cw edge cases: cursor on a space, support cpo-z (Vim), cpo-_ (Neovim)

autoload/wordmotion.vim

@@ -87,13 +87,19 @@ function wordmotion#motion(count, mode, flags, uppercase, extra, ...)
 	set cpoptions+=c
 
 	let l:flags = a:flags
+	let l:s = a:uppercase ? s:us : s:s
 
-	if a:mode == 'o' && v:operator == 'c' && l:flags == ''
-		" special case (see :help cw)
-		let l:flags = 'e'
-		let l:cw = 1
-	else
-		let l:cw = 0
+	" cw special case
+	" see :help cw, :help cpo-z (vim), :help cpo-_ (neovim)
+	let l:cpo_z = has('nvim') ? stridx(l:cpo, '_') : stridx(l:cpo, 'z')
+	let l:cw_special_case = 0
+
+	if l:cpo_z != -1 && a:mode == 'o' && v:operator == 'c' && l:flags == ''
+		let l:cursor_on_s = getline('.') =~# '\%.c' . l:s
+		if !l:cursor_on_s
+			let l:flags = 'e'
+			let l:cw_special_case = 1
+		endif
 	endif
 
 	if a:mode == 'x'
@@ -114,7 +120,7 @@ function wordmotion#motion(count, mode, flags, uppercase, extra, ...)
 	let l:pos = getpos('.')
 
 	let l:count = a:count
-	if l:cw
+	if l:cw_special_case
 		" cw on the last character of a word will match the cursor position
 		call search('\m'.l:pattern, l:flags.'cW')
 		let l:count -= 1
@@ -124,19 +130,17 @@ function wordmotion#motion(count, mode, flags, uppercase, extra, ...)
 		let l:count -= 1
 	endwhile
 
-	" dw at the end of a line should not consume the newline or leading white
-	" space on the next line
-	let l:is_dw = a:mode == 'o' && v:operator == 'd' && l:flags == ''
+	" operator-pending w at the end of a line should not include the newline or leading
+	" white space on the next line
 	let l:next_line = l:pos[1] < getpos('.')[1]
-	if l:is_dw && l:next_line
-		let l:s = a:uppercase ? s:us : s:s
+	if a:mode == 'o' && l:flags == '' && l:next_line
 		" newline, leading whitespace, cursor
 		if search('\m\n\%('.l:s.'\)*\%#', 'bW') != 0
-			let l:dwpos = getpos('.')
+			let l:wpos = getpos('.')
 			" need to make range inclusive
 			call setpos('.', l:pos)
 			normal! v
-			call setpos('.', l:dwpos)
+			call setpos('.', l:wpos)
 		endif
 	endif
 

tests/cpoptions.vader

@@ -28,6 +28,17 @@ Execute (w with cpo-<):
   normal w
   AssertEqual 5, col('.')
 
+Execute (cw without cpo-z):
+  if has('nvim')
+    set cpoptions-=_
+  else
+    set cpoptions-=z
+  endif
+  normal cw
+
+Expect (Delete the space):
+  bar
+
 Given (Leading spaces):
       foo
 

tests/cw.vader

@@ -262,18 +262,33 @@ Then (Assert that cursor is at z):
 Expect ("b c\nd e" changed to z):
   a z f
 
+Given (Snake case word):
+  foo_bar
+
+Execute (cw on underscore):
+  normal lllcw
+  AssertEqual 3, col('.')
+
+Expect (Only underscore deleted):
+  foobar
+
 Given (Leading spaces):
       foo
+      bar
 
-Execute (FIXME: cw):
-  normal cw
+Execute (cw):
+  normal jcw
   AssertEqual 1, col('.')
 
 Expect (Leading spaces deleted):
-  foo
+      foo
+  bar
 
-Execute (reference cw):
-  normal! cw
+Given (Leading spaces with only 1 line):
+      foo
+
+Execute (cw at the first line and col of the file):
+  normal cw
   AssertEqual 1, col('.')
 
 Expect (Leading spaces deleted):