From a8e47c38c6d70c202070fa585d4096592a9961cf Mon Sep 17 00:00:00 2001
From: David Steele <david@pgmasters.net>
Date: Fri, 31 Jul 2020 16:27:57 -0400
Subject: [PATCH] Add lstGetLast() and lstRemoveLast().

When a list is being treated as a stack it is useful to get/remove the last (top) item.
---
 src/common/type/list.c                | 33 +++++++++++++++++++++++++++
 src/common/type/list.h                |  2 ++
 test/src/module/common/typeListTest.c |  8 +++++--
 3 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/src/common/type/list.c b/src/common/type/list.c
index bd716edca..c5b017c1b 100644
--- a/src/common/type/list.c
+++ b/src/common/type/list.c
@@ -143,6 +143,23 @@ lstGet(const List *this, unsigned int listIdx)
     FUNCTION_TEST_RETURN(this->list + (listIdx * this->itemSize));
 }
 
+void *
+lstGetLast(const List *this)
+{
+    FUNCTION_TEST_BEGIN();
+        FUNCTION_TEST_PARAM(LIST, this);
+    FUNCTION_TEST_END();
+
+    ASSERT(this != NULL);
+
+    // Ensure there are items in the list
+    if (this->listSize == 0)
+        THROW(AssertError, "cannot get last from list with no values");
+
+    // Return pointer to list item
+    FUNCTION_TEST_RETURN(lstGet(this, this->listSize - 1));
+}
+
 /**********************************************************************************************************************************/
 bool
 lstExists(const List *this, const void *item)
@@ -300,6 +317,7 @@ lstRemoveIdx(List *this, unsigned int listIdx)
 {
     FUNCTION_TEST_BEGIN();
         FUNCTION_TEST_PARAM(LIST, this);
+        FUNCTION_TEST_PARAM(UINT, listIdx);
     FUNCTION_TEST_END();
 
     ASSERT(this != NULL);
@@ -337,6 +355,21 @@ lstRemove(List *this, const void *item)
     FUNCTION_TEST_RETURN(false);
 }
 
+List *
+lstRemoveLast(List *this)
+{
+    FUNCTION_TEST_BEGIN();
+        FUNCTION_TEST_PARAM(LIST, this);
+    FUNCTION_TEST_END();
+
+    ASSERT(this != NULL);
+
+    if (this->listSize == 0)
+        THROW(AssertError, "cannot remove last from list with no values");
+
+    FUNCTION_TEST_RETURN(lstRemoveIdx(this, this->listSize - 1));
+}
+
 /**********************************************************************************************************************************/
 MemContext *
 lstMemContext(const List *this)
diff --git a/src/common/type/list.h b/src/common/type/list.h
index 3651be8ca..c0f698fcf 100644
--- a/src/common/type/list.h
+++ b/src/common/type/list.h
@@ -74,6 +74,7 @@ List *lstClear(List *this);
 
 // Get an item from the list
 void *lstGet(const List *this, unsigned int listIdx);
+void *lstGetLast(const List *this);
 
 // Does an item exist in the list?
 bool lstExists(const List *this, const void *item);
@@ -98,6 +99,7 @@ List *lstMove(List *this, MemContext *parentNew);
 // Remove an item from the list
 bool lstRemove(List *this, const void *item);
 List *lstRemoveIdx(List *this, unsigned int listIdx);
+List *lstRemoveLast(List *this);
 
 // Return list size
 unsigned int lstSize(const List *this);
diff --git a/test/src/module/common/typeListTest.c b/test/src/module/common/typeListTest.c
index 59dd82bf3..60ffdb73c 100644
--- a/test/src/module/common/typeListTest.c
+++ b/test/src/module/common/typeListTest.c
@@ -79,6 +79,9 @@ testRun(void)
         {
             list = lstNewP(sizeof(int));
 
+            TEST_ERROR(lstGetLast(list), AssertError, "cannot get last from list with no values");
+            TEST_ERROR(lstRemoveLast(list), AssertError, "cannot remove last from list with no values");
+
             // Add ints to the list
             for (int listIdx = 1; listIdx <= LIST_INITIAL_SIZE; listIdx++)
                 TEST_RESULT_VOID(lstAdd(list, &listIdx), "add item %d", listIdx);
@@ -107,12 +110,13 @@ testRun(void)
         // Read them back and check values
         for (unsigned int listIdx = 0; listIdx < lstSize(list); listIdx++)
         {
-            int *item = lstGet(list, listIdx);
+            int *item = listIdx == lstSize(list) - 1 ? lstGetLast(list) : lstGet(list, listIdx);
+
             TEST_RESULT_INT(*item, listIdx + 1, "check item %u", listIdx);
         }
 
         // Remove last item
-        TEST_RESULT_VOID(lstRemoveIdx(list, lstSize(list) - 1), "remove last item");
+        TEST_RESULT_VOID(lstRemoveLast(list), "remove last item");
 
         // Read them back and check values
         for (unsigned int listIdx = 0; listIdx < lstSize(list); listIdx++)