25 files changed, 455 insertions, 210 deletions

diff --git a/.travis.yml b/.travis.yml
index 25ab961ec4..d883410123 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,5 +4,6 @@ env:
   - TRAVIS_BUILD_TYPE=gcc/ia32
   - TRAVIS_BUILD_TYPE=gcc/unittest
   - TRAVIS_BUILD_TYPE=clint
+  - TRAVIS_BUILD_TYPE=api/python
 script:
   - ./scripts/travis.sh
diff --git a/scripts/run-api-tests.exp b/scripts/run-api-tests.exp
new file mode 100755
index 0000000000..6a568e17cb
--- /dev/null
+++ b/scripts/run-api-tests.exp
@@ -0,0 +1,86 @@
+#!/usr/bin/env expect
+
+if {$argc < 2} {
+  puts "Need commands for running the tests and for starting nvim"
+  exit 1
+}
+
+set timeout 10
+set run_tests [split [lindex $argv 0] " "]
+set run_nvim [split [lindex $argv 1] " "]
+
+# don't echo to stdout
+log_user 0
+# set NEOVIM_LISTEN_ADDRESS, so nvim will listen on a known socket
+set env(NEOVIM_LISTEN_ADDRESS) "/tmp/nvim-[exec date +%s%N].sock"
+# start nvim
+spawn {*}$run_nvim
+# save the job descriptor
+set nvim_id $spawn_id
+# Reset function that can be invoked by test runners to put nvim in a cleaner
+# state
+send {
+:function BeforeEachTest()
+  set all&
+  redir => groups
+  silent augroup
+  redir END
+  for group in split(groups)
+    exe 'augroup '.group
+    autocmd!
+    augroup NONE
+    exe 'augroup! '.group
+  endfor
+  tabnew
+  let curbufnum = eval(bufnr('%'))
+  redir => buflist
+  silent ls!
+  redir END
+  let bufnums = []
+  for buf in split(buflist, '\n')
+    let bufnum = eval(split(buf, '[ u]')[0])
+    if bufnum != curbufnum
+      call add(bufnums, bufnum)
+    endif
+  endfor
+  if len(bufnums) > 0
+    exe 'silent bwipeout! '.join(bufnums, ' ')
+  endif
+  silent tabonly
+  for k in keys(g:)
+    exe 'unlet g:'.k
+  endfor
+  filetype plugin indent off
+  mapclear
+  mapclear!
+  abclear
+  comclear
+endfunction
+:echo "read"."y"
+}
+# wait until nvim is ready
+expect "ready"
+# run tests
+spawn {*}$run_tests
+set tests_id $spawn_id
+set status 1
+# listen for test output in the background
+expect_background {
+  * {
+    # show test output to the user
+    send_user -- $expect_out(buffer)
+  }
+  eof {
+    # collect the exit status code
+    set spawn_id $tests_id
+    catch wait result
+    set status [lindex $result 3]
+    set spawn_id $nvim_id
+    # quit nvim
+    send ":qa!\r"
+  }
+}
+# switch back nvim and wait until it exits 
+set spawn_id $nvim_id
+expect eof
+exit $status
diff --git a/scripts/travis.sh b/scripts/travis.sh
index 62c4fbe98e..3daa2652e5 100755
--- a/scripts/travis.sh
+++ b/scripts/travis.sh
@@ -1,8 +1,44 @@
 #!/bin/sh -e
 
-check_and_report() {
+tmpdir="$(pwd)/tmp"
+rm -rf "$tmpdir"
+mkdir -p "$tmpdir"
+
+valgrind_check() {
 	(
-	cd $tmpdir
+	cd $1
+	set -- valgrind-[*] valgrind-*
+	case $1$2 in
+		'valgrind-[*]valgrind-*')
+			;;
+		*)
+			shift
+			local err=''
+			for valgrind_log in "$@"; do
+				# Remove useless warning
+				sed -i "$valgrind_log" \
+					-e '/Warning: noted but unhandled ioctl/d' \
+					-e '/could cause spurious value errors to appear/d' \
+					-e '/See README_MISSING_SYSCALL_OR_IOCTL for guidance/d'
+				if [ "$(stat -c %s $valgrind_log)" != "0" ]; then
+					# if after removing the warning, the log still has errors, show its
+					# contents and set the flag so we exit with non-zero status
+					cat "$valgrind_log"
+					err=1
+				fi
+			done
+			if [ -n "$err" ]; then
+				echo "Runtime errors detected"
+				exit 1
+			fi
+			;;
+	esac
+	)
+}
+
+asan_check() {
+	(
+	cd $1
 	set -- [*]san.[*] *san.*
 	case $1$2 in
 		'[*]san.[*]*san.*')
@@ -68,9 +104,6 @@ if [ "$TRAVIS_BUILD_TYPE" = "clang/asan" ]; then
 
 	install_dir="$(pwd)/dist"
 	# temporary directory for writing sanitizer logs
-	tmpdir="$(pwd)/tmp"
-	rm -rf "$tmpdir"
-	mkdir -p "$tmpdir"
 
 	# need the symbolizer path for stack traces with source information
 	if [ -n "$USE_CLANG_34" ]; then
@@ -91,10 +124,10 @@ if [ "$TRAVIS_BUILD_TYPE" = "clang/asan" ]; then
 	$MAKE_CMD
 	if ! $MAKE_CMD test; then
 		reset
-		check_and_report
+		asan_check "$tmpdir"
 		exit 1
 	fi
-	check_and_report
+	asan_check "$tmpdir"
 	coveralls --encoding iso-8859-1 || echo 'coveralls upload failed.'
 	$MAKE_CMD install
 elif [ "$TRAVIS_BUILD_TYPE" = "gcc/unittest" ]; then
@@ -129,4 +162,19 @@ elif [ "$TRAVIS_BUILD_TYPE" = "gcc/ia32" ]; then
 	$MAKE_CMD test
 elif [ "$TRAVIS_BUILD_TYPE" = "clint" ]; then
 	./scripts/clint.sh
+elif [ "$TRAVIS_BUILD_TYPE" = "api/python" ]; then
+	set_environment /opt/neovim-deps
+	$MAKE_CMD
+	sudo apt-get install expect valgrind
+	git clone --depth=1 -b master git://github.com/neovim/python-client
+	cd python-client
+  sudo pip install .
+  sudo pip install nose
+	test_cmd="nosetests --verbosity=2"
+	nvim_cmd="valgrind -q --track-origins=yes --log-file=$tmpdir/valgrind-%p.log ../build/bin/nvim -u NONE"
+	if ! ../scripts/run-api-tests.exp "$test_cmd" "$nvim_cmd"; then
+		valgrind_check "$tmpdir"
+		exit 1
+	fi
+	valgrind_check "$tmpdir"
 fi
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index d9ec65af86..ad45f3ad3b 100644
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -6,17 +6,6 @@ file(GLOB API_HEADERS api/*.h)
 set(MSGPACK_RPC_HEADER ${PROJECT_SOURCE_DIR}/src/nvim/os/msgpack_rpc.h)
 set(MSGPACK_DISPATCH ${GENERATED_DIR}/msgpack_dispatch.c)
 
-# Remove helpers.h from API_HEADERS since it doesn't contain public API
-# functions
-foreach(sfile ${API_HEADERS})
-  get_filename_component(f ${sfile} NAME)
-  if(${f} MATCHES "^(helpers.h)$")
-    list(APPEND to_remove ${sfile})
-  endif()
-endforeach()
-list(REMOVE_ITEM API_HEADERS ${to_remove})
-set(to_remove)
-
 file(MAKE_DIRECTORY ${GENERATED_DIR})
 
 add_custom_command(OUTPUT ${MSGPACK_DISPATCH}
@@ -42,6 +31,7 @@ list(APPEND NEOVIM_SOURCES "${MSGPACK_DISPATCH}")
 
 file( GLOB OS_SOURCES os/*.c )
 file( GLOB API_SOURCES api/*.c )
+file( GLOB API_PRIV_SOURCES api/private/*.c )
 
 set(CONV_SRCS
   api.c
@@ -110,13 +100,14 @@ list(APPEND NVIM_LINK_LIBRARIES
     ${CMAKE_THREAD_LIBS_INIT})
 
 if(NOT DEFINED ENV{SKIP_EXEC})
-  add_executable(nvim ${NEOVIM_SOURCES} ${OS_SOURCES} ${API_SOURCES})
+  add_executable(nvim ${NEOVIM_SOURCES} ${OS_SOURCES} ${API_SOURCES}
+    ${API_PRIV_SOURCES})
   target_link_libraries(nvim ${NVIM_LINK_LIBRARIES})
   install(TARGETS nvim RUNTIME DESTINATION bin)
 endif()
 
 if(NOT DEFINED ENV{SKIP_UNITTEST})
   add_library(nvim-test MODULE EXCLUDE_FROM_ALL ${NEOVIM_SOURCES}
-    ${OS_SOURCES} ${API_SOURCES})
+    ${OS_SOURCES} ${API_SOURCES} ${API_PRIV_SOURCES})
   target_link_libraries(nvim-test ${NVIM_LINK_LIBRARIES})
 endif()
diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index e73823e5c3..bf30ccf856 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -4,8 +4,8 @@
 #include <stdlib.h>
 
 #include "nvim/api/buffer.h"
-#include "nvim/api/helpers.h"
-#include "nvim/api/defs.h"
+#include "nvim/api/private/helpers.h"
+#include "nvim/api/private/defs.h"
 #include "nvim/vim.h"
 #include "nvim/buffer.h"
 #include "nvim/memline.h"
@@ -56,7 +56,7 @@ String buffer_get_line(Buffer buffer, Integer index, Error *err)
   String rv = {.size = 0};
   StringArray slice = buffer_get_slice(buffer, index, index, true, true, err);
 
-  if (slice.size) {
+  if (!err->set && slice.size) {
     rv = slice.items[0];
   }
 
@@ -71,7 +71,7 @@ void buffer_set_line(Buffer buffer, Integer index, String line, Error *err)
 
 void buffer_del_line(Buffer buffer, Integer index, Error *err)
 {
-  StringArray array = {.size = 0};
+  StringArray array = ARRAY_DICT_INIT;
   buffer_set_slice(buffer, index, index, true, true, array, err);
 }
 
@@ -82,7 +82,7 @@ StringArray buffer_get_slice(Buffer buffer,
                              Boolean include_end,
                              Error *err)
 {
-  StringArray rv = {.size = 0};
+  StringArray rv = ARRAY_DICT_INIT;
   buf_T *buf = find_buffer(buffer, err);
 
   if (!buf) {
@@ -115,9 +115,7 @@ StringArray buffer_get_slice(Buffer buffer,
 end:
   if (err->set) {
     for (size_t i = 0; i < rv.size; i++) {
-      if (rv.items[i].data != NULL) {
-        free(rv.items[i].data);
-      }
+      free(rv.items[i].data);
     }
 
     free(rv.items);
@@ -221,7 +219,6 @@ void buffer_set_slice(Buffer buffer,
 
     // Same as with replacing
     lines[i] = NULL;
-    i++;
     extra++;
   }
 
@@ -240,10 +237,8 @@ void buffer_set_slice(Buffer buffer,
   }
 
 end:
-  for (uint32_t i = 0; i < new_len; i++) {
-    if (lines[i] != NULL) {
-      free(lines[i]);
-    }
+  for (size_t i = 0; i < new_len; i++) {
+    free(lines[i]);
   }
 
   free(lines);
@@ -298,6 +293,18 @@ void buffer_set_option(Buffer buffer, String name, Object value, Error *err)
   set_option_to(buf, SREQ_BUF, name, value, err);
 }
 
+Integer buffer_get_number(Buffer buffer, Error *err)
+{
+  Integer rv = 0;
+  buf_T *buf = find_buffer(buffer, err);
+
+  if (!buf) {
+    return rv;
+  }
+
+  return buf->b_fnum;
+}
+
 String buffer_get_name(Buffer buffer, Error *err)
 {
   String rv = {.size = 0, .data = ""};
@@ -357,7 +364,7 @@ Position buffer_get_mark(Buffer buffer, String name, Error *err)
     return rv;
   }
 
-  if (name.size != 0) {
+  if (name.size != 1) {
     set_api_error("mark name must be a single character", err);
     return rv;
   }
diff --git a/src/nvim/api/buffer.h b/src/nvim/api/buffer.h
index 5f39589679..52a3b7cdb3 100644
--- a/src/nvim/api/buffer.h
+++ b/src/nvim/api/buffer.h
@@ -4,7 +4,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-#include "nvim/api/defs.h"
+#include "nvim/api/private/defs.h"
 
 /// Gets the buffer line count
 ///
@@ -104,6 +104,13 @@ Object buffer_get_option(Buffer buffer, String name, Error *err);
 /// @param[out] err Details of an error that may have occurred
 void buffer_set_option(Buffer buffer, String name, Object value, Error *err);
 
+/// Gets the buffer number
+///
+/// @param buffer The buffer handle
+/// @param[out] err Details of an error that may have occurred
+/// @return The buffer number
+Integer buffer_get_number(Buffer buffer, Error *err);
+
 /// Gets the full file name for the buffer
 ///
 /// @param buffer The buffer handle
diff --git a/src/nvim/api/defs.h b/src/nvim/api/private/defs.h
index 3ee50310fb..a91907f4f8 100644
--- a/src/nvim/api/defs.h
+++ b/src/nvim/api/private/defs.h
@@ -5,6 +5,15 @@
 #include <stdbool.h>
 #include <string.h>
 
+#define ARRAY_DICT_INIT {.size = 0, .items = NULL}
+#define REMOTE_TYPE(type) typedef uint64_t type
+
+#define TYPED_ARRAY_OF(type)                                                  \
+  typedef struct {                                                            \
+    type *items;                                                              \
+    size_t size;                                                              \
+  } type##Array
+
 // Basic types
 typedef struct {
   char msg[256];
@@ -20,16 +29,16 @@ typedef struct {
   size_t size;
 } String;
 
-typedef Integer Buffer;
-typedef Integer Window;
-typedef Integer Tabpage;
+REMOTE_TYPE(Buffer);
+REMOTE_TYPE(Window);
+REMOTE_TYPE(Tabpage);
 
 typedef struct object Object;
 
-typedef struct {
-  String *items;
-  size_t size;
-} StringArray;
+TYPED_ARRAY_OF(Buffer);
+TYPED_ARRAY_OF(Window);
+TYPED_ARRAY_OF(Tabpage);
+TYPED_ARRAY_OF(String);
 
 typedef struct {
   Integer row, col;
diff --git a/src/nvim/api/private/handle.c b/src/nvim/api/private/handle.c
new file mode 100644
index 0000000000..88d176fccb
--- /dev/null
+++ b/src/nvim/api/private/handle.c
@@ -0,0 +1,40 @@
+#include <stdint.h>
+
+#include "nvim/vim.h"
+#include "nvim/map.h"
+#include "nvim/api/private/handle.h"
+
+#define HANDLE_INIT(name) name##_handles = map_new(uint64_t)()
+
+#define HANDLE_IMPL(type, name)                                               \
+  static Map(uint64_t) *name##_handles = NULL;                                \
+                                                                              \
+  type *handle_get_##name(uint64_t handle)                                    \
+  {                                                                           \
+    return map_get(uint64_t)(name##_handles, handle);                         \
+  }                                                                           \
+                                                                              \
+  void handle_register_##name(type *name)                                     \
+  {                                                                           \
+    assert(!name->handle);                                                    \
+    name->handle = next_handle++;                                             \
+    map_put(uint64_t)(name##_handles, name->handle, name);                    \
+  }                                                                           \
+                                                                              \
+  void handle_unregister_##name(type *name)                                   \
+  {                                                                           \
+    map_del(uint64_t)(name##_handles, name->handle);                          \
+  }
+
+static uint64_t next_handle = 1;
+
+HANDLE_IMPL(buf_T, buffer)
+HANDLE_IMPL(win_T, window)
+HANDLE_IMPL(tabpage_T, tabpage)
+
+void handle_init()
+{
+  HANDLE_INIT(buffer);
+  HANDLE_INIT(window);
+  HANDLE_INIT(tabpage);
+}
diff --git a/src/nvim/api/private/handle.h b/src/nvim/api/private/handle.h
new file mode 100644
index 0000000000..27df453233
--- /dev/null
+++ b/src/nvim/api/private/handle.h
@@ -0,0 +1,20 @@
+#ifndef NVIM_API_HANDLE_H
+#define NVIM_API_HANDLE_H
+
+#include "nvim/vim.h"
+#include "nvim/buffer_defs.h"
+
+#define HANDLE_DECLS(type, name)                                              \
+  type *handle_get_##name(uint64_t handle);                                   \
+  void handle_register_##name(type *name);                                    \
+  void handle_unregister_##name(type *name);
+
+HANDLE_DECLS(buf_T, buffer)
+HANDLE_DECLS(win_T, window)
+HANDLE_DECLS(tabpage_T, tabpage)
+
+void handle_init(void);
+
+
+#endif  // NVIM_API_HANDLE_H
+
diff --git a/src/nvim/api/helpers.c b/src/nvim/api/private/helpers.c
index a193c8721e..c4340ddd89 100644
--- a/src/nvim/api/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -2,8 +2,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "nvim/api/helpers.h"
-#include "nvim/api/defs.h"
+#include "nvim/api/private/helpers.h"
+#include "nvim/api/private/defs.h"
+#include "nvim/api/private/handle.h"
 #include "nvim/vim.h"
 #include "nvim/buffer.h"
 #include "nvim/window.h"
@@ -285,43 +286,29 @@ Object vim_to_object(typval_T *obj)
 
 buf_T *find_buffer(Buffer buffer, Error *err)
 {
-  if (buffer > INT_MAX || buffer < INT_MIN) {
-    set_api_error("Invalid buffer id", err);
-    return NULL;
-  }
-
-  buf_T *buf = buflist_findnr((int)buffer);
+  buf_T *rv = handle_get_buffer(buffer);
 
-  if (buf == NULL) {
+  if (!rv) {
     set_api_error("Invalid buffer id", err);
   }
 
-  return buf;
+  return rv;
 }
 
 win_T * find_window(Window window, Error *err)
 {
-  tabpage_T *tp;
-  win_T *wp;
+  win_T *rv = handle_get_window(window);
 
-  FOR_ALL_TAB_WINDOWS(tp, wp) {
-    if (!--window) {
-      return wp;
-    }
+  if (!rv) {
+    set_api_error("Invalid window id", err);
   }
 
-  set_api_error("Invalid window id", err);
-  return NULL;
+  return rv;
 }
 
 tabpage_T * find_tab(Tabpage tabpage, Error *err)
 {
-  if (tabpage > INT_MAX || tabpage < INT_MIN) {
-    set_api_error("Invalid tabpage id", err);
-    return NULL;
-  }
-
-  tabpage_T *rv = find_tabpage((int)tabpage);
+  tabpage_T *rv = handle_get_tabpage(tabpage);
 
   if (!rv) {
     set_api_error("Invalid tabpage id", err);
diff --git a/src/nvim/api/helpers.h b/src/nvim/api/private/helpers.h
index f93487d62f..da7e357d04 100644
--- a/src/nvim/api/helpers.h
+++ b/src/nvim/api/private/helpers.h
@@ -3,7 +3,7 @@
 
 #include <stdbool.h>
 
-#include "nvim/api/defs.h"
+#include "nvim/api/private/defs.h"
 #include "nvim/vim.h"
 
 #define set_api_error(message, err)                \
diff --git a/src/nvim/api/tabpage.c b/src/nvim/api/tabpage.c
index fc50723ba5..b7243c68a8 100644
--- a/src/nvim/api/tabpage.c
+++ b/src/nvim/api/tabpage.c
@@ -4,12 +4,13 @@
 
 #include "nvim/api/tabpage.h"
 #include "nvim/api/vim.h"
-#include "nvim/api/defs.h"
-#include "nvim/api/helpers.h"
+#include "nvim/api/private/defs.h"
+#include "nvim/api/private/helpers.h"
+#include "nvim/memory.h"
 
-Integer tabpage_get_window_count(Tabpage tabpage, Error *err)
+WindowArray tabpage_get_windows(Tabpage tabpage, Error *err)
 {
-  Integer rv = 0;
+  WindowArray rv = ARRAY_DICT_INIT;
   tabpage_T *tab = find_tab(tabpage, err);
 
   if (!tab) {
@@ -23,7 +24,17 @@ Integer tabpage_get_window_count(Tabpage tabpage, Error *err)
     if (tp != tab) {
       break;
     }
-    rv++;
+    rv.size++;
+  }
+
+  rv.items = xmalloc(sizeof(Window) * rv.size);
+  size_t i = 0;
+
+  FOR_ALL_TAB_WINDOWS(tp, wp) {
+    if (tp != tab) {
+      break;
+    }
+    rv.items[i++] = wp->handle;
   }
 
   return rv;
@@ -67,13 +78,11 @@ Window tabpage_get_window(Tabpage tabpage, Error *err)
   } else {
     tabpage_T *tp;
     win_T *wp;
-    rv = 1;
 
     FOR_ALL_TAB_WINDOWS(tp, wp) {
       if (tp == tab && wp == tab->tp_curwin) {
-        return rv;
+        return wp->handle;
       }
-      rv++;
     }
     // There should always be a current window for a tabpage
     abort();
diff --git a/src/nvim/api/tabpage.h b/src/nvim/api/tabpage.h
index ef049fb644..dddcecbdbd 100644
--- a/src/nvim/api/tabpage.h
+++ b/src/nvim/api/tabpage.h
@@ -4,14 +4,14 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-#include "nvim/api/defs.h"
+#include "nvim/api/private/defs.h"
 
 /// Gets the number of windows in a tabpage
 ///
 /// @param tabpage The tabpage
 /// @param[out] err Details of an error that may have occurred
 /// @return The number of windows in `tabpage`
-Integer tabpage_get_window_count(Tabpage tabpage, Error *err);
+WindowArray tabpage_get_windows(Tabpage tabpage, Error *err);
 
 /// Gets a tabpage variable
 ///
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 505844e651..694781e0a3 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -4,8 +4,8 @@
 #include <string.h>
 
 #include "nvim/api/vim.h"
-#include "nvim/api/helpers.h"
-#include "nvim/api/defs.h"
+#include "nvim/api/private/helpers.h"
+#include "nvim/api/private/defs.h"
 #include "nvim/api/buffer.h"
 #include "nvim/vim.h"
 #include "nvim/buffer.h"
@@ -73,12 +73,15 @@ Integer vim_strwidth(String str, Error *err)
     return 0;
   }
 
-  return mb_string2cells((char_u *)str.data, (int)str.size);
+  char *buf = xstrndup(str.data, str.size);
+  Integer rv = mb_string2cells((char_u *)buf, -1);
+  free(buf);
+  return rv;
 }
 
 StringArray vim_list_runtime_paths(void)
 {
-  StringArray rv = {.size = 0};
+  StringArray rv = ARRAY_DICT_INIT;
   uint8_t *rtp = p_rtp;
 
   if (*rtp == NUL) {
@@ -94,14 +97,12 @@ StringArray vim_list_runtime_paths(void)
     rtp++;
   }
 
-  // index
-  uint32_t i = 0;
   // Allocate memory for the copies
   rv.items = xmalloc(sizeof(String) * rv.size);
   // reset the position
   rtp = p_rtp;
   // Start copying
-  while (*rtp != NUL) {
+  for (size_t i = 0; i < rv.size && *rtp != NUL; i++) {
     rv.items[i].data = xmalloc(MAXPATHL);
     // Copy the path from 'runtimepath' to rv.items[i]
     int length = copy_option_part(&rtp,
@@ -110,7 +111,6 @@ StringArray vim_list_runtime_paths(void)
                                  ",");
     assert(length >= 0);
     rv.items[i].size = (size_t)length;
-    i++;
   }
 
   return rv;
@@ -118,8 +118,14 @@ StringArray vim_list_runtime_paths(void)
 
 void vim_change_directory(String dir, Error *err)
 {
+  if (dir.size >= MAXPATHL) {
+    set_api_error("directory string is too long", err);
+    return;
+  }
+
   char string[MAXPATHL];
   strncpy(string, dir.data, dir.size);
+  string[dir.size] = NUL;
 
   try_start();
 
@@ -136,17 +142,17 @@ void vim_change_directory(String dir, Error *err)
 
 String vim_get_current_line(Error *err)
 {
-  return buffer_get_line(curbuf->b_fnum, curwin->w_cursor.lnum - 1, err);
+  return buffer_get_line(curbuf->handle, curwin->w_cursor.lnum - 1, err);
 }
 
 void vim_set_current_line(String line, Error *err)
 {
-  buffer_set_line(curbuf->b_fnum, curwin->w_cursor.lnum - 1, line, err);
+  buffer_set_line(curbuf->handle, curwin->w_cursor.lnum - 1, line, err);
 }
 
 void vim_del_current_line(Error *err)
 {
-  buffer_del_line(curbuf->b_fnum, curwin->w_cursor.lnum - 1, err);
+  buffer_del_line(curbuf->handle, curwin->w_cursor.lnum - 1, err);
 }
 
 Object vim_get_var(String name, Error *err)
@@ -184,32 +190,43 @@ void vim_err_write(String str)
   write_msg(str, true);
 }
 
-Integer vim_get_buffer_count(void)
+BufferArray vim_get_buffers(void)
 {
+  BufferArray rv = ARRAY_DICT_INIT;
   buf_T *b = firstbuf;
-  Integer n = 0;
 
   while (b) {
-    n++;
+    rv.size++;
     b = b->b_next;
   }
 
-  return n;
+  rv.items = xmalloc(sizeof(Buffer) * rv.size);
+  size_t i = 0;
+  b = firstbuf;
+
+  while (b) {
+    rv.items[i++] = b->handle;
+    b = b->b_next;
+  }
+
+  return rv;
 }
 
 Buffer vim_get_current_buffer(void)
 {
-  return curbuf->b_fnum;
+  return curbuf->handle;
 }
 
 void vim_set_current_buffer(Buffer buffer, Error *err)
 {
-  if (!find_buffer(buffer, err)) {
+  buf_T *buf = find_buffer(buffer, err);
+
+  if (!buf) {
     return;
   }
 
   try_start();
-  if (do_buffer(DOBUF_GOTO, DOBUF_FIRST, FORWARD, (int)buffer, 0) == FAIL) {
+  if (do_buffer(DOBUF_GOTO, DOBUF_FIRST, FORWARD, buf->b_fnum, 0) == FAIL) {
     if (try_end(err)) {
       return;
     }
@@ -223,14 +240,21 @@ void vim_set_current_buffer(Buffer buffer, Error *err)
   try_end(err);
 }
 
-Integer vim_get_window_count(void)
+WindowArray vim_get_windows(void)
 {
+  WindowArray rv = ARRAY_DICT_INIT;
   tabpage_T *tp;
   win_T *wp;
-  Integer rv = 0;
 
   FOR_ALL_TAB_WINDOWS(tp, wp) {
-    rv++;
+    rv.size++;
+  }
+
+  rv.items = xmalloc(sizeof(Window) * rv.size);
+  size_t i = 0;
+
+  FOR_ALL_TAB_WINDOWS(tp, wp) {
+    rv.items[i++] = wp->handle;
   }
 
   return rv;
@@ -238,20 +262,7 @@ Integer vim_get_window_count(void)
 
 Window vim_get_current_window(void)
 {
-  tabpage_T *tp;
-  win_T *wp;
-  Window rv = 1;
-
-  FOR_ALL_TAB_WINDOWS(tp, wp) {
-    if (wp == curwin) {
-      return rv;
-    }
-
-    rv++;
-  }
-
-  // There should always be a current window
-  abort();
+  return curwin->handle;
 }
 
 void vim_set_current_window(Window window, Error *err)
@@ -263,7 +274,7 @@ void vim_set_current_window(Window window, Error *err)
   }
 
   try_start();
-  win_goto(win);
+  goto_tabpage_win(win_find_tabpage(win), win);
 
   if (win != curwin) {
     if (try_end(err)) {
@@ -276,14 +287,23 @@ void vim_set_current_window(Window window, Error *err)
   try_end(err);
 }
 
-Integer vim_get_tabpage_count(void)
+TabpageArray vim_get_tabpages(void)
 {
+  TabpageArray rv = ARRAY_DICT_INIT;
   tabpage_T *tp = first_tabpage;
-  Integer rv = 0;
 
-  while (tp != NULL) {
+  while (tp) {
+    rv.size++;
+    tp = tp->tp_next;
+  }
+
+  rv.items = xmalloc(sizeof(Tabpage) * rv.size);
+  size_t i = 0;
+  tp = first_tabpage;
+
+  while (tp) {
+    rv.items[i++] = tp->handle;
     tp = tp->tp_next;
-    rv++;
   }
 
   return rv;
@@ -291,24 +311,19 @@ Integer vim_get_tabpage_count(void)
 
 Tabpage vim_get_current_tabpage(void)
 {
-  Tabpage rv = 1;
-  tabpage_T *t;
-
-  for (t = first_tabpage; t != NULL && t != curtab; t = t->tp_next) {
-    rv++;
-  }
-
-  return rv;
+  return curtab->handle;
 }
 
 void vim_set_current_tabpage(Tabpage tabpage, Error *err)
 {
-  if (!find_tab(tabpage, err)) {
+  tabpage_T *tp = find_tab(tabpage, err);
+
+  if (!tp) {
     return;
   }
 
   try_start();
-  goto_tabpage((int)tabpage);
+  goto_tabpage_tp(tp, true, true);
   try_end(err);
 }
 
diff --git a/src/nvim/api/vim.h b/src/nvim/api/vim.h
index 4ecc9fc2d0..acfab11cf7 100644
--- a/src/nvim/api/vim.h
+++ b/src/nvim/api/vim.h
@@ -4,7 +4,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-#include "nvim/api/defs.h"
+#include "nvim/api/private/defs.h"
 
 /// Send keys to vim input buffer, simulating user input.
 ///
@@ -108,10 +108,10 @@ void vim_out_write(String str);
 /// @param str The message
 void vim_err_write(String str);
 
-/// Gets the number of buffers
+/// Gets the current list of buffer handles
 ///
 /// @return The number of buffers
-Integer vim_get_buffer_count(void);
+BufferArray vim_get_buffers(void);
 
 /// Return the current buffer
 ///
@@ -124,10 +124,10 @@ Buffer vim_get_current_buffer(void);
 /// @param[out] err Details of an error that may have occurred
 void vim_set_current_buffer(Buffer buffer, Error *err);
 
-/// Gets the number of windows
+/// Gets the current list of window handles
 ///
 /// @return The number of windows
-Integer vim_get_window_count(void);
+WindowArray vim_get_windows(void);
 
 /// Return the current window
 ///
@@ -139,10 +139,10 @@ Window vim_get_current_window(void);
 /// @param handle The window handle
 void vim_set_current_window(Window window, Error *err);
 
-/// Gets the number of tab pages
+/// Gets the current list of tabpage handles
 ///
 /// @return The number of tab pages
-Integer vim_get_tabpage_count(void);
+TabpageArray vim_get_tabpages(void);
 
 /// Return the current tab page
 ///
diff --git a/src/nvim/api/window.c b/src/nvim/api/window.c
index 8e21034c40..8bd8316477 100644
--- a/src/nvim/api/window.c
+++ b/src/nvim/api/window.c
@@ -3,8 +3,8 @@
 #include <stdlib.h>
 
 #include "nvim/api/window.h"
-#include "nvim/api/defs.h"
-#include "nvim/api/helpers.h"
+#include "nvim/api/private/defs.h"
+#include "nvim/api/private/helpers.h"
 #include "nvim/vim.h"
 #include "nvim/window.h"
 #include "nvim/screen.h"
@@ -19,7 +19,7 @@ Buffer window_get_buffer(Window window, Error *err)
     return 0;
   }
 
-  return win->w_buffer->b_fnum;
+  return win->w_buffer->handle;
 }
 
 Position window_get_cursor(Window window, Error *err)
@@ -192,8 +192,14 @@ Position window_get_position(Window window, Error *err)
 
 Tabpage window_get_tabpage(Window window, Error *err)
 {
-  set_api_error("Not implemented", err);
-  return 0;
+  Tabpage rv = 0;
+  win_T *win = find_window(window, err);
+
+  if (win) {
+    rv = win_find_tabpage(win)->handle;
+  }
+
+  return rv;
 }
 
 Boolean window_is_valid(Window window)
diff --git a/src/nvim/api/window.h b/src/nvim/api/window.h
index 525b7f86c7..4c036ff5d7 100644
--- a/src/nvim/api/window.h
+++ b/src/nvim/api/window.h
@@ -4,7 +4,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-#include "nvim/api/defs.h"
+#include "nvim/api/private/defs.h"
 
 /// Gets the current buffer in a window
 ///
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index ffb62add3c..7c50b1721c 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -26,6 +26,7 @@
 
 #include <string.h>
 
+#include "nvim/api/private/handle.h"
 #include "nvim/vim.h"
 #include "nvim/buffer.h"
 #include "nvim/charset.h"
@@ -538,6 +539,7 @@ void buf_freeall(buf_T *buf, int flags)
  */
 static void free_buffer(buf_T *buf)
 {
+  handle_unregister_buffer(buf);
   free_buffer_stuff(buf, TRUE);
   unref_var_dict(buf->b_vars);
   aubuflocal_remove(buf);
@@ -1362,6 +1364,7 @@ buflist_new (
   }
   if (buf != curbuf || curbuf == NULL) {
     buf = xcalloc(1, sizeof(buf_T));
+    handle_register_buffer(buf);
     /* init b: variables */
     buf->b_vars = dict_alloc();
     init_var_dict(buf->b_vars, &buf->b_bufvar, VAR_SCOPE);
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index d658da9502..0a24280b4a 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -401,6 +401,7 @@ typedef struct {
  */
 
 struct file_buffer {
+  uint64_t handle;              // unique identifier for the buffer
   memline_T b_ml;               /* associated memline (also contains line
                                    count) */
 
@@ -737,6 +738,7 @@ struct diffblock_S {
  */
 typedef struct tabpage_S tabpage_T;
 struct tabpage_S {
+  uint64_t handle;
   tabpage_T       *tp_next;         /* next tabpage or NULL */
   frame_T         *tp_topframe;     /* topframe for the windows */
   win_T           *tp_curwin;       /* current window in this Tab page */
@@ -839,6 +841,7 @@ struct matchitem {
  * All row numbers are relative to the start of the window, except w_winrow.
  */
 struct window_S {
+  uint64_t handle;
   buf_T       *w_buffer;            /* buffer we are a window into (used
                                        often, keep it the first item!) */
 
diff --git a/src/nvim/map.c b/src/nvim/map.c
index 28fd0af61c..559a5f261a 100644
--- a/src/nvim/map.c
+++ b/src/nvim/map.c
@@ -85,3 +85,4 @@
 
 MAP_IMPL(cstr_t)
 MAP_IMPL(ptr_t)
+MAP_IMPL(uint64_t)
diff --git a/src/nvim/map.h b/src/nvim/map.h
index ae47561deb..dba56dc5aa 100644
--- a/src/nvim/map.h
+++ b/src/nvim/map.h
@@ -21,6 +21,7 @@
 
 MAP_DECLS(cstr_t)
 MAP_DECLS(ptr_t)
+MAP_DECLS(uint64_t)
 
 #define map_new(T) map_##T##_new
 #define map_free(T) map_##T##_free
diff --git a/src/nvim/os/msgpack_rpc.c b/src/nvim/os/msgpack_rpc.c
index 45832070b1..d7ffa6f559 100644
--- a/src/nvim/os/msgpack_rpc.c
+++ b/src/nvim/os/msgpack_rpc.c
@@ -4,6 +4,54 @@
 #include "nvim/vim.h"
 #include "nvim/memory.h"
 
+#define REMOTE_FUNCS_IMPL(t, lt)                                            \
+  bool msgpack_rpc_to_##lt(msgpack_object *obj, t *arg)                     \
+  {                                                                         \
+    *arg = obj->via.u64;                                                    \
+    return obj->type == MSGPACK_OBJECT_POSITIVE_INTEGER;                    \
+  }                                                                         \
+                                                                            \
+  void msgpack_rpc_from_##lt(t result, msgpack_packer *res)                 \
+  {                                                                         \
+    msgpack_pack_uint64(res, result);                                       \
+  }
+
+#define TYPED_ARRAY_IMPL(t, lt)                                             \
+  bool msgpack_rpc_to_##lt##array(msgpack_object *obj, t##Array *arg)       \
+  {                                                                         \
+    if (obj->type != MSGPACK_OBJECT_ARRAY) {                                \
+      return false;                                                         \
+    }                                                                       \
+                                                                            \
+    arg->size = obj->via.array.size;                                        \
+    arg->items = xcalloc(obj->via.array.size, sizeof(t));                   \
+                                                                            \
+    for (size_t i = 0; i < obj->via.array.size; i++) {                      \
+      if (!msgpack_rpc_to_##lt(obj->via.array.ptr + i, &arg->items[i])) {   \
+        return false;                                                       \
+      }                                                                     \
+    }                                                                       \
+                                                                            \
+    return true;                                                            \
+  }                                                                         \
+                                                                            \
+  void msgpack_rpc_from_##lt##array(t##Array result, msgpack_packer *res)   \
+  {                                                                         \
+    msgpack_pack_array(res, result.size);                                   \
+                                                                            \
+    for (size_t i = 0; i < result.size; i++) {                              \
+      msgpack_rpc_from_##lt(result.items[i], res);                          \
+    }                                                                       \
+  }                                                                         \
+                                                                            \
+  void msgpack_rpc_free_##lt##array(t##Array value) {                       \
+    for (size_t i = 0; i < value.size; i++) {                               \
+      msgpack_rpc_free_##lt(value.items[i]);                                \
+    }                                                                       \
+                                                                            \
+    free(value.items);                                                      \
+  }
+
 void msgpack_rpc_call(msgpack_object *req, msgpack_packer *res)
 {
   // The initial response structure is the same no matter what happens,
@@ -104,21 +152,6 @@ bool msgpack_rpc_to_string(msgpack_object *obj, String *arg)
   return obj->type == MSGPACK_OBJECT_RAW;
 }
 
-bool msgpack_rpc_to_buffer(msgpack_object *obj, Buffer *arg)
-{
-  return msgpack_rpc_to_integer(obj, arg);
-}
-
-bool msgpack_rpc_to_window(msgpack_object *obj, Window *arg)
-{
-  return msgpack_rpc_to_integer(obj, arg);
-}
-
-bool msgpack_rpc_to_tabpage(msgpack_object *obj, Tabpage *arg)
-{
-  return msgpack_rpc_to_integer(obj, arg);
-}
-
 bool msgpack_rpc_to_object(msgpack_object *obj, Object *arg)
 {
   switch (obj->type) {
@@ -156,24 +189,6 @@ bool msgpack_rpc_to_object(msgpack_object *obj, Object *arg)
   }
 }
 
-bool msgpack_rpc_to_stringarray(msgpack_object *obj, StringArray *arg)
-{
-  if (obj->type != MSGPACK_OBJECT_ARRAY) {
-    return false;
-  }
-
-  arg->size = obj->via.array.size;
-  arg->items = xcalloc(obj->via.array.size, sizeof(String));
-
-  for (uint32_t i = 0; i < obj->via.array.size; i++) {
-    if (!msgpack_rpc_to_string(obj->via.array.ptr + i, &arg->items[i])) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
 bool msgpack_rpc_to_position(msgpack_object *obj, Position *arg)
 {
   return obj->type == MSGPACK_OBJECT_ARRAY
@@ -251,21 +266,6 @@ void msgpack_rpc_from_string(String result, msgpack_packer *res)
   msgpack_pack_raw_body(res, result.data, result.size);
 }
 
-void msgpack_rpc_from_buffer(Buffer result, msgpack_packer *res)
-{
-  msgpack_rpc_from_integer(result, res);
-}
-
-void msgpack_rpc_from_window(Window result, msgpack_packer *res)
-{
-  msgpack_rpc_from_integer(result, res);
-}
-
-void msgpack_rpc_from_tabpage(Tabpage result, msgpack_packer *res)
-{
-  msgpack_rpc_from_integer(result, res);
-}
-
 void msgpack_rpc_from_object(Object result, msgpack_packer *res)
 {
   switch (result.type) {
@@ -302,15 +302,6 @@ void msgpack_rpc_from_object(Object result, msgpack_packer *res)
   }
 }
 
-void msgpack_rpc_from_stringarray(StringArray result, msgpack_packer *res)
-{
-  msgpack_pack_array(res, result.size);
-
-  for (size_t i = 0; i < result.size; i++) {
-    msgpack_rpc_from_string(result.items[i], res);
-  }
-}
-
 void msgpack_rpc_from_position(Position result, msgpack_packer *res)
 {
   msgpack_pack_array(res, 2);;
@@ -363,14 +354,6 @@ void msgpack_rpc_free_object(Object value)
   }
 }
 
-void msgpack_rpc_free_stringarray(StringArray value) {
-  for (uint32_t i = 0; i < value.size; i++) {
-    msgpack_rpc_free_string(value.items[i]);
-  }
-
-  free(value.items);
-}
-
 void msgpack_rpc_free_array(Array value)
 {
   for (uint32_t i = 0; i < value.size; i++) {
@@ -390,3 +373,12 @@ void msgpack_rpc_free_dictionary(Dictionary value)
   free(value.items);
 }
 
+REMOTE_FUNCS_IMPL(Buffer, buffer)
+REMOTE_FUNCS_IMPL(Window, window)
+REMOTE_FUNCS_IMPL(Tabpage, tabpage)
+
+TYPED_ARRAY_IMPL(Buffer, buffer)
+TYPED_ARRAY_IMPL(Window, window)
+TYPED_ARRAY_IMPL(Tabpage, tabpage)
+TYPED_ARRAY_IMPL(String, string)
+
diff --git a/src/nvim/os/msgpack_rpc.h b/src/nvim/os/msgpack_rpc.h
index 0e9d474d8d..a6a909ac1f 100644
--- a/src/nvim/os/msgpack_rpc.h
+++ b/src/nvim/os/msgpack_rpc.h
@@ -6,7 +6,7 @@
 
 #include <msgpack.h>
 
-#include "nvim/api/defs.h"
+#include "nvim/api/private/defs.h"
 
 /// Validates the basic structure of the msgpack-rpc call and fills `res`
 /// with the basic response structure.
@@ -48,6 +48,9 @@ bool msgpack_rpc_to_window(msgpack_object *obj, Window *arg);
 bool msgpack_rpc_to_tabpage(msgpack_object *obj, Tabpage *arg);
 bool msgpack_rpc_to_object(msgpack_object *obj, Object *arg);
 bool msgpack_rpc_to_stringarray(msgpack_object *obj, StringArray *arg);
+bool msgpack_rpc_to_bufferarray(msgpack_object *obj, BufferArray *arg);
+bool msgpack_rpc_to_windowarray(msgpack_object *obj, WindowArray *arg);
+bool msgpack_rpc_to_tabpagearray(msgpack_object *obj, TabpageArray *arg);
 bool msgpack_rpc_to_array(msgpack_object *obj, Array *arg);
 bool msgpack_rpc_to_dictionary(msgpack_object *obj, Dictionary *arg);
 
@@ -67,6 +70,9 @@ void msgpack_rpc_from_window(Window result, msgpack_packer *res);
 void msgpack_rpc_from_tabpage(Tabpage result, msgpack_packer *res);
 void msgpack_rpc_from_object(Object result, msgpack_packer *res);
 void msgpack_rpc_from_stringarray(StringArray result, msgpack_packer *res);
+void msgpack_rpc_from_bufferarray(BufferArray result, msgpack_packer *res);
+void msgpack_rpc_from_windowarray(WindowArray result, msgpack_packer *res);
+void msgpack_rpc_from_tabpagearray(TabpageArray result, msgpack_packer *res);
 void msgpack_rpc_from_array(Array result, msgpack_packer *res);
 void msgpack_rpc_from_dictionary(Dictionary result, msgpack_packer *res);
 
@@ -80,9 +86,12 @@ void msgpack_rpc_from_dictionary(Dictionary result, msgpack_packer *res);
 #define msgpack_rpc_init_window
 #define msgpack_rpc_init_tabpage
 #define msgpack_rpc_init_object = {.type = kObjectTypeNil}
-#define msgpack_rpc_init_stringarray = {.items = NULL, .size = 0}
-#define msgpack_rpc_init_array = {.items = NULL, .size = 0}
-#define msgpack_rpc_init_dictionary = {.items = NULL, .size = 0}
+#define msgpack_rpc_init_stringarray = ARRAY_DICT_INIT
+#define msgpack_rpc_init_bufferarray = ARRAY_DICT_INIT
+#define msgpack_rpc_init_windowarray = ARRAY_DICT_INIT
+#define msgpack_rpc_init_tabpagearray = ARRAY_DICT_INIT
+#define msgpack_rpc_init_array = ARRAY_DICT_INIT
+#define msgpack_rpc_init_dictionary = ARRAY_DICT_INIT
 
 /// Helpers for freeing arguments/return value
 ///
@@ -99,9 +108,11 @@ void msgpack_rpc_from_dictionary(Dictionary result, msgpack_packer *res);
 #define msgpack_rpc_free_tabpage(value)
 void msgpack_rpc_free_object(Object value);
 void msgpack_rpc_free_stringarray(StringArray value);
+void msgpack_rpc_free_bufferarray(BufferArray value);
+void msgpack_rpc_free_windowarray(WindowArray value);
+void msgpack_rpc_free_tabpagearray(TabpageArray value);
 void msgpack_rpc_free_array(Array value);
 void msgpack_rpc_free_dictionary(Dictionary value);
 
-
 #endif  // NVIM_OS_MSGPACK_RPC_H
 
diff --git a/src/nvim/os_unix.c b/src/nvim/os_unix.c
index 52627b6a8b..e0b838ed26 100644
--- a/src/nvim/os_unix.c
+++ b/src/nvim/os_unix.c
@@ -27,6 +27,7 @@
 
 #include <string.h>
 
+#include "nvim/api/private/handle.h"
 #include "nvim/vim.h"
 #include "nvim/os_unix.h"
 #include "nvim/buffer.h"
@@ -542,6 +543,7 @@ int mch_nodetype(char_u *name)
 
 void mch_early_init()
 {
+  handle_init();
   time_init();
 }
 
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 851e9cead7..534805b766 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -6,6 +6,7 @@
  * See README.txt for an overview of the Vim source code.
  */
 
+#include "nvim/api/private/handle.h"
 #include "nvim/vim.h"
 #include "nvim/window.h"
 #include "nvim/buffer.h"
@@ -2844,6 +2845,7 @@ void win_init_size(void)
 static tabpage_T *alloc_tabpage(void)
 {
   tabpage_T *tp = xcalloc(1, sizeof(tabpage_T));
+  handle_register_tabpage(tp);
 
   /* init t: variables */
   tp->tp_vars = dict_alloc();
@@ -2858,6 +2860,7 @@ void free_tabpage(tabpage_T *tp)
 {
   int idx;
 
+  handle_unregister_tabpage(tp);
   diff_clear(tp);
   for (idx = 0; idx < SNAP_COUNT; ++idx)
     clear_snapshot(tp, idx);
@@ -3568,6 +3571,7 @@ static win_T *win_alloc(win_T *after, int hidden)
    * allocate window structure and linesizes arrays
    */
   win_T *new_wp = xcalloc(1, sizeof(win_T));
+  handle_register_window(new_wp);
   win_alloc_lines(new_wp);
 
   /* init w: variables */
@@ -3583,6 +3587,7 @@ static win_T *win_alloc(win_T *after, int hidden)
    */
   if (!hidden)
     win_append(after, new_wp);
+
   new_wp->w_wincol = 0;
   new_wp->w_width = Columns;
 
@@ -3618,6 +3623,7 @@ win_free (
   buf_T       *buf;
   wininfo_T   *wip;
 
+  handle_unregister_window(wp);
   clearFolding(wp);
 
   /* reduce the reference count to the argument list. */