicit LegacyEditingOffset(int offset) : m_offset(offset) { }
     77 
     78         friend Position createLegacyEditingPosition(PassRefPtr<Node>, int offset);
     79 
     80         int m_offset;
     81     };
     82     Position(PassRefPtr<Node> anchorNode, LegacyEditingOffset);
     83 
     84     // For creating before/after positions:
     85     Position(PassRefPtr<Node> anchorNode, AnchorType);
     86     Position(PassRefPtr<Text> textNode, unsigned offset);
     87 
     88     // For creating offset positions:
     89     // FIXME: This constructor should eventually go away. See bug 63040.
     90     Position(PassRefPtr<Node> anchorNode, int offset, AnchorType);
     91 
     92     AnchorType anchorType() const { return static_cast<AnchorType>(m_anchorType); }
     93 
     94     void clear() { m_anchorNode.clear(); m_offset = 0; m_anchorType = PositionIsOffsetInAnchor; m_isLegacyEditingPosition = false; }
     95 
     96     // These are always DOM compliant values.  Editing positions like [img, 0] (aka [img, before])
     97     // will return img->parentNode() and img->nodeIndex() from these functions.
     98     Node* containerNode() const; // NULL for a before/after position anchored to a node with no parent
     99     Text* containerText() const;
    100 
    101     int computeOffsetInContainerNode() const;  // O(n) for before/after-anchored positions, O(1) for parent-anchored positions
    102     Position parentAnchoredEquivalent() const; // Convenience method for DOM positions that also fixes up some positions for editing
    103 
    104     // Inline O(1) access for Positions which callers know to be parent-anchored
    105     int offsetInContainerNode() const
    106     {
    107         ASSERT(anchorType() == PositionIsOffsetInAnchor);
    108         return m_offset;
    109     }
    110 
    111     // New code should not use this function.
    112     int deprecatedEditingOffset() const
    113     {
    114         if (m_isLegacyEditingPosition || (m_anchorType != PositionIsAfterAnchor && m_anchorType != PositionIsAfterChildren))
    115             return m_offset;
    116         return offsetForPositionAfterAnchor();
    117     }
    118 
    119     // These are convenience methods which are smart about whether the position is neighbor anchored or parent anchored
    120     Node* computeNodeBeforePosition() const;
    121     Node* computeNodeAfterPosition() const;
    122 
    123     Node* anchorNode() const { return m_anchorNode.get(); }
    124 
    125     // FIXME: Callers should be moved off of node(), node() is not always the container for this position.
    126     // For nodes which editingIgnoresContent(node()) returns true, positions like [ignoredNode, 0]
    127     // will be treated as before ignoredNode (thus node() is really after the position, not containing it).
    128     Node* deprecatedNode() const { return m_anchorNode.get(); }
    129 
    130     Document* document() const { return m_anchorNode ? m_anchorNode->document() : 0; }
    131     Element* rootEditableElement() const
    132     {
    133         Node* container = containerNode();
    134         return container ? container->rootEditableElement() : 0;
    135     }
    136 
    137     // These should only be used for PositionIsOffsetInAnchor positions, unless
    138     // the position is a legacy editing position.
    139     void moveToPosition(PassRefPtr<Node> anchorNode, int offset);
    140     void moveToOffset(int offset);
    141 
    142     bool isNull() const { return !m_anchorNode; }
    143     bool isNotNull() const { return m_anchorNode; }
    144     bool isOrphan() const { return m_anchorNode && !m_anchorNode->inDocument(); }
    145 
    146     Element* element() const;
    147     PassRefPtr<CSSComputedStyleDeclaration> computedStyle() const;
    148 
    149     // Move up or down the DOM by one position.
    150     // Offsets are computed using render text for nodes that have renderers - but note that even when
    151     // using composed characters, the result may be inside a single user-visible character if a ligature is formed.
    152     Position previous(PositionMoveType = CodePoint) const;
    153     Position next(PositionMoveType = CodePoint) const;
    154     static int uncheckedPreviousOffset(const Node*, int current);
    155     static int uncheckedPreviousOffsetForBackwardDeletion(const Node*, int current);
    156     static int uncheckedNextOffset(const Node*, int current);
    157 
    158     // These can be either inside or just before/after the node, depending on
    159     // if the node is ignored by editing or not.
    160     // FIXME: These should go away. They only make sense for legacy positions.
    161     bool atFirstEditingPositionForNode() const;
    162     bool atLastEditingPositionForNode() const;
    163 
    164     // Returns true if the visually equivalent positions around have different editability
    165     bool atEditingBoundary() const;
    166     Node* parentEditingBoundary() const;
    167 
    168     bool atStartOfTree() const;
    169     bool atEndOfTree() const;
    170 
    171     // FIXME: Make these non-member functions and put them somewhere in the editing directory.
    172     // These aren't really basic "position" operations. More high level editing helper functions.
    173     Position leadingWhitespacePosition(EAffinity, bool considerNonCollapsibleWhitespace = false) const;
    174     Position trailingWhitespacePosition(EAffinity, bool considerNonCollapsibleWhitespace = false) const;
    175 
    176     // These return useful visually equivalent positions.
    177     Position upstream(EditingBoundaryCrossingRule = CannotCrossEditingBoundary) const;
    178     Position downstream(EditingBoundaryCrossingRule = CannotCrossEditingBoundary) const;
    179 
    180     bool isCandidate() const;
    181     bool inRenderedText() const;
    182     bool isRenderedCharacter() const;
    183     bool rendersInDifferentPosition(const Position&) const;
    184 
    185     void getInlineBoxAndOffset(EAffinity, InlineBox*&, int& caretOffset) const;
    186     void getInlineBoxAndOffset(EAffinity, TextDirection primaryDirection, InlineBox*&, int& caretOffset) const;
    187 
    188     TextDirection primaryDirection() const;
    189 
    190     static bool hasRenderedNonAnonymousDescendantsWithHeight(RenderObject*);
    191     static bool nodeIsUserSelectNone(Node*);
    192     static bool nodeIsUserSelectAll(const Node*);
    193     static Node* rootUserSelectAllForNode(Node*);
    194 
    195     static ContainerNode* findParent(const Node*);
    196 
    197     void debugPosition(const char* msg = "") const;
    198 
    199 #ifndef NDEBUG
    200     void formatForDebugger(char* buffer, unsigned length) const;
    201     void showAnchorTypeAndOffset() const;
    202     void showTreeForThis() const;
    203 #endif
    204 
    205 private:
    206     int offsetForPositionAfterAnchor() const;
    207 
    208     int renderedOffset() const;
    209 
    210 
    211     Position previousCharacterPosition(EAffinity) const;
    212     Position nextCharacterPosition(EAffinity) const;
    213 
    214     static AnchorType anchorTypeForLegacyEditingPosition(Node* anchorNode, int offset);
    215 
    216     RefPtr<Node> m_anchorNode;
    217     // m_offset can be the offset inside m_anchorNode, or if editingIgnoresContent(m_anchorNode)
    218     // returns true, then other places in editing will treat m_offset == 0 as "before the anchor"
    219     // and m_offset > 0 as "after the anchor node".  See parentAnchoredEquivalent for more info.
    220     int m_offset;
    221     unsigned m_anchorType : 3;
    222     bool m_isLegacyEditingPosition : 1;
    223 };
    224 
    225 inline Position createLegacyEditingPosition(PassRefPtr<Node> node, int offset)
    226 {
    227     return Position(node, Position::LegacyEditingOffset(offset));
    228 }
    229 
    230 inline bool operator==(const Position& a, const Position& b)
    231 {
    232     // FIXME: In <div><img></div> [div, 0] != [img, 0] even though most of the
    233     // editing code will treat them as identical.
    234     return a.anchorNode() == b.anchorNode() && a.deprecatedEditingOffset() == b.deprecatedEditingOffset() && a.anchorType() == b.anchorType();
    235 }
    236 
    237 inline bool operator!=(const Position& a, const Position& b)
    238 {
    239     return !(a == b);
    240 }
    241 
    242 // We define position creation functions to make callsites more readable.
    243 // These are inline to prevent ref-churn when returning a Position object.
    244 // If we ever add a PassPosition we can make these non-inline.
    245 
    246 inline Position positionInParentBeforeNode(const Node* node)
    247 {
    248     // FIXME: This should ASSERT(node->parentNode())
    249     // At least one caller currently hits this ASSERT though, which indicates
    250     // that the caller is trying to make a position relative to a disconnected node (which is likely an error)
    251     // Specifically, editing/deleting/delete-ligature-001.html crashes with ASSERT(node->parentNode())
    252     return Position(Position::findParent(node), node->nodeIndex(), Position::PositionIsOffsetInAnchor);
    253 }
    254 
    255 inline Position positionInParentAfterNode(const Node* node)
    256 {
    257     ASSERT(Position::findParent(node));
    258     return Position(Position::findParent(node), node->nodeIndex() + 1, Position::PositionIsOffsetInAnchor);
    259 }
    260 
    261 // positionBeforeNode and positionAfterNode return neighbor-anchored positions, construction is O(1)
    262 inline Position positionBeforeNode(Node* anchorNode)
    263 {
    264     ASSERT(anchorNode);
    265     return Position(anchorNode, Position::PositionIsBeforeAnchor);
    266 }
    267 
    268 inline Position positionAfterNode(Node* anchorNode)
    269 {
    270     ASSERT(anchorNode);
    271     return Position(anchorNode, Position::PositionIsAfterAnchor);
    272 }
    273 
    274 inline int lastOffsetInNode(Node* node)
    275 {
    276     return node->offsetInCharacters() ? node->maxCharacterOffset() : static_cast<int>(node->childNodeCount());
    277 }
    278 
    279 // firstPositionInNode and lastPositionInNode return parent-anchored positions, lastPositionInNode construction is O(n) due to childNodeCount()
    280 inline Position firstPositionInNode(Node* anchorNode)
    281 {
    282     if (anchorNode->isTextNode())
    283         return Position(anchorNode, 0, Position::PositionIsOffsetInAnchor);
    284     return Position(anchorNode, Position::PositionIsBeforeChildren);
    285 }
    286 
    287 inline Position lastPositionInNode(Node* anchorNode)
    288 {
    289     if (anchorNode->isTextNode())
    290         return Position(anchorNode, lastOffsetInNode(anchorNode), Position::PositionIsOffsetInAnchor);
    291     return Position(anchorNode, Position::PositionIsAfterChildren);
    292 }
    293 
    294 inline int minOffsetForNode(Node* anchorNode, int offset)
    295 {
    296     if (anchorNode->offsetInCharacters())
    297         return std::min(offset, anchorNode->maxCharacterOffset());
    298 
    299     int newOffset = 0;
    300     for (Node* node = anchorNode->firstChild(); node && newOffset < offset; node = node->nextSibling())
    301         newOffset++;
    302 
    303     return newOffset;
    304 }
    305 
    306 inline bool offsetIsBeforeLastNodeOffset(int offset, Node* anchorNode)
    307 {
    308     if (anchorNode->offsetInCharacters())
    309         return offset < anchorNode->maxCharacterOffset();
    310 
    311     int currentOffset = 0;
    312     for (Node* node = anchorNode->firstChild(); node && currentOffset < offset; node = node->nextSibling())
    313         currentOffset++;
    314 
    315 
    316     return offset < currentOffset;
    317 }
    318 
    319 class PositionWithAffinity {
    320 public:
    321     PositionWithAffinity()
    322         : m_affinity(DOWNSTREAM)
    323     {
    324     }
    325 
    326     PositionWithAffinity(const Position& position, EAffinity affinity = DOWNSTREAM)
    327         : m_position(position)
    328         , m_affinity(affinity)
    329     {
    330     }
    331 
    332     EAffinity affinity() const { return m_affinity; }
    333     const Position& position() const { return m_position; }
    334 
    335 private:
    336     Position m_position;
    337     EAffinity m_affinity;
    338 };
    339 
    340 } // namespace WebCore
    341 
    342 #ifndef NDEBUG
    343 // Outside the WebCore namespace for ease of invocation from gdb.
    344 void showTree(const WebCore::Position&);
    345 void showTree(const WebCore::Position*);
    346 #endif
    347 
    348 #endif // Position_h
    349