--- /dev/null
+package org.simantics.scl.compiler.elaboration.java;
+
+import org.simantics.scl.compiler.elaboration.expressions.EVariable;
+import org.simantics.scl.compiler.elaboration.expressions.Variable;
+import org.simantics.scl.compiler.elaboration.query.compilation.QueryCompilationContext;
+import org.simantics.scl.compiler.elaboration.relations.AbstractRelation;
+import org.simantics.scl.compiler.types.TVar;
+import org.simantics.scl.compiler.types.Type;
+import org.simantics.scl.compiler.types.Types;
+import org.simantics.scl.compiler.types.kinds.Kinds;
+
+public class EqRelation extends AbstractRelation {
+ public static final EqRelation INSTANCE = new EqRelation();
+
+ private EqRelation() {}
+
+ private static final TVar A = Types.var(Kinds.STAR);
+
+ private static final TVar[] TYPE_VARIABLES = new TVar[] {A};
+
+ @Override
+ public TVar[] getTypeVariables() {
+ return TYPE_VARIABLES;
+ }
+
+ private static final Type[] PARAMETER_TYPES = new Type[] {A, A};
+
+ @Override
+ public Type[] getParameterTypes() {
+ return PARAMETER_TYPES;
+ }
+
+ @Override
+ public int getPhase() {
+ return 0;
+ }
+
+ @Override
+ public double getSelectivity(int boundVariables) {
+ switch(boundVariables) {
+ case FF: return Double.POSITIVE_INFINITY;
+ case BF:
+ case FB: return 1.0;
+ case BB: return 0.1;
+ default: throw new IllegalArgumentException();
+ }
+ }
+
+ @Override
+ public int getRequiredVariablesMask() {
+ return FF;
+ }
+
+ @Override
+ public void generate(long location,
+ QueryCompilationContext context,
+ Type[] typeParameters, Variable[] parameters, int boundVariables) {
+ switch(boundVariables) {
+ case BF:
+ context.let(parameters[1], new EVariable(parameters[0]));
+ break;
+ case FB:
+ context.let(parameters[0], new EVariable(parameters[1]));
+ break;
+ case BB:
+ context.equalityCondition(location,
+ new EVariable(parameters[0]),
+ new EVariable(parameters[1]));
+ break;
+ default: throw new IllegalArgumentException();
+ }
+ }
+
+ @Override
+ public String toString() {
+ return "=";
+ }
+
+}