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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 "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     bool inDocument() const { return m_anchorNode && m_anchorNode->inDocument(); }
    132     Element* rootEditableElement() const
    133     {
    134         Node* container = containerNode();
    135         return container ? container->rootEditableElement() : 0;
    136     }
    137 
    138     // These should only be used for PositionIsOffsetInAnchor positions, unless
    139     // the position is a legacy editing position.
    140     void moveToPosition(PassRefPtr<Node> anchorNode, int offset);
    141     void moveToOffset(int offset);
    142 
    143     bool isNull() const { return !m_anchorNode; }
    144     bool isNotNull() const { return m_anchorNode; }
    145     bool isOrphan() const { return m_anchorNode && !m_anchorNode->inDocument(); }
    146 
    147     Element* element() const;
    148     PassRefPtr<CSSComputedStyleDeclaration> computedStyle() const;
    149 
    150     // Move up or down the DOM by one position.
    151     // Offsets are computed using render text for nodes that have renderers - but note that even when
    152     // using composed characters, the result may be inside a single user-visible character if a ligature is formed.
    153     Position previous(PositionMoveType = CodePoint) const;
    154     Position next(PositionMoveType = CodePoint) const;
    155     static int uncheckedPreviousOffset(const Node*, int current);
    156     static int uncheckedPreviousOffsetForBackwardDeletion(const Node*, int current);
    157     static int uncheckedNextOffset(const Node*, int current);
    158 
    159     // These can be either inside or just before/after the node, depending on
    160     // if the node is ignored by editing or not.
    161     // FIXME: These should go away. They only make sense for legacy positions.
    162     bool atFirstEditingPositionForNode() const;
    163     bool atLastEditingPositionForNode() const;
    164 
    165     // Returns true if the visually equivalent positions around have different editability
    166     bool atEditingBoundary() const;
    167     Node* parentEditingBoundary() const;
    168 
    169     bool atStartOfTree() const;
    170     bool atEndOfTree() const;
    171 
    172     // FIXME: Make these non-member functions and put them somewhere in the editing directory.
    173     // These aren't really basic "position" operations. More high level editing helper functions.
    174     Position leadingWhitespacePosition(EAffinity, bool considerNonCollapsibleWhitespace = false) const;
    175     Position trailingWhitespacePosition(EAffinity, bool considerNonCollapsibleWhitespace = false) const;
    176 
    177     // These return useful visually equivalent positions.
    178     Position upstream(EditingBoundaryCrossingRule = CannotCrossEditingBoundary) const;
    179     Position downstream(EditingBoundaryCrossingRule = CannotCrossEditingBoundary) const;
    180 
    181     bool isCandidate() const;
    182     bool inRenderedText() const;
    183     bool isRenderedCharacter() const;
    184     bool rendersInDifferentPosition(const Position&) const;
    185 
    186     void getInlineBoxAndOffset(EAffinity, InlineBox*&, int& caretOffset) const;
    187     void getInlineBoxAndOffset(EAffinity, TextDirection primaryDirection, InlineBox*&, int& caretOffset) const;
    188 
    189     TextDirection primaryDirection() const;
    190 
    191     static bool hasRenderedNonAnonymousDescendantsWithHeight(RenderObject*);
    192     static bool nodeIsUserSelectNone(Node*);
    193     static bool nodeIsUserSelectAll(const Node*);
    194     static Node* rootUserSelectAllForNode(Node*);
    195 
    196     static ContainerNode* findParent(const Node*);
    197 
    198     void debugPosition(const char* msg = "") const;
    199 
    200 #ifndef NDEBUG
    201     void formatForDebugger(char* buffer, unsigned length) const;
    202     void showAnchorTypeAndOffset() const;
    203     void showTreeForThis() const;
    204 #endif
    205 
    206 private:
    207     int offsetForPositionAfterAnchor() const;
    208 
    209     int renderedOffset() const;
    210 
    211 
    212     Position previousCharacterPosition(EAffinity) const;
    213     Position nextCharacterPosition(EAffinity) const;
    214 
    215     static AnchorType anchorTypeForLegacyEditingPosition(Node* anchorNode, int offset);
    216 
    217     RefPtr<Node> m_anchorNode;
    218     // m_offset can be the offset inside m_anchorNode, or if editingIgnoresContent(m_anchorNode)
    219     // returns true, then other places in editing will treat m_offset == 0 as "before the anchor"
    220     // and m_offset > 0 as "after the anchor node".  See parentAnchoredEquivalent for more info.
    221     int m_offset;
    222     unsigned m_anchorType : 3;
    223     bool m_isLegacyEditingPosition : 1;
    224 };
    225 
    226 inline Position createLegacyEditingPosition(PassRefPtr<Node> node, int offset)
    227 {
    228     return Position(node, Position::LegacyEditingOffset(offset));
    229 }
    230 
    231 inline bool operator==(const Position& a, const Position& b)
    232 {
    233     // FIXME: In <div><img></div> [div, 0] != [img, 0] even though most of the
    234     // editing code will treat them as identical.
    235     return a.anchorNode() == b.anchorNode() && a.deprecatedEditingOffset() == b.deprecatedEditingOffset() && a.anchorType() == b.anchorType();
    236 }
    237 
    238 inline bool operator!=(const Position& a, const Position& b)
    239 {
    240     return !(a == b);
    241 }
    242 
    243 // We define position creation functions to make callsites more readable.
    244 // These are inline to prevent ref-churn when returning a Position object.
    245 // If we ever add a PassPosition we can make these non-inline.
    246 
    247 inline Position positionInParentBeforeNode(const Node* node)
    248 {
    249     // FIXME: This should ASSERT(node->parentNode())
    250     // At least one caller currently hits this ASSERT though, which indicates
    251     // that the caller is trying to make a position relative to a disconnected node (which is likely an error)
    252     // Specifically, editing/deleting/delete-ligature-001.html crashes with ASSERT(node->parentNode())
    253     return Position(node->parentNode(), node->nodeIndex(), Position::PositionIsOffsetInAnchor);
    254 }
    255 
    256 inline Position positionInParentAfterNode(const Node* node)
    257 {
    258     ASSERT(node->parentNode());
    259     return Position(node->parentNode(), node->nodeIndex() + 1, Position::PositionIsOffsetInAnchor);
    260 }
    261 
    262 // positionBeforeNode and positionAfterNode return neighbor-anchored positions, construction is O(1)
    263 inline Position positionBeforeNode(Node* anchorNode)
    264 {
    265     ASSERT(anchorNode);
    266     return Position(anchorNode, Position::PositionIsBeforeAnchor);
    267 }
    268 
    269 inline Position positionAfterNode(Node* anchorNode)
    270 {
    271     ASSERT(anchorNode);
    272     return Position(anchorNode, Position::PositionIsAfterAnchor);
    273 }
    274 
    275 inline int lastOffsetInNode(Node* node)
    276 {
    277     return node->offsetInCharacters() ? node->maxCharacterOffset() : static_cast<int>(node->childNodeCount());
    278 }
    279 
    280 // firstPositionInNode and lastPositionInNode return parent-anchored positions, lastPositionInNode construction is O(n) due to childNodeCount()
    281 inline Position firstPositionInNode(Node* anchorNode)
    282 {
    283     if (anchorNode->isTextNode())
    284         return Position(anchorNode, 0, Position::PositionIsOffsetInAnchor);
    285     return Position(anchorNode, Position::PositionIsBeforeChildren);
    286 }
    287 
    288 inline Position lastPositionInNode(Node* anchorNode)
    289 {
    290     if (anchorNode->isTextNode())
    291         return Position(anchorNode, lastOffsetInNode(anchorNode), Position::PositionIsOffsetInAnchor);
    292     return Position(anchorNode, Position::PositionIsAfterChildren);
    293 }
    294 
    295 inline int minOffsetForNode(Node* anchorNode, int offset)
    296 {
    297     if (anchorNode->offsetInCharacters())
    298         return std::min(offset, anchorNode->maxCharacterOffset());
    299 
    300     int newOffset = 0;
    301     for (Node* node = anchorNode->firstChild(); node && newOffset < offset; node = node->nextSibling())
    302         newOffset++;
    303 
    304     return newOffset;
    305 }
    306 
    307 inline bool offsetIsBeforeLastNodeOffset(int offset, Node* anchorNode)
    308 {
    309     if (anchorNode->offsetInCharacters())
    310         return offset < anchorNode->maxCharacterOffset();
    311 
    312     int currentOffset = 0;
    313     for (Node* node = anchorNode->firstChild(); node && currentOffset < offset; node = node->nextSibling())
    314         currentOffset++;
    315 
    316 
    317     return offset < currentOffset;
    318 }
    319 
    320 class PositionWithAffinity {
    321 public:
    322     PositionWithAffinity()
    323         : m_affinity(DOWNSTREAM)
    324     {
    325     }
    326 
    327     PositionWithAffinity(const Position& position, EAffinity affinity = DOWNSTREAM)
    328         : m_position(position)
    329         , m_affinity(affinity)
    330     {
    331     }
    332 
    333     EAffinity affinity() const { return m_affinity; }
    334     const Position& position() const { return m_position; }
    335 
    336 private:
    337     Position m_position;
    338     EAffinity m_affinity;
    339 };
    340 
    341 } // namespace WebCore
    342 
    343 #ifndef NDEBUG
    344 // Outside the WebCore namespace for ease of invocation from gdb.
    345 void showTree(const WebCore::Position&);
    346 void showTree(const WebCore::Position*);
    347 #endif
    348 
    349 #endif // Position_h
    350