patch 9.1.0142: getregion() can be improved

Problem:  getregion() can be improved (after v9.1.120)
Solution: change getregion() implementation to use pos as lists and
          one optional {opt} dictionary (Shougo Matsushita)

Note: The following is a breaking change!

Currently, the getregion() function (included as of patch v9.1.120) takes
3 arguments: the first 2 arguments are strings, describing a position,
arg3 is the type string.

However, that is slightly inflexible, there is no way to specify
additional arguments. So let's instead change the function signature to:

getregion(pos1, pos2 [, {Dict}]) where both pos1 and pos2 are lists.
This is slightly cleaner, and gives us the flexibility to specify
additional arguments as key/value pairs to the optional Dict arg.

Now it supports the "type" key to specify the selection type
(characterwise, blockwise or linewise) and now in addition one can also
define the selection type, independently of what the 'selection' option
actually is.

Technically, this is a breaking change, but since the getregion()
Vimscript function is still quite new, this should be fine.

closes: #14090

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index 0af9b0e..6d1d372 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -1,4 +1,4 @@
-*builtin.txt*	For Vim version 9.1.  Last change: 2024 Feb 25
+*builtin.txt*	For Vim version 9.1.  Last change: 2024 Feb 28
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -263,7 +263,7 @@
 getreg([{regname} [, 1 [, {list}]]])
 				String or List   contents of a register
 getreginfo([{regname}])		Dict	information about a register
-getregion({pos1}, {pos2}, {type})
+getregion({pos1}, {pos2} [, {opts}])
 				List	get the text from {pos1} to {pos2}
 getregtype([{regname}])		String	type of a register
 getscriptinfo([{opts}])		List	list of sourced scripts
@@ -4271,14 +4271,25 @@
 		Can also be used as a |method|: >
 			GetRegname()->getreginfo()
 
-getregion({pos1}, {pos2}, {type})			*getregion()*
-		Returns the list of strings from {pos1} to {pos2} as if it's
-		selected in visual mode of {type}.
-		For possible values of {pos1} and {pos2} see |line()|.
-		{type} is the selection type:
-			"v" for |characterwise| mode
-			"V" for |linewise| mode
-			"<CTRL-V>" for |blockwise-visual| mode
+getregion({pos1}, {pos2} [, {opts}])			*getregion()*
+		Returns the list of strings from {pos1} to {pos2} in current
+		buffer.
+
+		{pos1} and {pos2} must both be |List|s with four numbers.
+		See |getpos()| for the format of the list.
+
+		The optional argument {opts} is a Dict and supports the
+		following items:
+
+			type		Specify the selection type
+					(default: "v"):
+			    "v"		for |characterwise| mode
+			    "V"		for |linewise| mode
+			    "<CTRL-V>"	for |blockwise-visual| mode
+
+			exclusive	If |true|, use exclusive selection
+					for the end position 'selection'.
+
 		You can get the last selection type by |visualmode()|.
 		If Visual mode is active, use |mode()| to get the Visual mode
 		(e.g., in a |:vmap|).
@@ -4296,19 +4307,16 @@
 		- If the selection starts or ends in the middle of a multibyte
 		  character, it is not included but its selected part is
 		  substituted with spaces.
-		- If {pos1} or {pos2} equals "v" (see |line()|) and it is not in
-		  |visual-mode|, an empty list is returned.
-		- If {pos1}, {pos2} or {type} is an invalid string, an empty
-		  list is returned.
-		- If {pos1} or {pos2} is a mark in different buffer, an empty
+		- If {pos1} or {pos2} is not current in the buffer, an empty
 		  list is returned.
 
 		Examples: >
 			:xnoremap <CR>
-			\ <Cmd>echow getregion('v', '.', mode())<CR>
+			\ <Cmd>echow getregion(
+			\ getpos('v'), getpos('.'), #{ type: mode() })<CR>
 <
 		Can also be used as a |method|: >
-			'.'->getregion("'a", 'v')
+			getpos('.')->getregion(getpos("'a"))
 <
 getregtype([{regname}])					*getregtype()*
 		The result is a String, which is type of register {regname}.