refacto/feat: better handling of parser updates

features:
- node_movement is moving between scopes.
- add selection initialization from normal mode
- add a decremental selection

improvements:
- attach to buffer to run tree parsing on change
- run state update on CursorMoved
- the buffer state is:
```
{
  cursor_pos = { row=row, col=col },
  current_node = node_under_cursor,
  selection = {
      range = nil, -- activates when starting a selection
      nodes = {} -- filling up when starting an incremental selection
  },
  parser = parser, -- parser for current buffer
}
```
- refacto all the modules reliant on parsing the tree, update the current nodes, get the current nodes...

fixes:
- fix has_parser to look for .so libraries
- fix should select the whole file when selection root in selection

lua/nvim-treesitter/incremental_selection.lua

@@ -1,77 +1,102 @@
 local api = vim.api
-local utils = require'nvim-treesitter.utils'
-local parsers = require'nvim-treesitter.parsers'
+
+local state = require'nvim-treesitter.state'
+local configs = require'nvim-treesitter.configs'
+local ts_utils = require'nvim-treesitter.ts_utils'
+
 local M = {}
 
-local function node_range_to_vim(node)
-  if not node then return end
-
+local function update_selection(buf, node)
   local start_row, start_col, end_row, end_col = node:range()
 
-  local select_range = [[
-  call cursor(%d, %d)
-  normal v
-  call cursor(%d, %d)
-  ]]
-  local exec_command = string.format(select_range,
-    start_row+1, start_col+1,
-    end_row+1, end_col+1)
+  if end_row == vim.fn.line('$') then
+    end_col = #vim.fn.getline('$')
+  end
 
-  api.nvim_exec(exec_command, false)
+  vim.fn.setpos(".", { buf, start_row+1, start_col+1, 0 })
+  vim.fn.nvim_exec("normal v", false)
+  vim.fn.setpos(".", { buf, end_row+1, end_col+1, 0 })
 end
 
-local function select_incremental(increment_func)
+local function select_incremental(get_parent)
   return function()
-    local buf, sel_start_line, sel_start_col, _ = unpack(vim.fn.getpos("'<"))
-    local buf, sel_end_line, sel_end_col, _ = unpack(vim.fn.getpos("'>"))
+    local buf = api.nvim_get_current_buf()
+    local buf_state = state.get_buf_state(buf)
 
-    local node = nil
-    if parsers.has_parser() then
-      local root = parsers.get_parser():parse():root()
-      node = root:named_descendant_for_range(sel_start_line-1, sel_start_col-1, sel_end_line-1, sel_end_col)
-      local node_start_row, node_start_col, node_end_row, node_end_col = node:range()
-
-      if (sel_start_line-1) == node_start_row and (sel_start_col-1) == node_start_col
-        and (sel_end_line-1) == node_end_row and sel_end_col == node_end_col then
-        node = increment_func(node)
+    local node
+    -- initialize incremental selection with current range
+    if #buf_state.selection.nodes == 0 then
+      local cur_range = buf_state.selection.range
+      if not cur_range then 
+        local _, cursor_row, cursor_col, _ = unpack(vim.fn.getpos("."))
+        cur_range = { cursor_row, cursor_col, cursor_row, cursor_col + 1 }
       end
+
+      local root = buf_state.parser.tree:root()
+      if not root then return end
+
+      node = root:named_descendant_for_range(cur_range[1]-1, cur_range[2]-1, cur_range[3]-1, cur_range[4]-1) 
+    else
+      node = get_parent(buf_state.selection.nodes[#buf_state.selection.nodes]) 
     end
 
-    return node_range_to_vim(node)
+    if not node then return end
+
+    if node ~= buf_state.selection.nodes[#buf_state.selection.nodes] then
+      state.insert_selection_node(buf, node)
+    end
+
+    update_selection(buf, node)
   end
 end
 
 M.node_incremental = select_incremental(function(node)
-  if node then
-    return node:parent() or node
-  end
+  return node:parent() or node
 end)
 
 M.scope_incremental = select_incremental(function(node)
-  if node then
-    return utils.smallest_containing_scope(node:parent() or node)
-  end
+  return ts_utils.containing_scope(node:parent() or node)
 end)
 
+function M.node_decremental()
+  local buf = api.nvim_get_current_buf()
+  local buf_state = state.get_buf_state(buf)
+
+  local nodes = buf_state.selection.nodes
+  if #nodes < 2 then return end
+
+  state.pop_selection_node(buf)
+
+  local node = nodes[#nodes]
+  update_selection(buf, node)
+end
+
 function M.attach(bufnr)
   local buf = bufnr or api.nvim_get_current_buf()
 
-  local config = require'nvim-treesitter.configs'.get_module('incremental_selection')
+  local config = configs.get_module('incremental_selection')
   for funcname, mapping in pairs(config.keymaps) do
-    api.nvim_buf_set_keymap(buf, 'v', mapping,
-      string.format(":lua require'nvim-treesitter.incremental_selection'.%s()<CR>", funcname), { silent = true })
-    api.nvim_buf_set_keymap(buf, 'o', mapping,
-      string.format(":normal v%s<CR>", mapping), { silent = true })
+
+    if funcname == "init_selection" then
+      local cmd = ":lua require'nvim-treesitter.incremental_selection'.node_incremental()<CR>"
+      api.nvim_buf_set_keymap(buf, 'n', mapping, cmd, { silent = true })
+    else
+      local cmd = string.format(":lua require'nvim-treesitter.incremental_selection'.%s()<CR>", funcname)
+      api.nvim_buf_set_keymap(buf, 'v', mapping, cmd, { silent = true })
+    end
   end
 end
 
 function M.detach(bufnr)
   local buf = bufnr or api.nvim_get_current_buf()
 
-  local config = require'nvim-treesitter.configs'.get_module('incremental_selection')
-  for _, mapping in pairs(config.keymaps) do
-    api.nvim_buf_del_keymap(buf, 'v', mapping)
-    api.nvim_buf_del_keymap(buf, 'o', mapping)
+  local config = configs.get_module('incremental_selection')
+  for f, mapping in pairs(config.keymaps) do
+    if f == "init_selection" then
+      api.nvim_buf_del_keymap(buf, 'n', mapping)
+    else
+      api.nvim_buf_del_keymap(buf, 'v', mapping)
+    end
   end
 end