This set of S3 classes describe the action of dplyr verbs. These are currently used for SQL sources to separate the description of operations in R from their computation in SQL. This API is very new so is likely to evolve in the future.
lazy_base_query(x, vars, class = character(), ...)op_grps(op)
op_vars(op)
op_sort(op)
op_frame(op)
op_vars() and op_grps() compute the variables and groups from
a sequence of lazy operations. op_sort() and op_frame() tracks the
order and frame for use in window functions.