tbl-lazy.R

tbl_lazy <- function(df) {
  make_tbl("lazy", ops = op_base_local(df, env = parent.frame()))
}

lazy_frame <- function(...) {
  tbl_lazy(data_frame(...))
}

#' @export
same_src.tbl_lazy <- function(x, y) {
  inherits(y, "tbl_lazy")
}

#' @export
tbl_vars.tbl_lazy <- function(x) {
  op_vars(x$ops)
}

#' @export
groups.tbl_lazy <- function(x) {
  lapply(op_grps(x$ops), as.name)
}

#' @export
print.tbl_lazy <- function(x, ...) {
  cat("Source: lazy\n")
  cat("Vars  : ", commas(op_vars(x$ops)), "\n", sep = "")
  cat("Groups: ", commas(op_grps(x$ops)), "\n", sep = "")
  cat("\n")

  print(x$ops)
}

# Single table methods ----------------------------------------------------

#' @export
filter_.tbl_lazy <- function(.data, ..., .dots) {
  dots <- lazyeval::all_dots(.dots, ...)
  add_op_single("filter", .data, dots = dots)
}

#' @export
arrange_.tbl_lazy <- function(.data, ..., .dots) {
  dots <- lazyeval::all_dots(.dots, ...)
  add_op_single("arrange", .data, dots = dots)
}

#' @export
select_.tbl_lazy <- function(.data, ..., .dots) {
  dots <- lazyeval::all_dots(.dots, ...)
  add_op_single("select", .data, dots = dots)
}

#' @export
rename_.tbl_lazy <- function(.data, ..., .dots) {
  dots <- lazyeval::all_dots(.dots, ...)
  add_op_single("rename", .data, dots = dots)
}

#' @export
summarise_.tbl_lazy <- function(.data, ..., .dots) {
  dots <- lazyeval::all_dots(.dots, ...)
  add_op_single("summarise", .data, dots = dots)
}

#' @export
mutate_.tbl_lazy <- function(.data, ..., .dots) {
  dots <- lazyeval::all_dots(.dots, ..., all_named = TRUE)
  add_op_single("mutate", .data, dots = dots)
}

#' @export
group_by_.tbl_lazy <- function(.data, ..., .dots, add = TRUE) {
  dots <- lazyeval::all_dots(.dots, ..., all_named = TRUE)
  add_op_single("group_by", .data, dots = dots, args = list(add = add))
}

#' @export
head.tbl_lazy <- function(x, n = 6L, ...) {
  add_op_single("head", x, args = list(n = n))
}

#' @export
ungroup.tbl_lazy <- function(x, ...) {
  add_op_single("ungroup", x)
}

#' @export
distinct_.tbl_lazy <- function(.data, ..., .dots, .keep_all = FALSE) {
  dots <- lazyeval::all_dots(.dots, ..., all_named = TRUE)
  add_op_single("distinct", .data, dots = dots, args = list(.keep_all = .keep_all))
}


# Dual table verbs ------------------------------------------------------------

add_op_join <- function(x, y, type, by = NULL, copy = FALSE,
                        suffix = c(".x", ".y"),
                        auto_index = FALSE, ...) {
  by <- common_by(by, x, y)
  y <- auto_copy(x, y, copy, indexes = if (auto_index) list(by$y))

  x$ops <- op_double("join", x, y, args = list(
    type = type,
    by = by,
    suffix = suffix
  ))
  x
}

add_op_semi_join <- function(x, y, anti = FALSE, by = NULL, copy = FALSE,
                             auto_index = FALSE, ...) {
  by <- common_by(by, x, y)
  y <- auto_copy(x, y, copy, indexes = if (auto_index) list(by$y))

  x$ops <- op_double("semi_join", x, y, args = list(
    anti = anti,
    by = by
  ))
  x
}

add_op_set_op <- function(x, y, type, copy = FALSE, ...) {
  y <- auto_copy(x, y, copy)
  x$ops <- op_double("set_op", x, y, args = list(type = type))
  x
}

# Currently the dual table verbs are defined on tbl_sql, because the
# because they definitions are bit too tightly connected to SQL.