{
    $Id$
    This file is part of the Free Component Library

    HTML writing routines
    Copyright (c) 2000 by
      Areca Systems GmbH / Sebastian Guenther, sg@freepascal.org

    See the file COPYING.FPC, included in this distribution,
    for details about the copyright.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 **********************************************************************}


unit HTMWrite;

{$MODE objfpc}
{$H+}

interface

uses Classes, DOM;

procedure WriteHTMLFile(doc: TXMLDocument; const AFileName: String);
procedure WriteHTMLFile(doc: TXMLDocument; var AFile: Text);
procedure WriteHTMLFile(doc: TXMLDocument; var AStream: TStream);

procedure WriteHTML(Element: TDOMElement; const AFileName: String);
procedure WriteHTML(Element: TDOMElement; var AFile: Text);
procedure WriteHTML(Element: TDOMElement; var AStream: TStream);


// ===================================================================

implementation

uses SysUtils;

// -------------------------------------------------------------------
//   Writers for the different node types
// -------------------------------------------------------------------

procedure WriteElement(node: TDOMNode); forward;
procedure WriteAttribute(node: TDOMNode); forward;
procedure WriteText(node: TDOMNode); forward;
procedure WriteCDATA(node: TDOMNode); forward;
procedure WriteEntityRef(node: TDOMNode); forward;
procedure WriteEntity(node: TDOMNode); forward;
procedure WritePI(node: TDOMNode); forward;
procedure WriteComment(node: TDOMNode); forward;
procedure WriteDocument(node: TDOMNode); forward;
procedure WriteDocumentType(node: TDOMNode); forward;
procedure WriteDocumentFragment(node: TDOMNode); forward;
procedure WriteNotation(node: TDOMNode); forward;


type
  TWriteNodeProc = procedure(node: TDOMNode);

const
  WriteProcs: array[ELEMENT_NODE..NOTATION_NODE] of TWriteNodeProc =
    (WriteElement, WriteAttribute, WriteText, WriteCDATA, WriteEntityRef,
     WriteEntity, WritePI, WriteComment, WriteDocument, WriteDocumentType,
     WriteDocumentFragment, WriteNotation);

procedure WriteNode(node: TDOMNode);
begin
  WriteProcs[node.NodeType](node);
end;


// -------------------------------------------------------------------
//   Text file and TStream support
// -------------------------------------------------------------------

type
  TOutputProc = procedure(s: String);

var
  f: ^Text;
  stream: TStream;
  wrt, wrtln: TOutputProc;
  InsideTextNode: Boolean;


procedure Text_Write(s: String);
begin
  Write(f^, s);
end;

procedure Text_WriteLn(s: String);
begin
  WriteLn(f^, s);
end;

procedure Stream_Write(s: String);
begin
  if Length(s) > 0 then
    stream.Write(s[1], Length(s));
end;

procedure Stream_WriteLn(s: String);
begin
  if Length(s) > 0 then
    stream.Write(s[1], Length(s));
  stream.WriteByte(10);
end;


// -------------------------------------------------------------------
//   String conversion
// -------------------------------------------------------------------

type
  TCharacters = set of Char;
  TSpecialCharCallback = procedure(c: Char);

const
  AttrSpecialChars = ['"', '&'];
  TextSpecialChars = ['<', '>', '&'];


procedure ConvWrite(const s: String; const SpecialChars: TCharacters;
  const SpecialCharCallback: TSpecialCharCallback);
var
  StartPos, EndPos: Integer;
begin
  StartPos := 1;
  EndPos := 1;
  while EndPos <= Length(s) do
  begin
    if s[EndPos] in SpecialChars then
    begin
      wrt(Copy(s, StartPos, EndPos - StartPos));
      SpecialCharCallback(s[EndPos]);
      StartPos := EndPos + 1;
    end;
    Inc(EndPos);
  end;
  if EndPos > StartPos then
    wrt(Copy(s, StartPos, EndPos - StartPos));
end;

procedure AttrSpecialCharCallback(c: Char);
begin
  if c = '"' then
    wrt('&quot;')
  else if c = '&' then
    wrt('&amp;')
  else
    wrt(c);
end;

procedure TextnodeSpecialCharCallback(c: Char);
begin
  if c = '<' then
    wrt('&lt;')
  else if c = '>' then
    wrt('&gt;')
  else if c = '&' then
    wrt('&amp;')
  else
    wrt(c);
end;

function IsTextNode(Node: TDOMNode): Boolean;
begin
  Result := Node.NodeType in [TEXT_NODE, ENTITY_REFERENCE_NODE];
end;


// -------------------------------------------------------------------
//   Node writers implementations
// -------------------------------------------------------------------

procedure WriteElement(node: TDOMNode);
var
  i: Integer;
  attr, child: TDOMNode;
  SavedInsideTextNode: Boolean;
  s: String;
begin
  wrt('<' + node.NodeName);
  for i := 0 to node.Attributes.Length - 1 do
  begin
    attr := node.Attributes.Item[i];
    wrt(' ' + attr.NodeName + '=');
    s := attr.NodeValue;
    // !!!: Replace special characters in "s" such as '&', '<', '>'
    wrt('"');
    ConvWrite(s, AttrSpecialChars, @AttrSpecialCharCallback);
    wrt('"');
  end;
  Child := node.FirstChild;
  if Child = nil then
    if InsideTextNode then
      wrt(' />')
    else
      wrtln(' />')
  else
  begin
    SavedInsideTextNode := InsideTextNode;
    if InsideTextNode or IsTextNode(Child) then
      wrt('>')
    else
      wrtln('>');
    repeat
      if IsTextNode(Child) then
        InsideTextNode := True;
      WriteNode(Child);
      Child := Child.NextSibling;
    until child = nil;
    InsideTextNode := SavedInsideTextNode;
    s := '</' + node.NodeName + '>';
    if InsideTextNode then
      wrt(s)
    else
      wrtln(s);
  end;
end;

procedure WriteAttribute(node: TDOMNode);
begin
  WriteLn('WriteAttribute');
end;

procedure WriteText(node: TDOMNode);
begin
  ConvWrite(node.NodeValue, TextSpecialChars, @TextnodeSpecialCharCallback);
end;

procedure WriteCDATA(node: TDOMNode);
begin
  if InsideTextNode then
    wrt('<![CDATA[' + node.NodeValue + ']]>')
  else
    wrtln('<![CDATA[' + node.NodeValue + ']]>')
end;

procedure WriteEntityRef(node: TDOMNode);
begin
  wrt('&' + node.NodeName + ';');
end;

procedure WriteEntity(node: TDOMNode);
begin
  WriteLn('WriteEntity');
end;

procedure WritePI(node: TDOMNode);
var
  s: String;
begin
  s := '<!' + TDOMProcessingInstruction(node).Target + ' ' +
    TDOMProcessingInstruction(node).Data + '>';
  if InsideTextNode then
    wrt(s)
  else
    wrtln( s);
end;

procedure WriteComment(node: TDOMNode);
begin
  if InsideTextNode then
    wrt('<!--' + node.NodeValue + '-->')
  else
    wrtln('<!--' + node.NodeValue + '-->')
end;

procedure WriteDocument(node: TDOMNode);
begin
  WriteLn('WriteDocument');
end;

procedure WriteDocumentType(node: TDOMNode);
begin
  WriteLn('WriteDocumentType');
end;

procedure WriteDocumentFragment(node: TDOMNode);
begin
  WriteLn('WriteDocumentFragment');
end;

procedure WriteNotation(node: TDOMNode);
begin
  WriteLn('WriteNotation');
end;


procedure InitWriter;
begin
  InsideTextNode := False;
end;

procedure RootWriter(doc: TXMLDocument);
var
  Child: TDOMNode;
begin
  InitWriter;
  child := doc.FirstChild;
  while Assigned(Child) do
  begin
    WriteNode(Child);
    Child := Child.NextSibling;
  end;
end;


// -------------------------------------------------------------------
//   Interface implementation
// -------------------------------------------------------------------

procedure WriteHTMLFile(doc: TXMLDocument; const AFileName: String);
begin
  Stream := TFileStream.Create(AFileName, fmCreate);
  wrt := @Stream_Write;
  wrtln := @Stream_WriteLn;
  RootWriter(doc);
  Stream.Free;
end;

procedure WriteHTMLFile(doc: TXMLDocument; var AFile: Text);
begin
  f := @AFile;
  wrt := @Text_Write;
  wrtln := @Text_WriteLn;
  RootWriter(doc);
end;

procedure WriteHTMLFile(doc: TXMLDocument; var AStream: TStream);
begin
  Stream := AStream;
  wrt := @Stream_Write;
  wrtln := @Stream_WriteLn;
  RootWriter(doc);
end;


procedure WriteHTML(Element: TDOMElement; const AFileName: String);
begin
  Stream := TFileStream.Create(AFileName, fmCreate);
  wrt := @Stream_Write;
  wrtln := @Stream_WriteLn;
  InitWriter;
  WriteNode(Element);
  Stream.Free;
end;

procedure WriteHTML(Element: TDOMElement; var AFile: Text);
begin
  f := @AFile;
  wrt := @Text_Write;
  wrtln := @Text_WriteLn;
  InitWriter;
  WriteNode(Element);
end;

procedure WriteHTML(Element: TDOMElement; var AStream: TStream);
begin
  stream := AStream;
  wrt := @Stream_Write;
  wrtln := @Stream_WriteLn;
  InitWriter;
  WriteNode(Element);
end;


end.


{
  $Log$
  Revision 1.2  2000-10-15 15:31:26  sg
  * Improved whitespace handling (entity references as first child of an
    element is now handled as indicator to stop the insertion of automatic
    linefeeds. Until now this was only the case with text nodes.)

  Revision 1.1  2000/10/03 20:33:22  sg
  * Added new Units "htmwrite" and "xhtml"

}