Handle quosured symbols in nth handlers

mpadge · Jun 16, 2017 · fd6be86 · fd6be86
1 parent 5ba12b6
commit fd6be86
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Showing 2 changed files with 18 additions and 1 deletion.
diff --git a/src/hybrid_nth.cpp b/src/hybrid_nth.cpp
@@ -204,7 +204,7 @@ Result* nth_prototype(SEXP call, const ILazySubsets& subsets, int nargs) {
   if (tag != R_NilValue && tag != Rf_install("x")) {
     return 0;
   }
-  SEXP data = CADR(call);
+  SEXP data = maybe_rhs(CADR(call));
   if (TYPEOF(data) != SYMSXP)
     return 0;
 

diff --git a/tests/testthat/test-nth-value.R b/tests/testthat/test-nth-value.R
@@ -38,3 +38,20 @@ test_that("firsts uses default value for 0 length augmented vectors", {
   expect_equal(first(dt[0]), dt[NA])
   expect_equal(first(tm[0]), tm[NA])
 })
+
+test_that("handle quosured symbols in nth handlers", {
+  first <- last <- nth <- bad_hybrid_handler
+
+  expect_identical(
+    pull(summarise(mtcars, first(!! quo(cyl)))),
+    dplyr::first(mtcars$cyl)
+  )
+  expect_identical(
+    pull(summarise(mtcars, last(!! quo(cyl)))),
+    dplyr::last(mtcars$cyl)
+  )
+  expect_identical(
+    pull(summarise(mtcars, nth(!! quo(cyl), 2))),
+    dplyr::nth(mtcars$cyl, 2)
+  )
+})