freepascal.compiler/packages/fcl-js/src/jsparser.pp

{ ********************************************************************* 
    This file is part of the Free Component Library (FCL)
    Copyright (c) 2016 Michael Van Canneyt.
       
    Javascript parser
            
    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 jsparser;

{ $define debugparser}
{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, jsscanner, jstree, jstoken;

Const
   SEmptyLabel = '';
   MinAsyncVersion = ecma2021;

Type
  TECMAVersion = jsScanner.TECMAVersion;

  { TJSParser }

  TJSParser = Class(TObject)
  Private
    FFunctionDepth: Integer;
    FInput : TStream;
    FIsLHS: Boolean;
    FNoIn: Boolean;
    FScanner : TJSScanner;
    FPrevious,
    FCurrent : TJSToken;
    FCurrentString : String;
    FFreeScanner : Boolean;
    FCurrentVars : TJSElementNodes;
    FPeekToken: TJSToken;
    FPeekTokenString: String;
    FLabelSets,
    FCurrentLabelSet:TJSLabelSet;
    FLabels : TJSLabel;
    function CheckSemiColonInsert(aToken: TJSToken; Consume: Boolean): Boolean;
    function EnterLabel(ALabelName: String): TJSLabel;
    procedure Expect(aToken: TJSToken);
    procedure Consume(aToken: TJSToken; AllowSemicolonInsert : Boolean = False);
    procedure FreeCurrentLabelSet;
    function GetVersion: TECMAVersion;
    procedure LeaveLabel;
    function LookupLabel(ALabelName: String; Kind: TJSToken): TJSLabel;
    function ParseAdditiveExpression: TJSElement;
    function ParseArguments: TJSarguments;
    function ParseArrayLiteral: TJSElement;
    function ParseAssignmentExpression: TJSElement;
    function ParseBitwiseAndExpression: TJSElement;
    function ParseBitwiseORExpression: TJSElement;
    function ParseBitwiseXORExpression: TJSElement;
    function ParseBlock: TJSElement;
    function ParseBreakStatement: TJSElement;
    function ParseConditionalExpression: TJSElement;
    function ParseContinueStatement: TJSElement;
    function ParseEmptyStatement: TJSElement;
    function ParseEqualityExpression: TJSElement;
    function ParseExpression: TJSElement;
    function ParseExpressionStatement: TJSElement;
    function ParseFormalParameterList: TStrings;
    function ParseFunctionDeclaration: TJSFunctionDeclarationStatement;
    function ParseFunctionExpression: TJSFunctionDeclarationStatement;
    function ParseFunctionStatement: TJSElement;
    function ParseFunctionBody: TJSFunctionBody;
    function ParseIdentifier: String;
    function ParseIfStatement: TJSElement;
    function ParseIterationStatement: TJSElement;
    function ParseLabeledStatement: TJSElement;
    function ParseLeftHandSideExpression: TJSElement;
    function ParseLiteral: TJSElement;
    function ParseLogicalAndExpression: TJSElement;
    function ParseLogicalORExpression: TJSElement;
    function ParseMemberExpression: TJSElement;
    function ParseMultiplicativeExpression: TJSElement;
    function ParseNumericLiteral: TJSElement;
    function ParseObjectLiteral: TJSElement;
    function ParsePostFixExpression: TJSElement;
    function ParsePrimaryExpression: TJSElement;
    function ParseRegularExpressionLiteral: TJSElement;
    function ParseRelationalExpression: TJSElement;
    function ParseReturnStatement: TJSElement;
    function ParseShiftExpression: TJSElement;
    function ParseStatement: TJSElement;
    function ParseStatementList: TJSElement;
    function ParseStringLiteral: TJSElement;
    function ParseSwitchStatement: TJSElement;
    function ParseThrowStatement: TJSElement;
    function ParseTryStatement: TJSElement;
    function ParseUnaryExpression: TJSElement;
    function ParseVariableDeclaration: TJSElement;
    function ParseVariableDeclarationList: TJSElement;
    function ParseVariableStatement: TJSElement;
    function ParseWithStatement: TJSElement;
  Protected
    Procedure CheckParser;
    Function CurrentLabelSet : TJSLabelSet;
    function CurSource: String;
    Function CurLine : Integer;
    Function CurPos : Integer;
    Function CreateElement(AElementClass : TJSElementClass)  : TJSElement;
    Procedure Error(Msg : String);
    Procedure Error(Fmt : String; Args : Array of const);
    // Parse functions
    function ParseSourceElements: TJSSourceElements;
    Property FunctionDepth : Integer Read FFunctionDepth Write FFunctionDepth;
    Property NoIn : Boolean Read FNoIn Write FNoIn;
    Property IsLHS : Boolean Read FIsLHS Write FIsLHS;
  Public
    Constructor Create(AInput: TStream; aVersion : TECMAVersion = ecma5);
    // Scanner has version
    Constructor Create(AScanner : TJSScanner);
    Destructor Destroy; override;
    Function Parse : TJSElement;
    Function ParseProgram : TJSFunctionDeclarationStatement;
    Function CurrentToken : TJSToken;
    Function CurrentTokenString : String;
    Function GetNextToken : TJSToken;
    Function PeekNextToken : TJSToken;
    Function IsEndOfLine : Boolean;
    Property ECMAVersion : TECMAVersion Read GetVersion;
  end;

implementation

uses typinfo;

Resourcestring
  SErrUnmatchedCurlyBrace    = 'Unmatched }';
  SErrUnmatchedSquareBrace   = 'Unmatched ]';
  SErrUnmatchedBrace         = 'Unmatched )';
  SErrUnexpectedToken        = 'Unexpected token: ''%s''';
  SErrTokenMismatch          = 'Unexpected token: ''%s'', expected: ''%s''';
  SErrSemicolonOrInExpected  = 'Unexpected token: ''%s'', expected ; or ''in''';
  SErrSemicolonExpected      = 'Unexpected token: ''%s'', expected ;';
  SErrDuplicateLabelName     = 'Duplicate label name: ''%s''';
  SErrLabelNotContinuable    = 'Label ''%s'' is not suitable for continue.';
  SErrLabelNOtDefinedOrReachable = 'Label ''%s'' is not defined or not reachable.';
  SErrContinueNotInLoop      = 'Continue statement not in loop';
  SErrBreakNotInLoop         = 'Break statement not in loop';
  SErrReturnNotInFunction    = 'return statement not in a function body';
  SErrCaseEndExpected        = 'Unexpected token: Expected }, case or default clause';
  SErrDuplicateSwitchDefault = 'Duplicate default clause for switch statement';
  SErrNewlineAfterThrow      = 'Newline after throw not allowed';
  SErrCatchFinallyExpected   = 'Unexpected token: Expected ''catch'' or ''finally''';
  SErrArgumentsExpected      = 'Unexpected token: Expected '','' or '')'', got %s';
  SErrArrayEnd               = 'Unexpected token: Expected '','' or '']'', got %s';
  //SErrObjectEnd              = 'Unexpected token: Expected '','' or ''}'', got %s';
  SErrObjectElement          = 'Unexpected token: Expected string, identifier or number after '','' got: %s';
  SErrLiteralExpected        = 'Unexpected token: Expected: null, true, false, number, string, or regex, got: %s';
  SErrInvalidnumber          = 'Invalid numerical value: %s';
  SErrInvalidRegularExpression = 'Invalid regular expression: %s';
  SErrFunctionNotAllowedHere = 'function keyword not allowed here';

{ TJSScanner }

Function TJSParser.CurrentToken: TJSToken;

begin
  Result:=FCurrent;
end;

Function TJSParser.CurrentTokenString: String;
begin
  Result:=FCurrentString;
end;

Function TJSParser.GetNextToken: TJSToken;
begin
  FPrevious:=FCurrent;
  If (FPeekToken<>tjsunknown) then
     begin
     FCurrent:=FPeekToken;
     FCurrentString:=FPeekTokenString;
     FPeekToken:=tjsUnknown;
     FPeekTokenString:='';
     end
  else
    begin
    FCurrent:=FScanner.FetchToken;
    FCurrentString:=FScanner.CurTokenString;
    end;
  Result:=FCurrent;
  {$ifdef debugparser}Writeln('GetNextToken (',FScanner.CurLine,',',FScanner.CurColumn,'): ',GetEnumName(TypeInfo(TJSToken),Ord(FCurrent)), ' As string: ',FCurrentString);{$endif debugparser}
end;

Function TJSParser.PeekNextToken: TJSToken;
begin
  If (FPeekToken=tjsUnknown) then
    begin
    FPeekToken:=FScanner.FetchToken;
    FPeekTokenString:=FScanner.CurTokenString;
    end;
  {$ifdef debugparser}Writeln('PeekNextToken : ',GetEnumName(TypeInfo(TJSToken),Ord(FPeekToken)), ' As string: ',FPeekTokenString);{$endif debugparser}
  Result:=FPeekToken;
end;

Function TJSParser.IsEndOfLine: Boolean;
begin
  Result:=FScanner.IsEndOfLine;
end;


Function TJSParser.CurPos: Integer;
begin
  If Assigned(FScanner) then
    Result:=FScanner.CurColumn
  else
    Result:=0;
end;

Function TJSParser.CurLine: Integer;
begin
  If Assigned(FScanner) then
    Result:=FScanner.CurRow
  else
    Result:=0;
end;

function TJSParser.CurSource: String;
begin
  If Assigned(FScanner) then
    Result:=FScanner.CurFileName
  else
    Result:='';
end;

Procedure TJSParser.CheckParser;
begin

end;

procedure TJSParser.LeaveLabel;

Var
  L : TJSLabel;

begin
  L:=FLabels;
  FLabels:=FLabels.Next;
  L.Free; // ??
end;

function TJSParser.LookupLabel(ALabelName : String; Kind : TJSToken) :TJSLabel;

Var
  L : TJSLabel;

begin
  L:=FLabels;
  Result:=Nil;
  While (L<>Nil) and (Result=Nil) do
    begin
    If (L.Name=ALabelName) then
      begin
      if (kind=tjsContinue) and (Not L.LabelSet.Continuable) and (ALabelName<>SEmptyLabel) then
        Error(SErrLabelNotContinuable,[ALabelName]);
      Result:=L;
      end;
    L:=L.Next;
    end;
  If (Result=Nil) then
    begin
    If (ALabelName<>'') then
      Error(SErrLabelNOtDefinedOrReachable,[ALabelName])
    else if kind=tjsCOntinue then
      Error(SErrContinueNotInLoop)
    else
      Error(SErrBreakNotInLoop);
    end;
end;

function TJSParser.EnterLabel(ALabelName : String) :TJSLabel;

Var
  L : TJSLabel;

begin
  If (ALAbelName<>SEmptyLabel) then
    begin
    L:=FLabels;
    While (L<>Nil) do
      begin
      If (L.Name=ALabelName) then
        Error(SErrDuplicateLabelName,[ALabelName]);
      L:=L.Next;
      end;
    end;
  L:=TJSLabel.Create;
  L.Name:=ALabelName;
  L.LabelSet:=CurrentLabelSet;
  L.LocationSource:=Self.CurSource;
  L.LocationLine:=CurLine;
  L.LocationPos:=CurPos;
  L.Next:=FLabels;
  FLabels:=L;
  Result:=L;
end;

Function TJSParser.CurrentLabelSet: TJSLabelSet;

Var
  LS : TJSLabelSet;

begin
  If (FCurrentLabelSet=Nil) then
    begin
    LS:=TJSLabelSet.Create;
    If (FLabelSets=Nil) then
      LS.Target:=1
    else
      LS.Target:=FLabelSets.Target;
    LS.Next:=FLabelSets;
    FLabelSets:=LS;
    FCurrentLabelSet:=LS;
    end;
  Result:=FCurrentLabelSet;
end;

Function TJSParser.CreateElement(AElementClass: TJSElementClass): TJSElement;
begin
  Result:=AElementClass.Create(CurLine,CurPos,CurSource);
end;

Procedure TJSParser.Error(Msg: String);

Var
  ErrAt : String;

begin
  If Assigned(FScanner) then
    If FScanner.CurFilename<>'' then
      ErrAt:=Format('Error: file "%s" line %d, pos %d: ',[FScanner.CurFileName,FScanner.CurRow,FScanner.CurColumn])
    else
      ErrAt:=Format('Error: line %d, pos %d: ',[FScanner.Currow,FScanner.CurColumn]);
  Raise Exception.Create(ErrAt+Msg)
end;

Procedure TJSParser.Error(Fmt: String; Args: Array of const);
begin
  Error(Format(Fmt,Args));
end;

Constructor TJSParser.Create(AInput: TStream; aVersion : TECMAVersion = ecma5);
begin
  FInput:=AInput;
  FCurrent:=TJSUnknown;
  FScanner:=TJSScanner.Create(FInput,aVersion);
  FFreeScanner:=True;
end;

Constructor TJSParser.Create(AScanner: TJSScanner);
begin
  FCurrent:=TJSUnknown;
  FScanner:=AScanner;
  FFreeScanner:=False;
end;

Destructor TJSParser.Destroy;
begin
  if FFreeScanner then
    FreeAndNil(FScanner);
  inherited;
end;



procedure TJSParser.Expect(aToken: TJSToken);

begin
  {$ifdef debugparser}  Writeln('Expecting : ',GetEnumName(TypeInfo(TJSToken),Ord(AToken)), ' As string: ',TokenInfos[AToken]);{$endif debugparser}
  If Not CheckSemiColonInsert(AToken,False) then
    if (CurrentToken<>aToken) then
      Error(SerrTokenMismatch,[CurrenttokenString,TokenInfos[aToken]]);
end;

function TJSParser.CheckSemiColonInsert(aToken : TJSToken; Consume : Boolean) : Boolean;

begin
  Result:=(AToken=tjsSemiColon);
  If Result then
    begin
    Result:=(CurrentToken=tjsCurlyBraceClose) or (FScanner.WasEndOfLine) or (CurrentToken=tjsEOF);
    If Result and Consume then
      FPrevious:=tjsSemiColon;
    end;
end;

procedure TJSParser.Consume(aToken: TJSToken; AllowSemicolonInsert: Boolean);
begin
  {$ifdef debugparser}  Writeln('Consuming : ',GetEnumName(TypeInfo(TJSToken),Ord(AToken)), ' As string: ',TokenInfos[AToken]);{$endif debugparser}
  Expect(aToken);
  If not (AllowSemiColonInsert and CheckSemiColonInsert(aToken,True)) then
    GetNextToken;
end;

function TJSParser.ParseIdentifier : String;

begin
  Result:='';
  Repeat
    Expect(tjsIdentifier);
    Result:=Result+CurrentTokenString;
    GetNextToken;
    If (CurrentToken=tjsDot) then
      begin
      If (Result<>'') then
         Result:=Result+'.';
      GetNextToken;
      end;
  until (CurrentToken<>tjsIdentifier);
end;

function TJSParser.ParseFormalParameterList : TStrings;

begin
  Result:=Nil;
  While (CurrentToken=tjsIdentifier) do
    begin
    Expect(tjsIdentifier);
    If (Result=Nil) then
      Result:=TstringList.Create;
    Result.Add(CurrentTokenString);
    GetNextToken;
    If (CurrentToken=tjsComma) then
       GetNextToken;
    end;
end;


function TJSParser.ParseFunctionDeclaration : TJSFunctionDeclarationStatement;

Var
  Id : String;
  D : TJSFuncDef;
  args : TStrings;
  body : TJSFunctionBody;

begin
  {$ifdef debugparser}  Writeln('>>> Entering ParseFunctionDeclaration');{$endif debugparser}
  Consume(tjsFunction);
  ID:=ParseIdentifier;
  Consume(tjsBraceOpen);
  Args:=ParseFormalParameterList;
  try
    Consume(tjsBraceClose);
    Consume(tjsCurlyBraceOpen);
    Inc(FFunctionDepth);
    try
      Body:=ParseFunctionBody;
      try
        // GetNextToken; not sure
        Consume(tjsCurlyBraceClose);
        D:=TJSFuncDef.Create;
        try
          D.Name:=ID;
          If Assigned(Args)then
            D.Params.Assign(Args);
          D.Body:=Body;
          Result:=TJSFunctionDeclarationStatement(CreateElement(TJSFunctionDeclarationStatement));
          Result.AFunction:=D;
        except
          FreeAndNil(D);
          Raise;
        end;
      except
        FreeAndNil(Body);
        Raise;
      end;
    finally
      Dec(FFunctionDepth);
    end;
  finally
    FreeAndNil(Args);
  end;
  {$ifdef debugparser}  Writeln('>>> Exiting ParseFunctionDeclaration');{$endif debugparser}
end;

function TJSParser.ParseStatementList : TJSElement;

Var
  E : TJSElement;
  SL : TJSSTatementList;

begin
  {$ifdef debugparser}  Writeln('>>> ParseStatementList');{$endif debugparser}
  E:=ParseStatement;
  try
    if (CurrentToken in [tjsCurlyBraceClose,tjsEof,tjsCase,tjsDefault]) then
      Result:=E
    else
      begin
      SL:=TJSSTatementList(CreateElement(TJSStatementList));
      try
        SL.A:=E;
        SL.B:=ParseStatementlist();
        Result:=SL;
      except
        FreeAndNil(SL);
        Raise;
      end;
      end;
  except
    FreeAndNil(E);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('<<< ParseStatementList');{$endif debugparser}
end;

function TJSParser.ParseBlock : TJSElement;

begin
  {$ifdef debugparser}  Writeln('>>> ParseBlock');{$endif debugparser}
  Consume(tjsCurlyBraceOpen);
  If (CurrentToken=tjsCurlyBraceClose) then
    Result:=CreateElement(TJSEmptyBlockStatement)
  else
    result:=ParseStatementList;
  Consume(tjsCurlyBraceClose);
  {$ifdef debugparser}  Writeln('<<< ParseBlock');{$endif debugparser}
end;

function TJSParser.ParseArrayLiteral: TJSElement;

Var
  N : TJSArrayLiteral;
  E : TJSArrayLiteralElement;
  I : Integer;

begin
  Consume(tjsSquaredBraceOpen);
  N:=TJSArrayLiteral(CreateElement(TJSArrayLiteral));
  Result:=N;
  try
    I:=0;
    While (CurrentToken<>tjsSquaredBraceClose) do
      begin
      If (CurrentToken=tjsComma) then
         begin
         GetNextToken;
         Inc(I);
         end
      else
         begin
         E:=N.Elements.AddElement;
         E.ElementIndex:=I;
         Inc(I);
         E.Expr:=ParseAssignmentExpression;
         If Not (CurrentToken in [tjsComma,tjsSquaredBraceClose]) then
           Error(SErrArrayEnd,[CurrentTokenString])
         end;
      end;
    Consume(tjsSquaredBraceClose);
  except
    FreeAndNil(Result);
    Raise;
  end;
end;

function TJSParser.ParseObjectLiteral: TJSElement;

Var
  N : TJSObjectLiteral;
  E : TJSObjectLiteralElement;
begin
  Consume(tjsCurlyBraceOpen);
  N:=TJSObjectLiteral(CreateElement(TJSObjectLiteral));
  Result:=N;
  try
    While (CurrentToken<>tjsCurlyBraceClose) do
      begin
      While CurrentToken=tjsComma do
         GetNextToken;
      If (CurrentToken in [tjsIdentifier,jstoken.tjsString,tjsnumber]) then
         begin
         E:=N.Elements.AddElement;
         E.Name:=CurrenttokenString;
         GetNextToken;
         end
      else
         Error(SErrObjectElement,[CurrentTokenString]);
      Consume(tjsColon);
      E.Expr:=ParseAssignmentExpression;
      While CurrentToken=tjsComma do
         GetNextToken;
{      If Not (CurrentToken in [tjsComma,tjsCurlyBraceClose]) then
        Error(SErrObjectEnd,[CurrentTokenString])}
      end;
    Consume(tjsCurlyBraceClose);
  except
    FreeAndNil(Result);
    Raise;
  end;
end;

function TJSParser.ParseNumericLiteral: TJSElement;

Var
  L : TJSLiteral;
  D : Double;
  I : Integer;

begin
  {$ifdef debugparser}  Writeln('Parsing numerical literal');{$endif debugparser}
  Result:=Nil;
  try
    Val(CurrentTokenString,D,I);
    If (I>0) then
      Error(SErrInvalidnumber,[CurrentTokenString]);
    L:=TJSLiteral(CreateElement(TJSLiteral));
    GetNextToken;
    L.Value.AsNumber:=D;
    Result:=L;
  except
    FreeAndNil(Result);
    Raise;
  end;
end;

function TJSParser.ParseStringLiteral: TJSElement;

Var
  L : TJSLiteral;
begin
    {$ifdef debugparser} Writeln('Parsing string literal');{$endif debugparser}
  Result:=Nil;
  try
    L:=TJSLiteral(CreateElement(TJSLiteral));
    L.Value.AsString:=CurrentTokenString;
    GetNextToken;
    Result:=L;
  except
    FreeAndNil(Result);
    Raise;
  end;
end;

function TJSParser.ParseRegularExpressionLiteral: TJSElement;

Var
  S,pa,fl : String;
  P : integer;
  R : TJSRegularExpressionLiteral;
begin
  Result:=Nil;
  If (CurrentToken=tjsRegex) then
    begin
    S:=CurrentTokenString;
    P:=Length(S);
    While (P>=1) and (S[P]<>'/') do
      Dec(P);
    If (P<=1) then
      Error(SErrInvalidRegularExpression,[CurrentTokenString]);
    pa:=Copy(S,2,P-1);
    fl:=Copy(S,P,Length(S)-P+1);
    R:=TJSRegularExpressionLiteral(CreateElement(TJSRegularExpressionLiteral));
    Result:=R;
    R.Pattern.AsString:=Pa;
    R.PatternFlags.AsString:=Fl;
    R.Argv[0]:=R.Pattern;
    R.Argv[1]:=R.PatternFlags;
    end;
  try
    Consume(tjsRegEx);
  except
    FreeAndNil(Result);
    Raise;
  end;
end;

function TJSParser.ParseLiteral: TJSElement;

Var
  L : TJSLiteral;

begin
  {$ifdef debugparser}Writeln('Parsing literal: ',GetEnumName(TypeInfo(TJSToken),Ord(CurrentToken)), ' As string: ',CurrentTokenString);{$endif debugparser}
  Result:=Nil;
  Case CurrentToken of
    tjsNull : begin
              L:=TJSLiteral(CreateElement(TJSLiteral));
              Result:=L;
              L.Value.IsNull:=True;
              GetNextToken;
              end;
    tjsTrue,
    tjsFalse: begin
              L:=TJSLiteral(CreateElement(TJSLiteral));
              Result:=L;
              L.Value.AsBoolean:=(CurrentToken=tjsTrue);
              GetNextToken;
              end;
    tjsNumber : Result:=ParseNumericLiteral;
    jstoken.tjsString : Result:=ParseStringLiteral;
    tjsDiv,
    tjsDivEq : Result:=ParseRegularExpressionLiteral
  else
    Error(SErrLiteralExpected,[CurrentTokenString]);
  end;
end;

function TJSParser.ParsePrimaryExpression: TJSElement;

Var
  R : TJSPrimaryExpressionIdent;

begin
  {$ifdef debugparser}  Writeln('ParsePrimaryExpression');{$endif debugparser}
  Result:=Nil;
  try
    Case CurrentToken of
      tjsThis :
        begin
        Result:=TJSPrimaryExpressionThis(CreateElement(TJSPrimaryExpressionThis));
        GetNextToken;
        end;
      tjsidentifier:
        begin
        R:=TJSPrimaryExpressionIdent(CreateElement(TJSPrimaryExpressionIdent));
        Result:=R;
        R.Name:=CurrentTokenString;
        GetNextToken;
        end;
      tjsSquaredBraceOpen: Result:=ParseArrayLiteral;
      tjsCurlyBraceOpen: Result:=ParseObjectLiteral;
      tjsBraceOpen:
        begin
        Consume(tjsBraceOpen);
        Result:=ParseExpression;
        Consume(tjsBraceClose);
        end;
    else
      Result:=ParseLiteral;
    end; // Case;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParsePrimaryExpression');{$endif debugparser}
end;


function TJSParser.ParseMemberExpression: TJSElement;

Var
  M  : TJSDotMemberExpression;
  N  : TJSNewMemberExpression;
  B  : TJSBracketMemberExpression;
  Done : Boolean;

begin
  {$ifdef debugparser}  Writeln('ParseMemberExpression');{$endif debugparser}
  Case CurrentToken of
    tjsFunction : Result:=ParseFunctionExpression();
    tjsNew      : begin
                  GetNextToken;
                  N:=TJSNewMemberExpression(CreateElement(TJSNewMemberExpression));
                  try
                    Result:=N;
                    N.MExpr:=ParseMemberExpression();
                    if (CurrentToken=tjsBraceOpen) then
                      N.Args:=ParseArguments;
                  except
                    FreeAndNil(N);
                    Raise;
                  end;
                  end;
  else
    Result:=ParsePrimaryExpression()
  end;
  try
    Done:=False;
    Repeat
      Case CurrentToken of
       tjsDot :
         begin
         M:=TJSDotMemberExpression(CreateElement(TJSDotMemberExpression));
         M.MExpr:=Result;
         Result:=M;
         GetNextToken;
         If (CurrentToken=tjsIdentifier) then
           M.Name:=CurrentTokenString;
         Consume(tjsIdentifier);
         end;
       tjsSquaredBraceOpen:
         begin
         B:=TJSBracketMemberExpression(CreateElement(TJSBracketMemberExpression));
         B.MExpr:=Result;
         Result:=B;
         GetNextToken;
         B.Name:=ParseExpression();
         Consume(tjsSquaredBraceClose);
         end;
      else
        Done:=True;
        isLHS:=True;
      end;
    Until Done;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseMemberExpression');{$endif debugparser}
end;

function TJSParser.ParseArguments: TJSarguments;

Var
  E : TJSArrayLiteralElement;

begin
  Consume(tjsBraceOpen);
  Result:=TJSArguments(CreateElement(TJSArguments));
  try
    While (CurrentToken<>tjsBraceClose) do
      begin
      E:=Result.Elements.AddElement;
      E.Expr:=ParseAssignmentExpression;
      If (CurrentToken<>tjsBraceClose) then
        If CurrentToken=tjsComma then
          GetNextToken
        else
          Error(SErrArgumentsExpected,[CurrentTokenString]);
      end;
    Consume(tjsBraceClose);
  except
    FreeAndNil(Result);
    Raise;
  end;
end;

function TJSParser.ParseLeftHandSideExpression: TJSElement;

Var
  M  : TJSDotMemberExpression;
  B  : TJSBracketMemberExpression;
  C : TJSCallExpression;
  Done : Boolean;

begin
  {$ifdef debugparser}  Writeln('ParseLeftHandSideExpression');{$endif debugparser}
  Case CurrentToken of
    tjsFunction : Result:=ParseFunctionExpression;
    tjsNew      : Result:=ParseMemberExpression;
  else
    Result:=ParsePrimaryExpression
  end;
  try
    Done:=False;
    Repeat
      Case CurrentToken of
       tjsDot :
         begin
         M:=TJSDotMemberExpression(CreateElement(TJSDotMemberExpression));
         M.MExpr:=Result;
         Result:=M;
         GetNextToken;
         If (CurrentToken=tjsIdentifier) then
           M.Name:=CurrentTokenString;
         Consume(tjsIdentifier);
         end;
       tjsSquaredBraceOpen:
         begin
         B:=TJSBracketMemberExpression(CreateElement(TJSBracketMemberExpression));
         B.MExpr:=Result;
         Result:=B;
         GetNextToken;
         B.Name:=ParseExpression;
         Consume(tjsSquaredBraceClose);
         end;
       tjsBraceOpen:
         begin
         C:=TJSCallExpression(CreateElement(TJSCallExpression));
         C.Expr:=Result;
         Result:=C;
         C.Args:=ParseArguments;
         end;
      else
        {$ifdef debugparser}Writeln('Leaving LHS');{$endif debugparser}
        Done:=True;
        isLHS:=True;
      end;
    Until Done;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseLeftHandSideExpression');{$endif debugparser}
end;

function TJSParser.ParsePostFixExpression: TJSElement;
Var
  R : TJSUnaryExpression;

begin
  {$ifdef debugparser}  Writeln('ParsePostfixExpression');{$endif debugparser}
  Result:=ParseLeftHandSideExpression;
  Try
  If (Not IsEndOfLine) and (CurrentToken in [tjsPlusPlus,tjsMinusMinus]) then
    begin
    If (CurrentToken=tjsPlusPLus) then
      R:=TJSUnaryExpression(CreateElement(TJSUnaryPostPlusPlusExpression))
    else
      R:=TJSUnaryExpression(CreateElement(TJSUnaryPostMinusMinusExpression));
    R.A:=Result;
    Result:=R;
    GetNextToken;
    isLHS:=False;
    end;
  except
    freeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParsePostfixExpression');{$endif debugparser}
end;

function TJSParser.ParseUnaryExpression: TJSElement;

Var
  C : TJSElementClass;
  R : TJSUnaryExpression;

begin
  {$ifdef debugparser} Writeln('ParseUnaryExpression');{$endif debugparser}
  C:=Nil;
  Result:=Nil;
  try
    Case CurrentToken of
      tjsDelete     : C:=TJSUnaryDeleteExpression;
      tjsVoid       : C:=TJSUnaryVoidExpression;
      tjsTypeOf     : C:=TJSUnaryTypeOfExpression;
      tjsPlusPlus   : C:=TJSUnaryPrePlusPlusExpression;
      tjsMinusMinus : C:=TJSUnaryPreMinusMinusExpression;
      tjsPlus       : C:=TJSUnaryPlusExpression;
      tjsMinus      : C:=TJSUnaryMinusExpression;
      tjsInv        : C:=TJSUnaryInvExpression;
      tjsNot        : C:=TJSUnaryNotExpression;
    else
      Result:=ParsePostFixExpression;
    end;
    If (Result=Nil) then
      begin
      {$ifdef debugparser} Writeln('Found Unary Expression',GetEnumName(TypeInfo(TJSToken),Ord(CurrentToken)), ' As string: ',CurrentTokenString);{$endif debugparser}
      R:=TJSUnaryExpression(CreateElement(C));
      Result:=R;
      GetNextToken;
      R.A:=ParseUnaryExpression();
      isLHS:=False;
      end;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser} Writeln('Exit ParseUnaryExpression');{$endif debugparser}
end;

function TJSParser.ParseMultiplicativeExpression: TJSElement;

Var
  C : TJSElementClass;
  R : TJSMultiplicativeExpression;

begin
  {$ifdef debugparser}  Writeln('ParseMultiplicativeExpression');{$endif debugparser}
  Result:=ParseUnaryExpression;
  try
    While (CurrentToken in [tjsMul,tjsDiv,tjsMod]) do
      begin
      if CurrentToken=tjsMul then
        C:=TJSMultiplicativeExpressionMul
      else if CurrentToken=tjsDiv then
        C:=TJSMultiplicativeExpressionDiv
      else
        C:=TJSMultiplicativeExpressionMod;
      R:=TJSMultiplicativeExpression(CreateElement(C));
      GetNextToken;
      R.A:=Result;
      Result:=R;
      R.B:=ParseUnaryExpression;
      isLHS:=False;
      end;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseMultiplicativeExpression');{$endif debugparser}
end;

function TJSParser.ParseAdditiveExpression: TJSElement;

Var
  C : TJSElementClass;
  R : TJSAdditiveExpression;

begin
  {$ifdef debugparser}  Writeln('ParseAdditiveExpression');{$endif debugparser}
  Result:=ParseMultiplicativeExpression;
  try
    While (CurrentToken in [tjsPlus,tjsMinus]) do
      begin
      if CurrentToken=tjsPlus then
        C:=TJSAdditiveExpressionPlus
      else
        C:=TJSAdditiveExpressionMinus;
      R:=TJSAdditiveExpression(CreateElement(C));
      GetNextToken;
      R.A:=Result;
      Result:=R;
      R.B:=ParseMultiplicativeExpression;
      isLHS:=False;
      end;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseAdditiveExpression');{$endif debugparser}
end;

function TJSParser.ParseShiftExpression: TJSElement;

Var
  C : TJSElementClass;
  R : TJSShiftExpression;

begin
  {$ifdef debugparser}  Writeln('ParseShiftExpression');{$endif debugparser}
  Result:=ParseAdditiveExpression;
  try
    While (CurrentToken in [tjsLshift,tjsRshift,tjsURShift]) do
      begin
      Case CurrentToken of
        tjsLshift : C:=TJSLShiftExpression;
        tjsRshift : C:=TJSRShiftExpression;
        tjsURshift : C:=TJSURShiftExpression;
      end;
      R:=TJSShiftExpression(CreateElement(C));
      R.A:=Result;
      Result:=R;
      GetNextToken;
      R.B:=ParseAdditiveExpression;
      IsLHS:=False;
      end;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseShiftExpression');{$endif debugparser}
end;

function TJSParser.ParseRelationalExpression: TJSElement;

Var
  S : Set of TJSToken;
  C : TJSElementClass;
  R : TJSRelationalExpression;

begin
  {$ifdef debugparser}  Writeln('ParseRelationalExpression');{$endif debugparser}
  Result:=ParseShiftExpression;
  try
    S:=[tjsLT,tjsGT,tjsLE,tjsGE,tjsInstanceOf];
    If Not Noin then
      Include(S,tjsIn);
    While (CurrentToken in S) do
      begin
      Case CurrentToken of
        tjsLT : C:=TJSRelationalExpressionLT;
        tjsGT : C:=TJSRelationalExpressionGT;
        tjsLE : C:=TJSRelationalExpressionLE;
        tjsGE : C:=TJSRelationalExpressionGE;
        tjsInstanceOf :C:=TJSRelationalExpressionInstanceOf;
        tjsIn : C:=TJSRelationalExpressionIn;
      end;
      R:=TJSRelationalExpression(CreateElement(C));
      R.A:=Result;
      Result:=R;
      GetNextToken;
      R.B:=ParseRelationalExpression();
      IsLHS:=False;
      end;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseRelationalExpression');{$endif debugparser}
end;

function TJSParser.ParseEqualityExpression: TJSElement;

Var
  C : TJSElementClass;
  E : TJSEqualityExpression;

begin
  {$ifdef debugparser}  Writeln('ParseEqualityExpression');{$endif debugparser}
  Result:=ParseRelationalExpression;
  try
     While (CurrentToken in [tjsEq,tjsNE,tjsSEQ,tjsSNE]) do
       begin
       Case CurrentToken of
         tjsEq : C:=TJSEqualityExpressionEQ;
         tjsNE : C:=TJSEqualityExpressionNE;
         tjsSEQ : C:=TJSEqualityExpressionSEQ;
         tjsSNE : C:=TJSEqualityExpressionSNE;
       end;
       GetNextToken;
       E:=TJSEqualityExpression(CreateElement(C));
       Result:=E;
       E.A:=Result;
       E.B:=ParseEqualityExpression();
       E:=Nil;
       IsLHS:=False;
       end;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseEqualityExpression');{$endif debugparser}
end;

function TJSParser.ParseBitwiseAndExpression: TJSElement;

Var
  L : TJSBitwiseAndExpression;

begin
  {$ifdef debugparser}  Writeln('ParseBitwiseAndExpression');{$endif debugparser}
  Result:=ParseEqualityExpression;
  try
    If (CurrentToken<>tjsAnd) then
      exit;
    GetNextToken;
    L:=TJSBitwiseAndExpression(CreateElement(TJSBitwiseAndExpression));
    L.A:=Result;
    Result:=L;
    L.B:=ParseBitwiseAndExpression();
    IsLHS:=False;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseBitwiseAndExpression');{$endif debugparser}
end;

function TJSParser.ParseBitwiseXORExpression: TJSElement;

Var
  L : TJSBitwiseXOrExpression;

begin
  {$ifdef debugparser}  Writeln('ParseBitwiseXorExpression');{$endif debugparser}
  Result:=ParseBitwiseAndExpression;
  try
    If (CurrentToken<>tjsXOr) then
      exit;
    GetNextToken;
    L:=TJSBitwiseXOrExpression(CreateElement(TJSBitwiseXOrExpression));
    L.A:=Result;
    Result:=L;
    L.B:=ParseBitwiseXORExpression();
    IsLHS:=False;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseBitwiseXorExpression');{$endif debugparser}
end;

function TJSParser.ParseBitwiseORExpression: TJSElement;

Var
  L : TJSBitwiseOrExpression;

begin
  {$ifdef debugparser}  Writeln('ParseBitWiseOrExpression');{$endif debugparser}
    Result:=ParseBitwiseXORExpression;
    try
      If (CurrentToken<>tjsOr) then
        exit;
      GetNextToken;
      L:=TJSBitwiseOrExpression(CreateElement(TJSBitwiseOrExpression));
      L.A:=Result;
      Result:=L;
      L.B:=ParseBitwiseORExpression();
      IsLHS:=False;
    except
      FreeAndNil(Result);
      Raise;
    end;
    {$ifdef debugparser}  Writeln('Exit ParseBitWiseOrExpression');{$endif debugparser}
end;

function TJSParser.ParseLogicalAndExpression: TJSElement;

Var
  L : TJSLogicalAndExpression;

begin
  {$ifdef debugparser}  Writeln('ParseLogicalAndExpression');{$endif debugparser}
  Result:=ParseBitwiseORExpression;
  try
    If (CurrentToken<>tjsAndAnd) then
      exit;
    GetNextToken;
    L:=TJSLogicalAndExpression(CreateElement(TJSLogicalAndExpression));
    L.A:=Result;
    Result:=L;
    L.B:=ParseLogicalAndExpression();
    IsLHS:=False;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseLogicalAndExpression');{$endif debugparser}
end;

function TJSParser.ParseLogicalORExpression: TJSElement;

Var
  L : TJSLogicalOrExpression;

begin
  {$ifdef debugparser}  Writeln('ParseLogicalOrExpression');{$endif debugparser}
  Result:=ParseLogicalAndExpression;
  try
    If (CurrentToken<>tjsOROR) then
      exit;
    GetNextToken;
    L:=TJSLogicalOrExpression(CreateElement(TJSLogicalOrExpression));
    L.A:=Result;
    Result:=L;
    L.B:=ParseLogicalOrExpression();
    IsLHS:=False;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseLogicalOrExpression');{$endif debugparser}
end;

function TJSParser.ParseConditionalExpression: TJSElement;

Var
  N : TJSConditionalExpression;
  L : TJSElement;
begin
  {$ifdef debugparser}  Writeln('ParseConditionalExpression');{$endif debugparser}
  Result:=Nil;
  Result:=ParseLogicalORExpression;
  try
    If (CurrentToken=tjsConditional) then
      begin
      {$ifdef debugparser}  Writeln('ParseConditionalExpression : Detected conditional ');{$endif debugparser}
      GetNextToken;
      L:=Result;
      N:=TJSConditionalExpression(CreateElement(TJSConditionalExpression));
      Result:=N;
      N.A:=L;
      L:=Nil;
      N.B:=ParseAssignmentExpression;
      Consume(tjsColon);
      N.C:=ParseAssignmentExpression;
      IsLHS:=False;
      end;
  except
    FreeandNil(Result);
  end;
  {$ifdef debugparser}  Writeln('Exit ParseConditionalExpression');{$endif debugparser}
end;

function TJSParser.ParseAssignmentExpression: TJSElement;

Var
  N : TJSElement;
  C : TJSElementClass;
  A : TJSAssignStatement;

begin
  {$ifdef debugparser}  Writeln('ParseAssignmentExpression');{$endif debugparser}
  Result:=Nil;
  N:=ParseConditionalExpression;
  If not isLHS then
    Result:=N
  else
    Case CurrentToken of
      tjsAssign    : C:=TJSSimpleAssignStatement;
      tjsMulEq     : C:=TJSMulEqAssignStatement;
      tjsDivEq     : C:=TJSDivEqAssignStatement;
      tjsModEq     : C:=TJSModEqAssignStatement;
      tjsPlusEq    : C:=TJSAddEqAssignStatement;
      tjsMinusEq   : C:=TJSSubEqAssignStatement;
      tjsLShiftEq  : C:=TJSLShiftEqAssignStatement;
      tjsRShiftEq  : C:=TJSRShiftEqAssignStatement;
      tjsURShiftEq : C:=TJSURShiftEqAssignStatement;
      tjsANDEq     : C:=TJSANDEqAssignStatement;
      tjsOREq      : C:=TJSOREqAssignStatement;
      tjsXOREq     : C:=TJSXOREqAssignStatement;
    else
//      writeln('Strange token',GetEnumName(TypeInfo(TJSToken),Ord(CurrentToken)), ' As string: ',CurrentTokenString);
      Result:=N
    end;
  If Result<>Nil then
    begin
    {$ifdef debugparser}  Writeln('Exit ParseAssignmentExpression - no assignment');{$endif debugparser}
    Exit;
    end;
  A:=TJSAssignStatement(CreateElement(C));
  try
    Result:=A;
    A.Lhs:=N;
    GetNextToken;
    {$ifdef debugparser}  Writeln('ParseAssignmentExpression - level 2');{$endif debugparser}
    N:=ParseAssignmentExpression();
    {$ifdef debugparser}  Writeln('Exit ParseAssignmentExpression - level 2');{$endif debugparser}
    A.Expr:=N;
    IsLhs:=False;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseAssignmentExpression');{$endif debugparser}
end;

function TJSParser.ParseVariableDeclaration: TJSElement;

Var
  V : TJSVarDeclaration;

begin
  {$ifdef debugparser}  Writeln('ParseVariableDeclaration');{$endif debugparser}
  V:=TJSVarDeclaration(CreateElement(TJSVarDeclaration));;
  try
    V.Name:=CurrenttokenString;
    Consume(tjsIdentifier);
    if (CurrentToken=tjsAssign) then
      begin
      GetNextToken;
      V.Init:=ParseAssignmentExpression;
      end;
    Result:=V;
    FCurrentVars.AddNode.Node:=Result;
  except
    FreeAndNil(V);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseVariableDeclaration');{$endif debugparser}
end;

function TJSParser.ParseVariableDeclarationList: TJSElement;

Var
  E,N : TJSElement;
  L : TJSVariableDeclarationList;

begin
  {$ifdef debugparser}  Writeln('ParseVariableDeclarationList entry');{$endif debugparser}
  E:=ParseVariableDeclaration;
  If (CurrentToken<>tjsComma) then
    Result:=E
  else
    begin
    L:=TJSVariableDeclarationList(CreateElement(TJSVariableDeclarationList));
    Result:=L;
    try
      Consume(tjsComma);
      N:=ParseVariableDeclarationList();
      L.A:=E;
      L.B:=N;
    except
      FreeAndNil(Result);
      Raise;
    end;
    end;
  {$ifdef debugparser}  Writeln('ParseVariableDeclarationList exit');{$endif debugparser}
end;

function TJSParser.ParseVariableStatement : TJSElement;

Var
  V : TJSVariableStatement;

begin
  {$ifdef debugparser}  Writeln('ParseVariableStatement entry');{$endif debugparser}
  Result:=Nil;
  Consume(tjsVar);
  Result:=ParseVariableDeclarationList;
  try
    Consume(tjsSemicolon,true);
    V:=TJSVariableStatement(CreateElement(TJSVariableStatement));
    V.A:=Result;
    Result:=V;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('ParseVariableStatement exit');{$endif debugparser}
end;

function TJSParser.ParseEmptyStatement : TJSElement;

begin
  Consume(tjsSemiColon,true);
  Result:=CreateElement(TJSEmptyStatement);
end;

function TJSParser.ParseIfStatement : TJSElement;

Var
  C,BTrue,BFalse : TJSElement;
  I : TJSIFstatement;

begin
  C:=Nil;
  BTrue:=Nil;
  BFalse:=Nil;
  try
    Consume(tjsIF);
    Consume(tjsBraceOpen);
    C:=ParseExpression;
    Consume(tjsBraceClose);
    BTrue:=ParseStatement;
    If (CurrentToken=tjsElse) then
      begin
      Consume(tjsElse);
      BFalse:=ParseStatement;
      end;
    I:=TJSIfStatement(CreateElement(TJSIfStatement));
    I.Cond:=C;
    I.BTrue:=Btrue;
    I.BFalse:=BFalse;
    Result:=I;
  except
    FreeAndNil(C);
    FreeAndNil(BTrue);
    FreeAndNil(BFalse);
    Raise;
  end;
end;

function TJSParser.ParseIterationStatement : TJSElement;

Var
  F : TJSForStatement;
  FI : TJSForInStatement;
  W : TJSWhileStatement;
  N : TJSElement;

begin
  Result:=Nil;
  N:=Nil;
  CurrentLabelSet.Continuable:=True;
  EnterLabel(SEmptyLabel);
  try
    try
    Case CurrentToken of
      tjsDo :
        begin
        GetNextToken;
        W:=TJSDoWhileStatement(CreateElement(TJSDoWhileStatement));
        Result:=W;
        W.Body:=ParseStatement;
        Consume(tjsWhile);
        Consume(tjsBraceOpen);
        W.Cond:=ParseExpression;
        Consume(tjsBraceClose);
        Consume(tjsSemicolon,True);
        end;
      tjsWhile :
        begin
        GetNextToken;
        W:=TJSWhileStatement(CreateElement(TJSWhileStatement));
        Result:=W;
        Consume(tjsBraceOpen);
        W.Cond:=ParseExpression;
        Consume(tjsBraceClose);
        W.Body:=ParseStatement;
        Result:=W;
        end;
      else
        // For ?
        GetNextToken;
        Consume(tjsBraceopen);
        If (CurrentToken=tjsVar) then
          begin
          GetNextToken;
          N:=ParseVariableDeclarationList;
          // for (var in
          If (CurrentToken=tjsIn) and (N is tJSVarDeclaration) then
            begin
            Fi:=TJSForInStatement(CreateElement(TJSForInStatement));
            Result:=Fi;
            Fi.LHS:=N;
            GetNextToken;
            Fi.List:=ParseExpression;
            Consume(tjsBraceClose);
            Fi.Body:=ParseStatement;
            end;
          // for (var ;
          If (CurrentToken<>tjsSemicolon) then
            If (N is tJSVarDeclaration) then
              Error(SErrSemicolonOrInExpected,[CurrentTokenString])
            else
              Error(SErrSemicolonExpected,[CurrentTokenString]);
          GetNextToken;
          F:=TJSForStatement(CreateElement(TJSForStatement));
          Result:=F;
          If (CurrentToken<>tjsSemicolon) then
            F.Cond:=ParseExpression;
          Consume(tjsSemicolon);
          If (CurrentToken<>tjsBraceClose) then
            F.Incr:=ParseExpression;
          Consume(tjsBraceClose);
          F.Body:=ParseStatement;
          end
        else
          begin
          If (CurrentToken<>tjsSemicolon) then
            begin
            N:=ParseExpression;
            If (CurrentToken=tjsIn) then
              begin
              Fi:=TJSForInStatement(CreateElement(TJSForInStatement));
              Result:=Fi;
              Fi.LHS:=N;
              N:=Nil; // prevent freeing a second time in case of an exception.
              GetNextToken;
              Fi.List:=ParseExpression;
              Consume(tjsBraceClose);
              Fi.Body:=ParseStatement;
              Exit; // We must jump out here
              end
            end
          else
            N:=Nil;
          // For ( Init; Cond; incr)
          F:=TJSForStatement(CreateElement(TJSForStatement));
          Result:=F;
          F.Init:=N;
          N:=Nil; // prevent freeing a second time in case of an exception.
          Consume(tjsSemicolon);
          if (CurrentToken<>tjsSemicolon) then
            F.Cond:=ParseExpression;
          Consume(tjsSemicolon);
          If (CurrentToken<>tjsBraceClose) Then
            F.Incr:=ParseExpression;
          Consume(tjsBraceClose);
          F.Body:=ParseStatement;
          end;
      end; // Case
  Finally
    LeaveLabel;
    FreeCurrentLabelSet;
  end;
  except
    FreeAndNil(N);
    FreeAndNil(Result);
    Raise;
  end;
end;

function TJSParser.ParseContinueStatement : TJSElement;

Var
  L : TJSLabel;
  C : TJSContinueStatement;

begin
  C:=TJSContinueStatement(CreateElement(TJSContinueStatement));
  try
    Result:=C;
    Consume(tjsContinue);
    If (CurrentToken=tjsSemicolon) then
      L:=LookupLabel(SEmptyLabel,tjsContinue)
    else
      begin
      if (CurrentToken=tjsIdentifier) then
        L:=LookupLabel(CurrentTokenString,tjsContinue);
      Consume(tjsIdentifier);
      end;
    Consume(tjsSemicolon,True);
    C.Target:=L.Labelset.Target;
    C.TargetName:=L.Name;
  except
    FreeAndNil(C);
    Raise;
  end;
end;

function TJSParser.ParseBreakStatement : TJSElement;

Var
  L : TJSLabel;
  B : TJSBreakStatement;

begin
  B:=TJSBreakStatement(CreateElement(TJSBreakStatement));
  try
  Result:=B;
    Consume(tjsBreak);
    If (CurrentToken=tjsSemicolon) then
      L:=LookupLabel(SEmptyLabel,tjsBreak)
    else
      begin
      if (CurrentToken=tjsIdentifier) then
        L:=LookupLabel(CurrentTokenString,tjsBreak);
      Consume(tjsIdentifier);
      end;
    Consume(tjsSemicolon,True);
    B.Target:=L.Labelset.Target;
    B.TargetName:=L.Name;
  except
    FreeAndNil(B);
    Raise;
  end;
end;

function TJSParser.ParseReturnStatement : TJSElement;

Var
  R : TJSreturnStatement;

begin
  R:=TJSReturnStatement(CreateElement(TJSReturnStatement));
  try
    Result:=R;
    Consume(tjsReturn);
    If (FunctionDepth=0) then
      Error(SErrReturnNotInFunction);
    If Not (CurrentToken in [tjsSemicolon,tjsCurlyBraceClose]) then
      R.Expr:=ParseExpression;
    Consume(tjsSemicolon,True);
  except
    FreeAndNil(R);
    Raise;
  end;
end;

function TJSParser.ParseWithStatement : TJSElement;

Var
  W : TJSWithStatement;
begin
  W:=TJSWithStatement(CreateElement(TJSWithStatement));
  try
    Consume(tjsWith);
    Consume(tjsBraceOpen);
    W.A:=ParseExpression;
    Consume(tjsBraceClose);
    W.B:=ParseStatement;
  except
    FreeAndNil(W);
    Raise;
  end;
  Result:=W;
end;

function TJSParser.ParseSwitchStatement : TJSElement;


Var
  N : TJSSwitchStatement;
  Ca : TJSCaseElement;

begin
  N:=TJSSwitchStatement(CreateElement(TJSSwitchStatement));
  try
    N.Target:=CurrentLabelset.Target;
    EnterLabel(SEmptyLabel);
    try
      Consume(tjsSwitch);
      Consume(tjsBraceOpen);
      N.Cond:=ParseExpression;
      Consume(tjsBraceClose);
      Consume(tjsCurlyBraceOpen);
      While (CurrentToken<>tjsCurlyBraceClose) do
        begin
        If (CurrentToken=tjsCase) then
          begin
          GetNextToken;
          Ca:=N.Cases.AddCase;
          Ca.Expr:=ParseExpression;
          end
        else if (CurrentToken=tjsDefault) then
          begin
          If (N.TheDefault<>Nil) then
            Error(SerrDuplicateSwitchDefault);
          Ca:=N.Cases.AddCase;
          N.TheDefault:=Ca;
          GetNextToken;
          end
        else
          Error(SerrCaseEndExpected);
        Consume(tjsColon);
        If Not (CurrentToken in [tjsCurlyBraceClose,tjsCase,tjsDefault]) then
          Ca.Body:=ParseStatementList;
        end;
      Consume(tjsCurlyBraceClose);
    finally
      LeaveLabel;
      FreeCurrentLabelSet;
    end;
    Result:=N;
  except
    FreeAndNil(N);
    Raise;
  end;
end;

function TJSParser.ParseThrowStatement : TJSElement;

Var
  TS : TJSThrowStatement;

begin
  TS:=TJSThrowStatement(CreateElement(TJSThrowStatement));
  try
    Result:=TS;
    Consume(tjsThrow);
    If IsEndOfLine then
      Error(SErrNewlineAfterThrow);
    TS.A:=ParseExpression;
    Consume(tjsSemicolon,true);
  except
    FreeAndNil(TS);
    Raise;
  end;
end;

function TJSParser.ParseTryStatement : TJSElement;

Var
  BO,BC,BF : TJSElement;
  Id : jstree.TJSString;
  T : TJSTryStatement;

begin
  BO:=Nil;
  BC:=Nil;
  BF:=Nil;
  Result:=Nil;
  Consume(tjsTry);
  try
    Bo:=ParseBlock;
    if (CurrentToken=tjscatch) then
      begin
      Consume(tjsCatch);
      Consume(tjsBraceOpen);
      if (CurrentToken=tjsIdentifier) then
        id:=CurrentTokenString;
      Consume(tjsIdentifier);
      Consume(tjsBraceClose);
      BC:=ParseBlock;
      end;
    if (CurrentToken=tjsFinally) then
      begin
      consume(tjsFinally);
      BF:=ParseBlock;
      end;
    If (BF=Nil) and (BC=Nil) then
      Error(SErrCatchFinallyExpected);
    If Assigned(BC) AND Assigned(BF) then
      T:=TJSTryStatement(CreateElement(TJSTryCatchFinallyStatement))
    else if Assigned(BC) then
      T:=TJSTryStatement(CreateElement(TJSTryCatchStatement))
    else
      T:=TJSTryStatement(CreateElement(TJSTryFinallyStatement));
    Result:=T;
    T.Block:=Bo;
    Bo:=Nil;
    T.BCatch:=BC;
    BC:=Nil;
    T.BFinally:=BF;
    BF:=Nil;
    T.Ident:=ID;
  except
    FreeAndNil(Bo);
    FreeAndNil(BC);
    FreeAndNil(BF);
    FreeAndNil(Result);
    Raise;
  end;

end;

function TJSParser.ParseFunctionExpression : TJSFunctionDeclarationStatement;

Var
  Oni,olhs: Boolean;
  F : TJSFunctionDeclarationStatement;
  N : String;
  Args : TStrings;

begin
  {$ifdef debugparser} Writeln('>>> ParseFunctionExpression');{$endif}
  oni:=NoIn;
  olhs:=IsLHS;
  F:=Nil;
  Args:=Nil;
  try
    NoIn:=False;
    IsLHS:=False;
    F:=TJSFunctionDeclarationStatement(CreateElement(TJSFunctionDeclarationStatement));
    try
      Consume(tjsFunction);
      if (CurrentToken=tjsIdentifier) then
        begin
        n:=CurrentTokenstring;
        GetNextToken;
        end
      else
        n:='';
      if n='' then ; // what to do with that?
      Consume(tjsBraceOpen);
      F.AFunction:= TJSFuncDef.Create;
      Args:=ParseFormalParameterList;
      try
        If Assigned(Args) then
          F.AFunction.Params.Assign(Args);
      finally
        FreeAndNil(Args);
      end;
      Consume(tjsBraceClose);
      Consume(tjsCurlyBraceOpen);
      Inc(FFunctionDepth);
      try
        F.AFunction.Body:=ParseFunctionBody;
      Finally
        Dec(FFunctionDepth);
      end;
      Consume(tjsCurlyBraceClose);
      Result:=F;
    except
      FreeAndNil(F);
      Raise;
    end;
  finally
    NoIn  := oni;
    IsLHS := olhs;
  end;
  {$ifdef debugparser} Writeln('<<< ParseFunctionExpression');{$endif}
end;

function TJSParser.ParseFunctionStatement : TJSElement;

Var
  F : TJSFunctionDeclarationStatement;
  I : TJSPrimaryExpressionIdent;
  A : TJSAssignStatement;
  E : TJSExpressionStatement;

begin
  {$ifdef debugparser} Writeln('>>> ParseFunctionStatement');{$endif}
  F:=Nil;
  I:=Nil;
  A:=Nil;
  try
    F:=ParseFunctionExpression;
    I:=TJSPrimaryExpressionIdent(CreateElement(TJSPrimaryExpressionIdent));
    I.Name:=F.AFunction.Name;
    A:=TJSAssignStatement(CreateElement(TJSAssignStatement));
    A.LHS:=I;
    I:=Nil;
    A.Expr:=F;
    F:=Nil;
    E:=TJSExpressionStatement(CreateElement(TJSExpressionStatement));
    E.A:=A;
    A:=Nil;
    Result:=E;
  except
    FreeAndNil(F);
    FreeAndNil(I);
    FreeAndNil(A);
    Raise;
  end;
  {$ifdef debugparser} Writeln('<<< ParseFunctionStatement');{$endif}
end;

function TJSParser.ParseLabeledStatement : TJSElement;

Var
  OL : TJSLabelSet;
  LS : TJSLabeledStatement;
begin
  LS:=TJSLabeledStatement(CreateElement(TJSLabeledStatement));
  try
    Result:=LS;
    OL:=FCurrentLabelSet;
    try
      FCurrentLabelSet:=Nil;
      LS.target:=CurrentLabelSet.Target;
      Repeat
        LS.TheLabel:=EnterLabel(CurrentTokenString);
        Consume(tjsIdentifier);
        Consume(tjsColon);
      Until (CurrentToken<>tjsIdentifier) or (PeekNextToken<>tjsColon);
      Case CurrentToken of
         tjsDo,tjsWhile,tjsFor : LS.A:=ParseIterationStatement;
         tjsswitch : LS.A:=ParseSwitchStatement;
      else
        LS.A:=ParseStatement;
      end;
    finally
      FreeCurrentLabelSet;
      FCurrentLabelSet:=Ol;
    end;
  except
    FreeAndNil(LS);
    Raise;
  end;
end;

procedure TJSParser.FreeCurrentLabelSet;

Var
  L : TJSLabelSet;

begin
  While Assigned(FCurrentLabelSet) do
    begin
    L:=FCurrentLabelset.Next;
    FCurrentLabelSet.Free;
    FCurrentLabelSet:=L;
    end;
end;

function TJSParser.GetVersion: TECMAVersion;
begin
  Result:=FSCanner.ECMAVersion;
end;

function TJSParser.ParseExpressionStatement : TJSElement;

Var
  E : TJSElement;
  R : TJSExpressionStatement;
begin
  {$ifdef debugparser}  Writeln('ParseExpressionStatement');{$endif debugparser}
  E:=ParseExpression;
  Consume(tjsSemicolon,True);
  R:=TJSExpressionStatement(CreateElement(TJSExpressionStatement));
  R.A:=E;
  Result:=R;
  {$ifdef debugparser}  Writeln('Exit ParseExpressionStatement');{$endif debugparser}
end;

function TJSParser.ParseExpression : TJSElement;

Var
  C : TJSCommaExpression;

begin
  {$ifdef debugparser}  Writeln('ParseExpression');{$endif debugparser}
  Result:=ParseAssignmentExpression;
  try
    If (CurrentToken=tjsComma) then
      begin
      C:=TJSCommaExpression(CreateElement(TJSCommaExpression));
      C.A:=Result;
      Result:=C;
      GetNextToken;
      C.B:=ParseExpression();
      end;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}  Writeln('Exit ParseExpression');{$endif debugparser}
end;

function TJSParser.ParseStatement : TJSElement;

begin
  {$ifdef debugparser} Writeln('>>> Parsestatement');{$endif}
  Result:=Nil;
  Case CurrentToken of
    tjsCurlyBraceOpen :
      Result:=ParseBlock;
    tjsVar:
      Result:=ParseVariableStatement;
    tjsSemicolon:
      Result:=ParseEmptyStatement;
    tjsIf:
      Result:=ParseIfStatement;
    tjsDo,tjsWhile,tjsFor:
      Result:=ParseIterationStatement;
    tjsContinue:
      Result:=ParseContinueStatement;
    tjsBreak:
      Result:=ParseBreakStatement;
    tjsReturn:
      Result:=ParseReturnStatement;
    tjsWith:
      Result:=ParseWithStatement;
    tjsSwitch:
      Result:=ParseSwitchStatement;
    tjsThrow:
      Result:=ParseThrowStatement;
    tjsTry:
      Result:=ParseTryStatement;
    tjsFunction:
      begin
      If (PeekNextToken<>tjsBraceOpen) then
        Result:=ParseFunctionStatement;
      Error(SErrFunctionNotAllowedHere);
      end;
    tjsIdentifier:
      If (PeekNextToken=tjsColon) then
        Result:=ParseLabeledStatement
      else
        Result:=ParseExpressionStatement;
  else
    Result:=ParseExpressionStatement;
  end;
  {$ifdef debugparser} If Assigned(Result) then Writeln('<<< Parsestatement ',Result.ClassName) else Writeln('<<< Parsestatement (null');{$endif}
end;

function TJSParser.ParseSourceElements : TJSSourceElements;

Const
  StatementTokens = [tjsNULL, tjsTRUE, tjsFALSE,
      tjsTHIS, tjsIdentifier,jstoken.tjsSTRING,tjsNUMBER,
      tjsBraceOpen,tjsCurlyBraceOpen,tjsSquaredBraceOpen,
      tjsNew,tjsDelete,tjsVoid,tjsTypeOf,
      tjsPlusPlus,tjsMinusMinus,
      tjsPlus,tjsMinus,tjsNot,tjsNE,tjsSNE,tjsSemicolon,
      tjsVAR,tjsIF,tjsDO,tjsWHILE,tjsFOR,jstoken.tjsCONTINUE,jstoken.tjsBREAK,jstoken.tjsReturn,
      tjsWith,jstoken.tjsSWITCH,tjsThrow,TjsTry,tjsDIV,tjsDIVEQ];

Var
  F : TJSFunctionDeclarationStatement;
  E : TJSElement;
  Done : Boolean;
  VS : TJSElementNodes;
  aSync : Boolean;
begin
  {$ifdef debugparser} Writeln('>>> Entering source elements');{$endif}
  Result:=TJSSourceElements(CreateElement(TJSSourceElements));
  try
    Done:=False;
    aSync:=False;
    VS:=FCurrentVars;
    Try
      FCurrentVars:=Result.Vars;
      Repeat
        {$ifdef debugparser} Writeln('Sourceelements start:',GetEnumName(TypeInfo(TJSToken),Ord(CurrentToken)), ' As string: ',CurrentTokenString);{$endif debugparser}
        aSync:= (ECMAVersion>=MinAsyncVersion) and (CurrentToken=tjsIdentifier) and (CurrentTokenString='async');
        if aSync then
          GetNextToken;
        If (CurrentToken=jstoken.tjsFunction) then
          begin
          If (PeekNextToken<>tjsBraceOpen) then
            begin
            F:=Self.ParseFunctionDeclaration;
            F.AFunction.IsAsync:=aSync;
            Result.Functions.AddNode.Node:=F;
            end
          else
            begin
            {$ifdef debugparser} Writeln('Function expression detected');{$endif}
            E:=Self.ParseStatement;
            Result.Statements.AddNode.Node:=E;
            end;
          end
        else if CurrentToken in StatementTokens then
          begin
          E:=Self.ParseStatement;
          Result.Statements.AddNode.Node:=E;
          end
        else
          Done:=True;
        {$ifdef debugparser} Writeln('Sourceelements Done : ',Done);{$endif}
      Until Done;
    Finally
      FCurrentVars:=VS;
    end;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser}   Writeln('<<< Exiting source elements');{$endif}
end;

function TJSParser.ParseFunctionBody : TJSFunctionBody;

Var
  E : TJSElement;

begin
  {$ifdef debugparser} Writeln('>>> Entering FunctionBody');{$endif}
  Result:=TJSFunctionBody(CreateElement(TJSFunctionBody));
  try
    E:=Self.ParseSourceElements;
    Result.A:=E;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser} Writeln('<<< Exiting FunctionBody');{$endif}
end;

Function TJSParser.ParseProgram: TJSFunctionDeclarationStatement;

Var
  B : TJSElement;
begin
  {$ifdef debugparser} Writeln('>>> Entering FunctionDeclarationStatement');{$endif}
  B:=Parse;
  If Not (B is TJSFunctionBody) then
    Error('Parse did not result in functionbody');
  Result:=TJSFunctionDeclarationStatement(CreateElement(TJSFunctionDeclarationStatement));
  Result.AFunction:=TJSFuncDef.Create;
  Result.AFunction.Body:=TJSFunctionBody(B);
  {$ifdef debugparser} Writeln('<<< Exiting FunctionDeclarationStatement');{$endif}
end;

Function TJSParser.Parse: TJSElement;

Var
  Body : TJSElement;

begin
  {$ifdef debugparser} Writeln('>>> Parse');{$endif}
  Result:=Nil;
  CheckParser;
  GetNextToken;
  Body:=ParseFunctionBody;
  Result:=Body;
  try
    if (CurrentToken<>tjsEOF) then
      begin
      if (CurrentToken=tjsCurlyBraceClose) then
        Error(SErrUnmatchedCurlyBrace)
      else if (CurrentToken=tjsBraceClose) then
        Error(SerrUnmatchedBrace)
      else if (CurrentToken=tjsSquaredBraceClose) then
        Error(SerrUnmatchedSquareBrace);
      Error(SErrUnexpectedToken,[CurrentTokenString]);
      end;
    If (Body is TJSFunctionBody) then
      TJSFunctionBody(Body).isProgram:=True;
  except
    FreeAndNil(Result);
    Raise;
  end;
  {$ifdef debugparser} Writeln('<<< Parse');{$endif}
end;


end.