Давайте создадим компилятор!   ::   Креншоу Джек

Я показал ее здесь полностью только для того, чтобы быть уверенным что все мы начинаем с одного места:



{–}

program Calls;

{–}

{ Constant Declarations }

const TAB = ^I;

CR = ^M;

LF = ^J;

{–}

{ Variable Declarations }

var Look: char; { Lookahead Character }

var ST: Array['A'..'Z'] of char;

{–}

{ 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;

{–}

{ Report an Undefined Identifier }

procedure Undefined(n: string);

begin

Abort('Undefined Identifier ' + n);

end;

{–}

{ Report an Duplicate Identifier }

procedure Duplicate(n: string);

begin

Abort('Duplicate Identifier ' + n);

end;

{–}

{ Get Type of Symbol }

function TypeOf(n: char): char;

begin

TypeOf := ST[n];

end;

{–}

{ Look for Symbol in Table }

function InTable(n: char): Boolean;

begin

InTable := ST[n] <> ' ';

end;

{–}

{ Add a New Symbol to Table }

procedure AddEntry(Name, T: char);

begin

if Intable(Name) then Duplicate(Name);

ST[Name] := T;

end;

{–}

{ Check an Entry to Make Sure It's a Variable }

procedure CheckVar(Name: char);

begin

if not InTable(Name) then Undefined(Name);

if TypeOf(Name) <> 'v' then Abort(Name + ' is not a

variable');

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'..