gecko-dev/editor/libeditor/WSRunObject.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef WSRunObject_h
#define WSRunObject_h

#include "nsCOMPtr.h"
#include "nsIEditor.h" // for EDirection
#include "nsINode.h"
#include "nscore.h"
#include "mozilla/Attributes.h"
#include "mozilla/dom/Text.h"
#include "mozilla/EditorDOMPoint.h" // for EditorDOMPoint

class nsIDOMNode;

namespace mozilla {

class HTMLEditor;
class HTMLEditRules;

// class WSRunObject represents the entire whitespace situation
// around a given point.  It collects up a list of nodes that contain
// whitespace and categorizes in up to 3 different WSFragments (detailed
// below).  Each WSFragment is a collection of whitespace that is
// either all insignificant, or that is significant.  A WSFragment could
// consist of insignificant whitespace because it is after a block
// boundary or after a break.  Or it could be insignificant because it
// is before a block.  Or it could be significant because it is
// surrounded by text, or starts and ends with nbsps, etc.

// Throughout I refer to LeadingWS, NormalWS, TrailingWS.  LeadingWS & TrailingWS
// are runs of ascii ws that are insignificant (do not render) because they
// are adjacent to block boundaries, or after a break.  NormalWS is ws that
// does cause soem rendering.  Note that not all the ws in a NormalWS run need
// render.  For example, two ascii spaces surrounded by text on both sides
// will only render as one space (in non-preformatted stlye html), yet both
// spaces count as NormalWS.  Together, they render as the one visible space.

/**
 * A type-safe bitfield indicating various types of whitespace or other things.
 * Used as a member variable in WSRunObject and WSFragment.
 *
 * XXX: If this idea is useful in other places, we should generalize it using a
 * template.
 */
class WSType
{
public:
  enum Enum
  {
    none       = 0,
    leadingWS  = 1,      // leading insignificant ws, ie, after block or br
    trailingWS = 1 << 1, // trailing insignificant ws, ie, before block
    normalWS   = 1 << 2, // normal significant ws, ie, after text, image, ...
    text       = 1 << 3, // indicates regular (non-ws) text
    special    = 1 << 4, // indicates an inline non-container, like image
    br         = 1 << 5, // indicates a br node
    otherBlock = 1 << 6, // indicates a block other than one ws run is in
    thisBlock  = 1 << 7, // indicates the block ws run is in
    block      = otherBlock | thisBlock // block found
  };

  /**
   * Implicit constructor, because the enums are logically just WSTypes
   * themselves, and are only a separate type because there's no other obvious
   * way to name specific WSType values.
   */
  MOZ_IMPLICIT WSType(const Enum& aEnum = none)
    : mEnum(aEnum)
  {}

  // operator==, &, and | need to access mEnum
  friend bool operator==(const WSType& aLeft, const WSType& aRight);
  friend const WSType operator&(const WSType& aLeft, const WSType& aRight);
  friend const WSType operator|(const WSType& aLeft, const WSType& aRight);
  WSType& operator=(const WSType& aOther)
  {
    // This handles self-assignment fine
    mEnum = aOther.mEnum;
    return *this;
  }
  WSType& operator&=(const WSType& aOther)
  {
    mEnum &= aOther.mEnum;
    return *this;
  }
  WSType& operator|=(const WSType& aOther)
  {
    mEnum |= aOther.mEnum;
    return *this;
  }

private:
  uint16_t mEnum;
  void bool_conversion_helper() {}

public:
  // Allow boolean conversion with no numeric conversion
  typedef void (WSType::*bool_type)();
  operator bool_type() const
  {
    return mEnum ? &WSType::bool_conversion_helper : nullptr;
  }
};

/**
 * These are declared as global functions so "WSType::Enum == WSType" et al.
 * will work using the implicit constructor.
 */
inline bool operator==(const WSType& aLeft, const WSType& aRight)
{
  return aLeft.mEnum == aRight.mEnum;
}

inline bool operator!=(const WSType& aLeft, const WSType& aRight)
{
  return !(aLeft == aRight);
}

inline const WSType operator&(const WSType& aLeft, const WSType& aRight)
{
  WSType ret;
  ret.mEnum = aLeft.mEnum & aRight.mEnum;
  return ret;
}

inline const WSType operator|(const WSType& aLeft, const WSType& aRight)
{
  WSType ret;
  ret.mEnum = aLeft.mEnum | aRight.mEnum;
  return ret;
}

/**
 * Make sure that & and | of WSType::Enum creates a WSType instead of an int,
 * because operators between WSType and int shouldn't work
 */
inline const WSType operator&(const WSType::Enum& aLeft,
                              const WSType::Enum& aRight)
{
  return WSType(aLeft) & WSType(aRight);
}

inline const WSType operator|(const WSType::Enum& aLeft,
                              const WSType::Enum& aRight)
{
  return WSType(aLeft) | WSType(aRight);
}

class MOZ_STACK_CLASS WSRunObject final
{
public:
  enum BlockBoundary
  {
    kBeforeBlock,
    kBlockStart,
    kBlockEnd,
    kAfterBlock
  };

  enum {eBefore = 1};
  enum {eAfter  = 1 << 1};
  enum {eBoth   = eBefore | eAfter};

  WSRunObject(HTMLEditor* aHTMLEditor, nsINode* aNode, int32_t aOffset);
  WSRunObject(HTMLEditor* aHTMLEditor, nsIDOMNode* aNode, int32_t aOffset);
  ~WSRunObject();

  // ScrubBlockBoundary removes any non-visible whitespace at the specified
  // location relative to a block node.
  static nsresult ScrubBlockBoundary(HTMLEditor* aHTMLEditor,
                                     BlockBoundary aBoundary,
                                     nsINode* aBlock,
                                     int32_t aOffset = -1);

  // PrepareToJoinBlocks fixes up ws at the end of aLeftBlock and the
  // beginning of aRightBlock in preperation for them to be joined.  Example
  // of fixup: trailingws in aLeftBlock needs to be removed.
  static nsresult PrepareToJoinBlocks(HTMLEditor* aHTMLEditor,
                                      dom::Element* aLeftBlock,
                                      dom::Element* aRightBlock);

  // PrepareToDeleteRange fixes up ws before {aStartNode,aStartOffset}
  // and after {aEndNode,aEndOffset} in preperation for content
  // in that range to be deleted.  Note that the nodes and offsets
  // are adjusted in response to any dom changes we make while
  // adjusting ws.
  // example of fixup: trailingws before {aStartNode,aStartOffset}
  //                   needs to be removed.
  static nsresult PrepareToDeleteRange(HTMLEditor* aHTMLEditor,
                                       nsCOMPtr<nsINode>* aStartNode,
                                       int32_t* aStartOffset,
                                       nsCOMPtr<nsINode>* aEndNode,
                                       int32_t* aEndOffset);

  // PrepareToDeleteNode fixes up ws before and after aContent in preparation
  // for aContent to be deleted.  Example of fixup: trailingws before
  // aContent needs to be removed.
  static nsresult PrepareToDeleteNode(HTMLEditor* aHTMLEditor,
                                      nsIContent* aContent);

  // PrepareToSplitAcrossBlocks fixes up ws before and after
  // {aSplitNode,aSplitOffset} in preparation for a block parent to be split.
  // Note that the aSplitNode and aSplitOffset are adjusted in response to
  // any DOM changes we make while adjusting ws.  Example of fixup: normalws
  // before {aSplitNode,aSplitOffset} needs to end with nbsp.
  static nsresult PrepareToSplitAcrossBlocks(HTMLEditor* aHTMLEditor,
                                             nsCOMPtr<nsINode>* aSplitNode,
                                             int32_t* aSplitOffset);

  /**
   * InsertBreak() inserts a <br> node at (before) aPointToInsert and delete
   * unnecessary whitespaces around there and/or replaces whitespaces with
   * non-breaking spaces.  Note that if the point is in a text node, the
   * text node will be split and insert new <br> node between the left node
   * and the right node.
   *
   * @param aSelection      The selection for the editor.
   * @param aPointToInsert  The point to insert new <br> element.  Note that
   *                        it'll be inserted before this point.  I.e., the
   *                        point will be the point of new <br>.
   * @param aSelect         If eNone, this won't change selection.
   *                        If eNext, selection will be collapsed after the
   *                        <br> element.
   *                        If ePrevious, selection will be collapsed at the
   *                        <br> element.
   * @return                The new <br> node.  If failed to create new <br>
   *                        node, returns nullptr.
   */
  already_AddRefed<dom::Element>
  InsertBreak(Selection& aSelection,
              const EditorRawDOMPoint& aPointToInsert,
              nsIEditor::EDirection aSelect);

  /**
   * InsertTextImpl() inserts aStringToInsert to aPointToInsert and makes any
   * needed adjustments to white spaces around that point. E.g., trailing white
   * spaces before aPointToInsert needs to be removed.
   * This calls EditorBase::InsertTextImpl() after adjusting white spaces.
   * So, please refer the method's explanation to know what this method exactly
   * does.
   *
   * @param aDocument       The document of this editor.
   * @param aStringToInsert The string to insert.
   * @param aPointToInser   The point to insert aStringToInsert.
   *                        Must be valid DOM point.
   * @param aPointAfterInsertedString
   *                        The point after inserted aStringToInsert.
   *                        So, when this method actually inserts string,
   *                        this is set to a point in the text node.
   *                        Otherwise, this may be set to aPointToInsert.
   * @return                When this succeeds to insert the string or
   *                        does nothing during composition, returns NS_OK.
   *                        Otherwise, an error code.
   */
  nsresult InsertText(nsIDocument& aDocument,
                      const nsAString& aStringToInsert,
                      const EditorRawDOMPoint& aPointToInsert,
                      EditorRawDOMPoint* aPointAfterInsertedString = nullptr);

  // DeleteWSBackward deletes a single visible piece of ws before the ws
  // point (the point to create the wsRunObject, passed to its constructor).
  // It makes any needed conversion to adjacent ws to retain its
  // significance.
  nsresult DeleteWSBackward();

  // DeleteWSForward deletes a single visible piece of ws after the ws point
  // (the point to create the wsRunObject, passed to its constructor).  It
  // makes any needed conversion to adjacent ws to retain its significance.
  nsresult DeleteWSForward();

  // PriorVisibleNode returns the first piece of visible thing before
  // {aNode,aOffset}.  If there is no visible ws qualifying it returns what
  // is before the ws run.  Note that {outVisNode,outVisOffset} is set to
  // just AFTER the visible object.
  void PriorVisibleNode(nsINode* aNode,
                        int32_t aOffset,
                        nsCOMPtr<nsINode>* outVisNode,
                        int32_t* outVisOffset,
                        WSType* outType);

  // NextVisibleNode returns the first piece of visible thing after
  // {aNode,aOffset}.  If there is no visible ws qualifying it returns what
  // is after the ws run.  Note that {outVisNode,outVisOffset} is set to just
  // BEFORE the visible object.
  void NextVisibleNode(nsINode* aNode,
                       int32_t aOffset,
                       nsCOMPtr<nsINode>* outVisNode,
                       int32_t* outVisOffset,
                       WSType* outType);

  // AdjustWhitespace examines the ws object for nbsp's that can
  // be safely converted to regular ascii space and converts them.
  nsresult AdjustWhitespace();

protected:
  // WSFragment represents a single run of ws (all leadingws, or all normalws,
  // or all trailingws, or all leading+trailingws).  Note that this single run
  // may still span multiple nodes.
  struct WSFragment final
  {
    nsCOMPtr<nsINode> mStartNode;  // node where ws run starts
    nsCOMPtr<nsINode> mEndNode;    // node where ws run ends
    int32_t mStartOffset;          // offset where ws run starts
    int32_t mEndOffset;            // offset where ws run ends
    // type of ws, and what is to left and right of it
    WSType mType, mLeftType, mRightType;
    // other ws runs to left or right.  may be null.
    WSFragment *mLeft, *mRight;

    WSFragment()
      : mStartOffset(0)
      , mEndOffset(0)
      , mLeft(nullptr)
      , mRight(nullptr)
    {}

    EditorRawDOMPoint StartPoint() const
    {
      return EditorRawDOMPoint(mStartNode, mStartOffset);
    }
    EditorRawDOMPoint EndPoint() const
    {
      return EditorRawDOMPoint(mEndNode, mEndOffset);
    }
  };

  // A WSPoint struct represents a unique location within the ws run.  It is
  // always within a textnode that is one of the nodes stored in the list
  // in the wsRunObject.  For convenience, the character at that point is also
  // stored in the struct.
  struct MOZ_STACK_CLASS WSPoint final
  {
    RefPtr<dom::Text> mTextNode;
    uint32_t mOffset;
    char16_t mChar;

    WSPoint()
      : mTextNode(nullptr)
      , mOffset(0)
      , mChar(0)
    {}

    WSPoint(dom::Text* aTextNode, int32_t aOffset, char16_t aChar)
      : mTextNode(aTextNode)
      , mOffset(aOffset)
      , mChar(aChar)
    {}
  };

  /**
   * Return the node which we will handle white-space under. This is the
   * closest block within the DOM subtree we're editing, or if none is
   * found, the (inline) root of the editable subtree.
   */
  nsINode* GetWSBoundingParent();

  nsresult GetWSNodes();
  void GetRuns();
  void ClearRuns();
  void MakeSingleWSRun(WSType aType);
  nsIContent* GetPreviousWSNodeInner(nsINode* aStartNode,
                                     nsINode* aBlockParent);
  nsIContent* GetPreviousWSNode(const EditorDOMPoint& aPoint,
                                nsINode* aBlockParent);
  nsIContent* GetNextWSNodeInner(nsINode* aStartNode, nsINode* aBlockParent);
  nsIContent* GetNextWSNode(const EditorDOMPoint& aPoint,
                            nsINode* aBlockParent);
  nsresult PrepareToDeleteRangePriv(WSRunObject* aEndObject);
  nsresult PrepareToSplitAcrossBlocksPriv();

  /**
   * DeleteRange() removes the range between aStartPoint and aEndPoint.
   * When aStartPoint and aEndPoint are same point, does nothing.
   * When aStartPoint and aEndPoint are in same text node, removes characters
   * between them.
   * When aStartPoint is in a text node, removes the text data after the point.
   * When aEndPoint is in a text node, removes the text data before the point.
   * Removes any nodes between them.
   */
  nsresult DeleteRange(const EditorRawDOMPoint& aStartPoint,
                       const EditorRawDOMPoint& aEndPoint);

  /**
   * GetNextCharPoint() returns next character's point of aPoint.  If there is
   * no character after aPoint, mTextNode is set to nullptr.
   */
  WSPoint GetNextCharPoint(const EditorRawDOMPoint& aPoint);
  WSPoint GetNextCharPoint(const WSPoint& aPoint);

  /**
   * GetPreviousCharPoint() returns previous character's point of of aPoint.
   * If there is no character before aPoint, mTextNode is set to nullptr.
   */
  WSPoint GetPreviousCharPoint(const EditorRawDOMPoint& aPoint);
  WSPoint GetPreviousCharPoint(const WSPoint& aPoint);

  /**
   * GetNextCharPointInternal() and GetPreviousCharPointInternal() are
   * helper methods of GetNextCharPoint(const EditorRawDOMPoint&) and
   * GetPreviousCharPoint(const EditorRawDOMPoint&).  When the container
   * isn't in mNodeArray, they call one of these methods.  Then, these
   * methods look for nearest text node in mNodeArray from aPoint.
   * Then, will call GetNextCharPoint(const WSPoint&) or
   * GetPreviousCharPoint(const WSPoint&) and returns its result.
   */
  WSPoint GetNextCharPointInternal(const EditorRawDOMPoint& aPoint);
  WSPoint GetPreviousCharPointInternal(const EditorRawDOMPoint& aPoint);

  /**
   * InsertNBSPAndRemoveFollowingASCIIWhitespaces() inserts an NBSP first.
   * Then, if following characters are ASCII whitespaces, will remove them.
   */
  nsresult InsertNBSPAndRemoveFollowingASCIIWhitespaces(WSPoint aPoint);

  /**
   * GetASCIIWhitespacesBounds() retrieves whitespaces before and/or after the
   * point specified by aNode and aOffset.
   *
   * @param aDir            Specify eBefore if you want to scan text backward.
   *                        Specify eAfter if you want to scan text forward.
   *                        Specify eBoth if you want to scan text to both
   *                        direction.
   * @param aNode           The container node where you want to start to scan
   *                        whitespaces from.
   * @param aOffset         The offset in aNode where you want to start to scan
   *                        whitespaces from.
   * @param outStartNode    [out] The container of first ASCII whitespace.
   *                              If there is no whitespaces, returns nullptr.
   * @param outStartOffset  [out] The offset of first ASCII whitespace in
   *                              outStartNode.
   * @param outEndNode      [out] The container of last ASCII whitespace.
   *                              If there is no whitespaces, returns nullptr.
   * @param outEndOffset    [out] The offset of last ASCII whitespace in
   *                              outEndNode.
   */
  void GetASCIIWhitespacesBounds(int16_t aDir,
                                 nsINode* aNode,
                                 int32_t aOffset,
                                 dom::Text** outStartNode,
                                 int32_t* outStartOffset,
                                 dom::Text** outEndNode,
                                 int32_t* outEndOffset);

  /**
   * FindNearestRun() looks for a WSFragment which is closest to specified
   * direction from aPoint.
   *
   * @param aPoint      The point to start to look for.
   * @param aForward    true if caller needs to look for a WSFragment after the
   *                    point in the DOM tree.  Otherwise, i.e., before the
   *                    point, false.
   * @return            Found WSFragment instance.
   *                    If aForward is true and:
   *                      if aPoint is end of a run, returns next run.
   *                      if aPoint is start of a run, returns the run.
   *                      if aPoint is before the first run, returns the first
   *                      run.
   *                      If aPoint is after the last run, returns nullptr.
   *                    If aForward is false and:
   *                      if aPoint is end of a run, returns the run.
   *                      if aPoint is start of a run, returns its next run.
   *                      if aPoint is before the first run, returns nullptr.
   *                      if aPoint is after the last run, returns the last run.
   */
  WSFragment* FindNearestRun(const EditorRawDOMPoint& aPoint, bool aForward);

  char16_t GetCharAt(dom::Text* aTextNode, int32_t aOffset);
  nsresult CheckTrailingNBSPOfRun(WSFragment *aRun);

  /**
   * ReplacePreviousNBSPIfUnncessary() replaces previous character of aPoint
   * if it's a NBSP and it's unnecessary.
   *
   * @param aRun        Current text run.  aPoint must be in this run.
   * @param aPoint      Current insertion point.  Its previous character is
   *                    unnecessary NBSP will be checked.
   */
  nsresult ReplacePreviousNBSPIfUnncessary(WSFragment* aRun,
                                           const EditorRawDOMPoint& aPoint);

  nsresult CheckLeadingNBSP(WSFragment* aRun, nsINode* aNode,
                            int32_t aOffset);

  nsresult Scrub();
  bool IsBlockNode(nsINode* aNode);

  EditorRawDOMPoint Point() const
  {
    return EditorRawDOMPoint(mNode, mOffset);
  }
  EditorRawDOMPoint StartPoint() const
  {
    return EditorRawDOMPoint(mStartNode, mStartOffset);
  }
  EditorRawDOMPoint EndPoint() const
  {
    return EditorRawDOMPoint(mEndNode, mEndOffset);
  }

  // The node passed to our constructor.
  nsCOMPtr<nsINode> mNode;
  // The offset passed to our contructor.
  int32_t mOffset;
  // Together, the above represent the point at which we are building up ws info.

  // true if we are in preformatted whitespace context.
  bool mPRE;
  // Node/offset where ws starts.
  nsCOMPtr<nsINode> mStartNode;
  int32_t mStartOffset;
  // Reason why ws starts (eText, eOtherBlock, etc.).
  WSType mStartReason;
  // The node that implicated by start reason.
  nsCOMPtr<nsINode> mStartReasonNode;

  // Node/offset where ws ends.
  nsCOMPtr<nsINode> mEndNode;
  int32_t mEndOffset;
  // Reason why ws ends (eText, eOtherBlock, etc.).
  WSType mEndReason;
  // The node that implicated by end reason.
  nsCOMPtr<nsINode> mEndReasonNode;

  // Location of first nbsp in ws run, if any.
  RefPtr<dom::Text> mFirstNBSPNode;
  int32_t mFirstNBSPOffset;

  // Location of last nbsp in ws run, if any.
  RefPtr<dom::Text> mLastNBSPNode;
  int32_t mLastNBSPOffset;

  // The list of nodes containing ws in this run.
  nsTArray<RefPtr<dom::Text>> mNodeArray;

  // The first WSFragment in the run.
  WSFragment* mStartRun;
  // The last WSFragment in the run, may be same as first.
  WSFragment* mEndRun;

  // Non-owning.
  HTMLEditor* mHTMLEditor;

  // Opening this class up for pillaging.
  friend class HTMLEditRules;
  // Opening this class up for more pillaging.
  friend class HTMLEditor;
};

} // namespace mozilla

#endif // #ifndef WSRunObject_h