freepascal.compiler/utils/fpdoc/dw_basemd.pp

unit dw_basemd;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, dwriter, DOM, pastree, dglobals;

Const
  MaxIndents = 10;
  MaxLists = 10;

Type
  THeaderLevel = 1..6;
  TRender = (rStrong,rEmphasis,rCode);
  TListType = (ltOrdered,ltUnordered, ltDefinition);

  TMarkdownEngine = (meMkDocs,meNone);

  { TBaseMarkdownWriter }

  TBaseMarkdownWriter = class(TMultifileDocWriter)
  private
    FIgnoreCount : Integer;
    FBaseImageURL: String;
    FContentPrefix: String;
    FCurrentIndentIndex: Word;
    FCurrentLine: UTF8String;
    FDefinitionSeparator: String;
    FDefinitionTermRender: TRender;
    FFileRendering: TRender;
    FIndentSize: Byte;
    FKeywordRendering: TRender;
    FModule: TPasModule;
    FPrefix : string;
    FMetadata,
    FMarkDown: TStrings;
    FSymbolRendering: TRender;
    FTheme: String;
    FUnderLineRendering: TRender;
    FVarRendering: TRender;
    FLink : String;
    FListStack : Integer;
    FIndents : Array[0..MaxIndents] of Word;
    FListTypes : Array[1..MaxLists] of TListType;
    FTableColCount : Integer;
    FMarkDownEngine: TMarkdownEngine;
    function GetCurrentIndent: Word;
    procedure SetIndentSize(AValue: Byte);
    procedure clearIndent;
    procedure CalcPrefix;
  Protected
    function CreateAllocator: TFileAllocator; override;
    Procedure DescrEmitNotesHeader(AContext : TPasElement); override;
    Procedure DescrEmitNotesFooter(AContext : TPasElement); override;
    procedure DescrWriteText(const AText: DOMString); override;
    procedure DescrBeginBold; override;
    procedure DescrEndBold; override;
    procedure DescrBeginItalic; override;
    procedure DescrEndItalic; override;
    procedure DescrBeginEmph; override;
    procedure DescrEndEmph; override;
    procedure DescrBeginUnderline; override;
    procedure DescrEndUnderline; override;
    procedure DescrWriteImageEl(const AFileName, ACaption, ALinkName : DOMString); override;
    procedure DescrWriteFileEl(const AText: DOMString); override;
    procedure DescrWriteKeywordEl(const AText: DOMString); override;
    procedure DescrWriteVarEl(const AText: DOMString); override;
    procedure DescrBeginLink(const AId: DOMString); override;
    procedure DescrEndLink; override;
    procedure DescrBeginURL(const AURL: DOMString); override;
    procedure DescrEndURL; override;
    procedure DescrWriteLinebreak; override;
    procedure DescrBeginParagraph; override;
    procedure DescrEndParagraph; override;
    procedure DescrBeginCode(HasBorder: Boolean; const AHighlighterName: String); override;
    procedure DescrWriteCodeLine(const ALine: String); override;
    procedure DescrEndCode; override;
    procedure DescrBeginOrderedList; override;
    procedure DescrEndOrderedList; override;
    procedure DescrBeginUnorderedList; override;
    procedure DescrEndUnorderedList; override;
    procedure DescrBeginDefinitionList; override;
    procedure DescrEndDefinitionList; override;
    procedure DescrBeginListItem; override;
    procedure DescrEndListItem; override;
    procedure DescrBeginDefinitionTerm; override;
    procedure DescrEndDefinitionTerm; override;
    procedure DescrBeginDefinitionEntry; override;
    procedure DescrEndDefinitionEntry; override;
    procedure DescrBeginSectionTitle; override;
    procedure DescrBeginSectionBody; override;
    procedure DescrEndSection; override;
    procedure DescrBeginRemark; override;
    procedure DescrEndRemark; override;
    procedure DescrBeginTable(ColCount: Integer; HasBorder: Boolean); override;
    procedure DescrEndTable; override;
    procedure DescrBeginTableCaption; override;
    procedure DescrEndTableCaption; override;
    procedure DescrBeginTableHeadRow; override;
    procedure DescrEndTableHeadRow; override;
    procedure DescrBeginTableRow; override;
    procedure DescrEndTableRow; override;
    procedure DescrBeginTableCell; override;
    procedure DescrEndTableCell; override;
  Protected
    // Emit current line, if any
    Function OutputCurrentLine : Boolean;
    function EscapeMarkDown(aText: Domstring): string;
    function EscapeMarkDown(aText: String): string;
    function CreateLink(Const aText,aLink : String) : String;
    // Append to current line
    procedure AppendToLine(aText: DomString; DoEscape: boolean = true);
    procedure AppendToLine(aText: UTF8String; DoEscape: boolean = true); virtual;
    procedure AppendToLine(aFmt: UTF8String; aArgs : Array of const; DoEscape: boolean = true);
    // Write current line and append new line
    procedure EmitLine(aText: UTF8String; DoEscape: boolean = true); virtual;
    procedure EmitLine(aFmt: UTF8String; aArgs : Array of const; DoEscape: boolean = true);
    // Append spans to current line
    procedure AppendLink(Const aText,aLink : String);
    Procedure AppendRendered(aText : String; aRender : TRender);
    Procedure AppendKeyWord(aText : String); inline;
    Procedure AppendSymbol(aText : String); inline;
    Procedure AppendTableHeader(aHeaders: Array of String);
    Procedure EmitCode(aCodeBlock : String; aIndent : Integer = 0);
    Procedure EmitCode(aCodeBlock : TStrings; aIndent : Integer = 0);
    Procedure EmitCodeLine(aCodeLine : string);
    procedure EndSpan(aRender: TRender);
    procedure StartSpan(aRender: TRender);
    Procedure PushIndent(aNewIndent : Byte);
    Procedure PopIndent;
    Procedure StartList(aType : TListType);
    Procedure StopList(aType : TListType);
    Procedure BeginIgnore;
    Procedure EndIgnore;
    Procedure DoLineBreak;
    Function InList : Boolean;
    Function CurrentList : TListType;
    Property ContentPrefix : String Read FContentPrefix Write FContentPrefix;
  Public
    Constructor Create(APackage: TPasPackage; AEngine: TFPDocEngine); override;
    destructor Destroy;  override;
    Procedure AppendHeader(aLevel : THeaderLevel; const AHeader : String; DoEscape : Boolean = true);
    Procedure Indent;
    Procedure Undent;
    Procedure ClearMarkDown;
    Procedure EnsureEmptyLine;
    procedure SaveToFile(aFileName : string);
    procedure AddMetaData(Const aName,aValue : string);
    Property CurrentLine : UTF8String Read FCurrentLine Write FCurrentLine;
    Property MarkDown : TStrings Read FMarkDown;
    Property CurrentIndent : Word Read GetCurrentIndent;
    Property Prefix : String Read FPrefix;
    Property IndentSize : Byte Read FIndentSize Write SetIndentSize;
    Property UnderLineRendering : TRender Read FUnderLineRendering Write FUnderLineRendering;
    Property FileRendering : TRender Read FFileRendering Write FFileRendering;
    Property VarRendering : TRender Read FVarRendering Write FVarRendering;
    Property KeywordRendering : TRender Read FKeywordRendering Write FKeyWordRendering;
    Property SymbolRendering : TRender Read FSymbolRendering Write FSymbolRendering;
    Property DefinitionSeparator : String Read FDefinitionSeparator Write FDefinitionSeparator;
    Property DefinitionTermRender : TRender Read FDefinitionTermRender Write FDefinitionTermRender;
    Property BaseImageURL : String Read FBaseImageURL Write FBaseIMageURL;
    Property MetaData : TStrings Read FMetaData;
    Property MarkDownEngine : TMarkdownEngine Read FMarkDownEngine Write FMarkDownEngine;
    Property Theme : String Read FTheme Write FTheme;
  end;



implementation

resourcestring
  SErrCannotChangeIndentSizeWhenIndented = 'Cannot change indent size while text is indented.';
  SErrIndentMismatch = 'Indent mismatch: trying to undent when current indent too small';
  SErrNotInList = 'Not in list';
  SErrPopListStack = 'Pop list stack list type mismatch';
  SErrMinListStack = 'Min list stack reached';
  SErrMaxListStack = 'Max list stack reached';
  SErrMinIndentStack = 'Min indent stack reached';
  SErrMaxIndentStack = 'Max indent stack reached';

procedure TBaseMarkdownWriter.SetIndentSize(AValue: Byte);
begin
  if FIndentSize=AValue then Exit;
  if CurrentIndent>0 then
    FPDocError(SErrCannotChangeIndentSizeWhenIndented);
  FIndentSize:=AValue;
end;

function TBaseMarkdownWriter.GetCurrentIndent: Word;
begin
  Result:=FIndents[FCurrentIndentIndex];
end;

procedure TBaseMarkdownWriter.clearIndent;
begin
  FIndents[FCurrentIndentIndex]:=0;
  CalcPrefix;
end;

procedure TBaseMarkdownWriter.CalcPrefix;

begin
  FPrefix:=StringOfChar(' ',CurrentIndent);
end;

function TBaseMarkdownWriter.CreateAllocator: TFileAllocator;
begin
  Result:=TLongNameFileAllocator.Create('.md');
end;

procedure TBaseMarkdownWriter.DescrEmitNotesHeader(AContext: TPasElement);
begin
  AppendHeader(2, SDocNotes);
end;

procedure TBaseMarkdownWriter.DescrEmitNotesFooter(AContext: TPasElement);
begin
  EnsureEmptyLine;
end;

function TBaseMarkdownWriter.EscapeMarkDown(aText: Domstring): string;

begin
  Result:=EscapeMarkDown(UTF8Encode(aText))
end;

function TBaseMarkdownWriter.EscapeMarkDown(aText: String): string;
begin
  Result:=StringReplace(aText,'*','\*',[rfReplaceAll]);
  Result:=StringReplace(Result,'_','\_',[rfReplaceAll]);
  Result:=StringReplace(Result,'`','\`',[rfReplaceAll]);
end;

function TBaseMarkdownWriter.CreateLink(const aText, aLink: String): String;
begin
  Result:=Format('[%s](%s)',[EscapeMarkDown(aText),aLink])
end;

procedure TBaseMarkdownWriter.AppendToLine(aText: DomString; DoEscape: boolean);

begin
  If FIgnoreCount>0 then
    exit;
  AppendToLine(UTF8Encode(aText),DoEscape);
end;

procedure TBaseMarkdownWriter.AppendToLine(aText: UTF8String; DoEscape: boolean
  );
begin
  if DoEscape then
     aText:=EscapeMarkDown(aText);
  if (FCurrentLine='') and (FContentPrefix<>'') then
     FCurrentLine:=FContentPrefix;
  FCurrentLine:=FCurrentLine+aText;
end;

procedure TBaseMarkdownWriter.AppendToLine(aFmt: UTF8String;
  aArgs: array of const; DoEscape: boolean);
begin
  AppendToLine(Format(aFmt,aArgs),DoEscape);
end;

procedure TBaseMarkdownWriter.EmitLine(aText: UTF8String; DoEscape: boolean);
begin
  OutputCurrentLine;
  AppendToLine(aText,DoEscape);
  OutputCurrentLine;
end;

procedure TBaseMarkdownWriter.EmitLine(aFmt: UTF8String; aArgs: array of const;
  DoEscape: boolean);
begin
  EmitLine(Format(aFmt,aArgs),DoEscape);
end;

procedure TBaseMarkdownWriter.AppendLink(const aText, aLink: String);
begin
  AppendToLine(CreateLink(aText,aLink),False);
end;

procedure TBaseMarkdownWriter.AppendRendered(aText: String; aRender: TRender);
begin
  StartSpan(aRender);
  AppendToLine(aText);
  EndSpan(aRender);
end;

procedure TBaseMarkdownWriter.AppendKeyWord(aText: String);
begin
  AppendRendered(aText,KeywordRendering);
end;

procedure TBaseMarkdownWriter.AppendSymbol(aText: String);
begin
  AppendRendered(aText,SymbolRendering);
end;

procedure TBaseMarkdownWriter.AppendTableHeader(aHeaders: array of String);

Var
  S : String;

begin
  DescrBeginTable(Length(aHeaders),False);
  DescrBeginTableHeadRow;
  for S in aHeaders do
    begin
    DescrBeginTableCell;
    AppendToLine(S);
    DescrEndTableCell;
    end;
  DescrEndTableHeadRow;
end;


procedure TBaseMarkdownWriter.EmitCode(aCodeBlock: String; aIndent : Integer = 0);

Var
  L : TStringList;

begin
  L:=TStringList.Create;
  try
    L.Text:=aCodeBlock;
    EmitCode(L,aIndent);
  finally
    L.Free;
  end;
end;

procedure TBaseMarkdownWriter.EmitCode(aCodeBlock: TStrings; aIndent : Integer = 0);
var
  S,aPrefix : string;
begin
  aPrefix:=StringOfChar(' ',aIndent);
  For S in aCodeBlock do
    EmitCodeLine(aPrefix+S);
end;

procedure TBaseMarkdownWriter.EmitCodeLine(aCodeLine: string);
begin
  EmitLine(aCodeLine,False);
end;

procedure TBaseMarkdownWriter.DescrWriteText(const AText: DOMString);
begin
  AppendToLine(aText);
end;

procedure TBaseMarkdownWriter.DescrBeginBold;
begin
  AppendToLine('**',False);
end;

procedure TBaseMarkdownWriter.DescrEndBold;
begin
  AppendToLine('**',False);
end;

procedure TBaseMarkdownWriter.DescrBeginItalic;
begin
  AppendToLine('*',False);
end;

procedure TBaseMarkdownWriter.DescrEndItalic;
begin
  AppendToLine('*',False);
end;

procedure TBaseMarkdownWriter.DescrBeginEmph;
begin
  AppendToLine('*',False);
end;

procedure TBaseMarkdownWriter.DescrEndEmph;
begin
  AppendToLine('*',False);
end;

procedure TBaseMarkdownWriter.StartSpan(aRender : TRender);

begin
  case aRender of
    rStrong : AppendToLine('**',False);
    rEmphasis : AppendToLine('*',False);
    rCode : AppendToLine('`',False);
  end;
end;

procedure TBaseMarkdownWriter.PushIndent(aNewIndent: Byte);
begin
  if FCurrentIndentIndex>=MaxIndents then
     FPDocError(SErrMaxIndentStack);
  Inc(FCurrentIndentIndex);
  Findents[FCurrentIndentIndex]:=aNewIndent;
  CalcPrefix;
end;

procedure TBaseMarkdownWriter.PopIndent;
begin
  if FCurrentIndentIndex<=0 then
     FPDocError(SErrMinIndentStack);
  Dec(FCurrentIndentIndex);
end;

procedure TBaseMarkdownWriter.StartList(aType: TListType);
begin
  If FListStack>=MaxLists then
    FPDocError(SErrMaxListStack);
  Inc(FListStack);
  FListTypes[FListStack]:=aType;
end;

procedure TBaseMarkdownWriter.StopList(aType: TListType);
begin
  If FListStack<=0 then
    FPDocError(SErrMinListStack);
  if FListTypes[FListStack]<>aType then
    FPDocError(SErrPopListStack);
  Dec(FListStack);
end;

procedure TBaseMarkdownWriter.BeginIgnore;
begin
  Inc(FIgnoreCount);
end;

procedure TBaseMarkdownWriter.EndIgnore;
begin
  If FignoreCount>0 then
    Dec(FIgnoreCount);
end;

procedure TBaseMarkdownWriter.DoLineBreak;
begin
  if FCurrentLine<>'' then
    begin
    FCurrentLine:=FCurrentLine+'  ';
    OutputCurrentLine;
    end;
end;

function TBaseMarkdownWriter.InList: Boolean;
begin
  Result:=FlistStack>0;
end;

function TBaseMarkdownWriter.CurrentList: TListType;
begin
  if FListStack=0 then
    FPDOcError(SErrNotInList);
end;

procedure TBaseMarkdownWriter.EndSpan(aRender : TRender);

begin
  case aRender of
    rStrong : AppendToLine('**',False);
    rEmphasis : AppendToLine('*',False);
    rCode : AppendToLine('`',False);
  end;
end;

procedure TBaseMarkdownWriter.DescrBeginUnderline;
begin
  StartSpan(UnderlineRendering);
end;

procedure TBaseMarkdownWriter.DescrEndUnderline;
begin
  EndSpan(UnderlineRendering);
end;

procedure TBaseMarkdownWriter.DescrWriteImageEl(const AFileName, ACaption, ALinkName : DOMString);

Var
  D,FN : String;
  L : integer;
begin
  // Determine URL for image.
  If (Module=Nil) then
    D:=Allocator.GetRelativePathToTop(Package)
  else
    D:=Allocator.GetRelativePathToTop(Module);
  L:=Length(D);
  If (L>0) and (D[L]<>'/') then
    D:=D+'/';

  FN:=UTF8Decode(D + BaseImageURL) + AFileName;
  EnsureEmptyLine;
  AppendToLine('!['+aCaption+']('+FN+')',False);
end;

procedure TBaseMarkdownWriter.DescrWriteFileEl(const AText: DOMString);

begin
  AppendRendered(aText,FileRendering);
end;

procedure TBaseMarkdownWriter.DescrWriteKeywordEl(const AText: DOMString);
begin
  AppendKeyWord(UTF8ENcode(aText));
end;

procedure TBaseMarkdownWriter.DescrWriteVarEl(const AText: DOMString);
begin
  AppendRendered(aText,VarRendering);
end;

procedure TBaseMarkdownWriter.DescrBeginLink(const AId: DOMString);
var
  a,s,n : String;

begin
  a:=UTF8Encode(AId);
  s := UTF8Encode(ResolveLinkID(a));

  if Length(s) > 0 then
    begin
    FLink:=S;
    AppendToLine('[');
    end
  else
    begin
    FLink:='';
    if assigned(module) then
      s:=module.name
    else
      s:='?';
    if a='' then a:='<empty>';
    if Assigned(CurrentContext) then
      N:=CurrentContext.Name
    else
      N:='?';
    DoLog(SErrUnknownLinkID, [s,n,a]);
    end
end;

procedure TBaseMarkdownWriter.DescrEndLink;
begin
  AppendToLine(']('+FLink+') ',false);
  FLink:='';
end;

procedure TBaseMarkdownWriter.DescrBeginURL(const AURL: DOMString);
begin
  FLink:=aURL;
  AppendToLine('[');
end;

procedure TBaseMarkdownWriter.DescrEndURL;
begin
  AppendToLine(']('+FLink+') ',false);
  FLink:='';
end;

procedure TBaseMarkdownWriter.DescrWriteLinebreak;
begin
  AppendToLine('  ');
  OutputCurrentLine;
end;

procedure TBaseMarkdownWriter.DescrBeginParagraph;
begin
  EnsureEmptyLine;
end;

procedure TBaseMarkdownWriter.DescrEndParagraph;
begin
  EnsureEmptyLine;
end;

procedure TBaseMarkdownWriter.DescrBeginCode(HasBorder: Boolean; const AHighlighterName: String);

Var
  hl : string;

begin
  hl:=AHighlighterName;
  if SameText(hl,'Pascal') or (hl='') then
    hl:='delphi';
  OutputCurrentLine;
  AppendToLine('```'+hl,False);
  PushIndent(0);
end;

procedure TBaseMarkdownWriter.DescrWriteCodeLine(const ALine: String);
begin
  EmitCodeLine(aLine);
end;

procedure TBaseMarkdownWriter.DescrEndCode;
begin
  OutputCurrentLine;
  AppendToLine('```',False);
  OutputCurrentLine;
  PopIndent;
end;

procedure TBaseMarkdownWriter.DescrBeginOrderedList;
begin
  StartList(ltOrdered);
end;

procedure TBaseMarkdownWriter.DescrEndOrderedList;
begin
  StopList(ltOrdered);
end;

procedure TBaseMarkdownWriter.DescrBeginUnorderedList;
begin
  StartList(ltUnordered);
end;

procedure TBaseMarkdownWriter.DescrEndUnorderedList;
begin
  StopList(ltUnordered);
end;

procedure TBaseMarkdownWriter.DescrBeginDefinitionList;
begin
  StartList(ltDefinition);
end;

procedure TBaseMarkdownWriter.DescrEndDefinitionList;
begin
  StopList(ltDefinition);
end;

procedure TBaseMarkdownWriter.DescrBeginListItem;
begin
  Case CurrentList of
    ltOrdered   : AppendToLine('1. ');
    ltUnordered : AppendToLine('- ');
    ltDefinition :
      begin
      AppendToLine('- ');
      end;
  end;
end;


procedure TBaseMarkdownWriter.DescrEndListItem;
begin
  OutputCurrentLine;
end;

procedure TBaseMarkdownWriter.DescrBeginDefinitionTerm;
begin
  if MarkDownEngine=meMkDocs then
    EnsureEmptyLine
  else
    begin
    AppendToLine('- ');
    StartSpan(DefinitionTermRender);
    end;
end;

procedure TBaseMarkdownWriter.DescrEndDefinitionTerm;
begin
  if MarkDownEngine=meMkDocs then
    OutputCurrentLine
  else
    EndSpan(DefinitionTermRender);
end;

procedure TBaseMarkdownWriter.DescrBeginDefinitionEntry;
begin
  if MarkDownEngine=meMkDocs then
    begin
    AppendToLine(':    ');
    Indent;
    end
  else
    AppendToLine(DefinitionSeparator);
end;

procedure TBaseMarkdownWriter.DescrEndDefinitionEntry;
begin
  OutputCurrentLine;
  if MarkDownEngine=meMkDocs then
    begin
    Undent;
    EnsureEmptyLine;
    end;
end;

procedure TBaseMarkdownWriter.DescrBeginSectionTitle;
begin
  EnsureEmptyLine;
end;

procedure TBaseMarkdownWriter.DescrBeginSectionBody;
begin
  EnsureEmptyLine;
end;

procedure TBaseMarkdownWriter.DescrEndSection;
begin
  EnsureEmptyLine;
end;

procedure TBaseMarkdownWriter.DescrBeginRemark;
begin
  if MarkDownEngine=meMkDocs then
    begin
    EnsureEmptyLine;
    AppendToLine('!!! Remark',False);
    OutputCurrentLine;
    end
  else
    FContentPrefix:='> ';
end;

procedure TBaseMarkdownWriter.DescrEndRemark;
begin
  if MarkDownEngine=meMkDocs then
    begin
    OutputCurrentLine;
    AppendToLine('!!!',False);
    end;
  EnsureEmptyLine;
  FContentPrefix:='';
end;

procedure TBaseMarkdownWriter.DescrBeginTable(ColCount: Integer; HasBorder: Boolean);
begin
  EnsureEmptyLine;
  FTableColCount:=ColCount;
end;

procedure TBaseMarkdownWriter.DescrEndTable;
begin
  EnsureEmptyLine;
end;

procedure TBaseMarkdownWriter.DescrBeginTableCaption;
begin
  BeginIgnore;
end;

procedure TBaseMarkdownWriter.DescrEndTableCaption;
begin
  EndIgnore;
end;

procedure TBaseMarkdownWriter.DescrBeginTableHeadRow;

begin
end;

procedure TBaseMarkdownWriter.DescrEndTableHeadRow;

Var
  I : Integer;

begin
  AppendToLine(' |',False);
  OutputCurrentLine;
  AppendToLine('|',False);
  For I:=1 to FTableColCount do
    AppendToLine('---|',False);
  OutputCurrentLine;
end;

procedure TBaseMarkdownWriter.DescrBeginTableRow;
begin
end;

procedure TBaseMarkdownWriter.DescrEndTableRow;
begin
  AppendToLine(' |',False);
  OutputCurrentLine;
end;

procedure TBaseMarkdownWriter.DescrBeginTableCell;
begin
  AppendToLine('| ',False);
end;

procedure TBaseMarkdownWriter.DescrEndTableCell;
begin
  AppendToLine(' ',False);
end;

function TBaseMarkdownWriter.OutputCurrentLine: Boolean;
begin
  If FIgnoreCount>0 then
    exit(False);
  Result:=FCurrentLine<>'';
  if Result then
    begin
    FMarkDown.Add(Prefix+FCurrentLine);
    FCurrentLine:='';
    end;
end;

constructor TBaseMarkdownWriter.Create(APackage: TPasPackage;
  AEngine: TFPDocEngine);
begin
  inherited Create(APackage, AEngine);
  FMarkDown:=TStringList.Create;
  FMetaData:=TStringList.Create;
  FMetaData.NameValueSeparator:=':';
  FIndents[FCurrentIndentIndex]:=0;
  CalcPrefix;
  Theme:='readthedocs';
end;

destructor TBaseMarkdownWriter.Destroy;
begin
  FreeAndNil(FMarkDown);
  inherited Destroy;
end;

procedure TBaseMarkdownWriter.AppendHeader(aLevel: THeaderLevel;
  const AHeader: String; DoEscape : Boolean = true);
begin
  EnsureEmptyLine;
  AppendToLine(StringOfChar('#',aLevel)+' ',False);
  AppendToLine(aHeader,DoEscape);
end;

procedure TBaseMarkdownWriter.Indent;
begin
  Inc(FIndents[FCurrentIndentIndex],IndentSize);
  CalcPrefix;
end;

procedure TBaseMarkdownWriter.Undent;
begin
  if IndentSize>CurrentIndent then
    FPDocError(SErrIndentMismatch);
  Dec(FIndents[FCurrentIndentIndex],IndentSize);
  CalcPrefix;
end;

procedure TBaseMarkdownWriter.ClearMarkDown;
begin
  FMarkDown.Clear;
  FMetaData.Clear;
  FCurrentLine:='';
  FContentPrefix:='';
  FCurrentIndentIndex:=0;;
  FIndents[FCurrentIndentIndex]:=0;
  CalcPrefix;
end;


procedure TBaseMarkdownWriter.EnsureEmptyLine;
begin
  if OutputCurrentLine then
    FMarkDown.Add('')
  else if (FmarkDown.Count>0) and (FMarkDown[FmarkDown.Count-1]<>'') then
    FMarkDown.Add('');
 end;

procedure TBaseMarkdownWriter.SaveToFile(aFileName: string);

Var
  Doc: TStrings;
  I : Integer;
  N,V : String;

begin
  Doc:=TStringList.Create;
  try
    if FMetadata.Count>0 then
      begin
      Doc.Add('---');
      For I:=0 to FMetadata.Count-1 do
        begin
        FMetaData.GetNameValue(I,N,V);
        Doc.Add(Lowercase(N)+': "'+V+'"');
        end;
      Doc.Add('---');
      end;
    Doc.AddStrings(FMarkDown);
    Doc.SaveToFile(aFileName);
  finally
    Doc.Free;
  end;
end;

procedure TBaseMarkdownWriter.AddMetaData(const aName, aValue: string);
begin
  FMetadata.Values[aName]:=aValue;
end;

end.