as_map() keeps attributes (#186)

Co-authored-by: Hadley Wickham <[email protected]>

NEWS.md

@@ -1,5 +1,6 @@
 # waldo (development version)
 
+* `as_map()` now preserves attributes (#185).
 * `compare()` can now distinguish between objects that differ only in the value of their S4 bit (#189).
 * Double comparisons now always display one more digit than the absolute minimum necessary (#141).
 * waldo no longer imports tibble and rematch2 (@olivroy, #196).

R/utils.R

@@ -156,9 +156,10 @@ compact <- function(x) {
 }
 
 as_map <- function(x) {
+  attr <- attributes(x)
+
   # Remove nulls
-  is_null <- vapply(x, is.null, logical(1))
-  x <- x[!is_null]
+  x <- compact(x)
 
   # Sort named components, preserving positions of unnamed
   nx <- names2(x)
@@ -169,6 +170,11 @@ as_map <- function(x) {
     x <- x[idx]
   }
 
+  # Restore attributes (which might have been lost by [)
+  new_attr <- attributes(x)
+  attr[names(new_attr)] <- new_attr
+  attributes(x) <- attr
+
   x
 }
 

tests/testthat/test-utils.R

@@ -1,3 +1,10 @@
+test_that("as_map() keeps attributes", {
+  expect_equal(
+    as_map(structure(list(b = 1, a = 2), attr1 = "a")),
+    structure(list(a = 2, b = 1), attr1 = "a")
+  )
+})
+
 test_that("as_map() leaves unnnamed components alone", {
   expect_equal(as_map(c(c = 5, 2, b = 3, 4, a = 1)), c(a = 1, 2, b = 3, 4, c = 5))
   expect_equal(as_map(c(c = 3, b = 2, a = 1)), c(a = 1, b = 2, c = 3))