Delphi Magazine Collection 2001/Delphi Magazine Collection 20001 (2001).iso/DISKS/Issue38/Parser/newparse.pas

Pascal/Delphi Source File | 1998-07-08 | 16.3 KB | 624 lines

{ *****************************************************
                 NewParse Unit

                  Paul Warren
         HomeGrown Software Development
       (c) 1997 Langley British Columbia.
                [phone]
         e-mail:  [e-mail]
    Home page: http://users.uniserve.com/~hg_soft
  ***************************************************** }

unit Newparse;
{ $DEFINE DEBUG}

interface

uses Classes, Consts, SysUtils, Dialogs;

type
  TParserClass = class of TCustomParser;

  TCustomParser = class
  private
    { private declarations }
    FStream: TStream;
    FOrigin: Longint;
    FBuffer: PChar;
    FBufPtr: PChar;
    FBufEnd: PChar;
    FSourcePtr: PChar;
    FSourceEnd: PChar;
    FTokenPtr: PChar;
    FStringPtr: PChar;
    FSourceLine: Integer;
    FSaveChar: Char;
    FToken: Char;
    procedure ReadBuffer;
    procedure SkipBlanks;
    {$IFDEF Win32}
    procedure Error(const Ident: string); virtual;
    {$ELSE}
    procedure Error(MessageID: Word); virtual;
    {$ENDIF}
    procedure ErrorStr(const Message: string);
  public
    { public declarations }
    constructor Create(Stream: TStream); virtual;
    destructor Destroy; override;
    function NextToken: Char; virtual;
    function TokenString: string; virtual;
    function SourcePos: Longint;
    property Token: Char read FToken;
    property SourceLine: integer read FSourceLine;
  end;

  TCSVParser = class(TCustomParser)
  private
    { private declarations }
  public
    { public declarations }
    function TokenString: string; override;
    function NextToken: char; override;
  end;
  TTextParser = class(TCustomParser)
  private
    { private declarations }
  public
    { public declarations }
    function NextToken: Char; override;  end;
  TPasParser = class(TTextParser)
  private
    { private declarations }
  public
    { public declarations }
    function NextToken: Char; override;  end;
const
  toComment = Char(5);

type
  TEnhPasParser = class(TPasParser)
  private
    { private declarations }
  public
    { public declarations }
    function TokenString: string; override;    function NextToken: Char; override;  end;
const
  toOpenTag = Char(6);
  toCloseTag = Char(7);

type
  THtmlParser = class(TTextParser)
  private
    { private declarations }
  public
    { public declarations }
    function TokenString: string; override;    function NextToken: Char; override;  end;
var
  Log: TextFile;

implementation

{ TCustomParser }

const
  ParseBufSize: integer = 4096;

constructor TCustomParser.Create(Stream: TStream);
begin
  FStream := Stream;
  GetMem(FBuffer, ParseBufSize);
  FBuffer[0] := #0;
  FBufPtr := FBuffer;
  FBufEnd := FBuffer + ParseBufSize;
  FSourcePtr := FBuffer;
  FSourceEnd := FBuffer;
  FTokenPtr := FBuffer;
  FSourceLine := 1;
  {$IFDEF DEBUG}
  writeln(log,'');
  writeln(log, 'FBuffer FBufPtr FSrcPtr   FSrcEnd FBufEnd Pos Occured');
  writeln(log,'');
  writeln(log,LongInt(FBuffer), ' ', LongInt(FBufPtr), ' ', LongInt(FSourcePtr),' ', FSourcePtr^, ' ', LongInt(FSourceEnd), ' ', LongInt(FBufEnd), ' ',FStream.Position,' on create');
  {$ENDIF}
  NextToken;
end;

destructor TCustomParser.Destroy;
begin
  if FBuffer <> nil then
  begin
    FStream.Seek(Longint(FTokenPtr) - Longint(FSourceEnd), 1);
    FreeMem(FBuffer, ParseBufSize);
  end;
end;

procedure TCustomParser.ReadBuffer;
var
  Count: Integer;
begin
  try
    Inc(FOrigin, FSourcePtr - FBuffer);
    FSourceEnd[0] := FSaveChar;
  {$IFDEF DEBUG}
    writeln(log,LongInt(FBuffer), ' ', LongInt(FBufPtr), ' ', LongInt(FSourcePtr),' ', FSourcePtr^,' ', LongInt(FSourceEnd),' ',LongInt(FBufEnd), ' ',FStream.Position, ' before read');
  {$ENDIF}
    Count := FBufPtr - FSourcePtr;
    if Count <> 0 then Move(FSourcePtr[0], FBuffer[0], Count);
    FBufPtr := FBuffer + Count;
    Inc(FBufPtr, FStream.Read(FBufPtr[0], FBufEnd - FBufPtr));
  {$IFDEF DEBUG}
    writeln(log,LongInt(FBuffer), ' ', LongInt(FBufPtr), ' ', LongInt(FSourcePtr),' ', FSourcePtr^, ' ', LongInt(FSourceEnd), ' ', LongInt(FBufEnd), ' ',FStream.Position, ' after read');
  {$ENDIF}
    FSourcePtr := FBuffer;
    FSourceEnd := FBufPtr;
    if FSourceEnd = FBufEnd then
    begin
      FSourceEnd := LineStart(FBuffer, FSourceEnd - 1);
      if FSourceEnd = FBuffer then Error(SLineTooLong);
    end;
    FSaveChar := FSourceEnd[0];
    FSourceEnd[0] := #0;
  except
    on EStreamError do
      MessageDlg('FSourcePtr^ = '+FSourcePtr^,mtError,
        [mbOK],0);
    on EAccessViolation do
      MessageDlg('FSourcePtr^ = '+FSourcePtr^,mtError,
        [mbOK],0);
  end;
end;

function TCustomParser.NextToken: Char;
begin
  FToken := FSourcePtr^;
  if FToken <> toEOF then Inc(FSourcePtr);
  Result := FToken;
end;

procedure TCustomParser.SkipBlanks;
begin
  while True do
  begin
    case FSourcePtr^ of
      #0:
        begin
          ReadBuffer;
          if FSourcePtr^ = #0 then Exit;
          Continue;
        end;
      #10:
        Inc(FSourceLine);
      #33..#255:
        Exit;
    end;
    Inc(FSourcePtr);
  end;
end;

function TCustomParser.TokenString: string;
var
  L: Integer;
begin
  if (FToken = toString) then
    L := FStringPtr - FTokenPtr else
    L := FSourcePtr - FTokenPtr;
  {$IFDEF Win32}
  SetString(Result, FTokenPtr, L);
  {$ELSE}
  if L > 255 then L := 255;
  Result[0] := Char(L);
  {$ENDIF}
  Move(FTokenPtr[0], Result[1], L);
end;

{$IFDEF Win32}
procedure TCustomParser.Error(const Ident: string);
begin
  ErrorStr(Ident);
end;

procedure TCustomParser.ErrorStr(const Message: string);
begin
  raise EParserError.CreateFmt(SParseError, [Message, FSourceLine]);
end;
{$ELSE}
procedure TCustomParser.Error(MessageID: Word);
begin
  ErrorStr(LoadStr(MessageID));
end;

procedure TCustomParser.ErrorStr(const Message: string);
begin
  raise EParserError.Create(FmtLoadStr(SParseError, [Message, FSourceLine]));
end;
{$ENDIF}

function TCustomParser.SourcePos: Longint;
begin
  Result := FOrigin + (FTokenPtr - FBuffer);
end;

{ TCSVParser }
function TCSVParser.TokenString: string;
var
  L: Integer;
begin
  if (FToken = toSymbol) then
    L := FStringPtr - FTokenPtr else
    L := FSourcePtr - FTokenPtr;
  {$IFDEF Win32}
  SetString(Result, FTokenPtr, L);
  {$ELSE}
  if L > 255 then L := 255;
  Result[0] := Char(L);
  {$ENDIF}
  Move(FTokenPtr[0], Result[1], L);
end;

function TCSVParser.NextToken: Char;
begin
  SkipBlanks;
  FTokenPtr := FSourcePtr;
  case FSourcePtr^ of
    'A'..'Z', 'a'..'z', '_':
      begin
        Inc(FSourcePtr);
        FStringPtr := FSourcePtr;
        while true do
        begin
          case FSourcePtr^ of
            ',': Break;
            #0: Break;
          end;
          FStringPtr^ := FSourcePtr^;
          Inc(FStringPtr);
          Inc(FSourcePtr);
        end;
        FToken := toSymbol;
        Result := FToken;
      end;
    '-', '0'..'9':
      begin
        Inc(FSourcePtr);
        while FSourcePtr^ in ['0'..'9'] do Inc(FSourcePtr);
        FToken := toInteger;
        Result := FToken;
        while FSourcePtr^ in ['0'..'9', '.', 'e', 'E', '+', '-'] do
        begin
          Inc(FSourcePtr);
          FToken := toFloat;
          Result := FToken;
        end;
      end;
    else Result := inherited NextToken;
  end;
end;

{ TTextParser }
function TTextParser.NextToken: Char;
begin
  SkipBlanks;
  FTokenPtr := FSourcePtr;
  case FSourcePtr^ of
    'A'..'Z', 'a'..'z', '_':
      begin
        Inc(FSourcePtr);
        while True do
          case FSourcePtr^ of
            'A'..'Z', 'a'..'z', '0'..'9', '_': Inc(FSourcePtr);
            '''': begin  { apostrophies }
                if (FSourcePtr+1)^ in ['A'..'Z', 'a'..'z', '0'..'9', '_'] then Inc(FSourcePtr)
                else Break;
              end;
            '-': begin  { hyphenated words }
                if (FSourcePtr+1)^ in ['A'..'Z', 'a'..'z', '0'..'9', '_'] then Inc(FSourcePtr)
                else Break;
              end;
            else Break;
          end;
        FToken := toSymbol;
        Result := FToken;
      end;
    '-', '0'..'9':
      begin
        Inc(FSourcePtr);
        while FSourcePtr^ in ['0'..'9'] do Inc(FSourcePtr);
        FToken := toInteger;
        Result := FToken;
        while FSourcePtr^ in ['0'..'9', '.', 'e', 'E', '+', '-'] do
        begin
          Inc(FSourcePtr);
          FToken := toFloat;
          Result := FToken;
        end;
      end;
    else Result := inherited NextToken;
  end;
end;

{ TPasParser }
function TPasParser.NextToken: Char;
var
  I: integer;
begin
  SkipBlanks;
  FTokenPtr := FSourcePtr;
  case FSourcePtr^ of
    'A'..'Z', 'a'..'z', '_':
      begin
        Inc(FSourcePtr);
        while FSourcePtr^ in ['A'..'Z', 'a'..'z', '0'..'9', '_'] do Inc(FSourcePtr);
        FToken := toSymbol;
        Result := FToken;
      end;
    '#', '''':
      begin
        FStringPtr := FSourcePtr;
        while True do
          case FSourcePtr^ of
            '#':
              begin
                Inc(FSourcePtr);
                I := 0;
                while FSourcePtr^ in ['0'..'9'] do
                begin
                  I := I * 10 + (Ord(FSourcePtr^) - Ord('0'));
                  Inc(FSourcePtr);
                end;
                FStringPtr^ := Chr(I);
                Inc(FStringPtr);
              end;
            '''':
              begin
                Inc(FSourcePtr);
                while True do
                begin
                  case FSourcePtr^ of
                    #0, #10, #13:
                      Error(SInvalidString);
                    '''':
                      begin
                        Inc(FSourcePtr);
                        if FSourcePtr^ <> '''' then Break;
                      end;
                  end;
                  FStringPtr^ := FSourcePtr^;
                  Inc(FStringPtr);
                  Inc(FSourcePtr);
                end;
              end;
          else
            Break;
          end;
        FToken := toString;
        Result := FToken;
      end;
    '$':
      begin
        FToken := FSourcePtr^;  { assume NOT an integer }
        Result := FToken;
        Inc(FSourcePtr);
        while true do
        begin
          case FSourcePtr^ of
            '0'..'9', 'A'..'F', 'a'..'f': Inc(FSourcePtr);
            else Break;
          end;
          FToken := toInteger;
          Result := FToken;
        end;
      end;
  (*  '-', '0'..'9':
      begin
        Inc(FSourcePtr);
        while FSourcePtr^ in ['0'..'9'] do Inc(FSourcePtr);
        FToken := toInteger;
        Result := FToken;
        while FSourcePtr^ in ['0'..'9', '.', 'e', 'E', '+', '-'] do
        begin
          Inc(FSourcePtr);
          FToken := toFloat;
          Result := FToken;
        end;
      end;  *)
    else Result := inherited NextToken;
  end;
end;

{ TEnhPasParser }
function TEnhPasParser.TokenString: string;
var
  L: Integer;
begin
  if (FToken = toString) or (FToken = toComment) then
    L := FStringPtr - FTokenPtr else
    L := FSourcePtr - FTokenPtr;
  {$IFDEF Win32}
  SetString(Result, FTokenPtr, L);
  {$ELSE}
  if L > 255 then L := 255;
  Result[0] := Char(L);
  {$ENDIF}
  Move(FTokenPtr[0], Result[1], L);
end;

function TEnhPasParser.NextToken: Char;
begin
  SkipBlanks;
  FTokenPtr := FSourcePtr;
  case FSourcePtr^ of
    '{':
      begin { comment or compiler directive... }
        FStringPtr := FSourcePtr;
        Inc(FSourcePtr);  { check next char... }
        while true do
        begin
          case FSourcePtr^ of
            #0: begin
              ReadBuffer;
              FStringPtr := FSourcePtr;
              if FSourcePtr^ = #0 then Break;
              {$IFDEF DEBUG}
              writeln(Log, 'in comment');
              {$ENDIF}
            end;
            #10: Inc(FSourceLine);
            '}':
              begin
                Inc(FSourcePtr);
                Break;      { end comment... }
              end;
          end;
          FStringPtr^ := FSourcePtr^;
          Inc(FStringPtr);
          Inc(FSourcePtr);
        end;
        FToken := toComment;
        Result := FToken;
      end;
    '(', '/':  { possible comment or compiler directive... }
      begin
        FToken := FSourcePtr^; { assume NOT a comment }
        Result := FToken;
        FStringPtr := FSourcePtr;
        Inc(FSourcePtr);  { check next char... }
        case FSourcePtr^ of
          '*':  { is a comment }
            begin
              Inc(FSourcePtr);  { check next char... }
              while True do
              begin
                case FSourcePtr^ of
                  #0: begin
                    ReadBuffer;
                    FStringPtr := FSourcePtr;
                    if FSourcePtr^ = #0 then Break;
                    {$IFDEF DEBUG}
                    writeln(Log, 'in comment');
                    {$ENDIF}
                  end;
                  #10: Inc(FSourceLine);
                  '*':
                    begin
                      Inc(FSourcePtr);
                      if FSourcePtr^ = ')' then
                      begin
                        Inc(FSourcePtr);
                        Break; { end of comment }
                      end;
                    end;
                end;
                FStringPtr^ := FSourcePtr^;
                Inc(FStringPtr);
                Inc(FSourcePtr);
              end;
              FToken := toComment;
              Result := FToken;
            end;
          '/':  { is a comment }
            begin
              Inc(FSourcePtr);
              while (FSourcePtr^ <> #13) do  { end of line, hence comment }
              begin
                FStringPtr^ := FSourcePtr^;
                Inc(FStringPtr);
                Inc(FSourcePtr);
              end;
              FToken := toComment;
              Result := FToken;
            end;
        end;
      end;
    else Result := inherited NextToken;
  end;
end;

{ THtmlParser }
function THtmlParser.TokenString: string;
var
  L: Integer;
begin
  if (FToken = toString) or (FToken = toOpenTag)
    or (FToken = toCloseTag) then
      L := FStringPtr - FTokenPtr else
      L := FSourcePtr - FTokenPtr;
  {$IFDEF Win32}
  SetString(Result, FTokenPtr, L);
  {$ELSE}
  if L > 255 then L := 255;
  Result[0] := Char(L);
  {$ENDIF}
  Move(FTokenPtr[0], Result[1], L);
end;

function THtmlParser.NextToken: Char;
begin
  SkipBlanks;
  FTokenPtr := FSourcePtr;
  case FSourcePtr^ of
    '<':   { is a tag }
    begin
      FStringPtr := FSourcePtr;
      Inc(FSourcePtr);
      case FSourcePtr^ of
        '/':  { is an 'close' tag }
          begin
            Inc(FSourcePtr);
            while true do
            begin
              case FSourcePtr^ of
                #0: begin
                  ReadBuffer;
                  FStringPtr := FSourcePtr;
                  if FSourcePtr^ = #0 then Break;
                end;
                '>': begin
                  Inc(FSourcePtr);
                  Break; { end of tag }
                end;
              end; {case}
              FStringPtr^ := FSourcePtr^;
              Inc(FStringPtr);
              Inc(FSourcePtr);
            end;
            FToken := toCloseTag;
            Result := FToken;
          end;
        else
          begin
            while true do
            begin
              case FSourcePtr^ of
                #0: begin
                  ReadBuffer;
                  FStringPtr := FSourcePtr;
                  if FSourcePtr^ = #0 then Break;
                end;
                '>': begin
                  Inc(FSourcePtr);
                  Break; { end of tag }
                end;
              end; {case}
              FStringPtr^ := FSourcePtr^;
              Inc(FStringPtr);
              Inc(FSourcePtr);
            end;
            FToken := toOpenTag;
            Result := FToken;
          end;
      end; {case}
    end;
    else Result := inherited NextToken;
  end;
end;

{$IFDEF DEBUG}
initialization
  AssignFile(Log, 'debug.log');
  Rewrite(Log);
finalization
  CloseFile(Log);
{$ENDIF}
end.