1 files changed, 116 insertions, 0 deletions
diff --git a/runtime/lua/vim/tshighlighter.lua b/runtime/lua/vim/tshighlighter.lua
new file mode 100644
index 0000000000..6465751ae8
--- /dev/null
+++ b/runtime/lua/vim/tshighlighter.lua
@@ -0,0 +1,116 @@
+local a = vim.api
+
+-- support reload for quick experimentation
+local TSHighlighter = rawget(vim.treesitter, 'TSHighlighter') or {}
+TSHighlighter.__index = TSHighlighter
+local ts_hs_ns = a.nvim_create_namespace("treesitter_hl")
+
+-- These are conventions defined by tree-sitter, though it
+-- needs to be user extensible also.
+-- TODO(bfredl): this is very much incomplete, we will need to
+-- go through a few tree-sitter provided queries and decide
+-- on translations that makes the most sense.
+TSHighlighter.hl_map = {
+    keyword="Keyword",
+    string="String",
+    type="Type",
+    comment="Comment",
+    constant="Constant",
+    operator="Operator",
+    number="Number",
+    label="Label",
+    ["function"]="Function",
+    ["function.special"]="Function",
+}
+
+function TSHighlighter.new(query, bufnr, ft)
+  local self = setmetatable({}, TSHighlighter)
+  self.parser = vim.treesitter.get_parser(
+    bufnr,
+    ft,
+    {
+      on_changedtree = function(...) self:on_changedtree(...) end,
+      on_lines = function() self.root = self.parser:parse():root() end
+    }
+  )
+
+  self.buf = self.parser.bufnr
+
+  local tree = self.parser:parse()
+  self.root = tree:root()
+  self:set_query(query)
+  self.edit_count = 0
+  self.redraw_count = 0
+  self.line_count = {}
+  a.nvim_buf_set_option(self.buf, "syntax", "")
+
+  -- Tricky: if syntax hasn't been enabled, we need to reload color scheme
+  -- but use synload.vim rather than syntax.vim to not enable
+  -- syntax FileType autocmds. Later on we should integrate with the
+  -- `:syntax` and `set syntax=...` machinery properly.
+  if vim.g.syntax_on ~= 1 then
+    vim.api.nvim_command("runtime! syntax/synload.vim")
+  end
+  return self
+end
+
+local function is_highlight_name(capture_name)
+  local firstc = string.sub(capture_name, 1, 1)
+  return firstc ~= string.lower(firstc)
+end
+
+function TSHighlighter:get_hl_from_capture(capture)
+
+  local name = self.query.captures[capture]
+
+  if is_highlight_name(name) then
+    -- From "Normal.left" only keep "Normal"
+    return vim.split(name, '.', true)[1]
+  else
+    -- Default to false to avoid recomputing
+    return TSHighlighter.hl_map[name]
+  end
+end
+
+function TSHighlighter:set_query(query)
+  if type(query) == "string" then
+    query = vim.treesitter.parse_query(self.parser.lang, query)
+  end
+  self.query = query
+
+  self.hl_cache = setmetatable({}, {
+    __index = function(table, capture)
+      local hl = self:get_hl_from_capture(capture)
+      rawset(table, capture, hl)
+
+      return hl
+    end
+  })
+
+  self:on_changedtree({{self.root:range()}})
+end
+
+function TSHighlighter:on_changedtree(changes)
+  -- Get a fresh root
+  self.root = self.parser.tree:root()
+
+  for _, ch in ipairs(changes or {}) do
+    -- Try to be as exact as possible
+    local changed_node = self.root:descendant_for_range(ch[1], ch[2], ch[3], ch[4])
+
+    a.nvim_buf_clear_namespace(self.buf, ts_hs_ns, ch[1], ch[3])
+
+    for capture, node in self.query:iter_captures(changed_node, self.buf, ch[1], ch[3] + 1) do
+      local start_row, start_col, end_row, end_col = node:range()
+      local hl = self.hl_cache[capture]
+      if hl then
+        a.nvim__buf_add_decoration(self.buf, ts_hs_ns, hl,
+          start_row, start_col,
+          end_row, end_col,
+          {})
+      end
+    end
+  end
+end
+
+return TSHighlighter