feat(treesitter): vertical conceal support for highlighter

TSHighlighter now places marks for conceal_lines metadata. A new
internal decor provider callback _on_conceal_line was added that
instructs the highlighter to place conceal_lines marks whenever the
editor needs to know whether a line is concealed. The bundled markdown
queries use conceal_lines metadata to conceal code block fence lines.

1 files changed, 104 insertions, 3 deletions

diff --git a/test/functional/treesitter/highlight_spec.lua b/test/functional/treesitter/highlight_spec.lua
index 02b50fd80e..c59160d8c7 100644
--- a/test/functional/treesitter/highlight_spec.lua
+++ b/test/functional/treesitter/highlight_spec.lua
@@ -1152,14 +1152,16 @@ describe('treesitter highlighting (markdown)', function()
     })
   end)
 
-  it('works with spellchecked and smoothscrolled topline', function()
-    insert([[
+  local code_block = [[
 - $f(0)=\sum_{k=1}^{\infty}\frac{2}{\pi^{2}k^{2}}+\lim_{w \to 0}x$.
 
 ```c
 printf('Hello World!');
 ```
-    ]])
+    ]]
+
+  it('works with spellchecked and smoothscrolled topline', function()
+    insert(code_block)
     command('set spell smoothscroll')
     feed('gg<C-E>')
     screen:add_extra_attr_ids({ [100] = { undercurl = true, special = Screen.colors.Red } })
@@ -1174,6 +1176,105 @@ printf('Hello World!');
       ]],
     })
   end)
+
+  it('works with concealed lines', function()
+    insert(code_block)
+    screen:expect({
+      grid = [[
+                                                |
+        {18:```}{15:c}                                    |
+        {25:printf}{16:(}{26:'Hello World!'}{16:);}                 |
+        {18:```}                                     |
+           ^                                     |
+                                                |
+      ]],
+    })
+    feed('ggj')
+    command('set number conceallevel=3')
+    screen:expect({
+      grid = [[
+        {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+        {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+        {8:  2 }^                                    |
+        {8:  4 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+        {8:  6 }                                    |
+                                                |
+      ]],
+    })
+    feed('j')
+    screen:expect({
+      grid = [[
+        {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+        {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+        {8:  2 }                                    |
+        {8:  3 }{18:^```}{15:c}                                |
+        {8:  4 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+                                                |
+      ]],
+    })
+    feed('j')
+    screen:expect({
+      grid = [[
+        {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+        {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+        {8:  2 }                                    |
+        {8:  4 }{25:^printf}{16:(}{26:'Hello World!'}{16:);}             |
+        {8:  6 }                                    |
+                                                |
+      ]],
+    })
+    feed('j')
+    screen:expect({
+      grid = [[
+        {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+        {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+        {8:  2 }                                    |
+        {8:  4 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+        {8:  5 }{18:^```}                                 |
+                                                |
+      ]],
+    })
+    -- Concealed lines highlight until changed botline
+    screen:try_resize(screen._width, 16)
+    feed('y3k30P:<Esc><C-F><C-B>')
+    screen:expect([[
+      {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+      {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+      {8:  2 }                                    |
+      {8:  4 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:  6 }                                    |
+      {8:  8 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 10 }                                    |
+      {8: 12 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 14 }                                    |
+      {8: 16 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 18 }                                    |
+      {8: 20 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 22 }                                    |
+      {8: 24 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 25 }{18:^```}                                 |
+                                              |
+    ]])
+    feed('G')
+    screen:expect([[
+      {8: 98 }                                    |
+      {8:100 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:102 }                                    |
+      {8:104 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:106 }                                    |
+      {8:108 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:110 }                                    |
+      {8:112 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:114 }                                    |
+      {8:116 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:118 }                                    |
+      {8:120 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:122 }                                    |
+      {8:124 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:126 }   ^                                 |
+                                              |
+    ]])
+  end)
 end)
 
 it('starting and stopping treesitter highlight in init.lua works #29541', function()