patch 9.1.1857: Missing clipboard provider support

Problem:  Missing clipboard provider support
          (lilydjwg)
Solution: Add clipboard provider feature
          (Foxe Chen)

fixes: #12419
closes: #17998

Signed-off-by: Foxe Chen <chen.foxe@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/builtin.txt

@@ -1,4 +1,4 @@
-*builtin.txt*	For Vim version 9.1.  Last change: 2025 Oct 13
+*builtin.txt*	For Vim version 9.1.  Last change: 2025 Oct 14
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -13061,6 +13061,7 @@ channel			Compiled with support for |channel| and |job|
 cindent			Compiled with 'cindent' support. (always true)
 clientserver		Compiled with remote invocation support |clientserver|.
 clipboard		Compiled with 'clipboard' support.
+clipboard_provider	Compiled with |clipboard-providers| support
 clipboard_working	Compiled with 'clipboard' support and it can be used.
 cmdline_compl		Compiled with |cmdline-completion| support.
 cmdline_hist		Compiled with |cmdline-history| support.

runtime/doc/eval.txt

@@ -1,4 +1,4 @@
-*eval.txt*	For Vim version 9.1.  Last change: 2025 Oct 12
+*eval.txt*	For Vim version 9.1.  Last change: 2025 Oct 14
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -38,6 +38,7 @@ a remark is given.
 12. The sandbox			|eval-sandbox|
 13. Textlock			|textlock|
 14. Vim script library		|vim-script-library|
+15. Clipboard providers		|clipboard-providers|
 
 Testing support is documented in |testing.txt|.
 Profiling is documented at |profiling|.
@@ -2251,6 +2252,11 @@ v:clipmethod	The current method of accessing the clipboard that is being
 					unavailable.
 		See 'clipmethod' for more details.
 
+					*v:clipproviders*
+v:clipproviders
+		A dictionary containing clipboard providers, see
+		|clipboard-providers| for more information.
+
 					*v:cmdarg* *cmdarg-variable*
 v:cmdarg	This variable is used for two purposes:
 		1. The extra arguments given to a file read/write command.
@@ -5263,5 +5269,133 @@ Usage: >vim
 	:call dist#vim9#Launch(<args>)
 	:Launch <app> <args>.
 <
+==============================================================================
+15. Clipboard providers					*clipboard-providers*
 
+When Vim is compiled with the |+clipboard_provider| feature, which requires
+the |+eval| feature, creating custom clipboards is possible.  These providers
+handle the "+" and "*" registers.  Note that on non-Unix or non-VMS systems,
+only the "*" register will be available for use.
+
+To add a provider, add a new entry to the |v:clipproviders| dictionary, in the
+format of: >
+	let v:clipproviders["name"] = {
+            \   "available": function("Available"),
+            \   "paste": {
+            \       '+': function("Paste"), " For the + register
+            \       '*': function("Paste"), " For the * register
+            \   },
+            \   "copy": {
+            \       '+': function("Copy"), " Same thing as above
+            \       '*': function("Copy"),
+            \   },
+            \ }
+
+The key is the provider name, which should be used in 'clipmethod', for
+example in the following example, you would add "name" to 'clipmethod' in
+order to use it. >
+	set clipmethod=name,wayland,x11,gui
+
+Each callback can either be a name of a function in a string, a |Funcref|, or
+a |lambda| expression.
+
+Note that these dictionary entries are optional, for example, if you don't
+care about the "copy" functions, then you can simply exclude them.  When Vim
+yanks/copies something, then simply nothing will be done.
+
+						*clipboard-provider-available*
+The "available" callback should return a string, which should contain which
+clipboard registers are available.  For example, if the "+" register is only
+available, then the function would return "+", or if both "+" and "*" are
+available, then return "+*".
+
+						*clipboard-provider-paste*
+The "paste" callback takes a first argument which is the register being put
+(string), and a second argument which is the type of access (string).  It
+should return either a tuple/list or string.  If a tuple/list is returned, it
+should have two elements:
+	- The register type conforming to |setreg()|.
+	- A list of strings
+If the register type is an empty string, then the type is automatically
+chosen, see |setreg()|.  If a string is returned, then it can either be "clear"
+or "previous".  "clear" makes Vim clear the register, and "previous" makes Vim
+use the previous register contents (or current depending on how you view it).
+
+The second argument, the access type, can either be "explicit" or "implicit".
+"explicit" means that the user is directly accessing the clipboard, such as
+putting text, or calling |getreg()|;  "implicit" means that the clipboard is
+being accessed indirectly, such when |:registers| is called, or when an
+unrelated operation causes Vim to access the clipboard.
+
+This is useful since some operations in Vim implicity access the clipboard
+indirectly.  For example, if when you want to create a provider for the OSC52
+command (accessing the clipboard via an escape code).  Many terminals show a
+confirmation if you want Vim to access the clipboard.  This can be very
+annoying with the terminal asking for permission everytime you do something
+that accesses the clipboard behind the scenes.  A good way to handle implicit
+access is to return "previous", which leaves the register contents unchanged.
+
+						*clipboard-provider-copy*
+The "copy" callback returns nothing, and takes the given arguments in order:
+	- The register being operated on
+	- The register type, conforming to |getregtype()|
+	- A list of strings to copy
+
+The provider can do whatever it wants with the given information.  This
+function is called on every request to change the clipboard register(s).
+
+						*clipboard-provider-textlock*
+In both the "paste" and "copy" callbacks, it is not allowed to change the
+buffer text, see |textlock|.
+
+						*clipboard-provider-example*
+Here is an example script that uses the clipboard provider feature through the
+OSC52 command: >vim
+
+	func Available()
+	  return "+"
+	endfunc
+	
+	func Paste(reg, type)
+	  " If implicit access, don't do anything
+	  if a:type == "implicit"
+	    return "previous"
+	  endif
+	
+	  augroup OSC
+	    autocmd!
+	    autocmd TermResponseAll osc ++once call feedkeys("\<F30>", '!')
+	  augroup END
+	
+	  " Send command
+	  call echoraw("\<Esc>]52;c;?\<Esc>\\")
+	
+	  " Wait until autocmd is triggered
+	  while getchar(-1) != "\<F30>"
+	  endwhile
+	
+	  autocmd! OSC
+	
+	  " Extract the base64 stuff
+	  let l:stuff = matchstr(v:termosc, '52;c;\zs[A-Za-z0-9+/=]\+')
+	
+	  return ("", blob2str(base64_decode(l:stuff)))
+	endfunc
+
+	func Copy(reg, type, lines)
+	  call echoraw("\<Esc>]52;c;" ..
+	    \ base64_encode(str2blob(a:lines)) .. "\<Esc>\\")
+	endfunc
+	let v:clipproviders["myosc"] = {
+	    \   "available": function("Available"),
+	    \   "paste": {
+	    \     '+': function("Paste"),
+	    \   },
+	    \   "copy": {
+	    \     '+': function("Copy"),
+	    \   },
+	    \ }
+	set clipmethod=myosc
+
+<
  vim:tw=78:ts=8:noet:ft=help:norl:

runtime/doc/options.txt

@@ -1919,10 +1919,15 @@ A jump table for the options with a short description can be found at |Q_op|.
 		x11		X11 selections
 		gui		GUI specific method
 		other		Some other method
+		*		Clipboard provider method
 
 	Note: "other" is used on systems without X11/Wayland, such as
 	MS-Windows or MacOS, when running Vim without the GUI.
 
+	Note that the name of the clipboard provider should be used when you
+	want to use a clipboard provider.  See |clipboard-providers| for more
+	information.
+
 	The option value is a list of comma separated items.  The list is
 	parsed left to right in order, and the first method that Vim
 	determines is available or is working is used as the actual method for

runtime/doc/tags

@@ -1411,6 +1411,7 @@ $quote	eval.txt	/*$quote*
 +cindent	various.txt	/*+cindent*
 +clientserver	various.txt	/*+clientserver*
 +clipboard	various.txt	/*+clipboard*
++clipboard_provider	various.txt	/*+clipboard_provider*
 +clipboard_working	various.txt	/*+clipboard_working*
 +cmd	editing.txt	/*+cmd*
 +cmdline_compl	various.txt	/*+cmdline_compl*
@@ -6691,6 +6692,12 @@ clipboard-autoselectml	options.txt	/*clipboard-autoselectml*
 clipboard-autoselectplus	options.txt	/*clipboard-autoselectplus*
 clipboard-exclude	options.txt	/*clipboard-exclude*
 clipboard-html	options.txt	/*clipboard-html*
+clipboard-provider-available	eval.txt	/*clipboard-provider-available*
+clipboard-provider-copy	eval.txt	/*clipboard-provider-copy*
+clipboard-provider-example	eval.txt	/*clipboard-provider-example*
+clipboard-provider-paste	eval.txt	/*clipboard-provider-paste*
+clipboard-provider-textlock	eval.txt	/*clipboard-provider-textlock*
+clipboard-providers	eval.txt	/*clipboard-providers*
 clipboard-unnamed	options.txt	/*clipboard-unnamed*
 clipboard-unnamedplus	options.txt	/*clipboard-unnamedplus*
 clojure-indent	indent.txt	/*clojure-indent*
@@ -11254,6 +11261,7 @@ v:char	eval.txt	/*v:char*
 v:charconvert_from	eval.txt	/*v:charconvert_from*
 v:charconvert_to	eval.txt	/*v:charconvert_to*
 v:clipmethod	eval.txt	/*v:clipmethod*
+v:clipproviders	eval.txt	/*v:clipproviders*
 v:cmdarg	eval.txt	/*v:cmdarg*
 v:cmdbang	eval.txt	/*v:cmdbang*
 v:collate	eval.txt	/*v:collate*

runtime/doc/various.txt

@@ -1,4 +1,4 @@
-*various.txt*   For Vim version 9.1.  Last change: 2025 Oct 12
+*various.txt*   For Vim version 9.1.  Last change: 2025 Oct 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -378,6 +378,7 @@ m  *+channel*		inter process communication |channel|
 T  *+cindent*		'cindent', C indenting; Always enabled
 N  *+clientserver*	Unix and Win32: Remote invocation |clientserver|
    *+clipboard*		|clipboard| support compiled-in
+N  *+clipboard_provider*  |clipboard-providers| support compiled-in
    *+clipboard_working*	|clipboard| support compiled-in and working
 T  *+cmdline_compl*	command line completion |cmdline-completion|
 T  *+cmdline_hist*	command line history |cmdline-history|
@@ -807,7 +808,10 @@ K			Run a program to lookup the keyword under the
 :clip[reset]		Attempts to choose a new method for accessing the
 			clipboard, using the 'clipmethod' option.  This is
 			useful when the current method has become unavailable,
-			and you want to try using another method.
+			and you want to try using another method.  If the
+			|+clipboard_provider| feature is being used, this
+			command should be called after the availability of one
+			of the clipboard registers changes.
 			{only available when compiled with the |+clipboard|
 			feature}
 

runtime/doc/version9.txt

@@ -1,4 +1,4 @@
-*version9.txt*  For Vim version 9.1.  Last change: 2025 Oct 12
+*version9.txt*  For Vim version 9.1.  Last change: 2025 Oct 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -41653,6 +41653,8 @@ Other new features ~
 
 - |items()| function now supports Blob.
 
+- |clipboard-providers| support.
+
 							*changed-9.2*
 Changed~
 -------
@@ -41900,13 +41902,29 @@ Options: ~
 			compositor
 
 Vim Variables: ~
+|v:clipmethod|		The current 'clipmethod'.
+|v:clipproviders|	A dictionary containing clipboard providers
+			information.
+|v:stacktrace|		The most recent caught exception.
+|v:t_enumvalue|		Value of |enumvalue|.
+|v:t_enum|		Value of |enum| type.
+|v:t_tuple|		Value of |Tuple| type.
 |v:termda1|		The escape sequence returned for the primary device
 			attribute query (DA1).
+|v:termosc|		The most recent received OSC response.
+|v:wayland_display|	The name of the Wayland display Vim is connected to.
 
 Vim Arguments: ~
 |-Y|			Do not connect to the |wayland| compositor.
 |--clientserver|	Specify backend for clientserver functionality.
 
+Configure Switches: ~
+--with-wayland			Enable the |wayland| feature.
+--enable-wayland-focus-steal	Enable the |wayland-focus-steal| feature.
+--enable-socketserver		Enable the |socketserver-clientserver|
+				feature.
+--enable-clipboard-provider	Enable the |clipboard-providers| feature.
+
 
 ==============================================================================
 INCOMPATIBLE CHANGES					*incompatible-9.2*

runtime/syntax/vim.vim

@@ -2,7 +2,7 @@
 " Language:	   Vim script
 " Maintainer:	   Hirohito Higashi <h.east.727 ATMARK gmail.com>
 "	   Doug Kearns <dougkearns@gmail.com>
-" Last Change:	   2025 Oct 11
+" Last Change:	   2025 Oct 14
 " Former Maintainer: Charles E. Campbell
 
 " DO NOT CHANGE DIRECTLY.
@@ -166,7 +166,7 @@ syn keyword vimFuncName contained win_execute win_findbuf win_getid win_gettype
 " Predefined variable names {{{2
 " GEN_SYN_VIM: vimVarName, START_STR='syn keyword vimVimVarName contained', END_STR=''
 syn keyword vimVimVarName contained count count1 prevcount errmsg warningmsg statusmsg shell_error this_session version lnum termresponse fname lang lc_time ctype charconvert_from charconvert_to fname_in fname_out fname_new fname_diff cmdarg foldstart foldend folddashes foldlevel progname servername dying exception throwpoint register cmdbang insertmode val key profiling fcs_reason fcs_choice beval_bufnr beval_winnr beval_winid beval_lnum beval_col beval_text scrollstart swapname swapchoice swapcommand char mouse_win mouse_winid mouse_lnum mouse_col operator searchforward hlsearch oldfiles windowid progpath completed_item option_new option_old option_oldlocal option_oldglobal option_command option_type errors false true none null numbermax numbermin numbersize
-syn keyword vimVimVarName contained vim_did_enter testing t_number t_string t_func t_list t_dict t_float t_bool t_none t_job t_channel t_blob t_class t_object termrfgresp termrbgresp termu7resp termstyleresp termblinkresp event versionlong echospace argv collate exiting colornames sizeofint sizeoflong sizeofpointer maxcol python3_version t_typealias t_enum t_enumvalue stacktrace t_tuple wayland_display clipmethod termda1 termosc
+syn keyword vimVimVarName contained vim_did_enter testing t_number t_string t_func t_list t_dict t_float t_bool t_none t_job t_channel t_blob t_class t_object termrfgresp termrbgresp termu7resp termstyleresp termblinkresp event versionlong echospace argv collate exiting colornames sizeofint sizeoflong sizeofpointer maxcol python3_version t_typealias t_enum t_enumvalue stacktrace t_tuple wayland_display clipmethod termda1 termosc clipproviders
 
 "--- syntax here and above generated by runtime/syntax/generator/gen_syntax_vim.vim ---
 

src/auto/configure

@@ -857,6 +857,7 @@ enable_arabic
 enable_farsi
 enable_xim
 enable_fontset
+enable_clipboard_provider
 with_wayland
 enable_wayland_focus_steal
 with_x
@@ -1539,6 +1540,7 @@ Optional Features:
   --disable-farsi         Deprecated.
   --enable-xim            Include XIM input support.
   --enable-fontset        Include X fontset output support.
+  --enable-clipboard-provider  Include clipboard provider support.
   --enable-wayland-focus-steal
                           Include focus stealing support for Wayland
                           clipboard.
@@ -9208,6 +9210,35 @@ fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $enable_fontset" >&5
 printf "%s\n" "$enable_fontset" >&6; }
 
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking --enable-clipboard-provider" >&5
+printf %s "checking --enable-clipboard-provider... " >&6; }
+# Check whether --enable-clipboard-provider was given.
+if test ${enable_clipboard_provider+y}
+then :
+  enableval=$enable_clipboard_provider; enable_clipboard_provider=$enableval
+	 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $enableval" >&5
+printf "%s\n" "$enableval" >&6; }
+else case e in #(
+  e) if test "x$features" = xtiny
+then :
+  enable_clipboard_provider="no"
+			 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: cannot use clipboard provider with tiny features" >&5
+printf "%s\n" "cannot use clipboard provider with tiny features" >&6; }
+else case e in #(
+  e) enable_clipboard_provider="yes"
+			 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; } ;;
+esac
+fi ;;
+esac
+fi
+
+if test "$enable_clipboard_provider" = "yes"; then
+  printf "%s\n" "#define FEAT_CLIPBOARD_PROVIDER 1" >>confdefs.h
+
+fi
+
+
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking if shm_open is available" >&5
 printf %s "checking if shm_open is available... " >&6; }
 cppflags_save=$CPPFLAGS

src/clipboard.c

@@ -134,6 +134,12 @@ static bool clip_wl_owner_exists(Clipboard_T *cbd);
 
 #endif // FEAT_WAYLAND_CLIPBOARD
 
+#ifdef FEAT_CLIPBOARD_PROVIDER
+static int clip_provider_is_available(Clipboard_T *cbd, char_u *provider);
+static void clip_provider_set_selection(Clipboard_T *cbd, char_u *provider);
+static void clip_provider_request_selection(Clipboard_T *cbd, char_u *provider);
+#endif
+
 /*
  * Selection stuff using Visual mode, for cutting and pasting text to other
  * windows.
@@ -254,7 +260,7 @@ clip_gen_own_selection(Clipboard_T *cbd UNUSED)
     }
     else if (clipmethod == CLIPMETHOD_OTHER)
     {
-#if !defined(FEAT_XCLIPBOARD) && !defined(FEAT_WAYLAND_CLIPBOARD)
+#ifndef UNIX
 	return clip_mch_own_selection(cbd);
 #endif
     }
@@ -321,7 +327,7 @@ clip_gen_lose_selection(Clipboard_T *cbd UNUSED)
     }
     else if (clipmethod == CLIPMETHOD_OTHER)
     {
-#if !defined(FEAT_XCLIPBOARD) && !defined(FEAT_WAYLAND_CLIPBOARD)
+#ifndef UNIX
 	clip_mch_lose_selection(cbd);
 #endif
     }
@@ -1354,7 +1360,7 @@ clip_gen_set_selection(Clipboard_T *cbd)
     {
 #ifdef FEAT_GUI
 	if (gui.in_use)
-	clip_mch_set_selection(cbd);
+	    clip_mch_set_selection(cbd);
 #endif
     }
     else if (clipmethod == CLIPMETHOD_WAYLAND)
@@ -1371,8 +1377,14 @@ clip_gen_set_selection(Clipboard_T *cbd)
     }
     else if (clipmethod == CLIPMETHOD_OTHER)
     {
-#if !defined(FEAT_XCLIPBOARD) && !defined(FEAT_WAYLAND_CLIPBOARD)
+#ifndef UNIX
 	clip_mch_set_selection(cbd);
+#endif
+    }
+    else if (clipmethod == CLIPMETHOD_PROVIDER)
+    {
+#ifdef FEAT_CLIPBOARD_PROVIDER
+	clip_provider_set_selection(cbd, clipprovider_name);
 #endif
     }
 }
@@ -1401,8 +1413,14 @@ clip_gen_request_selection(Clipboard_T *cbd UNUSED)
     }
     else if (clipmethod == CLIPMETHOD_OTHER)
     {
-#if !defined(FEAT_XCLIPBOARD) && !defined(FEAT_WAYLAND_CLIPBOARD)
+#ifndef UNIX
 	clip_mch_request_selection(cbd);
+#endif
+    }
+    else if (clipmethod == CLIPMETHOD_PROVIDER)
+    {
+#ifdef FEAT_CLIPBOARD_PROVIDER
+	clip_provider_request_selection(cbd, clipprovider_name);
 #endif
     }
 }
@@ -2266,10 +2284,18 @@ clip_get_selection(Clipboard_T *cbd)
     }
     else if (!is_clipboard_needs_update())
     {
-	clip_free_selection(cbd);
+#ifdef FEAT_CLIPBOARD_PROVIDER
+	// We will choose if we want to the free the selection if using provider
+	if (clipmethod != CLIPMETHOD_PROVIDER)
+	    clip_free_selection(cbd);
+#endif
 
 	// Try to get selected text from another window
 	clip_gen_request_selection(cbd);
+#ifdef FEAT_CLIPBOARD_PROVIDER
+	if (clipmethod == CLIPMETHOD_PROVIDER)
+	    clip_access_type = CLIP_ACCESS_IMPLICIT;
+#endif
     }
 }
 
@@ -3507,15 +3533,34 @@ get_clipmethod(char_u *str, bool *regular, bool *primary)
 	}
 	else if (STRCMP(buf, "other") == 0)
 	{
-#if !defined(FEAT_XCLIPBOARD) && !defined(FEAT_WAYLAND_CLIPBOARD)
+#ifndef UNIX
 		method = CLIPMETHOD_OTHER;
 		*regular = *primary = true;
 #endif
 	}
 	else
 	{
-	    ret = CLIPMETHOD_FAIL;
+#ifdef FEAT_CLIPBOARD_PROVIDER
-	    goto exit;
+	    // Check if it is the name of a provider
+	    int reg = clip_provider_is_available(&clip_plus, buf);
+	    int pri = clip_provider_is_available(&clip_star, buf);
+
+	    if (reg == 1 || pri == 1)
+	    {
+		method = CLIPMETHOD_PROVIDER;
+
+		vim_free(clipprovider_name);
+		clipprovider_name = vim_strsave(buf);
+
+		*regular = reg == 1;
+		*primary = pri == 1;
+	    }
+	    else if (reg == -1)
+#endif
+	    {
+		ret = CLIPMETHOD_FAIL;
+		goto exit;
+	    }
 	}
 
 	// Keep on going in order to catch errors
@@ -3548,6 +3593,15 @@ clipmethod_to_str(clipmethod_T method)
 	    return (char_u *)"gui";
 	case CLIPMETHOD_OTHER:
 	    return (char_u *)"other";
+	case CLIPMETHOD_PROVIDER:
+#ifdef FEAT_CLIPBOARD_PROVIDER
+	    if (clipprovider_name == NULL)
+		return (char_u *)"none";
+	    else
+		return clipprovider_name;
+#else
+	    return (char_u *)"none";
+#endif
 	default:
 	    return (char_u *)"none";
     }
@@ -3584,16 +3638,26 @@ choose_clipmethod(void)
 	clip_plus.did_warn = false;
 	clip_star.did_warn = false;
     }
-    // Disown clipboard if we are switching to a new method
+    else if ((clipmethod != CLIPMETHOD_NONE && method != clipmethod))
-    else if (clipmethod != CLIPMETHOD_NONE && method != clipmethod)
     {
+	// Disown clipboard if we are switching to a new method
 	if (clip_star.owned)
 	    clip_lose_selection(&clip_star);
 	if (clip_plus.owned)
 	    clip_lose_selection(&clip_plus);
+
 	clip_init_single(&clip_plus, regular);
 	clip_init_single(&clip_star, primary);
     }
+    else
+    {
+	// If availability of a clipboard changed, then update the clipboard
+	// structure.
+	if (regular != clip_plus.available)
+	    clip_init_single(&clip_plus, regular);
+	if (primary != clip_star.available)
+	    clip_init_single(&clip_star, primary);
+    }
 
     clipmethod = method;
 
@@ -3621,4 +3685,321 @@ ex_clipreset(exarg_T *eap UNUSED)
 		clipmethod_to_str(clipmethod));
 }
 
+#ifdef FEAT_CLIPBOARD_PROVIDER
+
+/*
+ * Check if a clipboard provider with given name exists and is available for the
+ * given clipboard. Returns 1 if the provider exists and the 'available'
+ * function returned true, 0 if the provider exists but the function returned
+ * false, and -1 on error.
+ */
+    static int
+clip_provider_is_available(Clipboard_T *cbd, char_u *provider)
+{
+    dict_T	*providers = get_vim_var_dict(VV_CLIPPROVIDERS);
+    typval_T	provider_tv = {0};
+    callback_T	callback = {0};
+    typval_T	rettv = {0};
+    typval_T	func_tv = {0};
+    char_u	*avail;
+    int		res = 0;
+
+    if (dict_get_tv(providers, (char *)provider, &provider_tv) == FAIL
+	    || provider_tv.v_type != VAR_DICT)
+	return -1;
+
+    if (dict_get_tv(provider_tv.vval.v_dict, "available", &func_tv) == FAIL)
+    {
+	clear_tv(&provider_tv);
+	// If "available" functon not specified assume always TRUE
+	return 1;
+    }
+
+    if ((callback = get_callback(&func_tv)).cb_name == NULL)
+	goto fail;
+
+    if (call_callback(&callback, -1, &rettv, 0, NULL) == FAIL ||
+	    rettv.v_type != VAR_STRING)
+	goto fail;
+
+    avail = rettv.vval.v_string;
+
+    if ((vim_strchr(avail, '+') != NULL && cbd == &clip_plus)
+	    || (vim_strchr(avail, '*') != NULL && cbd == &clip_star))
+	res = 1;
+
+    if (FALSE)
+fail:
+	res = -1;
+
+    free_callback(&callback);
+    clear_tv(&func_tv);
+    clear_tv(&rettv);
+    clear_tv(&provider_tv);
+
+    return res;
+}
+
+/*
+ * Get the specified callback "function" from the provider dictionary of for
+ * register "reg".
+ */
+    static int
+clip_provider_get_callback(
+	char_u *reg,
+	char_u *provider,
+	char_u *function,
+	callback_T *callback)
+{
+    dict_T	*providers = get_vim_var_dict(VV_CLIPPROVIDERS);
+    typval_T	provider_tv;
+    typval_T	action_tv;
+    typval_T	func_tv;
+    callback_T	cb;
+
+    if (dict_get_tv(providers, (char *)provider, &provider_tv) == FAIL)
+	return FAIL;
+    else if (provider_tv.v_type != VAR_DICT)
+    {
+	clear_tv(&provider_tv);
+	return FAIL;
+    }
+    else if (dict_get_tv(
+		provider_tv.vval.v_dict,
+		(char *)function,
+		&action_tv) == FAIL)
+    {
+	clear_tv(&provider_tv);
+	return FAIL;
+    }
+    else if (action_tv.v_type != VAR_DICT)
+    {
+	clear_tv(&provider_tv);
+	clear_tv(&action_tv);
+	return FAIL;
+    }
+    else if (dict_get_tv(action_tv.vval.v_dict, (char *)reg, &func_tv) == FAIL)
+    {
+	clear_tv(&provider_tv);
+	clear_tv(&action_tv);
+	return FAIL;
+    }
+    else if ((cb = get_callback(&func_tv)).cb_name == NULL)
+    {
+	clear_tv(&provider_tv);
+	clear_tv(&action_tv);
+	clear_tv(&func_tv);
+	return FAIL;
+    }
+    clear_tv(&provider_tv);
+    clear_tv(&action_tv);
+
+    // func_tv owns the function name, so we must make a copy for the callback
+    set_callback(callback, &cb);
+    free_callback(&cb);
+    clear_tv(&func_tv);
+    return OK;
+}
+
+    static void
+clip_provider_set_selection(Clipboard_T *cbd, char_u *provider)
+{
+    char_u	*reg = (char_u *)(cbd == &clip_star ? "*" : "+");
+    callback_T	callback;
+    typval_T	rettv;
+    typval_T	argvars[4];
+    yankreg_T	*y_ptr;
+    char_u	type[2 + NUMBUFLEN] = {0};
+    list_T	*list = NULL;
+
+    if (clip_provider_get_callback(
+		reg,
+		provider,
+		(char_u *)"copy",
+		&callback) == FAIL)
+	return;
+
+    // Possibly get selected text, if using autoselect for 'clipboard'
+    cbd->owned = TRUE;
+    clip_get_selection(cbd);
+    cbd->owned = FALSE;
+
+    // Convert register type into a string
+    if (cbd == &clip_plus)
+	y_ptr = get_y_register(PLUS_REGISTER);
+    else
+	y_ptr = get_y_register(STAR_REGISTER);
+
+    switch (y_ptr->y_type)
+    {
+	case MCHAR:
+	    type[0] = 'v';
+	    break;
+	case MLINE:
+	    type[0] = 'V';
+	    break;
+	case MBLOCK:
+	    sprintf((char *)type, "%c%d", Ctrl_V, y_ptr->y_width + 1);
+	    break;
+	default:
+	    type[0] = 0;
+	    break;
+    }
+
+    argvars[0].v_type = VAR_STRING;
+    argvars[0].vval.v_string = reg;
+
+    argvars[1].v_type = VAR_STRING;
+    argvars[1].vval.v_string = type;
+
+    // Get register contents by creating a list of lines
+    list = list_alloc();
+
+    if (list == NULL)
+    {
+	free_callback(&callback);
+	return;
+    }
+
+    for (int i = 0; i < y_ptr->y_size; i++)
+	if (list_append_string(list, y_ptr->y_array[i].string, -1) == FAIL)
+	{
+	    free_callback(&callback);
+	    list_unref(list);
+	    return;
+	}
+
+    list->lv_refcount++;
+
+    argvars[2].v_type = VAR_LIST;
+    argvars[2].v_lock = VAR_FIXED;
+    argvars[2].vval.v_list = list;
+
+    argvars[3].v_type = VAR_UNKNOWN;
+
+    textlock++;
+    call_callback(&callback, -1, &rettv, 3, argvars);
+    clear_tv(&rettv);
+    textlock--;
+
+    free_callback(&callback);
+    list_unref(list);
+}
+
+    static void
+clip_provider_request_selection(Clipboard_T *cbd, char_u *provider)
+{
+    char_u	*reg = (char_u *)(cbd == &clip_star ? "*" : "+");
+    callback_T	callback;
+    typval_T	argvars[3];
+    typval_T	rettv;
+    int		ret;
+    char_u	*reg_type;
+    list_T	*lines;
+
+    if (clip_provider_get_callback(
+		reg,
+		provider,
+		(char_u *)"paste",
+		&callback) == FAIL)
+	return;
+
+    argvars[0].v_type = VAR_STRING;
+    argvars[0].vval.v_string = reg;
+
+    argvars[1].v_type = VAR_STRING;
+    argvars[1].vval.v_string = (char_u *)
+	(clip_access_type == CLIP_ACCESS_EXPLICIT ? "explicit" : "implicit");
+
+    argvars[2].v_type = VAR_UNKNOWN;
+
+    textlock++;
+    ret = call_callback(&callback, -1, &rettv, 2, argvars);
+    textlock--;
+
+    if (ret == FAIL)
+	goto exit;
+    else if (rettv.v_type == VAR_STRING
+	    && STRCMP(rettv.vval.v_string, "clear") == 0)
+    {
+	clip_free_selection(cbd);
+	goto exit;
+    }
+    else if (rettv.v_type == VAR_STRING
+	    && STRCMP(rettv.vval.v_string, "previous") == 0)
+	goto exit;
+    else if (rettv.v_type == VAR_TUPLE
+	    && TUPLE_LEN(rettv.vval.v_tuple) == 2
+	    && TUPLE_ITEM(rettv.vval.v_tuple, 0)->v_type == VAR_STRING
+	    && TUPLE_ITEM(rettv.vval.v_tuple, 1)->v_type == VAR_LIST)
+    {
+	reg_type = TUPLE_ITEM(rettv.vval.v_tuple, 0)->vval.v_string;
+	lines = TUPLE_ITEM(rettv.vval.v_tuple, 1)->vval.v_list;
+    }
+    else if (rettv.v_type == VAR_LIST
+	    && rettv.vval.v_list->lv_len == 2
+	    && rettv.vval.v_list->lv_first->li_tv.v_type == VAR_STRING
+	    && rettv.vval.v_list->lv_first->li_next->li_tv.v_type == VAR_LIST)
+    {
+	reg_type = rettv.vval.v_list->lv_first->li_tv.vval.v_string;
+	lines = rettv.vval.v_list->lv_first->li_next->li_tv.vval.v_list;
+    }
+    else
+	goto exit;
+
+    {
+	char_u	    yank_type = MAUTO;
+	long	    block_len = -1;
+	yankreg_T   *y_ptr;
+	char_u	    **contents;
+	listitem_T  *li;
+	int	    i = 0;
+
+	contents = ALLOC_MULT(char_u *, lines->lv_len + 1); // Ends with a NULL
+
+	if (contents == NULL)
+	    goto exit;
+
+	// Convert strings in list to type char_u **
+	FOR_ALL_LIST_ITEMS(lines, li)
+	{
+	    char_u *str = tv_get_string_chk(&li->li_tv);
+
+	    if (str == NULL)
+		goto exit;
+
+	    contents[i++] = vim_strsave(str);
+	}
+	contents[i] = NULL;
+
+	if (STRLEN(reg_type) > 0
+		&& get_yank_type(&reg_type, &yank_type, &block_len) == FAIL)
+	    goto exit;
+
+	if (cbd == &clip_plus)
+	    y_ptr = get_y_register(PLUS_REGISTER);
+	else
+	    y_ptr = get_y_register(STAR_REGISTER);
+
+	clip_free_selection(cbd);
+
+	str_to_reg(y_ptr,
+		yank_type,
+		(char_u *)contents,
+		STRLEN(contents),
+		block_len,
+		TRUE);
+
+	for (int k = 0; k < i; k++)
+	    vim_free(contents[k]);
+	vim_free(contents);
+    }
+
+exit:
+    free_callback(&callback);
+    clear_tv(&rettv);
+}
+
+#endif // FEAT_CLIPBOARD_PROVIDER
+
 #endif // FEAT_CLIPBOARD

src/config.h.in

@@ -528,3 +528,6 @@
 
 /* Define if you want to load libgpm dynamically */
 #undef DYNAMIC_GPM
+
+/* Define if you want to have clipboard provider functionality*/
+#undef FEAT_CLIPBOARD_PROVIDER

src/configure.ac

@@ -2434,6 +2434,21 @@ AC_ARG_ENABLE(fontset,
 AC_MSG_RESULT($enable_fontset)
 dnl defining FEAT_XFONTSET is delayed, so that it can be disabled for no GUI
 
+AC_MSG_CHECKING(--enable-clipboard-provider)
+AC_ARG_ENABLE(clipboard-provider,
+	[  --enable-clipboard-provider  Include clipboard provider support.],
+	[enable_clipboard_provider=$enableval
+	 AC_MSG_RESULT($enableval)],
+	AS_IF([test "x$features" = xtiny], 
+			[enable_clipboard_provider="no"
+			 AC_MSG_RESULT([cannot use clipboard provider with tiny features])],
+			[enable_clipboard_provider="yes"
+			 AC_MSG_RESULT([yes])]))
+if test "$enable_clipboard_provider" = "yes"; then
+  AC_DEFINE(FEAT_CLIPBOARD_PROVIDER)
+fi
+
+
 AC_MSG_CHECKING(if shm_open is available)
 cppflags_save=$CPPFLAGS
 CPPFLAGS="$CPPFLAGS $X_CFLAGS"

src/evalfunc.c

@@ -6500,6 +6500,11 @@ f_getreg(typval_T *argvars, typval_T *rettv)
 	    return;
     }
 
+#ifdef FEAT_CLIPBOARD_PROVIDER
+    if (clipmethod == CLIPMETHOD_PROVIDER)
+	clip_access_type = CLIP_ACCESS_EXPLICIT;
+#endif
+
     if (return_list)
     {
 	rettv->v_type = VAR_LIST;
@@ -6866,6 +6871,13 @@ f_has(typval_T *argvars, typval_T *rettv)
 		1
 #else
 		0
+#endif
+		},
+	{"clipboard_provider",
+#ifdef FEAT_CLIPBOARD_PROVIDER
+		1
+#else
+		0
 #endif
 		},
 	{"cmdline_compl", 1},
@@ -11493,7 +11505,7 @@ f_setpos(typval_T *argvars, typval_T *rettv)
 /*
  * Translate a register type string to the yank type and block length
  */
-    static int
+    int
 get_yank_type(char_u **pp, char_u *yank_type, long *block_len)
 {
     char_u *stropt = *pp;

src/evalvars.c

@@ -166,7 +166,8 @@ static struct vimvar
     {VV_NAME("wayland_display",  VAR_STRING), NULL, VV_RO},
     {VV_NAME("clipmethod",	 VAR_STRING), NULL, VV_RO},
     {VV_NAME("termda1",		 VAR_STRING), NULL, VV_RO},
-    {VV_NAME("termosc",	 VAR_STRING), NULL, VV_RO},
+    {VV_NAME("termosc",		 VAR_STRING), NULL, VV_RO},
+    {VV_NAME("clipproviders",	 VAR_DICT), &t_dict_string, VV_RO}
 };
 
 // shorthand

src/feature.h

@@ -905,6 +905,19 @@
 # define FEAT_CLIPBOARD
 #endif
 
+/*
+ * +clipboard_provider	Allow Vim to use clipboard providers
+ */
+#if defined(FEAT_CLIPBOARD_PROVIDER)
+# ifndef FEAT_EVAL
+#  undef FEAT_CLIPBOARD_PROVIDER
+# else
+#  ifndef FEAT_CLIPBOARD
+#   define FEAT_CLIPBOARD
+#  endif
+# endif
+#endif
+
 #ifdef FEAT_GUI
 # ifndef FEAT_CLIPBOARD
 #  define FEAT_CLIPBOARD

src/globals.h

@@ -972,7 +972,8 @@ EXTERN int	gui_win_y INIT(= -1);
 
 #ifdef FEAT_CLIPBOARD
 EXTERN Clipboard_T clip_star;	// PRIMARY selection in X11/Wayland
-# if defined(FEAT_X11) || defined(FEAT_WAYLAND_CLIPBOARD)
+# if defined(FEAT_X11) || defined(FEAT_WAYLAND_CLIPBOARD) \
+    || ((defined(UNIX) || defined(VMS)) && defined(FEAT_CLIPBOARD_PROVIDER))
 EXTERN Clipboard_T clip_plus;	// CLIPBOARD selection in X11/Wayland
 # else
 #  define clip_plus clip_star	// there is only one clipboard
@@ -2067,6 +2068,9 @@ EXTERN int	p_tgc_set INIT(= FALSE);
 
 #ifdef FEAT_CLIPBOARD
 EXTERN clipmethod_T clipmethod INIT(= CLIPMETHOD_NONE);
+# ifdef FEAT_CLIPBOARD_PROVIDER
+EXTERN char_u *clipprovider_name INIT(= NULL);
+# endif
 #endif
 
 #ifdef FEAT_WAYLAND
@@ -2116,3 +2120,16 @@ INIT(= CLIENTSERVER_METHOD_NONE);
 // Path to socket of last client that communicated with us
 EXTERN char_u *client_socket INIT(= NULL);
 #endif
+
+#ifdef FEAT_CLIPBOARD_PROVIDER
+typedef enum
+{
+    CLIP_ACCESS_IMPLICIT,
+    CLIP_ACCESS_EXPLICIT,
+} clip_access_T;
+
+// Only relevant for the clipboard provider feature. This indicates if the
+// clipboard request is implicit (ex. access when doing :registers),
+// explicit (ex. typing "+p). Always defaults to implicit.
+EXTERN clip_access_T clip_access_type INIT(= CLIP_ACCESS_IMPLICIT);
+#endif

src/proto/evalfunc.pro

@@ -28,4 +28,5 @@ void f_len(typval_T *argvars, typval_T *rettv);
 void mzscheme_call_vim(char_u *name, typval_T *args, typval_T *rettv);
 void range_list_materialize(list_T *list);
 long do_searchpair(char_u *spat, char_u *mpat, char_u *epat, int dir, typval_T *skip, int flags, pos_T *match_pos, linenr_T lnum_stop, long time_limit);
+int get_yank_type(char_u **pp, char_u *yank_type, long *block_len);
 /* vim: set ft=c : */

src/register.c

@@ -1559,6 +1559,10 @@ do_put(
 #ifdef FEAT_CLIPBOARD
     // Adjust register name for "unnamed" in 'clipboard'.
     adjust_clip_reg(&regname);
+# ifdef FEAT_CLIPBOARD_PROVIDER
+    if (clipmethod == CLIPMETHOD_PROVIDER)
+	clip_access_type = CLIP_ACCESS_EXPLICIT;
+# endif
     (void)may_get_selection(regname);
 #endif
 

src/testdir/Make_all.mak

@@ -105,6 +105,7 @@ NEW_TESTS = \
 	test_cjk_linebreak \
 	test_clientserver \
 	test_clipmethod \
+	test_clipboard_provider \
 	test_close_count \
 	test_cmd_lists \
 	test_cmdline \
@@ -395,6 +396,7 @@ NEW_TESTS_RES = \
 	test_cjk_linebreak.res \
 	test_clientserver.res \
 	test_clipmethod.res \
+	test_clipboard_provider.res \
 	test_close_count.res \
 	test_cmd_lists.res \
 	test_cmdline.res \

src/testdir/test_clipboard_provider.vim

@@ -0,0 +1,170 @@
+" Test for clipboard provider feature
+
+CheckFeature clipboard_provider
+
+func! AvailableBoth()
+    return "+*"
+endfunc
+
+func! AvailablePlus()
+    return "+"
+endfunc
+
+func! PasteList(reg, type)
+    return ["c", ["list"]]
+endfunc
+
+func! PasteTuple(reg, type)
+    return ("", ["tuple", "of", "strings"])
+endfunc
+
+func! PasteType(reg, type)
+    let g:vim_test_type = a:type
+    return ("c", [a:type])
+endfunc
+
+func! PasteRegType(reg, type)
+    return (g:vim_test_reg_type, ["7 chars"])
+endfunc
+
+func! Copy(reg, type, lines)
+    let g:vim_test_stuff = {
+                \ "type": a:type,
+                \ "lines": a:lines
+                \ }
+endfunc
+
+" Test if "available" function works properly for provider
+func Test_clipboard_provider_available()
+    CheckUnix
+    let v:clipproviders["test"] = {
+                \ "available": function("AvailablePlus"),
+                \ "paste": {
+                \       '+': function("PasteList"),
+                \       '*': function("PasteList")
+                \   }
+                \ }
+
+    set clipmethod=test
+    call assert_equal("test", v:clipmethod)
+
+    call assert_equal("list", getreg("+"))
+    " Test if star register is unavailable
+    call assert_equal("", getreg("*"))
+
+    let v:clipproviders["test"] = {
+                \ "available": function("AvailableBoth"),
+                \ "paste": {
+                \       '+': function("PasteList"),
+                \       '*': function("PasteList")
+                \   }
+                \ }
+
+    clipreset
+
+    call assert_equal("list", getreg("+"))
+    call assert_equal("list", getreg("*"))
+
+    let v:clipproviders["test"] = {
+                \ "paste": {
+                \       '+': function("PasteList"),
+                \       '*': function("PasteList")
+                \   }
+                \ }
+
+    " Should default to TRUE
+    call assert_equal("list", getreg("+"))
+    call assert_equal("list", getreg("*"))
+
+    set clipmethod&
+endfunc
+
+" Test if "paste" functions work properly for provider
+func Test_clipboard_provider_paste()
+    " Test if tuples and lists work the same
+    let v:clipproviders["test"] = {
+                \ "paste": {
+                \       '*': function("PasteList")
+                \   }
+                \ }
+
+    set clipmethod=test
+    call assert_equal("test", v:clipmethod)
+
+    call assert_equal("list", getreg("*"))
+
+    let v:clipproviders["test"] = {
+                \ "paste": {
+                \       '*': function("PasteTuple")
+                \   }
+                \ }
+
+    call assert_equal("tuple\nof\nstrings\n", getreg("*"))
+
+    " Test if "implicit" and "explicit" arguments are correctly used
+    let v:clipproviders["test"] = {
+                \ "paste": {
+                \       '*': function("PasteType")
+                \   }
+                \ }
+
+    call assert_equal("explicit", getreg("*"))
+
+    :registers
+
+    call assert_equal("implicit", g:vim_test_type)
+    unlet g:vim_test_type
+
+    " Test if correct register type is used
+    let v:clipproviders["test"] = {
+                \ "paste": {
+                \       '*': function("PasteRegType")
+                \   }
+                \ }
+
+    let g:vim_test_reg_type = "v"
+    call assert_equal("v", getregtype("*"))
+    let g:vim_test_reg_type = "c"
+    call assert_equal("v", getregtype("*"))
+
+    let g:vim_test_reg_type = "l"
+    call assert_equal("V", getregtype("*"))
+    let g:vim_test_reg_type = "l"
+    call assert_equal("V", getregtype("*"))
+
+    let g:vim_test_reg_type = "b"
+    call assert_equal("7", getregtype("*"))
+    let g:vim_test_reg_type = ""
+    call assert_equal("7", getregtype("*"))
+
+    let g:vim_test_reg_type = "b40"
+    call assert_equal("40", getregtype("*"))
+
+    set clipmethod&
+endfunc
+
+" Test if "copy" functions work properly for provider
+func Test_clipboard_provider_copy()
+    let v:clipproviders["test"] = {
+                \ "copy": {
+                \       '*': function("Copy")
+                \   }
+                \ }
+
+    set clipmethod=test
+    call assert_equal("test", v:clipmethod)
+
+    call setreg("*", ["hello", "world", "!"], "c")
+    call assert_equal(["hello", "world", "!"], g:vim_test_stuff.lines)
+    call assert_equal("v", g:vim_test_stuff.type)
+
+    call setreg("*", ["hello", "world", "!"], "l")
+    call assert_equal(["hello", "world", "!"], g:vim_test_stuff.lines)
+    call assert_equal("V", g:vim_test_stuff.type)
+
+    call setreg("*", ["hello", "world", "!"], "b40")
+    call assert_equal(["hello", "world", "!"], g:vim_test_stuff.lines)
+    call assert_equal("40", g:vim_test_stuff.type)
+
+    set clipmethod&
+endfunc

src/version.c

@@ -155,6 +155,11 @@ static char *(features[]) =
 	"+clipboard",
 #else
 	"-clipboard",
+#endif
+#ifdef FEAT_CLIPBOARD_PROVIDER
+	"+clipboard_provider",
+#else
+	"-clipboard_provider",
 #endif
 	"+cmdline_compl",
 	"+cmdline_hist",
@@ -729,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1857,
 /**/
     1856,
 /**/

src/vim.h

@@ -2256,7 +2256,8 @@ typedef int sock_T;
 #define VV_CLIPMETHOD 113
 #define VV_TERMDA1 114
 #define VV_TERMOSC 115
-#define VV_LEN		116	// number of v: vars
+#define VV_CLIPPROVIDERS 116
+#define VV_LEN		117	// number of v: vars
 
 // used for v_number in VAR_BOOL and VAR_SPECIAL
 #define VVAL_FALSE	0L	// VAR_BOOL
@@ -2318,6 +2319,7 @@ typedef enum {
     CLIPMETHOD_X11,
     CLIPMETHOD_GUI,
     CLIPMETHOD_OTHER,
+    CLIPMETHOD_PROVIDER
 } clipmethod_T;
 
 // Info about selected text