From 8a13a511de5a668b08e2fc8238b21ce6ee262cfd Mon Sep 17 00:00:00 2001
From: Nick Christofides <118103879+NicChr@users.noreply.github.com>
Date: Fri, 5 Apr 2024 08:36:53 +0100
Subject: [PATCH] Updated cpp_sset_range to use 'R_xlen_t' throughout and
 updated documentation.

---
 R/sset.R     |  9 ++++++++-
 man/sset.Rd  | 10 +++++++++-
 src/sset.cpp |  6 +++---
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/R/sset.R b/R/sset.R
index 8d619d9..d1950a4 100644
--- a/R/sset.R
+++ b/R/sset.R
@@ -16,7 +16,7 @@
 #' `sset` will fall back on using `[` when no suitable method is found.
 #'
 #' To get into more detail, using `sset()` on a data frame, a new
-#' list is always allocated through `cheapr:::cpp_new_list()`.
+#' list is always allocated through `new_list()`.
 #'
 #' ### Difference to base R
 #'
@@ -25,6 +25,13 @@
 #' is not recycled, so it is good practice to make sure the logical vector
 #' matches the length of x. To return `NA` values, use `x[NA_integer_]`.
 #'
+#' ### ALTREP range subsetting
+#'
+#' When `i` is an ALTREP compact integer sequence which can be commonly created
+#' using e.g. `1:10` or using `seq_len`, `seq_along` and `seq.int`,
+#' `sset` internally uses a range-based subsetting which is faster and doesn't
+#' allocate `i` into memory.
+#'
 #' @examples
 #' library(cheapr)
 #' library(bench)
diff --git a/man/sset.Rd b/man/sset.Rd
index 2f77435..7a484e4 100644
--- a/man/sset.Rd
+++ b/man/sset.Rd
@@ -50,7 +50,7 @@ You can either write methods for \code{sset} or \code{[}. \cr
 \code{sset} will fall back on using \code{[} when no suitable method is found.
 
 To get into more detail, using \code{sset()} on a data frame, a new
-list is always allocated through \code{cheapr:::cpp_new_list()}.
+list is always allocated through \code{new_list()}.
 \subsection{Difference to base R}{
 
 When \code{i} is a logical vector, it is passed directly to \code{which_()}. \cr
@@ -58,6 +58,14 @@ This means that \code{NA} values are ignored and this also means that \code{i}
 is not recycled, so it is good practice to make sure the logical vector
 matches the length of x. To return \code{NA} values, use \code{x[NA_integer_]}.
 }
+
+\subsection{ALTREP range subsetting}{
+
+When \code{i} is an ALTREP compact integer sequence which can be commonly created
+using e.g. \code{1:10} or using \code{seq_len}, \code{seq_along} and \code{seq.int},
+\code{sset} internally uses a range-based subsetting which is faster and doesn't
+allocate \code{i} into memory.
+}
 }
 \examples{
 library(cheapr)
diff --git a/src/sset.cpp b/src/sset.cpp
index ed2582c..2bb27ec 100644
--- a/src/sset.cpp
+++ b/src/sset.cpp
@@ -250,7 +250,7 @@ SEXP cpp_sset_range(SEXP x, R_xlen_t from, R_xlen_t to, R_xlen_t by){
     }
     // We first switch them
     if (istart < iend){
-      int iend_temp = iend;
+      R_xlen_t iend_temp = iend;
       iend = istart;
       istart = iend_temp;
     }
@@ -393,7 +393,7 @@ case REALSXP: {
   } else {
     if (by > 0){
 #pragma omp parallel for simd num_threads(n_cores) if (do_parallel)
-      for (int i = istart - 1; i < iend; ++i){
+      for (R_xlen_t i = istart - 1; i < iend; ++i){
         p_out[i - istart + 1] = i < n ? p_x[i] : NA_REAL;
       }
     } else {
@@ -415,7 +415,7 @@ case STRSXP: {
       SET_STRING_ELT(out, k++, i < n ? p_x[i] : NA_STRING);
     }
 #pragma omp for simd
-    for (int j = istart2 - 1; j < iend2; ++j){
+    for (R_xlen_t j = istart2 - 1; j < iend2; ++j){
       SET_STRING_ELT(out, k++, j < n ? p_x[j] : NA_STRING);
     }
   } else {