Experimental BBS Explossion 3/Experimental BBS Explossion III.iso/pascal/scanh313.zip/HELPFILE.PAS

Pascal/Delphi Source File | 1993-07-27 | 12KB | 438 lines

unit HelpFiles;

  { Unit to define abstract help file object.  Included in SCANH3xx.ZIP
    as sample of comment formatting and TeX output. }

  {#M}
  { This comment will be highlighted as example text in most output formats.
    The sample below won't be word-wrapped. }
  {#F}
  {  program HelloWorld;  }
  {  begin                }
  {    writeln('Hello, world!'); }
  {  end.                 }
  {#F}
  {#M}

interface

uses OPString, Objects, Sorts, TokenUnit;

type
  PTopic = ^TTopic;
  TTopic
  = object(TObject)
      { An object holding a single topic as part of a #THelpFile#. }

      Text : PStream;
      { A stream to which the text of the topic is written. }

      TopicNum : Word; { The topic number in the help file. }
      StartofLine : Boolean; { Whether the text is currently at the
                             start of a line. }
      FixedLines : Boolean;  { Whether lines should be fixed or wrapped }
      Marked : Boolean;      { Whether text is currently being marked }
      Highlighting : byte;   { Counts the current highlight level }

      constructor Init(Atopicnum : Word);
        { Initialize an empty topic with the given value for #TopicNum#. }

      destructor Done; virtual;
        { Dispose of #Text# and destroy object. }

      function GetLine(var Buffer; MaxLen : Word) : Word; virtual;
        { Gets the next line of text, return the length }

      function MoreLines : Boolean; virtual;
        { True if there are more lines of text. }

      procedure Write(s : String); virtual;
        { Writes the string to the help text }

      procedure WriteLn(const s : String); virtual;
        { Writes, then adds a newline }

      procedure WriteKeyWord(const s : String; Crossref : Word); virtual;
        { Writes the string with a marker that it's a cross-reference }

      procedure HighLight(On : Boolean); virtual;
    { Turns highlighting of the text on or off.  If turned on twice, it will need
      to be turned off twice to return to standard. }

      procedure ResetHighLight; virtual;
    { Turns highlighting off regardless of the initial state. }

      procedure BlankLine; virtual;
    { Writes a blank line to the help topic, starting a new paragraph
      afterwards. }

      procedure StartXrefList(const s : String); virtual;
    { Starts a list of cross-referenced topics. End the list with
      #EndXrefList#. }

      procedure WriteXref(const s : String; Len, Crossref : Word); virtual;
    { Like #WriteKeyWord#, but writes an entry to a cross-ref list. Len
      is the length in characters of the longest Xref to come; this may
      be used to format nicely. Assumes that #StartXrefList# has been called. }

      procedure EndXrefList; virtual;
    { Ends a list of cross-referenced topics started by #StartXrefList#. }

      procedure ToggleFixed; virtual;
    { Toggles word-wrap mode.  Generally, help files start out word-wrapping;
      this should turn it off.  The TTopic method just toggles #FixedLines#. }

      procedure ToggleMarked; virtual;
    { Toggles word marking mode.  Typically marked text would be used for
      code samples, as in the Borland help files.  This one just toggles
      #Marked#. }
    end;

  PIndexItem = ^TIndexItem;
  TIndexItem
  = record
      { This is an item stored in the index for a help file. }

      Context : Word;
      { The context or topic number. }

      Subtitle,
      { The token number of the subtitle string. }
      Token : TToken;
      { The token number of the name of index entry. }
    end;

  PIndex = ^TIndex;
  TIndex
  = object(TSortableCollection)
      { This is an index for a help file, meant to hold #TIndexItem# records. }

      Sortby : (ByToken, BySubTitle, ByContext);
      { Marks which sort order should be used. }

      procedure FreeItem(Item : Pointer); virtual;
        { Disposes of a TIndexItem }

      function Compare(Item1, Item2 : Pointer) : Integer; virtual;
        { Compares two index items according to the #Sortby# field. }

      procedure Insert(Item : Pointer); virtual;
        { This inserts duplicates after existing values. }

      procedure AddItem(const ATitle, ASubtitle : String; Atopicnum : Word);
        { Add a new index entry by specifying the strings to use. }

      procedure AddTokens(ATitle, ASubtitle : TToken; Atopicnum : Word);
        { Add a new index entry by specifying the token numbers. }
    end;

  PHelpFile = ^THelpFile;
  THelpFile
  = object(TObject)
  { This is the main abstract object representing a help file.  It serves
    as a container for #THelpTopic#s. }

      Index : PIndex;
      { This is a #TIndex# maintained by the help file. }

      constructor Init;
        { Construct an empty help file, and initialize #Index# to nil. }

      destructor Done; virtual;
        { Destroy the object and dispose of the #Index#. }

      function NumTopics : Word; virtual;
        { Return the number of topics in this file. }

      function GetTitle(TopicNum : Word) : String; virtual;
        { Constructs a topic title for the given topic number. }

      function GetSubTitle(TopicNum : Word) : String; virtual;
        { Constructs a topic subtitle. }

      function GetTopic(Context : Word) : PTopic; virtual;
        { Extracts the given topic from the help file. }

      function NewTopic(Context : Word; Someinfo : Pointer) : PTopic; virtual;
    { Constructs a new topic of the appropriate type. Someinfo might
      be used by a descendant type. }

      procedure AddTopic(ATopic : PTopic); virtual;
    { Writes the topic at the end of the base file, and records it with the
      appropriate topic number.  If a topic with that number existed previously,
      it'll effectively be deleted.
      Atopic is disposed after adding it.}

      procedure DisplayTopic(var Where : Text; TopicNum : Word); virtual;
        { Displays the given topic number. }

      procedure SetMainTopic(TopicNum : Word); virtual;
        { Defines which Topic is the main contents topic. }

      procedure Rewrite(s : PStream); virtual;
        { Rewrites the help file to the given stream.  }
    end;

implementation

  constructor TTopic.Init(Atopicnum : Word);
  begin
    inherited Init;
    TopicNum := Atopicnum;
    StartofLine := True;
  end;

  destructor TTopic.Done;
  begin
    if Text <> nil then
      Dispose(Text, Done);
    inherited Done;
  end;

  function TTopic.GetLine(var Buffer; MaxLen : Word) : Word;
    { Gets the next line of text, return the length }
  begin
    Abstract;
  end;

  function TTopic.MoreLines : Boolean;
    { True if there are more lines of text. }
  begin
    Abstract;
  end;

  procedure TTopic.Write(s : String);
    { Writes the string to the help text }
  begin
    if Length(s) > 0 then
    begin
      Text^.Write(s[1], Length(s));
      StartofLine := False;
    end;
  end;

  procedure TTopic.WriteLn(const s : String);
    { Writes, then adds a newline }
  const
    CRLF : array[1..2] of Char = ^M^J;
  begin
    Write(s);
    Text^.Write(CRLF, 2);
    StartofLine := True;
  end;

  procedure TTopic.WriteKeyWord(const s : String; Crossref : Word);
    { Writes the string with a marker that it's a cross-reference }
  begin
    Abstract;
  end;

  procedure TTopic.HighLight(On : Boolean);
  begin
    if On then
      inc(highlighting)
    else
      dec(highlighting);
  end;

  procedure TTopic.ResetHighLight;
  begin
    while highlighting > 0 do
      HighLight(false);
    while highlighting < 0 do
      HighLight(true);
  end;

  procedure TTopic.BlankLine;
  begin
    if not StartofLine then
      WriteLn('');
    WriteLn('');
  end;

  procedure TTopic.StartXrefList(const s : String);
  begin
    BlankLine;
    WriteLn(s);
    BlankLine;
  end;

  procedure TTopic.WriteXref(const s : String; Len, Crossref : Word);
  begin
    WriteKeyWord(s, Crossref);
    WriteLn(Pad('', Len+1-Length(s)));
  end;

  procedure TTopic.EndXrefList;
  begin
  end;

  procedure TTopic.ToggleFixed;
  begin
    FixedLines := not FixedLines;
  end;

  procedure TTopic.ToggleMarked;
  begin
    Marked := not Marked;
  end;

  procedure TIndex.FreeItem(Item : Pointer);
  begin
    Dispose(PIndexItem(Item));
  end;

  function TIndex.Compare(Item1, Item2 : Pointer) : Integer;
  var
    i1 : PIndexItem absolute Item1;
    i2 : PIndexItem absolute Item2;
    s1, s2 : String;
  begin
    case Sortby of
      ByContext :
        begin
          s1 := HexW(i1^.Context);
          s2 := HexW(i2^.Context);
        end;
      ByToken :
        begin
          s1 := Tokens.Num2Pstr(i1^.Token)^+#0+HexW(i1^.Context);
          s2 := Tokens.Num2Pstr(i2^.Token)^+#0+HexW(i2^.Context);
        end;
      BySubTitle : { Sort by context number within subtitle }
        begin
          s1 := Tokens.Num2Pstr(i1^.Subtitle)^+#0+HexW(i1^.Context);
          s2 := Tokens.Num2Pstr(i2^.Subtitle)^+#0+HexW(i2^.Context);
        end;
    end;
    Compare := Ord(CompUCString(s1, s2))-1;
  end;

  procedure TIndex.Insert(Item : Pointer);
  var
    i : Integer;
    Key : Pointer;
  begin
    Key := KeyOf(Item);
    if Search(Key, i) then
    repeat
      Inc(i);
    until (i >= Count) or (Compare(Key, KeyOf(At(i))) <> 0);
    AtInsert(i, Item);
  end;

  procedure TIndex.AddItem(const ATitle, ASubtitle : String; Atopicnum : Word);
  begin
    if ASubtitle <> '' then
      AddTokens(Tokens.Str2Num(ATitle), Tokens.Str2Num(ASubtitle),
        Atopicnum)
    else
      AddTokens(Tokens.Str2Num(ATitle), NoToken, Atopicnum)
  end;

  procedure TIndex.AddTokens(ATitle, ASubtitle : TToken; Atopicnum : Word);
  var
    Item : PIndexItem;
  begin
    New(Item);
    if Item <> nil then
    begin
      with Item^ do
      begin
        Token := ATitle;
        Context := Atopicnum;
        Subtitle := ASubtitle;
      end;
      Insert(Item);
    end;
  end;

  constructor THelpFile.Init;
  begin
    inherited Init;
    Index := nil;
  end;

  destructor THelpFile.Done;
  begin
    if Index <> nil then
      Dispose(Index, Done);
    inherited Done;
  end;

  function THelpFile.NumTopics : Word;
  begin
    Abstract;
  end;

  function THelpFile.GetTitle(TopicNum : Word) : String;
    { Constructs a topic title }
  var
    i : Word;
  begin
    for i := 0 to Pred(Index^.Count) do
      with PIndexItem(Index^.At(i))^ do
        if TopicNum = Context then
        begin
          GetTitle := Tokens.Num2Pstr(Token)^;
          Exit;
        end;
    GetTitle := '';
  end;

  function THelpFile.GetSubTitle(TopicNum : Word) : String;
    { Constructs a topic subtitle }
  var
    i : Word;
  begin
    for i := 0 to Pred(Index^.Count) do
      with PIndexItem(Index^.At(i))^ do
        if TopicNum = Context then
        begin
          GetSubTitle := Tokens.Num2Pstr(Subtitle)^;
          Exit;
        end;
    GetSubTitle := '';
  end;

  function THelpFile.GetTopic(Context : Word) : PTopic;
  begin
    Abstract;
  end;

  function THelpFile.NewTopic(Context : Word; Someinfo : Pointer) : PTopic;
  begin
    Abstract;
  end;

  procedure THelpFile.AddTopic(ATopic : PTopic);
  begin
    with ATopic^ do
    begin
      if highlighting <> 0 then
        ResetHighlight;
      if FixedLines then
        ToggleFixed;
      if Marked then
        ToggleMarked;
    end;
  end;

  procedure THelpFile.DisplayTopic(var Where : Text; TopicNum : Word);
    { Displays the given topic number }
  begin
    Abstract;
  end;

  procedure THelpFile.SetMainTopic(TopicNum : Word);
  begin
    Abstract;
  end;

  procedure THelpFile.Rewrite(s : PStream);
  begin
    Abstract;
  end;

end.