package org.jruby.util;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.runtime.ThreadContext;
import org.jruby.RubyHash;
import org.jruby.RubyArray;
import org.jruby.Ruby;
import static org.jruby.javasupport.util.RuntimeHelpers.invokedynamic;
import java.util.Set;
import java.util.HashSet;
public class RecursiveComparator
{
public static IRubyObject compare(ThreadContext context, final int method, IRubyObject a, IRubyObject b) {
Ruby runtime = context.getRuntime();
if (a == b) {
return runtime.getTrue();
}
boolean clear = false; // whether to clear thread-local set (at top comparison)
try {
Set<Pair> seen = null;
if (a instanceof RubyHash && b instanceof RubyHash ||
a instanceof RubyArray && b instanceof RubyArray) {
RecursiveComparator.Pair pair = new RecursiveComparator.Pair(a, b);
if ((seen = context.getRecursiveSet()) == null) {
context.setRecursiveSet(seen = new HashSet<Pair>());
clear = true;
}
else if (seen.contains(pair)) { // are we recursing?
return runtime.getTrue();
}
seen.add(pair);
}
if (a instanceof RubyHash) {
RubyHash hash = (RubyHash) a;
return hash.compare(context, method, b);
}
else if (a instanceof RubyArray) {
RubyArray array = (RubyArray) a;
return array.compare(context, method, b);
}
else {
return invokedynamic(context, a, method, b);
}
} finally {
if (clear) context.setRecursiveSet(null);
}
}
public static class Pair
{
private int a;
private int b;
public Pair(IRubyObject a, IRubyObject b) {
this.a = System.identityHashCode(a);
this.b = System.identityHashCode(b);
}
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other == null || !(other instanceof Pair)) {
return false;
}
Pair pair = (Pair) other;
return a == pair.a && b == pair.b;
}
@Override
public int hashCode() {
int result = a;
result = 31 * result + b;
return result;
}
}
}