fpc/fcl/xml/xmlwrite.pp

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

    XML writing routines
    Copyright (c) 1999-2000 by Sebastian Guenther

    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 XMLWrite;

{$MODE objfpc}
{$H+}

interface

uses Classes, DOM;

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

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


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

implementation

// -------------------------------------------------------------------
//   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;


// -------------------------------------------------------------------
//   Indent handling
// -------------------------------------------------------------------

var
  Indent: String;


procedure IncIndent;
begin
  Indent := Indent + '  ';
end;

procedure DecIndent;
begin
  if Length(Indent) >= 2 then
    SetLength(Indent, Length(Indent) - 2);
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
    wrt(c);
end;

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


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

procedure WriteElement(node: TDOMNode);
var
  i: Integer;
  attr, child: TDOMNode;
  SavedInsideTextNode: Boolean;
  s: String;
begin
  if not InsideTextNode then
    wrt(Indent);
  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 Child.InheritsFrom(TDOMText) then
      wrt('>')
    else
      wrtln('>');
    IncIndent;
    repeat
      if Child.InheritsFrom(TDOMText) then
        InsideTextNode := True;
      WriteNode(Child);
      Child := Child.NextSibling;
    until child = nil;
    DecIndent;
    if not InsideTextNode then
      wrt(Indent);
    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(Indent + '<![CDATA[' + node.NodeValue + ']]>')
end;

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

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

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

procedure WriteComment(node: TDOMNode);
begin
  if InsideTextNode then
    wrt('<!--' + node.NodeValue + '-->')
  else
    wrtln(Indent + '<!--' + 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;
  wrt('<?xml version="');
  if doc.XMLVersion <> '' then
    wrt(doc.XMLVersion)
  else
    wrt('1.0');
  wrt('"');
  if doc.Encoding <> '' then
    wrt(' encoding="' + doc.Encoding + '"');
  wrtln('?>');

  indent := '';

  child := doc.FirstChild;
  while Assigned(Child) do
  begin
    WriteNode(Child);
    Child := Child.NextSibling;
  end;
end;


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

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

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

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


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

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

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


end.


{
  $Log$
  Revision 1.8  2000-06-29 08:45:32  sg
  * Now produces _much_ better output...!

  Revision 1.7  2000/04/20 14:15:45  sg
  * Minor bugfixes
  * Started support for DOM level 2
}