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begin

NextExpression;

SetNEqual;

end;

{–}

{ Recognize and Translate a Relational «Less Than» }

procedure Less;

begin

Next;

case Token of

'=': LessOrEqual;

'>': NotEqual;

else begin

CompareExpression;

SetLess;

end;

end;

end;

{–}

{ Recognize and Translate a Relational «Greater Than» }

procedure Greater;

begin

Next;

if Token = '=' then begin

NextExpression;

SetGreaterOrEqual;

end

else begin

CompareExpression;

SetGreater;

end;

end;

{–}

{ Parse and Translate a Relation }

procedure Relation;

begin

Expression;

if IsRelop(Token) then begin

Push;

case Token of

'=': Equal;

'<': Less;

'>': Greater;

end;

end;

end;

{–}

{ Parse and Translate a Boolean Factor with Leading NOT }

procedure NotFactor;

begin

if Token = '!' then begin

Next;

Relation;

NotIt;

end

else

Relation;

end;

{–}

{ Parse and Translate a Boolean Term }

procedure BoolTerm;

begin

NotFactor;

while Token = '&' do begin

Push;

Next;

NotFactor;

PopAnd;

end;

end;

{–}

{ Recognize and Translate a Boolean OR }

procedure BoolOr;

begin

Next;

BoolTerm;

PopOr;

end;

{–}

{ Recognize and Translate an Exclusive Or }

procedure BoolXor;

begin

Next;

BoolTerm;

PopXor;

end;

{–}

{ Parse and Translate a Boolean Expression }

procedure BoolExpression;

begin

BoolTerm;

while IsOrOp(Token) do begin

Push;

case Token of

'|': BoolOr;

'~': BoolXor;

end;

end;

end;

{–}

{ Parse and Translate an Assignment Statement }

procedure Assignment;

var Name: string;

begin

CheckTable(Value);

Name := Value;

Next;

MatchString('=');

BoolExpression;

Store(Name);

end;

{–}

{ Recognize and Translate an IF Construct }

procedure Block; Forward;

procedure DoIf;

var L1, L2: string;

begin

Next;

BoolExpression;

L1 := NewLabel;

L2 := L1;

BranchFalse(L1);

Block;

if Token = 'l' then begin

Next;

L2 := NewLabel;

Branch(L2);

PostLabel(L1);

Block;

end;

PostLabel(L2);

MatchString('ENDIF');

end;

{–}

{ Parse and Translate a WHILE Statement }

procedure DoWhile;

var L1, L2: string;

begin

Next;

L1 := NewLabel;

L2 := NewLabel;

PostLabel(L1);

BoolExpression;

BranchFalse(L2);

Block;

MatchString('ENDWHILE');

Branch(L1);

PostLabel(L2);

end;

{–}

{ Read a Single Variable }

procedure ReadVar;

begin

CheckIdent;

CheckTable(Value);

ReadIt(Value);

Next;

end;

{–}

{ Process a Read Statement }

procedure DoRead;

begin

Next;

MatchString('(');

ReadVar;

while Token = ',' do begin

Next;

ReadVar;

end;

MatchString(')');

end;

{–}

{ Process a Write Statement }

procedure DoWrite;

begin

Next;

MatchString('(');

Expression;

WriteIt;

while Token = ',' do begin

Next;

Expression;

WriteIt;

end;

MatchString(')');

end;

{–}

{ Parse and Translate a Block of Statements }

procedure Block;

begin

Scan;

while not(Token in ['e', 'l']) do begin

case Token of

'i': DoIf;

'w': DoWhile;

'R': DoRead;

'W': DoWrite;

else Assignment;

end;

Scan;

end;

end;

{–}

{ Allocate Storage for a Variable }

procedure Alloc;

begin

Next;

if Token <> 'x' then Expected('Variable Name');

CheckDup(Value);

AddEntry(Value, 'v');

Allocate(Value, '0');

Next;

end;

{–}

{ Parse and Translate Global Declarations }

procedure TopDecls;

begin

Scan;

while Token = 'v' do

Alloc;

while Token = ',' do

Alloc;

end;

{–}

{ Initialize }

procedure Init;

begin

GetChar;

Next;


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