feat: add is_polars_* functions (#658)

DESCRIPTION

@@ -93,6 +93,7 @@ Collate:
     'group_by.R'
     'info.R'
     'ipc.R'
+    'is_polars.R'
     'json.R'
     'lazyframe__group_by.R'
     'lazyframe__lazy.R'

NAMESPACE

@@ -182,6 +182,9 @@ export(.pr)
 export(as_polars_df)
 export(as_polars_lf)
 export(as_polars_series)
+export(is_polars_df)
+export(is_polars_lf)
+export(is_polars_series)
 export(pl)
 importFrom(stats,median)
 importFrom(stats,na.omit)

NEWS.md

@@ -7,6 +7,7 @@
 -   New methods `$str$reverse()`, `$str$contains_any()`, and `$str$replace_many()`
     (#641).
 -   New methods `$rle()` and `$rle_id()` (#648).
+-   New functions `is_polars_df()`, `is_polars_lf()`, `is_polars_series()` (#658).
 
 ### Miscellaneous
 

R/is_polars.R

@@ -0,0 +1,41 @@
+#' Test if the object is a polars DataFrame
+#'
+#' These functions test if the object is a polars DataFrame.
+#' @param x An object
+#' @return A logical value
+#' @export
+#' @examples
+#' is_polars_df(mtcars)
+#'
+#' is_polars_df(as_polars_df(mtcars))
+is_polars_df = function(x) {
+  inherits(x, "RPolarsDataFrame")
+}
+
+
+#' Test if the object is a polars LazyFrame
+#'
+#' These functions test if the object is a polars LazyFrame.
+#' @inherit is_polars_df params return
+#' @export
+#' @examples
+#' is_polars_lf(mtcars)
+#'
+#' is_polars_lf(as_polars_lf(mtcars))
+is_polars_lf = function(x) {
+  inherits(x, "RPolarsLazyFrame")
+}
+
+
+#' Test if the object is a polars Series
+#'
+#' These functions test if the object is a polars Series.
+#' @inherit is_polars_df params return
+#' @export
+#' @examples
+#' is_polars_series(1:3)
+#'
+#' is_polars_series(as_polars_series(1:3))
+is_polars_series = function(x) {
+  inherits(x, "RPolarsSeries")
+}

tests/testthat/test-is_polars.R

@@ -0,0 +1,17 @@
+make_is_polars_cases = function() {
+  tibble::tribble(
+    ~.test_name, ~is_func, ~as_func, ~x,
+    "is_polars_df", is_polars_df, as_polars_df, mtcars,
+    "is_polars_lf", is_polars_lf, as_polars_lf, mtcars,
+    "is_polars_series", is_polars_series, as_polars_series, 1:4,
+  )
+}
+
+patrick::with_parameters_test_that("is_polars_* functions",
+  {
+    polars_obj = as_func(x)
+    expect_true(is_func(polars_obj))
+    expect_false(is_func(x))
+  },
+  .cases = make_is_polars_cases()
+)