From 13e2d2d63ce7bc5d875e8bdf89cb070bc8cc7a00 Mon Sep 17 00:00:00 2001
From: Pedro Castro <aspeddro@gmail.com>
Date: Fri, 8 Apr 2022 13:44:00 -0300
Subject: [PATCH] feat: add TSNodeUnderCursor (#74)

add `hl-info.show_ts_node({opts})` to show tree-sitter node under cursor, exposed via `:TSNodeUnderCursor`
---
 lua/nvim-treesitter-playground.lua         |   3 +
 lua/nvim-treesitter-playground/hl-info.lua | 110 +++++++++++++++++++++
 2 files changed, 113 insertions(+)

diff --git a/lua/nvim-treesitter-playground.lua b/lua/nvim-treesitter-playground.lua
index 8be6695..9c2f39f 100644
--- a/lua/nvim-treesitter-playground.lua
+++ b/lua/nvim-treesitter-playground.lua
@@ -33,6 +33,9 @@ function M.init()
   vim.cmd [[
     command! TSHighlightCapturesUnderCursor :lua require'nvim-treesitter-playground.hl-info'.show_hl_captures()<cr>
   ]]
+  vim.cmd [[
+    command! TSNodeUnderCursor :lua require'nvim-treesitter-playground.hl-info'.show_ts_node()<cr>
+  ]]
 end
 
 return M
diff --git a/lua/nvim-treesitter-playground/hl-info.lua b/lua/nvim-treesitter-playground/hl-info.lua
index 350de0c..96a9f86 100644
--- a/lua/nvim-treesitter-playground/hl-info.lua
+++ b/lua/nvim-treesitter-playground/hl-info.lua
@@ -1,5 +1,7 @@
 local utils = require "nvim-treesitter-playground.utils"
 local highlighter = require "vim.treesitter.highlighter"
+local ts_utils = require "nvim-treesitter.ts_utils"
+local parsers = require "nvim-treesitter.parsers"
 
 local M = {}
 
@@ -68,4 +70,112 @@ function M.show_hl_captures()
   vim.lsp.util.open_floating_preview(lines, "markdown", { border = "single", pad_left = 4, pad_right = 4 })
 end
 
+-- Show Node at Cursor
+---@param opts? table with optional fields
+---             - full_path: (boolean, default false) show full path to current node
+---             - show_range: (boolean, default true) show range of current node
+---             - include_anonymous: (boolean, default false) include anonymous node
+---             - highlight_node: (boolean, default true) highlight the current node
+---             - hl_group: (string, default "TSPlaygroundFocus") name of group
+--- @return number|nil bufnr number
+function M.show_ts_node(opts)
+  opts = vim.tbl_deep_extend("keep", opts or {}, {
+    full_path = false,
+    show_range = true,
+    include_anonymous = false,
+    highlight_node = true,
+    hl_group = "TSPlaygroundFocus",
+  })
+
+  if not parsers.has_parser() then
+    return
+  end
+
+  -- Get Full Path to node
+  -- @param node
+  -- @param array?
+  -- @return string
+  local function get_full_path(node, array)
+    local parent = node:parent()
+    if parent == nil then
+      if array == nil then
+        return node:type()
+      end
+      local reverse = vim.tbl_map(function(index)
+        return array[#array + 1 - index]:type()
+      end, vim.tbl_keys(array))
+      return table.concat(reverse, " -> ")
+    end
+    return get_full_path(parent, vim.list_extend(array or {}, { node }))
+  end
+
+  local cursor = vim.api.nvim_win_get_cursor(0)
+  local line = cursor[1] - 1
+  local col = cursor[2]
+
+  local bufnr = 0
+  local root_lang_tree = parsers.get_parser(bufnr)
+  local lang_tree = root_lang_tree:language_for_range { line, col, line, col }
+
+  local lines = { "# Treesitter" }
+  local node_under_cursor
+
+  for _, tree in ipairs(lang_tree:trees()) do
+    local root = tree:root()
+    if root and ts_utils.is_in_node_range(root, line, col) then
+      local node = root:named_descendant_for_range(line, col, line, col)
+      local path = opts.full_path and get_full_path(node) or node:type()
+
+      node_under_cursor = node
+
+      vim.list_extend(lines, {
+        "* Parser: " .. lang_tree:lang(),
+        string.format("* %s: ", opts.full_path and "Node path" or "Node") .. path,
+      })
+
+      if opts.include_anonymous then
+        local anonymous_node = root:descendant_for_range(line, col, line, col)
+        vim.list_extend(lines, {
+          " - Anonymous: " .. anonymous_node:type(),
+        })
+      end
+
+      if opts.show_range then
+        local srow, scol, erow, ecol = ts_utils.get_vim_range({ node:range() }, bufnr)
+
+        vim.list_extend(lines, {
+          "* Range: ",
+          "  - Start row: " .. srow,
+          "  - End row: " .. erow,
+          "  - Start col: " .. scol,
+          "  - End col: " .. ecol,
+        })
+      end
+    end
+  end
+
+  if not node_under_cursor then
+    lines[#lines + 1] = "* Node not found"
+  end
+
+  local ns = vim.api.nvim_create_namespace "nvim-treesitter-current-node"
+
+  if opts.highlight_node and node_under_cursor then
+    ts_utils.highlight_node(node_under_cursor, bufnr, ns, opts.hl_group)
+    vim.cmd(string.format(
+      [[
+      augroup TreesitterNodeUnderCursor
+      au!
+      autocmd CursorMoved <buffer=%d> lua require'nvim-treesitter-playground.internal'.clear_highlights(%d, %d)
+      augroup END
+    ]],
+      bufnr,
+      bufnr,
+      ns
+    ))
+  end
+
+  return vim.lsp.util.open_floating_preview(lines, "markdown", { border = "single", pad_left = 4, pad_right = 4 })
+end
+
 return M