presto-main/src/main/java/io/prestosql/sql/relational/StandardFunctionResolution.java/StandardFunctionResolution/comparisonFunction
class StandardFunctionResolution:    public ResolvedFunction comparisonFunction(ComparisonExpression.Operator operator, Type leftType, Type rightType)
    {
        OperatorType operatorType;
        switch (operator) {
            case EQUAL:
                operatorType = EQUAL;
                break;
            case NOT_EQUAL:
                operatorType = NOT_EQUAL;
                break;
            case LESS_THAN:
                operatorType = LESS_THAN;
                break;
            case LESS_THAN_OR_EQUAL:
                operatorType = LESS_THAN_OR_EQUAL;
                break;
            case GREATER_THAN:
                operatorType = GREATER_THAN;
                break;
            case GREATER_THAN_OR_EQUAL:
                operatorType = GREATER_THAN_OR_EQUAL;
                break;
            case IS_DISTINCT_FROM:
                operatorType = IS_DISTINCT_FROM;
                break;
            default:
                throw new IllegalStateException("Unsupported comparison operator type: " + operator);
        }

        return metadata.resolveOperator(operatorType, ImmutableList.of(leftType, rightType));
    }