AST Visitor Pattern in Java
0
$begingroup$
I am trying to make a simple expression evaluator in Java using Jacc (a parser generator). I am done with the AST creation and now need to create an evaluator. For this I made a simple test to try to understand how visitors work. Here is my code
interface Visitor
{
public void visitB(B b);
public void visitC(C c);
public void visitD(D d);
}
class PrintVisitor implements Visitor
{
public void visitB(B b)
{
b.child1.accept(this);
b.child2.accept(this);
System.out.println("a B visited: " + b.name);
}
public void visitC(C c)
{
c.child.accept(this);
System.out.println("a C visited: " + c.name);
}
public void visitD(D d)
{
System.out.println("a D visited: " + d.name);
}
}
abstract class A
{
public String name;
abstract void accept(Visitor v);
}
class B extends A
{
public A child1;
public A child2;
public B(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitB(this);
}
}
class C extends A
{
public A child;
public C(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitC(this);
}
}
class D extends A
{
public D(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitD(this);
}
}
class Main
{
public static void main(String args)
{
B b1 = new B("b1");
B b2 = new B("b2");
C c1 = new C("c1");
C c2 = new C("c2");
D d1 = new D("d1");
D d2 = new D("d2");
D d3 = new D("d3");
D d4 = new D("d4");
/*
b1
/
c1 c2
/
b2 d2
/
d3 d4
*/
b1.child1 = c1;
b1.child2 = c2;
c1.child = b2;
c2.child = d2;
b2.child1 = d3;
b2.child2 = d4;
PrintVisitor v = new PrintVisitor();
b1.accept(v);
}
}
I would appreciate if you guys commented on my understanding of visitors.
java parsing visitor-pattern
asked 15 mins ago
AnonimistaAnonimista
111
$endgroup$
add a comment |
0
$begingroup$
I am trying to make a simple expression evaluator in Java using Jacc (a parser generator). I am done with the AST creation and now need to create an evaluator. For this I made a simple test to try to understand how visitors work. Here is my code
interface Visitor
{
public void visitB(B b);
public void visitC(C c);
public void visitD(D d);
}
class PrintVisitor implements Visitor
{
public void visitB(B b)
{
b.child1.accept(this);
b.child2.accept(this);
System.out.println("a B visited: " + b.name);
}
public void visitC(C c)
{
c.child.accept(this);
System.out.println("a C visited: " + c.name);
}
public void visitD(D d)
{
System.out.println("a D visited: " + d.name);
}
}
abstract class A
{
public String name;
abstract void accept(Visitor v);
}
class B extends A
{
public A child1;
public A child2;
public B(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitB(this);
}
}
class C extends A
{
public A child;
public C(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitC(this);
}
}
class D extends A
{
public D(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitD(this);
}
}
class Main
{
public static void main(String args)
{
B b1 = new B("b1");
B b2 = new B("b2");
C c1 = new C("c1");
C c2 = new C("c2");
D d1 = new D("d1");
D d2 = new D("d2");
D d3 = new D("d3");
D d4 = new D("d4");
/*
b1
/
c1 c2
/
b2 d2
/
d3 d4
*/
b1.child1 = c1;
b1.child2 = c2;
c1.child = b2;
c2.child = d2;
b2.child1 = d3;
b2.child2 = d4;
PrintVisitor v = new PrintVisitor();
b1.accept(v);
}
}
I would appreciate if you guys commented on my understanding of visitors.
java parsing visitor-pattern
asked 15 mins ago
AnonimistaAnonimista
111
$endgroup$
add a comment |
0
0
0
$begingroup$
I am trying to make a simple expression evaluator in Java using Jacc (a parser generator). I am done with the AST creation and now need to create an evaluator. For this I made a simple test to try to understand how visitors work. Here is my code
interface Visitor
{
public void visitB(B b);
public void visitC(C c);
public void visitD(D d);
}
class PrintVisitor implements Visitor
{
public void visitB(B b)
{
b.child1.accept(this);
b.child2.accept(this);
System.out.println("a B visited: " + b.name);
}
public void visitC(C c)
{
c.child.accept(this);
System.out.println("a C visited: " + c.name);
}
public void visitD(D d)
{
System.out.println("a D visited: " + d.name);
}
}
abstract class A
{
public String name;
abstract void accept(Visitor v);
}
class B extends A
{
public A child1;
public A child2;
public B(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitB(this);
}
}
class C extends A
{
public A child;
public C(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitC(this);
}
}
class D extends A
{
public D(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitD(this);
}
}
class Main
{
public static void main(String args)
{
B b1 = new B("b1");
B b2 = new B("b2");
C c1 = new C("c1");
C c2 = new C("c2");
D d1 = new D("d1");
D d2 = new D("d2");
D d3 = new D("d3");
D d4 = new D("d4");
/*
b1
/
c1 c2
/
b2 d2
/
d3 d4
*/
b1.child1 = c1;
b1.child2 = c2;
c1.child = b2;
c2.child = d2;
b2.child1 = d3;
b2.child2 = d4;
PrintVisitor v = new PrintVisitor();
b1.accept(v);
}
}
I would appreciate if you guys commented on my understanding of visitors.
java parsing visitor-pattern
asked 15 mins ago
AnonimistaAnonimista
111
$endgroup$
I am trying to make a simple expression evaluator in Java using Jacc (a parser generator). I am done with the AST creation and now need to create an evaluator. For this I made a simple test to try to understand how visitors work. Here is my code
interface Visitor
{
public void visitB(B b);
public void visitC(C c);
public void visitD(D d);
}
class PrintVisitor implements Visitor
{
public void visitB(B b)
{
b.child1.accept(this);
b.child2.accept(this);
System.out.println("a B visited: " + b.name);
}
public void visitC(C c)
{
c.child.accept(this);
System.out.println("a C visited: " + c.name);
}
public void visitD(D d)
{
System.out.println("a D visited: " + d.name);
}
}
abstract class A
{
public String name;
abstract void accept(Visitor v);
}
class B extends A
{
public A child1;
public A child2;
public B(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitB(this);
}
}
class C extends A
{
public A child;
public C(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitC(this);
}
}
class D extends A
{
public D(String name)
{
this.name = name;
}
@Override
void accept(Visitor v)
{
v.visitD(this);
}
}
class Main
{
public static void main(String args)
{
B b1 = new B("b1");
B b2 = new B("b2");
C c1 = new C("c1");
C c2 = new C("c2");
D d1 = new D("d1");
D d2 = new D("d2");
D d3 = new D("d3");
D d4 = new D("d4");
/*
b1
/
c1 c2
/
b2 d2
/
d3 d4
*/
b1.child1 = c1;
b1.child2 = c2;
c1.child = b2;
c2.child = d2;
b2.child1 = d3;
b2.child2 = d4;
PrintVisitor v = new PrintVisitor();
b1.accept(v);
}
}
I would appreciate if you guys commented on my understanding of visitors.
java parsing visitor-pattern
java parsing visitor-pattern
asked 15 mins ago
AnonimistaAnonimista
111
asked 15 mins ago
AnonimistaAnonimista
111
asked 15 mins ago
AnonimistaAnonimista
111
asked 15 mins ago
AnonimistaAnonimista
111
asked 15 mins ago
AnonimistaAnonimista
111
111
add a comment |
add a comment |
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