Давайте создадим компилятор!   ::   Креншоу Джек

Для справочных целей привожу полный текст синтаксического анализатора для этого урока:



{–}

program Branch;

{–}

{ Constant Declarations }

const TAB = ^I;

CR = ^M;

{–}

{ Variable Declarations }

var Look : char; { Lookahead Character }

Lcount: integer; { Label Counter }

{–}

{ Read New Character From Input Stream }

procedure GetChar;

begin

Read(Look);

end;

{–}

{ Report an Error }

procedure Error(s: string);

begin

WriteLn;

WriteLn(^G, 'Error: ', s, '.');

end;

{–}

{ Report Error and Halt }

procedure Abort(s: string);

begin

Error(s);

Halt;

end;

{–}

{ Report What Was Expected }

procedure Expected(s: string);

begin

Abort(s + ' Expected');

end;

{–}

{ Match a Specific Input Character }

procedure Match(x: char);

begin

if Look = x then GetChar

else Expected('''' + x + '''');

end;

{–}

{ Recognize an Alpha Character }

function IsAlpha(c: char): boolean;

begin

IsAlpha := UpCase(c) in ['A'..'Z'];

end;

{–}

{ Recognize a Decimal Digit }

function IsDigit(c: char): boolean;

begin

IsDigit := c in ['0'..