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package composite.one;
public interface Expr {
int eval();
}
final class Const implements Expr {
private final int v;
public Const(int v) {
this.v = v;
}
public int eval() {
return v;
}
public String toString() {
return Integer.toString(v);
}
}
final class Plus implements Expr {
private final Expr l;
private final Expr r;
public Plus(Expr l, Expr r) {
if ((l == null) || (r == null)) {
throw new IllegalArgumentException();
}
this.l = l;
this.r = r;
}
public int eval() {
return l.eval() + r.eval();
}
public String toString() {
return l.toString() + " " + r.toString() + " +";
}
}
final class Minus implements Expr {
private final Expr l;
private final Expr r;
public Minus(Expr l, Expr r) {
if ((l == null) || (r == null)) {
throw new IllegalArgumentException();
}
this.l = l;
this.r = r;
}
public int eval() {
return l.eval() - r.eval();
}
public String toString() {
return l.toString() + " " + r.toString() + " -";
}
}
final class Mult implements Expr {
private final Expr l;
private final Expr r;
public Mult(Expr l, Expr r) {
if ((l == null) || (r == null)) {
throw new IllegalArgumentException();
}
this.l = l;
this.r = r;
}
public int eval() {
return l.eval() * r.eval();
}
public String toString() {
return l.toString() + " " + r.toString() + " *";
}
}
final class Quot implements Expr {
private final Expr l;
private final Expr r;
public Quot(Expr l, Expr r) {
if ((l == null) || (r == null)) {
throw new IllegalArgumentException();
}
this.l = l;
this.r = r;
}
public int eval() {
return l.eval() / r.eval();
}
public String toString() {
return l.toString() + " " + r.toString() + " /";
}
}
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