1 files changed, 57 insertions, 0 deletions
diff --git a/runtime/lua/vim/treesitter.lua b/runtime/lua/vim/treesitter.lua
new file mode 100644
index 0000000000..1b5f416b67
--- /dev/null
+++ b/runtime/lua/vim/treesitter.lua
@@ -0,0 +1,57 @@
+local a = vim.api
+
+local Parser = {}
+Parser.__index = Parser
+
+function Parser:parse_tree(force)
+  if self.valid and not force then
+    return self.tree
+  end
+  self.tree = self._parser:parse_buf(self.bufnr)
+  self.valid = true
+  return self.tree
+end
+
+local function change_cb(self, ev, bufnr, tick, start_row, oldstopline, stop_row)
+  local start_byte = a.nvim_buf_get_offset(bufnr,start_row)
+  -- a bit messy, should we expose edited but not reparsed tree?
+  -- are multiple edits safe in general?
+  local root = self._parser:tree():root()
+  -- TODO: add proper lookup function!
+  local inode = root:descendant_for_point_range(oldstopline+9000,0, oldstopline,0)
+  if inode == nil then
+    local stop_byte = a.nvim_buf_get_offset(bufnr,stop_row)
+    self._parser:edit(start_byte,stop_byte,stop_byte,start_row,0,stop_row,0,stop_row,0)
+  else
+    local fakeoldstoprow, fakeoldstopcol, fakebyteoldstop = inode:start()
+    local fake_rows = fakeoldstoprow-oldstopline
+    local fakestop = stop_row+fake_rows
+    local fakebytestop = a.nvim_buf_get_offset(bufnr,fakestop)+fakeoldstopcol
+    self._parser:edit(start_byte,fakebyteoldstop,fakebytestop,start_row,0,fakeoldstoprow,fakeoldstopcol,fakestop,fakeoldstopcol)
+  end
+  self.valid = false
+end
+
+local function create_parser(bufnr, ft)
+  if bufnr == 0 then
+    bufnr = a.nvim_get_current_buf()
+  end
+  if ft == nil then
+    ft = a.nvim_buf_get_option(bufnr, "filetype")
+  end
+  local self = setmetatable({bufnr=bufnr, valid=false}, Parser)
+  self._parser = vim._create_ts_parser(ft)
+  self:parse_tree()
+  local function cb(ev, ...)
+    -- TODO: use weakref to self, so that the parser is free'd is no plugin is
+    -- using it.
+    return change_cb(self, ev, ...)
+  end
+  a.nvim_buf_attach(self.bufnr, false, {on_lines=cb})
+  return self
+end
+
+-- TODO: weak table with reusable parser per buffer.
+
+return {create_parser=create_parser, add_language=vim._ts_add_language}
+