presto-parser/src/main/java/io/prestosql/sql/parser/AstBuilder.java/AstBuilder/visitPosition
class AstBuilder:    @Override
    public Node visitPosition(SqlBaseParser.PositionContext context)
    {
        List<Expression> arguments = Lists.reverse(visit(context.valueExpression(), Expression.class));
        return new FunctionCall(getLocation(context), QualifiedName.of("strpos"), arguments);
    }