Add last.sift() to see last result

Closes #26

R/exp_last.sift.R

@@ -0,0 +1,56 @@
+
+
+#' View all matches from the most recent sift
+#'
+#' This is an alias for `utils::View(.Last.result)`, but its stores the last
+#' sift result so that it's accessible even if you've done other things
+#' since then.
+#'
+#' It returns the complete table of matches, i.e. even if there were too many
+#' results to print to the console, all results are visible here. If run in
+#' RStudio, it will open the results in the Viewer pane so that you can search,
+#' filter, resort, etc.
+#'
+#' @return
+#' Invisibly returns a dataframe.
+#'
+#' @export
+#' @md
+last.sift <- function() {
+    result <- get("last_sift", envir = .siftr_env)
+    deets  <- get("last_query", envir = .siftr_env)
+
+    if (identical(data.frame(), result)) {
+        # No sifts have been done.
+        cli::cli_inform(
+            message = c(
+                "x" = "No {.fn sift}s have been performed yet."
+            ))
+
+        return(invisible(data.frame()))
+    }
+
+    if (nrow(result) == 0) {
+        # A sift has been performed, but there were no results.
+        cli::cli_inform(
+            message = c(
+                "i" = "The last query was {.val {deets$query}} in the {deets$loc} of {.var {deets$df}}.",
+                "x" = "There were 0 matches out of {deets$total} variable{?s}.",
+                " " = "Showing the empty data frame anyway."))
+    } else {
+        cli::cli_inform(
+            message = c(
+                "i" = "The last query was {.val {deets$query}} in the {deets$loc} of {.var {deets$df}}.",
+                "v" = "There {cli::qty({deets$matches})} {?was/were} {deets$matches} match{?es} out of {deets$total} variable{?s}."))
+    }
+
+    # Retrieves the RStudio version of View() if it exists, otherwise gets the
+    # regular utils::View().
+    # https://stackoverflow.com/a/48242386/5578429
+    myView <- function(x, title) {
+        get("View", envir = as.environment("package:utils"))(x, title)
+    }
+
+    myView(result[, !(names(result) %in% "haystack")] , "Last sift")
+    return(invisible(result))
+}