{-------------------------------------------------------------------------------
The contents of this file are subject to the Mozilla Public License
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-------------------------------------------------------------------------------}
unit SynEditTextTabExpander;

{$I synedit.inc}

interface

uses
  LCLProc, Classes, SysUtils, LazSynEditText, SynEditTextBase;

type

  // lines longer than 16383 chars, will be stored as unknown
  TLineLen = Word;
  PLineLen = ^TLineLen;

  { TSynEditStringTabData }

  TSynEditStringTabData = class(TSynManagedStorageMem)
  private
    FRefCount: Integer;
    function GetLineLen(Index: Integer): TLineLen;
    procedure SetLineLen(Index: Integer; const AValue: TLineLen);
  public
    constructor Create;
    procedure IncRefCount;
    procedure DecRefCount;
    property RefCount: Integer read FRefCount;
    property LineLen[Index: Integer]: TLineLen read GetLineLen write SetLineLen; default;
  end;

{ TSynEditStringTabExpander }

  TSynEditStringTabExpander = class(TSynEditStringsLinked)
  private
    FTabWidth: integer;
    FIndexOfLongestLine: Integer;
    FTabData: TSynEditStringTabData;
    FLastLineHasTab: Boolean; // Last line, parsed by GetPhysicalCharWidths
    FLastLinePhysLen: Integer;
    FViewChangeStamp: int64;
    procedure TextBufferChanged(Sender: TObject);
    procedure LineCountChanged(Sender: TSynEditStrings; AIndex, ACount : Integer);
    function ExpandedString(Index: integer): string;
    function ExpandedStringLength(Index: integer): Integer;
  protected
    function GetViewChangeStamp: int64; override;
    function  GetTabWidth : integer;
    procedure SetTabWidth(const AValue : integer);
    function  GetExpandedString(Index: integer): string; override;
    function  GetLengthOfLongestLine: integer; override;
    procedure DoGetPhysicalCharWidths(Line: PChar; LineLen, Index: Integer; PWidths: PPhysicalCharWidth); override;
  public
    constructor Create(ASynStringSource: TSynEditStrings);
    destructor Destroy; override;

    property LengthOfLongestLine: integer read GetLengthOfLongestLine;
  public
    property TabWidth: integer read GetTabWidth write SetTabWidth;
  end;


implementation

const
  // Offset to add to LengthOfLine, if Line has no tabs.
  // (Length will still be valid if tab-width changes)
  NO_TAB_IN_LINE_OFFSET = high(TLineLen) div 2;
  LINE_LEN_UNKNOWN = high(TLineLen);
  MAX_LINE_LEN_STORED = NO_TAB_IN_LINE_OFFSET - 1;

function GetHasTabs(pLine: PChar): boolean;
begin
  if Assigned(pLine) then begin
    while (pLine^ <> #0) do begin
      if (pLine^ = #9) then break;
      Inc(pLine);
    end;
    Result := (pLine^ = #9);
  end else
    Result := FALSE;
end;

{ TSynEditStringTabData }

function TSynEditStringTabData.GetLineLen(Index: Integer): TLineLen;
begin
  Result := PLineLen(ItemPointer[Index])^;
end;

procedure TSynEditStringTabData.SetLineLen(Index: Integer; const AValue: TLineLen);
begin
  PLineLen(ItemPointer[Index])^ := AValue;
end;

constructor TSynEditStringTabData.Create;
begin
  inherited;
  ItemSize := SizeOf(TLineLen);
  FRefCount := 1;
end;

procedure TSynEditStringTabData.IncRefCount;
begin
  inc(FRefCount);
end;

procedure TSynEditStringTabData.DecRefCount;
begin
  dec(FRefCount);
end;

{ TSynEditStringTabExpander }

constructor TSynEditStringTabExpander.Create(ASynStringSource: TSynEditStrings);
begin
  FIndexOfLongestLine := -1;
  inherited Create(ASynStringSource);
  TextBufferChanged(nil);
  TabWidth := 8;
  fSynStrings.AddChangeHandler(senrLineCount, @LineCountChanged);
  fSynStrings.AddChangeHandler(senrLineChange, @LineCountChanged);
  fSynStrings.AddNotifyHandler(senrTextBufferChanged, @TextBufferChanged);
end;

destructor TSynEditStringTabExpander.Destroy;
var
  Data: TSynEditStringTabData;
begin
  Data := TSynEditStringTabData(fSynStrings.Ranges[Self]);
  if Assigned(Data) then begin
    Data.DecRefCount;
    if Data.RefCount = 0 then begin
      fSynStrings.Ranges[Self] := nil;
      Data.Free;
    end;
  end;
  fSynStrings.RemoveChangeHandler(senrLineChange, @LineCountChanged);
  fSynStrings.RemoveChangeHandler(senrLineCount, @LineCountChanged);
  fSynStrings.RemoveNotifyHandler(senrTextBufferChanged, @TextBufferChanged);
  inherited Destroy;
end;

function TSynEditStringTabExpander.GetTabWidth: integer;
begin
  Result := FTabWidth;
end;

procedure TSynEditStringTabExpander.SetTabWidth(const AValue: integer);
var
  i: integer;
begin
  if FTabWidth = AValue then exit;

  {$PUSH}{$Q-}{$R-}
  FViewChangeStamp := FViewChangeStamp + 1;
  {$POP}

  FTabWidth := AValue;
  FIndexOfLongestLine := -1;
  for i := 0 to Count - 1 do
    if not(FTabData[i] >= NO_TAB_IN_LINE_OFFSET) then
      FTabData[i] := LINE_LEN_UNKNOWN;
end;

function TSynEditStringTabExpander.GetViewChangeStamp: int64;
begin
  Result := inherited GetViewChangeStamp;
  {$PUSH}{$Q-}{$R-}
  Result := Result + FViewChangeStamp;
  {$POP}
end;

procedure TSynEditStringTabExpander.TextBufferChanged(Sender: TObject);
var
  Data: TSynEditStringTabData;
begin
  // Using self, instead as class, to register tab-width-data
  // other shared edits can have different tab-width
  if (Sender <> nil) and
     (FTabData = TSynEditStringTabData(NextLines.Ranges[Self]))
  then
    exit;

  if Sender <> nil then begin
    Data := TSynEditStringTabData(TSynEditStrings(Sender).Ranges[Self]);
    if Assigned(Data) then begin
      Data.DecRefCount;
      if Data.RefCount = 0 then begin
        TSynEditStrings(Sender).Ranges[Self] := nil;
        Data.Free;
      end;
    end;
  end;
  FTabData := TSynEditStringTabData(NextLines.Ranges[Self]);
  if FTabData = nil then begin
    FTabData := TSynEditStringTabData.Create;
    NextLines.Ranges[Self] := FTabData;
  end
  else
    FTabData.IncRefCount;
  LineCountChanged(TSynEditStrings(Sender), 0, Count);
end;

procedure TSynEditStringTabExpander.LineCountChanged(Sender: TSynEditStrings; AIndex, ACount: Integer);
var
  i: integer;
begin
  FIndexOfLongestLine := -1;
  for i := AIndex to AIndex + ACount - 1 do
    FTabData[i] := LINE_LEN_UNKNOWN;
end;

function TSynEditStringTabExpander.ExpandedString(Index: integer): string;
var
  Line: String;
  CharWidths: TPhysicalCharWidths;
  i, j, l: Integer;
begin
// this is only used by trimmer.lengthOfLongestLine / which is not called, if a tab module is present
  Line := fSynStrings[Index];
  if (Line = '') or (not GetHasTabs(PChar(Line))) then begin
    Result := Line;
    // xxx wrong double width // none latin ...
    //FTabData[Index] := length(Result) + NO_TAB_IN_LINE_OFFSET;
  end else begin
    CharWidths := GetPhysicalCharWidths(Pchar(Line), length(Line), Index);
    l := 0;
    for i := 0 to length(CharWidths)-1 do
      l := l + (CharWidths[i] and PCWMask);
    SetLength(Result, l);

    l := 1;
    for i := 1 to length(CharWidths) do begin
      if Line[i] <> #9 then begin
        Result[l] := Line[i];
        inc(l);
      end else begin
        for j := 1 to (CharWidths[i-1] and PCWMask) do begin
          Result[l] := ' ';
          inc(l);
        end;
      end;
    end;
    FTabData[Index] := length(Result);
  end;
end;

function TSynEditStringTabExpander.ExpandedStringLength(Index: integer): Integer;
var
  Line: String;
  CharWidths: TPhysicalCharWidths;
  i: Integer;
begin
  Line := fSynStrings[Index];
  if (Line = '') then begin
    Result := 0;
    FTabData[Index] := Result + NO_TAB_IN_LINE_OFFSET;
  end else begin
    i := length(Line);
    SetLength(CharWidths, i);
    DoGetPhysicalCharWidths(Pchar(Line), i, Index, @CharWidths[0]);
    Result := 0;
    for i := 0 to length(CharWidths)-1 do
      Result := Result + (CharWidths[i] and PCWMask);

    if FLastLineHasTab then // FLastLineHasTab is set by GetPhysicalCharWidths
      FTabData[Index] := Result
    else
      FTabData[Index] := Result + NO_TAB_IN_LINE_OFFSET;
  end;
end;

function TSynEditStringTabExpander.GetExpandedString(Index: integer): string;
begin
  if (Index >= 0) and (Index < Count) then begin
    if FTabData[Index] >= NO_TAB_IN_LINE_OFFSET then
      Result := fSynStrings[Index]
    else
      Result := ExpandedString(Index);
  end else
    Result := '';
end;

procedure TSynEditStringTabExpander.DoGetPhysicalCharWidths(Line: PChar;
  LineLen, Index: Integer; PWidths: PPhysicalCharWidth);
var
  HasTab: Boolean;
  i, j: Integer;
begin
  inherited DoGetPhysicalCharWidths(Line, LineLen, Index, PWidths);
  HasTab := False;
  j := 0;
  for i := 0 to LineLen - 1 do begin
    if (PWidths^ and PCWMask) <> 0 then begin
      if Line^ = #9 then begin
        PWidths^ := (FTabWidth - (j mod FTabWidth) and PCWMask) or (PWidths^  and (not PCWMask));
        HasTab := True;
      end;
      j := j + (PWidths^ and PCWMask);
    end;
    inc(Line);
    inc(PWidths);
  end;
  FLastLineHasTab := HasTab;
  FLastLinePhysLen := j;
end;

function TSynEditStringTabExpander.GetLengthOfLongestLine: integer;
var
  Line: PChar;
  LineLen: Integer;
  CharWidths: PPhysicalCharWidth;
  i, j, m: Integer;
  Line1, Line2: Integer;
begin
  Line1 := 0;
  Line2 := Count - 1;
  if (fIndexOfLongestLine >= 0) and (fIndexOfLongestLine < Count) then begin
    Result := FTabData[fIndexOfLongestLine];
    if Result <> LINE_LEN_UNKNOWN then begin
      if Result >= NO_TAB_IN_LINE_OFFSET then Result := Result -  NO_TAB_IN_LINE_OFFSET;
      exit;
    end;
    Line1 := fIndexOfLongestLine;
    Line2 := fIndexOfLongestLine;
  end;

  try
    Result := 0;
    m := 0;
    CharWidths := nil;
    for i := Line1 to Line2 do begin
      j := FTabData[i];
      if j = LINE_LEN_UNKNOWN then begin
        // embedd a copy of ExpandedStringLength
        // allows one to re-use CharWidths
        Line := NextLines.GetPChar(i,LineLen); // fSynStrings[i];
        j := 0;
        if (LineLen = 0) then begin
          FTabData[i] := j + NO_TAB_IN_LINE_OFFSET;
        end else begin
          if LineLen > m then begin
            ReAllocMem(CharWidths, LineLen * SizeOf(TPhysicalCharWidth));
            m := LineLen;
          end;
          DoGetPhysicalCharWidths(Line, LineLen, i, CharWidths);
          j := FLastLinePhysLen;

          if j > MAX_LINE_LEN_STORED then
            FTabData[i] := LINE_LEN_UNKNOWN
          else if FLastLineHasTab then // FLastLineHasTab is set by GetPhysicalCharWidths
            FTabData[i] := j
          else
            FTabData[i] := j + NO_TAB_IN_LINE_OFFSET;
        end;
      end
      else
      if j >= NO_TAB_IN_LINE_OFFSET then
        j := j -  NO_TAB_IN_LINE_OFFSET;
      if j > Result then begin
        Result := j;
        fIndexOfLongestLine := i;
      end;
    end;
  finally
    ReAllocMem(CharWidths, 0);
  end;
end;

end.