1 Prática: um pretty printer para SOL Giovanny Lucero Departamento de Estatística e Informática Universidade Federal de Sergipe Compiladores

2 Program(ClassDecs, Statement) ClassDec EmptyClassDec() ClassDeclaration(Symbol name, Symbol superclass, ClassInterf, ClassImp) SequenceClassDec(ClassDec, ClassDec) ClassInterf(VarDec, MethodHeader) ClassImp(VarDec, MethodDec)

3 VarDec EmptyVarDecs() VarDeclaration(Symbol, Type) SequenceVarDec(VarDec, VarDec) Em VarDeclaration não usamos IdList, pois é açucar sintático.

4 MethodHeader EmptyMehtodHeader() FunctionHeader(Symbol, VarDeclararionList, Type) ProcedureHeader(Symbol, VarDeclarationList) ConstructorHeader(VarDeclarationList) SequenceMethodHeader(MehtodHeader, MethodHeader)

5 MethodDec EmptyMethodDec() FunctionDec(Symbol, VarDeclararionList, Type, Expression) ProcedureDec(Symbol, VarDeclarationList, Statement) ConstructorDec(VarDeclarationList, Statement) SequenceMethodDec(MethodDec, MethodDec)

6 Type Primitive() IdType(Symbol) ArrayP(Primitive, int) ArrayO(Symbol, int) Primitivos: integer, character ou boolean Por simplicidade podemos, alternativamente, representar tipos com Strings ou Symbols.

7 Statement BlockStmt(varDecList, Statement) IfStmt(Expression, Statement, Statement) WhileStmt(Expression, Statement) PrintStmt(Expression) CallStmt(Expression target, Symbol name, ExpressionList) AssignStmt(Variable, Expression) SkipStmt() SequenceStmt(Statement, Statement) else condicional é açucar sintático f(x) é um açucar sintático de this.f(x)

8 Expression BlockExp(VarDec, Statement, Expression) BinaryBoolExp(int operand, Expression, Expression) BinaryArithmeticExp(int operand, Expression, Expression) BinaryComparissonExp(int operand, Expression, Expression) UnaryOperationExp(int operand, Expression, Expression)...

9 CallExp(Expression target, Symbol name, ExpressionList) VarExp(Variable) NewObjectExp(Symbol, ExpressionList) NewArrayExp(Type, Expression) IntLiteralExp(int) CharLiteralExp(char) BoolLiteralExp(bool) selfExp() nullExp()

10 Variable IdVar(Symbol) FieldVar(Expression target, Symbol field) ArrayElementVar(Expression target, Expression index)

11 SolVisitor interface SolVisitor { visitProgram(Program p); visitEmptyClassDec(EmptyClassDec dec); visitClassDeclaration(ClassDeclaration dec); visitSequenceClassDec(SequenceClassDec dec);.... visitAssignStmt(AssignStmt stm); }

12 class ClassDeclaration extends ClassDec {.... void accept(SolVisitor visitor) { visitor.visitClassDeclaration(this) } class AssingStmt extends Statement {.... void accept(SolVisitor visitor) { visitor.visitAssingStmt(this); } Sintaxe Abstrata com visitors

13 class AssignStmt extends Statement { Variable var; Expression exp; AssignStm(Variable var, Expression exp) { this.var = var; this.exp = exp; void accept(SolVisitor visitor) { visitor.visitAssingStmt(this); }

14 abstract class ClassDec { void abstract accept(SolVisitor visitor); }

15 Um Pretty Printer public class PrettySol implementes SolVisitor { private int indent = 0; private static int indInc = 3; private void indent() { indent += indInc; } private void unindent() { unindent -= indInc; } private void write(String st) { System.out.print(st); } private void writeln(String st) { System.out.println(st); char [] ws = Arrays.fill(new char[indent], ' '); System.out.print(new String(ws)); }

16 void visitProgram(Program p) { p.classDec.accept(this); writeln(“main”); indent(); p.main.accept(this); }

17 void visitBinaryArithmeticExp (BinaryArithmeticExp exp) { write (“( ”); exp.left.accept(this); switch (exp.operator) { case '+': write(“ + ”); break; case '*': write (“ * ”); break;... } exp.right.accept(this); write(“)”); }

18 void visitAssignStm(AssignStm stm) { stm.var.accept(this); write(" := "); stm.exp.accept(this); write(";") } void visitSequenceStmt(SequenceStmt stm) { stm.stm1.accept(this); writeln(""); stm.stm2.accept(this); }

19 void visitIfStm(IfStm stm) { write("if “); stm.exp.accept(this); writeln(“ then ”); indent(); stm.stm1.accept(this); unindent(); writeln(""); writeln("else "); indent(); stm.stm2.accept(this); unindent(); }