Unquoting RHS of magrittr pipe with quosure support

magrittr-tidy-eval.R

# Actually does not work because quosured magrittr pronouns are not
# evaluated in the right environment


library("magrittr")
library("rlang")

# Anticipate renaming of `quo_is_lang()` in rlang
quo_is_call <- quo_is_lang

quo_call_smash <- function(quo) {
  if (!quo_is_call(quo)) {
    abort("Expected quosured call")
  }

  expr <- duplicate(get_expr(quo), shallow = TRUE)
  env <- get_env(quo)

  rest <- expr
  while (!is_null(rest)) {
    node_poke_car(rest, new_quosure(node_car(rest), env))
    rest <- node_cdr(rest)
  }

  expr
}

`%foo%` <- function(lhs, rhs) {
  rhs <- enquo(rhs)
  lhs <- enquo(lhs)

  if (quo_is_call(rhs)) {
    eval_tidy(quo(`%>%`(!!lhs, !!quo_call_smash(rhs))))
  } else {
    eval_tidy(quo(`%>%`(!!lhs, (!!rhs)())))
  }
}

(!!letters) %foo% toupper
letters %foo% toupper()