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 {aInOutParent,aInOutOffset}
  // and makes any needed adjustments to ws around that point.
  // example of fixup: normalws after {aInOutParent,aInOutOffset}
  //                   needs to begin with nbsp.
  already_AddRefed<dom::Element> InsertBreak(nsCOMPtr<nsINode>* aInOutParent,
                                             int32_t* aInOutOffset,
                                             nsIEditor::EDirection aSelect);

  // InsertText inserts a string at {aInOutParent,aInOutOffset} and makes any
  // needed adjustments to ws around that point.  Example of fixup:
  // trailingws before {aInOutParent,aInOutOffset} needs to be removed.
  nsresult InsertText(const nsAString& aStringToInsert,
                      nsCOMPtr<nsINode>* aInOutNode,
                      nsCOMPtr<nsIContent>* aInOutChildAtOffset,
                      int32_t* aInOutOffset,
                      nsIDocument* aDoc);

  // 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)
    {}
  };

  // 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();
  nsresult DeleteChars(nsINode* aStartNode, int32_t aStartOffset,
                       nsINode* aEndNode, int32_t aEndOffset);
  WSPoint GetCharAfter(nsINode* aNode, int32_t aOffset);
  WSPoint GetCharBefore(nsINode* aNode, int32_t aOffset);
  WSPoint GetCharAfter(const WSPoint& aPoint);
  WSPoint GetCharBefore(const WSPoint& aPoint);
  nsresult ConvertToNBSP(WSPoint aPoint);
  void GetAsciiWSBounds(int16_t aDir, nsINode* aNode, int32_t aOffset,
                        dom::Text** outStartNode, int32_t* outStartOffset,
                        dom::Text** outEndNode, int32_t* outEndOffset);
  void FindRun(nsINode* aNode, int32_t aOffset, WSFragment** outRun,
               bool after);
  char16_t GetCharAt(dom::Text* aTextNode, int32_t aOffset);
  WSPoint GetWSPointAfter(nsINode* aNode, int32_t aOffset);
  WSPoint GetWSPointBefore(nsINode* aNode, int32_t aOffset);
  nsresult CheckTrailingNBSPOfRun(WSFragment *aRun);
  nsresult CheckTrailingNBSP(WSFragment* aRun, nsINode* aNode,
                             int32_t aOffset);
  nsresult CheckLeadingNBSP(WSFragment* aRun, nsINode* aNode,
                            int32_t aOffset);

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

  // 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