feat: add node manipulation utils

1 files changed, 66 insertions, 0 deletions

diff --git a/lua/nvim-treesitter/utils.lua b/lua/nvim-treesitter/utils.lua
new file mode 100644
index 000000000..8313a46a7
--- /dev/null
+++ b/lua/nvim-treesitter/utils.lua
@@ -0,0 +1,66 @@
+-- Utils collection for nvim-treesitter
+local api = vim.api
+local parsers = require'nvim-treesitter.parsers'
+
+local M = {}
+
+--- Gets the smallest expression containing the current cursor position
+function M.expression_at_point(bufnr, lang)
+  local bufnr = bufnr or api.nvim_get_current_buf()
+  local lang = lang or api.nvim_buf_get_option(bufnr, 'ft')
+
+  local parser = parsers.get_parser(bufnr, lang)
+  if not parser then return end
+
+  local tsroot = parser:parse():root()
+  if not tsroot then return end
+
+  local curwin = api.nvim_get_current_win()
+
+  if api.nvim_win_get_buf(curwin) == bufnr then
+    local cursor = vim.api.nvim_win_get_cursor(curwin)
+    local current_node = tsroot:named_descendant_for_range(cursor[1] - 1, cursor[2], cursor[1] - 1, cursor[2])
+    return current_node
+  end
+end
+
+--- Gets the actual text content of a node
+-- @param node the node to get the text from
+-- @param bufnr the buffer containing the node
+-- @return list of lines of text of the node
+function M.get_node_text(node, bufnr)
+  local bufnr = bufnr or api.nvim_get_current_buf()
+  if not node then return {} end
+
+  -- We have to remember that end_col is end-exclusive
+  local start_row, start_col, end_row, end_col = node:range()
+  if start_row ~= end_row then
+    local lines = api.nvim_buf_get_lines(bufnr, start_row, end_row+1, false)
+    lines[1] = string.sub(lines[1], start_col+1)
+    lines[#lines] = string.sub(lines[#lines], 1, end_col)
+    return lines
+  else
+    local line = api.nvim_buf_get_lines(bufnr, start_row, start_row+1, true)[1]
+    return { string.sub(line, start_col+1, end_col) }
+  end
+end
+
+--- Determines wether a node is the parent of another
+-- @param dest the possible parent
+-- @param source the possible child node
+function M.is_parent(dest, source)
+  if not (dest and source) then return false end
+
+  local current = source
+  while current ~= nil do
+    if current == dest then
+      return true
+    end
+
+    current = current:parent()
+  end
+
+  return false
+end
+
+return M