vim-patch:8.1.1807: more functions can be used as a method

Problem:    More functions can be used as a method.
Solution:   Add append(), appendbufline(), assert_equal(), etc.
            Also add the :eval command.
https://github.com/vim/vim/commit/25e42231d3ee27feec2568fa4be2aa2bfba82ae5

:eval is already ported.

7 files changed, 83 insertions, 26 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index eee401baa1..070c94da3b 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -669,12 +669,14 @@ Expression syntax summary, from least to most significant:
 	expr8[expr1 : expr1]	substring of a String or sublist of a |List|
 	expr8.name		entry in a |Dictionary|
 	expr8(expr1, ...)	function call with |Funcref| variable
+	expr8->name(expr1, ...)	|method| call
 
 |expr9|	number			number constant
 	"string"		string constant, backslash is special
 	'string'		string constant, ' is doubled
 	[expr1, ...]		|List|
 	{expr1: expr1, ...}	|Dictionary|
+	#{key: expr1, ...}	|Dictionary|
 	&option			option value
 	(expr1)			nested expression
 	variable		internal variable
@@ -939,10 +941,10 @@ expr8							*expr8*
 -----
 This expression is either |expr9| or a sequence of the alternatives below,
 in any order.  E.g., these are all possible:
-	expr9[expr1].name
-	expr9.name[expr1]
-	expr9(expr1, ...)[expr1].name
-	expr9->(expr1, ...)[expr1]
+	expr8[expr1].name
+	expr8.name[expr1]
+	expr8(expr1, ...)[expr1].name
+	expr8->(expr1, ...)[expr1]
 Evaluation is always from left to right.
 
 
@@ -1047,10 +1049,17 @@ When expr8 is a |Funcref| type variable, invoke the function it refers to.
 
 expr8->name([args])	method call			*method*
 
-For global methods this is the same as: >
+For methods that are also available as global functions this is the same as: >
 	name(expr8 [, args])
 There can also be methods specifically for the type of "expr8".
 
+"->name(" must not contain white space.  There can be white space before "->"
+and after the "(".
+
+This allows for chaining, using the type that the method returns: >
+	mylist->filter(filterexpr)->map(mapexpr)->sort()->join()
+<
+
 							*expr9*
 number
 ------
@@ -2637,6 +2646,9 @@ append({lnum}, {text})					*append()*
 			:let failed = append(line('$'), "# THE END")
 			:let failed = append(0, ["Chapter 1", "the beginning"])
 
+<		Can also be used as a |method| after a List: >
+			mylist->append(lnum)
+
 appendbufline({expr}, {lnum}, {text})			*appendbufline()*
 		Like |append()| but append the text in buffer {expr}.
 
@@ -2655,8 +2667,10 @@ appendbufline({expr}, {lnum}, {text})			*appendbufline()*
 		error message is given. Example: >
 			:let failed = appendbufline(13, 0, "# THE START")
 <
-							*argc()*
-argc([{winid}])
+		Can also be used as a |method| after a List: >
+			mylist->appendbufline(buf, lnum)
+
+argc([{winid}])					*argc()*
 		The result is the number of files in the argument list.  See
 		|arglist|.
 		If {winid} is not supplied, the argument list of the current
@@ -3518,6 +3532,9 @@ eval({string})	Evaluate {string} and return the result.  Especially useful to
 		them.  Also works for |Funcref|s that refer to existing
 		functions.
 
+		Can also be used as a |method|: >
+			argv->join()->eval()
+
 eventhandler()						*eventhandler()*
 		Returns 1 when inside an event handler.  That is that Vim got
 		interrupted while waiting for the user to type a character,
@@ -3864,7 +3881,11 @@ filereadable({file})					*filereadable()*
 		expression, which is used as a String.
 		If you don't care about the file being readable you can use
 		|glob()|.
-
+		{file} is used as-is, you may want to expand wildcards first: >
+			echo filereadable('~/.vimrc')
+			0
+			echo filereadable(expand('~/.vimrc'))
+			1
 
 filewritable({file})					*filewritable()*
 		The result is a Number, which is 1 when a file with the
@@ -10006,7 +10027,9 @@ This function can then be called with: >
 The recursiveness of user functions is restricted with the |'maxfuncdepth'|
 option.
 
-It is also possible to use `:eval`.  It does not support a range.
+It is also possible to use `:eval`.  It does not support a range, but does
+allow for method chaining, e.g.: >
+	eval GetList()->Filter()->append('$')
 
 
 AUTOMATICALLY LOADING FUNCTIONS ~
@@ -10749,7 +10772,7 @@ text...
 <
 							*:eval*
 :eval {expr}		Evaluate {expr} and discard the result.  Example: >
-				:eval append(Filter(Getlist()), '$')
+				:eval Getlist()->Filter()->append('$')
 
 <			The expression is supposed to have a side effect,
 			since the resulting value is not used.  In the example
diff --git a/runtime/doc/testing.txt b/runtime/doc/testing.txt
index ef8d6b5ea9..eca2025ed7 100644
--- a/runtime/doc/testing.txt
+++ b/runtime/doc/testing.txt
@@ -69,7 +69,10 @@ assert_equal({expected}, {actual} [, {msg}])
 <		Will result in a string to be added to |v:errors|:
 	test.vim line 12: Expected 'foo' but got 'bar' ~
 
-							*assert_equalfile()*
+		Can also be used as a |method|: >
+			mylist->assert_equal([1, 2, 3])
+
+<							*assert_equalfile()*
 assert_equalfile({fname-one}, {fname-two})
 		When the files {fname-one} and {fname-two} do not contain
 		exactly the same text an error message is added to |v:errors|.
@@ -145,7 +148,10 @@ assert_notequal({expected}, {actual} [, {msg}])
 		|v:errors| when {expected} and {actual} are equal.
 		Also see |assert-return|.
 
-							*assert_notmatch()*
+		Can also be used as a |method|: >
+			mylist->assert_notequal([1, 2, 3])
+
+<							*assert_notmatch()*
 assert_notmatch({pattern}, {actual} [, {msg}])
 		The opposite of `assert_match()`: add an error message to
 		|v:errors| when {pattern} matches {actual}.
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index f94ecffed9..506368a3b2 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -7,7 +7,7 @@
 --       arguments.
 -- base  For methods: the argument to use as the base argument (1-indexed):
 --       base->method()
---       Defaults to zero (function cannot be used as a method).
+--       Defaults to BASE_NONE (function cannot be used as a method).
 -- func  Name of the C function which implements the VimL function. Defaults to
 --       `f_{funcname}`.
 
@@ -15,6 +15,10 @@ local varargs = function(nr)
   return {nr}
 end
 
+-- Usable with the base key: use the last function argument as the method base.
+-- Value is from funcs.h file. "BASE_" prefix is omitted.
+local LAST = "BASE_LAST"
+
 return {
   funcs={
     abs={args=1},
@@ -22,15 +26,15 @@ return {
     add={args=2, base=1},
     ['and']={args=2},
     api_info={},
-    append={args=2},
-    appendbufline={args=3},
+    append={args=2, base=LAST},
+    appendbufline={args=3, base=LAST},
     argc={args={0, 1}},
     argidx={},
     arglistid={args={0, 2}},
     argv={args={0, 2}},
     asin={args=1, func="float_op_wrapper", data="&asin"},  -- WJMc
     assert_beeps={args={1}},
-    assert_equal={args={2, 3}},
+    assert_equal={args={2, 3}, base=2},
     assert_equalfile={args={2, 3}},
     assert_exception={args={1, 2}},
     assert_fails={args={1, 3}},
@@ -38,7 +42,7 @@ return {
     assert_inrange={args={3, 4}},
     assert_match={args={2, 3}},
     assert_nobeep={args={1}},
-    assert_notequal={args={2, 3}},
+    assert_notequal={args={2, 3}, base=2},
     assert_notmatch={args={2, 3}},
     assert_report={args=1},
     assert_true={args={1, 2}},
@@ -99,7 +103,7 @@ return {
     empty={args=1, base=1},
     environ={},
     escape={args=2},
-    eval={args=1},
+    eval={args=1, base=1},
     eventhandler={},
     executable={args=1},
     execute={args={1, 2}},
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 787d5aaf78..e090f3b37f 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -199,7 +199,7 @@ int call_internal_method(const char_u *const fname, const int argcount,
   FUNC_ATTR_NONNULL_ALL
 {
   const VimLFuncDef *const fdef = find_internal_func((const char *)fname);
-  if (fdef == NULL || fdef->base_arg == 0) {
+  if (fdef == NULL || fdef->base_arg == BASE_NONE) {
     return ERROR_UNKNOWN;
   } else if (argcount + 1 < fdef->min_argc) {
     return ERROR_TOOFEW;
@@ -208,7 +208,8 @@ int call_internal_method(const char_u *const fname, const int argcount,
   }
 
   typval_T argv[MAX_FUNC_ARGS + 1];
-  const ptrdiff_t base_index = fdef->base_arg - 1;
+  const ptrdiff_t base_index
+      = fdef->base_arg == BASE_LAST ? argcount : fdef->base_arg - 1;
   memcpy(argv, argvars, base_index * sizeof(typval_T));
   argv[base_index] = *basetv;
   memcpy(argv + base_index + 1, argvars + base_index,
diff --git a/src/nvim/eval/funcs.h b/src/nvim/eval/funcs.h
index 3ad0b8282a..c6a0cb959e 100644
--- a/src/nvim/eval/funcs.h
+++ b/src/nvim/eval/funcs.h
@@ -9,12 +9,16 @@ typedef void (*FunPtr)(void);
 /// Prototype of C function that implements VimL function
 typedef void (*VimLFunc)(typval_T *args, typval_T *rvar, FunPtr data);
 
+/// Special flags for base_arg @see VimLFuncDef
+#define BASE_NONE 0          ///< Not a method (no base argument).
+#define BASE_LAST UINT8_MAX  ///< Use the last argument as the method base.
+
 /// Structure holding VimL function definition
 typedef struct fst {
   char *name;        ///< Name of the function.
   uint8_t min_argc;  ///< Minimal number of arguments.
   uint8_t max_argc;  ///< Maximal number of arguments.
-  uint8_t base_arg;  ///< Method base arg # (1-indexed), or 0 if not a method.
+  uint8_t base_arg;  ///< Method base arg # (1-indexed), BASE_NONE or BASE_LAST.
   VimLFunc func;     ///< Function implementation.
   FunPtr data;       ///< Userdata for function implementation.
 } VimLFuncDef;
diff --git a/src/nvim/generators/gen_eval.lua b/src/nvim/generators/gen_eval.lua
index aa2274e0a2..945fa5099f 100644
--- a/src/nvim/generators/gen_eval.lua
+++ b/src/nvim/generators/gen_eval.lua
@@ -42,7 +42,7 @@ gperfpipe:write([[
 %language=ANSI-C
 %global-table
 %readonly-tables
-%define initializer-suffix ,0,0,0,NULL,NULL
+%define initializer-suffix ,0,0,BASE_NONE,NULL,NULL
 %define word-array-name functions
 %define hash-function-name hash_internal_func_gperf
 %define lookup-function-name find_internal_func_gperf
@@ -59,7 +59,7 @@ for name, def in pairs(funcs) do
   elseif #args == 1 then
     args[2] = 'MAX_FUNC_ARGS'
   end
-  local base = def.base or 0
+  local base = def.base or "BASE_NONE"
   local func = def.func or ('f_' .. name)
   local data = def.data or "NULL"
   gperfpipe:write(('%s,  %s, %s, %s, &%s, (FunPtr)%s\n')
diff --git a/src/nvim/testdir/test_method.vim b/src/nvim/testdir/test_method.vim
index 1c0de01ac5..43ed830aba 100644
--- a/src/nvim/testdir/test_method.vim
+++ b/src/nvim/testdir/test_method.vim
@@ -3,18 +3,23 @@
 func Test_list()
   let l = [1, 2, 3]
   call assert_equal([1, 2, 3, 4], [1, 2, 3]->add(4))
+  eval l->assert_equal(l)
+  eval l->assert_equal(l, 'wrong')
+  eval l->assert_notequal([3, 2, 1])
+  eval l->assert_notequal([3, 2, 1], 'wrong')
   call assert_equal(l, l->copy())
   call assert_equal(1, l->count(2))
   call assert_false(l->empty())
   call assert_true([]->empty())
+  call assert_equal(579, ['123', '+', '456']->join()->eval())
   call assert_equal([1, 2, 3, 4, 5], [1, 2, 3]->extend([4, 5]))
   call assert_equal([1, 3], [1, 2, 3]->filter('v:val != 2'))
   call assert_equal(2, l->get(1))
   call assert_equal(1, l->index(2))
   call assert_equal([0, 1, 2, 3], [1, 2, 3]->insert(0))
-  call assert_fails('let x = l->items()', 'E715:')
+  call assert_fails('eval l->items()', 'E715:')
   call assert_equal('1 2 3', l->join())
-  call assert_fails('let x = l->keys()', 'E715:')
+  call assert_fails('eval l->keys()', 'E715:')
   call assert_equal(3, l->len())
   call assert_equal([2, 3, 4], [1, 2, 3]->map('v:val + 1'))
   call assert_equal(3, l->max())
@@ -26,7 +31,7 @@ func Test_list()
   call assert_equal('[1, 2, 3]', l->string())
   call assert_equal(v:t_list, l->type())
   call assert_equal([1, 2, 3], [1, 1, 2, 3, 3]->uniq())
-  call assert_fails('let x = l->values()', 'E715:')
+  call assert_fails('eval l->values()', 'E715:')
 endfunc
 
 func Test_dict()
@@ -65,4 +70,18 @@ func Test_dict()
   call assert_equal([1, 2, 3], d->values())
 endfunc
 
+func Test_append()
+  new
+  eval ['one', 'two', 'three']->append(1)
+  call assert_equal(['', 'one', 'two', 'three'], getline(1, '$'))
+
+  %del
+  let bnr = bufnr('')
+  wincmd w
+  eval ['one', 'two', 'three']->appendbufline(bnr, 1)
+  call assert_equal(['', 'one', 'two', 'three'], getbufline(bnr, 1, '$'))
+
+  exe 'bwipe! ' .. bnr
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab