Add param sep2

DESCRIPTION

@@ -5,6 +5,8 @@ Authors@R: c(
     person("Gábor", "Csárdi", , "[email protected]", role = c("aut", "cre")),
     person("Hadley", "Wickham", role = "ctb"),
     person("Kirill", "Müller", role = "ctb"),
+    person("Salim", "Brüggemann", , "[email protected]", role = "ctb",
+           comment = c(ORCID = "0000-0002-5329-5987")),
     person("RStudio", role = c("cph", "fnd"))
   )
 Description: A suite of tools to build attractive command line interfaces

NEWS.md

@@ -3,6 +3,12 @@
 * `ansi_collapse(x, trunc = 1, style = "head")` now indeed show one element
   if `length(x) == 2`, as documented (@salim-b, #572).
 
+* `ansi_collapse()` gains a `sep2` argument to specify a seperate separator
+  for length-two inputs. It defaults to `" and "` which, in conjunction with
+  the other defaults, produces a collapsed string that fully adheres to the
+  [serial comma](https://en.wikipedia.org/wiki/Serial_comma) rules.
+  (@salim-b, #569)
+
 * `ansi_string()` is now an exported function (@multimeric, #573).
 
 # cli 3.6.1

R/glue.R

@@ -66,8 +66,9 @@ drop_null <- function(x) {
 #' @description
 #' Features:
 #'
-#' - custom separator,
-#' - custom last separator: `last` argument,
+#' - custom separator (`sep`),
+#' - custom separator for length-two input (`sep2`),
+#' - custom last separator (`last`),
 #' - adds ellipsis to truncated strings,
 #' - uses Unicode ellipsis character on UTF-8 console,
 #' - can collapse "from both ends", with `style = "both-ends"`,
@@ -76,9 +77,12 @@ drop_null <- function(x) {
 #'
 #' @param x Character vector, or an object with an `as.character()` method
 #' to collapse.
-#' @param sep Character string, separator.
+#' @param sep Separator. A character string.
+#' @param sep2 Separator for the special case that `x` contains only two
+#' elements. A character string.
 #' @param last Last separator, if there is no truncation. E.g. use
-#' `", and "` for the Oxford comma.
+#' `", and "` for the [serial
+#' comma](https://en.wikipedia.org/wiki/Serial_comma). A character string.
 #' @param trunc Maximum number of elements to show. For `style = "head"`
 #' at least `trunc = 1` is used. For `style = "both-ends"` at least
 #' `trunc = 5` is used, even if a smaller number is specified.
@@ -94,10 +98,10 @@ drop_null <- function(x) {
 #'   and skips elements in the middle if needed.
 #' * `head`: shows the beginning of the vector, and skips elements at the
 #'   end, if needed.
-#' @return Character scalar. It is `NA_character_` if any elements in the
-#' vector are `NA`.
+#' @return Character scalar. It is `NA_character_` if any elements in `x`
+#' are `NA`.
 #'
-#' @seealso `glue_collapse` in the glue package inspired this function
+#' @seealso `glue_collapse` in the glue package inspired this function.
 #' @export
 #' @examples
 #' ansi_collapse(letters)
@@ -108,21 +112,26 @@ drop_null <- function(x) {
 #' # head style
 #' ansi_collapse(letters, trunc = 5, style = "head")
 
-ansi_collapse <- function(x, sep = ", ", last = ", and ", trunc = Inf,
-                          width = Inf, ellipsis = symbol$ellipsis,
+ansi_collapse <- function(x, sep = ", ", sep2 = " and ", last = ", and ",
+                          trunc = Inf, width = Inf, ellipsis = symbol$ellipsis,
                           style = c("both-ends", "head")) {
 
   style <- match.arg(style)
   switch(
     style,
-    "both-ends" = collapse_both_ends(x, sep, last, trunc, width, ellipsis),
-    "head" = collapse_head(x, sep, last, trunc, width, ellipsis)
+    "both-ends" = collapse_both_ends(
+      x, sep, sep2, last, trunc, width, ellipsis
+    ),
+    "head" = collapse_head(x, sep, sep2, last, trunc, width, ellipsis)
   )
 }
 
-collapse_head_notrim <- function(x, trunc, sep, last, ellipsis) {
+collapse_head_notrim <- function(x, trunc, sep, sep2, last, ellipsis) {
+
   lnx <- length(x)
+
   if (lnx == 1L) return(x)
+  if (lnx == 2L) return(paste0(x, collapse = sep2))
   if (lnx <= trunc) {
     # no truncation
     return(paste0(
@@ -140,8 +149,7 @@ collapse_head_notrim <- function(x, trunc, sep, last, ellipsis) {
   }
 }
 
-collapse_head <- function(x, sep = ", ", last = ", and ", trunc = Inf,
-                          width = Inf, ellipsis = symbol$ellipsis) {
+collapse_head <- function(x, sep, sep2, last, trunc, width, ellipsis) {
 
   trunc <- max(trunc, 1L)
   x <- as.character(x)
@@ -156,7 +164,7 @@ collapse_head <- function(x, sep = ", ", last = ", and ", trunc = Inf,
 
   # easier case, no width trimming
   if (width == Inf) {
-    return(collapse_head_notrim(x, trunc, sep, last, ellipsis))
+    return(collapse_head_notrim(x, trunc, sep, sep2, last, ellipsis))
   }
 
   # complex case, with width wrapping
@@ -165,23 +173,29 @@ collapse_head <- function(x, sep = ", ", last = ", and ", trunc = Inf,
   if (tcd) x <- x[1:trunc]
 
   # then we calculate the width w/o trimming
-  wx <- ansi_nchar(x)
-  wsep <- ansi_nchar(sep, "width")
-  wlst <- ansi_nchar(last, "width")
-  well <- ansi_nchar(ellipsis, "width")
+  wx    <- ansi_nchar(x)
+  wsep  <- ansi_nchar(sep, "width")
+  wsep2 <- ansi_nchar(sep2, "width")
+  wlast <- ansi_nchar(last, "width")
+  well  <- ansi_nchar(ellipsis, "width")
   if (!tcd) {
     # x[1]
-    # x[1], and x[2]
+    # x[1] and x[2]
     # x[1], x[2], and x[3]
-    nsep <- if (lnx >= 2) lnx - 2L else 0L
-    nlst <- if (lnx >= 2) 1L else 0L
-    wtot <- sum(wx) + nsep * wsep + nlst * wlst
+    nsep  <- if (lnx > 2L) lnx - 2L else 0L
+    nsep2 <- if (lnx == 2L) 1L else 0L
+    nlast <- if (lnx > 2L) 1L else 0L
+    wtot  <- sum(wx) + nsep * wsep + nsep2 * wsep2 + nlast * wlast
     if (wtot <= width) {
-      return(paste0(
-        paste(x[1:(lnx - 1L)], collapse = sep),
-        last,
-        x[lnx]
-      ))
+      if (lnx == 2L) {
+        return(paste0(x, collapse = sep2))
+      } else {
+        return(paste0(
+          paste(x[1:(lnx - 1L)], collapse = sep),
+          last,
+          x[lnx]
+        ))
+      }
     }
 
   } else {
@@ -226,8 +240,7 @@ collapse_head <- function(x, sep = ", ", last = ", and ", trunc = Inf,
   ))
 }
 
-collapse_both_ends <- function(x, sep = ", ", last = ", and ", trunc = Inf,
-                               width = Inf, ellipsis = symbol$ellipsis) {
+collapse_both_ends <- function(x, sep, sep2, last, trunc, width, ellipsis) {
 
   if (width != Inf) {
     warning(format_warning(c(
@@ -240,8 +253,8 @@ collapse_both_ends <- function(x, sep = ", ", last = ", and ", trunc = Inf,
   # we always list at least 5 elements
   trunc <- max(trunc, 5L)
   trunc <- min(trunc, length(x))
-  if (length(x) <= 5 || length(x) <= trunc) {
-    return(collapse_head(x, sep, last, trunc = trunc, width, ellipsis))
+  if (length(x) <= 5L || length(x) <= trunc) {
+    return(collapse_head(x, sep, sep2, last, trunc = trunc, width, ellipsis))
   }
 
   # we have at least six elements in the vector

R/inline.R

@@ -44,18 +44,16 @@ inline_generic <- function(app, x, style) {
 
 inline_collapse <- function(x, style = list()) {
   sep <- style[["vec-sep"]] %||% style[["vec_sep"]] %||% ", "
-  if (length(x) >= 3) {
-    last <- style[["vec-last"]] %||% style[["vec_last"]] %||% ", and "
-  } else {
-    last <- style[["vec-sep2"]] %||% style[["vec_sep2"]] %||% style[["vec-last"]] %||%
-      style[["vec_last"]] %||% " and "
-  }
+  sep2 <- style[["vec-sep2"]] %||% style[["vec_sep2"]] %||% " and "
+  last <- style[["vec-last"]] %||% style[["vec_last"]] %||% ", and "
+
   trunc <- style[["vec-trunc"]] %||% style[["vec_trunc"]] %||% 20L
   col_style <- style[["vec-trunc-style"]] %||% "both-ends"
 
   ansi_collapse(
     x,
     sep = sep,
+    sep2 = sep2,
     last = last,
     trunc = trunc,
     style = col_style

tests/testthat/_snaps/collapsing.md

@@ -81,7 +81,7 @@
     Code
       cli_text("{v(2,1)}")
     Message
-      1, ...
+      1 and 2
     Code
       cli_text("{v(3,1)}")
     Message

tests/testthat/test-collapsing.R

@@ -190,3 +190,10 @@ test_that("ansi_collapse produces consistent truncation results", {
   expect_equal(ansi_collapse(1:2, trunc = 1, style = "head"),
                ansi_collapse(1:2, trunc = 0, style = "head"))
 })
+
+test_that("ansi_collapse uses `sep2` for length-two inputs", {
+  expect_equal(ansi_collapse(1:2),
+               "1 and 2")
+  expect_equal(ansi_collapse(1:2, trunc = 2, style = "head"),
+               "1 and 2")
+})