feat(statusline): support multibyte fillchar

This includes a partial port of Vim patch 8.2.2569 and some changes to
nvim_eval_statusline() to allow a multibyte fillchar. Literally every
line of C code touched by that patch has been refactored in Nvim, and
that patch contains some irrelevant foldcolumn tests I'm not sure how to
port (as Nvim's foldcolumn behavior has diverged from Vim's).

1 files changed, 78 insertions, 63 deletions

diff --git a/test/unit/buffer_spec.lua b/test/unit/buffer_spec.lua
index 3692e19379..34c88248e6 100644
--- a/test/unit/buffer_spec.lua
+++ b/test/unit/buffer_spec.lua
@@ -249,7 +249,7 @@ describe('buffer functions', function()
     --
     -- @param arg Options can be placed in an optional dictionary as the last parameter
     --    .expected_cell_count The expected number of cells build_stl_str_hl will return
-    --    .expected_byte_length The expected byte length of the string
+    --    .expected_byte_length The expected byte length of the string (defaults to byte length of expected_stl)
     --    .file_name The name of the file to be tested (useful in %f type tests)
     --    .fillchar The character that will be used to fill any 'extra' space in the stl
     local function statusline_test (description,
@@ -264,7 +264,7 @@ describe('buffer functions', function()
 
       local fillchar = option.fillchar or (' '):byte()
       local expected_cell_count = option.expected_cell_count or statusline_cell_count
-      local expected_byte_length = option.expected_byte_length or expected_cell_count
+      local expected_byte_length = option.expected_byte_length or #expected_stl
 
       itp(description, function()
         if option.file_name then
@@ -312,12 +312,12 @@ describe('buffer functions', function()
     statusline_test('should put fillchar `~` in between text', 10,
       'abc%=def',            'abc~~~~def',
       {fillchar=('~'):byte()})
+    statusline_test('should put fillchar `━` in between text', 10,
+      'abc%=def',            'abc━━━━def',
+      {fillchar=0x2501})
     statusline_test('should handle zero-fillchar as a space', 10,
       'abcde%=',             'abcde     ',
       {fillchar=0})
-    statusline_test('should handle multibyte-fillchar as a dash', 10,
-      'abcde%=',             'abcde-----',
-      {fillchar=0x80})
     statusline_test('should print the tail file name', 80,
       '%t',                  'buffer_spec.lua',
       {file_name='test/unit/buffer_spec.lua', expected_cell_count=15})
@@ -366,70 +366,86 @@ describe('buffer functions', function()
 
     statusline_test('should ignore trailing %', 3, 'abc%', 'abc')
 
-    -- alignment testing
-    statusline_test('should right align when using =', 20,
-      'neo%=vim',            'neo              vim')
-    statusline_test('should, when possible, center text when using %=text%=', 20,
-      'abc%=neovim%=def',    'abc    neovim    def')
-    statusline_test('should handle uneven spacing in the buffer when using %=text%=', 20,
-      'abc%=neo_vim%=def',   'abc   neo_vim    def')
-    statusline_test('should have equal spaces even with non-equal sides when using =', 20,
-      'foobar%=test%=baz',   'foobar   test    baz')
-    statusline_test('should have equal spaces even with longer right side when using =', 20,
-      'a%=test%=longtext',   'a   test    longtext')
-    statusline_test('should handle an empty left side when using ==', 20,
-      '%=test%=baz',         '      test       baz')
-    statusline_test('should handle an empty right side when using ==', 20,
-      'foobar%=test%=',      'foobar     test     ')
-    statusline_test('should handle consecutive empty ==', 20,
-      '%=%=test%=',          '          test      ')
-    statusline_test('should handle an = alone', 20,
-      '%=',                  '                    ')
-    statusline_test('should right align text when it is alone with =', 20,
-      '%=foo',               '                 foo')
-    statusline_test('should left align text when it is alone with =', 20,
-      'foo%=',               'foo                 ')
-
-    statusline_test('should approximately center text when using %=text%=', 21,
-      'abc%=neovim%=def',    'abc    neovim     def')
-    statusline_test('should completely fill the buffer when using %=text%=', 21,
-      'abc%=neo_vim%=def',   'abc    neo_vim    def')
-    statusline_test('should have equal spaces even with non-equal sides when using =', 21,
-      'foobar%=test%=baz',   'foobar    test    baz')
-    statusline_test('should have equal spaces even with longer right side when using =', 21,
-      'a%=test%=longtext',   'a    test    longtext')
-    statusline_test('should handle an empty left side when using ==', 21,
-      '%=test%=baz',         '       test       baz')
-    statusline_test('should handle an empty right side when using ==', 21,
-      'foobar%=test%=',      'foobar     test      ')
-
-    statusline_test('should quadrant the text when using 3 %=', 40,
-      'abcd%=n%=eovim%=ef',  'abcd         n         eovim          ef')
-    statusline_test('should work well with %t', 40,
-      '%t%=right_aligned',   'buffer_spec.lua            right_aligned',
+    -- alignment testing with fillchar
+    local function statusline_test_align (description,
+                                                       statusline_cell_count,
+                                                       input_stl,
+                                                       expected_stl,
+                                                       arg)
+      arg = arg or {}
+      statusline_test(description .. ' without fillchar',
+        statusline_cell_count, input_stl, expected_stl:gsub('%~', ' '), arg)
+      arg.fillchar = ('!'):byte()
+      statusline_test(description .. ' with fillchar `!`',
+        statusline_cell_count, input_stl, expected_stl:gsub('%~', '!'), arg)
+      arg.fillchar = 0x2501
+      statusline_test(description .. ' with fillchar `━`',
+        statusline_cell_count, input_stl, expected_stl:gsub('%~', '━'), arg)
+    end
+
+    statusline_test_align('should right align when using =', 20,
+      'neo%=vim',            'neo~~~~~~~~~~~~~~vim')
+    statusline_test_align('should, when possible, center text when using %=text%=', 20,
+      'abc%=neovim%=def',    'abc~~~~neovim~~~~def')
+    statusline_test_align('should handle uneven spacing in the buffer when using %=text%=', 20,
+      'abc%=neo_vim%=def',   'abc~~~neo_vim~~~~def')
+    statusline_test_align('should have equal spaces even with non-equal sides when using =', 20,
+      'foobar%=test%=baz',   'foobar~~~test~~~~baz')
+    statusline_test_align('should have equal spaces even with longer right side when using =', 20,
+      'a%=test%=longtext',   'a~~~test~~~~longtext')
+    statusline_test_align('should handle an empty left side when using ==', 20,
+      '%=test%=baz',         '~~~~~~test~~~~~~~baz')
+    statusline_test_align('should handle an empty right side when using ==', 20,
+      'foobar%=test%=',      'foobar~~~~~test~~~~~')
+    statusline_test_align('should handle consecutive empty ==', 20,
+      '%=%=test%=',          '~~~~~~~~~~test~~~~~~')
+    statusline_test_align('should handle an = alone', 20,
+      '%=',                  '~~~~~~~~~~~~~~~~~~~~')
+    statusline_test_align('should right align text when it is alone with =', 20,
+      '%=foo',               '~~~~~~~~~~~~~~~~~foo')
+    statusline_test_align('should left align text when it is alone with =', 20,
+      'foo%=',               'foo~~~~~~~~~~~~~~~~~')
+
+    statusline_test_align('should approximately center text when using %=text%=', 21,
+      'abc%=neovim%=def',    'abc~~~~neovim~~~~~def')
+    statusline_test_align('should completely fill the buffer when using %=text%=', 21,
+      'abc%=neo_vim%=def',   'abc~~~~neo_vim~~~~def')
+    statusline_test_align('should have equal spacing even with non-equal sides when using =', 21,
+      'foobar%=test%=baz',   'foobar~~~~test~~~~baz')
+    statusline_test_align('should have equal spacing even with longer right side when using =', 21,
+      'a%=test%=longtext',   'a~~~~test~~~~longtext')
+    statusline_test_align('should handle an empty left side when using ==', 21,
+      '%=test%=baz',         '~~~~~~~test~~~~~~~baz')
+    statusline_test_align('should handle an empty right side when using ==', 21,
+      'foobar%=test%=',      'foobar~~~~~test~~~~~~')
+
+    statusline_test_align('should quadrant the text when using 3 %=', 40,
+      'abcd%=n%=eovim%=ef',  'abcd~~~~~~~~~n~~~~~~~~~eovim~~~~~~~~~~ef')
+    statusline_test_align('should work well with %t', 40,
+      '%t%=right_aligned',   'buffer_spec.lua~~~~~~~~~~~~right_aligned',
       {file_name='test/unit/buffer_spec.lua'})
-    statusline_test('should work well with %t and regular text', 40,
-      'l%=m_l %t m_r%=r',    'l       m_l buffer_spec.lua m_r        r',
+    statusline_test_align('should work well with %t and regular text', 40,
+      'l%=m_l %t m_r%=r',    'l~~~~~~~m_l buffer_spec.lua m_r~~~~~~~~r',
       {file_name='test/unit/buffer_spec.lua'})
-    statusline_test('should work well with %=, %t, %L, and %l', 40,
-      '%t %= %L %= %l',      'buffer_spec.lua           1            0',
+    statusline_test_align('should work well with %=, %t, %L, and %l', 40,
+      '%t %= %L %= %l',      'buffer_spec.lua ~~~~~~~~~ 1 ~~~~~~~~~~ 0',
       {file_name='test/unit/buffer_spec.lua'})
 
-    statusline_test('should quadrant the text when using 3 %=', 41,
-      'abcd%=n%=eovim%=ef',  'abcd         n         eovim           ef')
-    statusline_test('should work well with %t', 41,
-      '%t%=right_aligned',   'buffer_spec.lua             right_aligned',
+    statusline_test_align('should quadrant the text when using 3 %=', 41,
+      'abcd%=n%=eovim%=ef',  'abcd~~~~~~~~~n~~~~~~~~~eovim~~~~~~~~~~~ef')
+    statusline_test_align('should work well with %t', 41,
+      '%t%=right_aligned',   'buffer_spec.lua~~~~~~~~~~~~~right_aligned',
       {file_name='test/unit/buffer_spec.lua'})
-    statusline_test('should work well with %t and regular text', 41,
-      'l%=m_l %t m_r%=r',    'l        m_l buffer_spec.lua m_r        r',
+    statusline_test_align('should work well with %t and regular text', 41,
+      'l%=m_l %t m_r%=r',    'l~~~~~~~~m_l buffer_spec.lua m_r~~~~~~~~r',
       {file_name='test/unit/buffer_spec.lua'})
-    statusline_test('should work well with %=, %t, %L, and %l', 41,
-      '%t %= %L %= %l',      'buffer_spec.lua            1            0',
+    statusline_test_align('should work well with %=, %t, %L, and %l', 41,
+      '%t %= %L %= %l',      'buffer_spec.lua ~~~~~~~~~~ 1 ~~~~~~~~~~ 0',
       {file_name='test/unit/buffer_spec.lua'})
 
-    statusline_test('should work with 10 %=', 50,
+    statusline_test_align('should work with 10 %=', 50,
       'aaaa%=b%=c%=d%=e%=fg%=hi%=jk%=lmnop%=qrstuv%=wxyz',
-      'aaaa  b  c  d  e  fg  hi  jk  lmnop  qrstuv   wxyz')
+      'aaaa~~b~~c~~d~~e~~fg~~hi~~jk~~lmnop~~qrstuv~~~wxyz')
 
     -- stl item testing
     local tabline = ''
@@ -452,11 +468,10 @@ describe('buffer functions', function()
 
     -- multi-byte testing
     statusline_test('should handle multibyte characters', 10,
-      'Ĉ%=x',                'Ĉ        x',
-      {expected_byte_length=11})
+      'Ĉ%=x',                'Ĉ        x')
     statusline_test('should handle multibyte characters and different fillchars', 10,
       'Ą%=mid%=end',         'Ą@mid@@end',
-      {fillchar=('@'):byte(), expected_byte_length=11})
+      {fillchar=('@'):byte()})
 
     -- escaping % testing
     statusline_test('should handle escape of %', 4, 'abc%%', 'abc%')