From 7cb6488decdd14e6fb245e23f2af5bc868cbbcde Mon Sep 17 00:00:00 2001
From: Herwin Weststrate <herwin@snt.utwente.nl>
Date: Sun, 21 Feb 2021 11:21:34 +0100
Subject: [PATCH 1/4] Move jtisempty to a cpp file

For now it's a direct copy of the original C code, with a nodiscard
added to be on the safe side.
---
 jsrc/CMakeLists.txt            | 1 +
 jsrc/verbs/monadic/isempty.cpp | 7 +++++++
 jsrc/verbs/v.c                 | 6 ------
 3 files changed, 8 insertions(+), 6 deletions(-)
 create mode 100644 jsrc/verbs/monadic/isempty.cpp

diff --git a/jsrc/CMakeLists.txt b/jsrc/CMakeLists.txt
index 7c91ae9f..80f4d083 100644
--- a/jsrc/CMakeLists.txt
+++ b/jsrc/CMakeLists.txt
@@ -73,6 +73,7 @@ target_sources(j PRIVATE
         verbs/vsb.c
         verbs/vx.c
         verbs/vz.c
+        verbs/monadic/isempty.cpp
         verbs/monadic/rank.cpp
         verbs/monadic/same.cpp
         verbs/monadic/shape.cpp
diff --git a/jsrc/verbs/monadic/isempty.cpp b/jsrc/verbs/monadic/isempty.cpp
new file mode 100644
index 00000000..ce7e2ec7
--- /dev/null
+++ b/jsrc/verbs/monadic/isempty.cpp
@@ -0,0 +1,7 @@
+#include "array.hpp"
+
+[[nodiscard]] A
+jtisempty(J jt, A w) {
+    if ((AT(w) & SPARSE) != 0) return jteps(jt, num(0), shape(jt, w));
+    return AN(w) == 0 ? jtrue : jfalse;
+}  // 0 e. $
diff --git a/jsrc/verbs/v.c b/jsrc/verbs/v.c
index e73ee98b..1e71c02b 100644
--- a/jsrc/verbs/v.c
+++ b/jsrc/verbs/v.c
@@ -4,12 +4,6 @@
 /* Verbs                                                                   */
 
 #include "j.h"
-
-A
-jtisempty(J jt, A w) {
-    if ((AT(w) & SPARSE) != 0) return jteps(jt, num(0), shape(jt, w));
-    return AN(w) == 0 ? jtrue : jfalse;
-}  // 0 e. $
 A
 jtisnotempty(J jt, A w) {
     if ((AT(w) & SPARSE) != 0) return jtnot(jt, jteps(jt, num(0), shape(jt, w)));

From 8ba4852388310c325cfa26229b4c0ea377c9d80a Mon Sep 17 00:00:00 2001
From: Herwin Weststrate <herwin@snt.utwente.nl>
Date: Sun, 21 Feb 2021 11:28:22 +0100
Subject: [PATCH 2/4] Restructure jtisempty to use preferred layout

* Replace `A` with `array`
* Use trailing return types
---
 jsrc/verbs/monadic/isempty.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/jsrc/verbs/monadic/isempty.cpp b/jsrc/verbs/monadic/isempty.cpp
index ce7e2ec7..d4e7b8ac 100644
--- a/jsrc/verbs/monadic/isempty.cpp
+++ b/jsrc/verbs/monadic/isempty.cpp
@@ -1,7 +1,7 @@
 #include "array.hpp"
 
-[[nodiscard]] A
-jtisempty(J jt, A w) {
+[[nodiscard]] auto
+jtisempty(J jt, array w) -> array {
     if ((AT(w) & SPARSE) != 0) return jteps(jt, num(0), shape(jt, w));
     return AN(w) == 0 ? jtrue : jfalse;
 }  // 0 e. $

From 6392a5afb2a002b234de3660f8fb0e3f57587855 Mon Sep 17 00:00:00 2001
From: Herwin Weststrate <herwin@snt.utwente.nl>
Date: Sun, 21 Feb 2021 11:30:45 +0100
Subject: [PATCH 3/4] Improve documentation for jtisempty

---
 jsrc/verbs/monadic/isempty.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/jsrc/verbs/monadic/isempty.cpp b/jsrc/verbs/monadic/isempty.cpp
index d4e7b8ac..39a87742 100644
--- a/jsrc/verbs/monadic/isempty.cpp
+++ b/jsrc/verbs/monadic/isempty.cpp
@@ -1,7 +1,15 @@
 #include "array.hpp"
 
+/** @file */
+
+/**
+ * @brief `0 e. $` IsEmpty
+ * @param jt       JST (J Syntax Tree)
+ * @param w        Input aray
+ * @return         boolean jtrue or jfalse
+ */
 [[nodiscard]] auto
 jtisempty(J jt, array w) -> array {
     if ((AT(w) & SPARSE) != 0) return jteps(jt, num(0), shape(jt, w));
     return AN(w) == 0 ? jtrue : jfalse;
-}  // 0 e. $
+}

From 9bec2a82f59e0518c0994121fc7c9dd3c0883351 Mon Sep 17 00:00:00 2001
From: Herwin Weststrate <herwin@snt.utwente.nl>
Date: Sun, 21 Feb 2021 11:57:30 +0100
Subject: [PATCH 4/4] Use is_sparse method

---
 jsrc/verbs/monadic/isempty.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/jsrc/verbs/monadic/isempty.cpp b/jsrc/verbs/monadic/isempty.cpp
index 39a87742..fd82c93c 100644
--- a/jsrc/verbs/monadic/isempty.cpp
+++ b/jsrc/verbs/monadic/isempty.cpp
@@ -10,6 +10,6 @@
  */
 [[nodiscard]] auto
 jtisempty(J jt, array w) -> array {
-    if ((AT(w) & SPARSE) != 0) return jteps(jt, num(0), shape(jt, w));
+    if (is_sparse(w)) return jteps(jt, num(0), shape(jt, w));
     return AN(w) == 0 ? jtrue : jfalse;
 }