R/match-arg.R

In jmbarbone/mark: Miscellaneous, Analytic R Kernels

#' Match arguments
#'
#' Match arguments
#'
#' @description
#' This function is essentially a clear version of [base::match.arg()] which
#'   produces a cleaner warning message and does not restrict the `table` param
#'   to `character` vectors only.
#'
#' @param x An argument
#' @param table A table of choices
#' @return A single value from `x` matched on `table`
#'
#' @seealso [match_param()]
#' @examples
#' x <- c("apple", "banana", "orange")
#' match_arg("b", x)
#'
#' # Produces error
#' try(match_arg("pear", x))
#'
#' foo <- function(x, op = c(1, 2, 3)) {
#'   op <- match_arg(op)
#'   x / op
#' }
#'
#' foo(10, 3)
#'
#' # Error
#' try(foo(1, 0))
#' @export
match_arg <- function(x, table) {
  if (is.null(x)) {
    return(NULL)
  }

  if (missing(table)) {
    sp <- sys.parent()
    args <- formals(sys.function(sp))
    table <- eval(args[[as.character(substitute(x))]], envir = sys.frame(sp))
  }

  out <- table[pmatch(x[1], table, nomatch = 0L, duplicates.ok = FALSE)]

  if (!length(out)) {
    csx <- as.character(substitute(x))
    stop(cond_match_arg(csx, x, table))
  }

  out
}

#' Match params
#'
#' Param matching for an argument
#'
#' @description Much like [base::match.arg()] with a few key differences:
#' * Will not perform partial matching
#' * Will not return error messages with ugly quotation marks
#'
#' @param param The parameter
#' @param choices The available choices; named lists will return the name (a
#'   character) for when matched to the value within the list element.  A list
#'   of formula objects (preferred) retains the LHS of the formula as the return
#'   value when matched to the RHS of the formula.
#' @param null If `TRUE` allows `NULL` to be passed a `param`
#' @param partial If `TRUE` allows partial matching via [pmatch()]
#' @param multiple If `TRUE` allows multiple values to be returned
#' @param simplify If `TRUE` will simplify the output to a single value
#' @return A single value from `param` matched on `choices`
#'
#' @seealso [match_arg()]
#' @examples
#' fruits <- function(x = c("apple", "banana", "orange")) {
#'   match_param(x)
#' }
#'
#' fruits()         # apple
#' try(fruits("b")) # must be exact fruits("banana")
#'
#' pfruits <- function(x = c("apple", "apricot", "banana")) {
#'   match_param(x, partial = TRUE)
#' }
#' pfruits()          # apple
#' try(pfruits("ap")) # matchParamMatchError
#' pfruits("app")     # apple
#'
#' afruits <- function(x = c("apple", "banana", "orange")) {
#'   match_param(x, multiple = TRUE)
#' }
#'
#' afruits() # apple, banana, orange
#'
#' # can have multiple responses
#' how_much <- function(x = list(too_few = 0:2, ok = 3:5, too_many = 6:10)) {
#'   match_param(x)
#' }
#'
#' how_much(1)
#' how_much(3)
#' how_much(9)
#'
#' # use a list of formulas instead
#' ls <- list(1L ~ 0:1, 2L, 3L ~ 3:5)
#' sapply(0:5, match_param, choices = ls)
#' @export
match_param <- function(
    param,
    choices,
    null = TRUE,
    partial = getOption("mark.match_param.partial", FALSE),
    multiple = FALSE,
    simplify = TRUE
) {
  param_c <- charexpr(substitute(param))
  force(param)

  if (is.null(param)) {
    if (null) {
      return(NULL)
    }

    stop(cond_match_param_null())
  }

  missing_choices <- missing(choices)
  if (missing_choices) {
    parent <- sys.parent()
    forms <- formals(sys.function(parent))
    choices <- eval(forms[[param_c]], envir = parent)
  }

  mparam <- cleanup_param_list(param)
  mchoices <- cleanup_param_list(choices)

  if (anyDuplicated(unlist(mchoices$choices))) {
    # TODO implement cond_match_param_dupes()
    stop(cond_match_param_dupes(choices))
  }

  fun <- if (partial) pmatch else match
  m <- fun(mparam$choices, mchoices$choices, nomatch = NA_integer_)

  if (!multiple && length(m)) {
    m <- m[1L]
  }

  ocall <- outer_call()
  if (no_length(param) || identical(m, NA_integer_)) {
    if (is_length0(param)) {
      param <- deparse(param)
    }

    stop(cond_match_param_match(
      input = param_c,
      argument = ocall,
      param = param,
      choices = choices
    ))
  }

  res <- lapply(m, function(i) mchoices$values[[i]])

  if (simplify) {
    res <- unlist0(res)
  }

  res
}

cleanup_param_list <- function(x) {
  x <- as.list(x)
  env <- parent.frame()

  eval_expr <- function(x, i) {
    eval(as.expression(x[[i]]), env)
  }

  out <- list(values = NULL, choices = NULL)
  nms <- names(x)
  for (i in seq_along(x)) {
    if (inherits(x[[i]], "formula")) {
      out$values[[i]] <- eval_expr(x[[i]], 2L)
      out$choices[[i]] <- eval_expr(x[[i]], 3L)
    } else {
      out$values[[i]] <- if (isTRUE(nzchar(nms[i]))) nms[i] else x[[i]]
      out$choices[[i]] <- x[[i]]
    }
  }

  out$values <- rep(out$values, lengths(out$choices))
  out$choices <- unlist(lapply(out$choices, as.list), recursive = FALSE)
  out
}

# conditions --------------------------------------------------------------

cond_match_arg <- function(csx, x, table) {
  table <-  collapse(table, sep = "\', \'")
  new_condition(
    sprintf(
      "%s : '%s' did not match of of the following:\n   '%s'",
      csx, x, table
    ),
    "cond_match_arg"
  )
}

cond_match_param_null <- function() {
  new_condition(
    "match_param() requires non-NULL params",
    "cond_match_param_null"
  )
}

cond_match_param_match <- function(
    input,
    argument,
    param,
    choices
) {
  to_value <- function(x) {
    if (all(names(x) == as.character(x))) {
      return(toString(x))
    }

    nms <- names(x)
    if (is.null(nms)) {
      return(toString(x))
    }

    ok <- nzchar(nms)
    nms[ok] <- paste(nms[ok], "= ")
    toString(paste0(nms, x))
  }

  to_options <- function(x) {
    if (all(names(x) == as.character(x))) {
      return(toString(x))
    }

    collapse(mapply(
      function(x, nm) {
        if (nzchar(nm)) {
          sprintf("%s = %s", nm, toString(x))
        } else {
          toString(x)
        }
      },
      x = x,
      nm = names(x),
      USE.NAMES = FALSE
    ), sep = " | ")
  }

  msg <- sprintf(
    paste0(
      "`match_param(%s)` failed in `%s`:\n",
      "  param    %s\n",
      "  choices  %s"
    ),
    input,
    argument,
    to_value(param),
    to_options(choices)
  )

  new_condition(msg, "match_param_match")
}

cond_match_param_dupes <- function(choices) {
  to_choices <- function(x) {
    if (all(names(x) == as.character(x))) {
      dupe <- duplicated(x)
      x[dupe] <- paste0(x[dupe], "*")
      return(toString(x))
    }

    collapse(mapply(
      function(x, nm, d) {
        sprintf(
          "%s = %s",
          nm,
          toString(paste0(x, ifelse(d, "*", "")))
        )
      },
      x = x,
      nm = names(x),
      d = split(
        duplicated(unlist(x)),
        rep(seq_along(x), lengths(x))
      ),
      USE.NAMES = FALSE
    ), sep = "\n  ")
  }

  new_condition(
    msg = paste0(
      "duplicate values found in `choices`:\n  ",
      to_choices(choices)
    ),
    class = "match_param_dupes"
  )
}