feat(snip_expand): make indenting snippets optional

DOC.md

@@ -3708,6 +3708,27 @@ These are the settings you can provide to `luasnip.setup()`:
       	return snip.insert_nodes[0]
       end
       ```
+    - `indent`: bool?, defaults to `true`. Whether LuaSnip will try to add
+      additional indents to fit current indent level in snippet expanding. This
+      option is useful when some LSP server already take indents into
+      consideration. In such cases, LuaSnip should not try to add additional
+      indents. If you are using `nvim-cmp`, sample config:
+
+      ```lua
+      require("cmp").setup {
+        snippet = {
+          expand = function(args)
+            local indent_nodes = true
+            if vim.api.nvim_get_option_value("filetype", { buf = 0 }) == "dart" then
+              indent_nodes = false
+            end
+            require("luasnip").lsp_expand(args.body, {
+              indent = indent_nodes,
+            })
+          end,
+        },
+      }
+      ```
 
   `opts` and any of its parameters may be nil.
 

doc/luasnip.txt

@@ -3503,6 +3503,26 @@ GENERAL ~
         jump_into set the placeholder of the snippet, 1 -- to jump forwards. return
         snip:jump_into(1)` while this can be used to only insert the snippet: `lua
         function(snip) return snip.insert_nodes[0] end`
+    - `indent`: bool?, defaults to `true`. Whether LuaSnip will try to add additional
+        indents to fit current indent level in snippet expanding. This option is useful
+        when some LSP server already take indents into consideration. In such cases,
+        LuaSnip should not try to add additional indents. If you are using `nvim-cmp`,
+        sample config:
+        >lua
+            require("cmp").setup {
+              snippet = {
+                expand = function(args)
+                  local indent_nodes = true
+                  if vim.api.nvim_get_option_value("filetype", { buf = 0 }) == "dart" then
+                    indent_nodes = false
+                  end
+                  require("luasnip").lsp_expand(args.body, {
+                    indent = indent_nodes,
+                  })
+                end,
+              },
+            }
+        <
     `opts` and any of its parameters may be nil.
 - `get_active_snip()`: returns the currently active snippet (not node!).
 - `choice_active()`: true if inside a choiceNode.

lua/luasnip/init.lua

@@ -234,6 +234,7 @@ local function snip_expand(snippet, opts)
 	-- override with current position if none given.
 	opts.pos = opts.pos or util.get_cursor_0ind()
 	opts.jump_into_func = opts.jump_into_func or _jump_into_default
+	opts.indent = vim.F.if_nil(opts.indent, true)
 
 	snip.trigger = opts.expand_params.trigger or snip.trigger
 	snip.captures = opts.expand_params.captures or {}
@@ -271,7 +272,8 @@ local function snip_expand(snippet, opts)
 	local snip_parent_node = snip:trigger_expand(
 		session.current_nodes[vim.api.nvim_get_current_buf()],
 		pos_id,
-		env
+		env,
+		opts.indent
 	)
 
 	-- jump_into-callback returns new active node.

lua/luasnip/nodes/snippet.lua

@@ -625,7 +625,7 @@ local function insert_into_jumplist(
 	table.insert(sibling_snippets, own_indx, snippet)
 end
 
-function Snippet:trigger_expand(current_node, pos_id, env)
+function Snippet:trigger_expand(current_node, pos_id, env, indent_nodes)
 	local pos = vim.api.nvim_buf_get_extmark_by_id(0, session.ns_id, pos_id, {})
 
 	-- find tree-node the snippet should be inserted at (could be before another node).
@@ -661,12 +661,14 @@ function Snippet:trigger_expand(current_node, pos_id, env)
 
 	Environ:override(env, pre_expand_res.env_override or {})
 
-	local indentstring = util.line_chars_before(pos):match("^%s*")
-	-- expand tabs before indenting to keep indentstring unmodified
-	if vim.bo.expandtab then
-		self:expand_tabs(util.tab_width(), #indentstring)
+	if indent_nodes then
+		local indentstring = util.line_chars_before(pos):match("^%s*")
+		-- expand tabs before indenting to keep indentstring unmodified
+		if vim.bo.expandtab then
+			self:expand_tabs(util.tab_width(), #indentstring)
+		end
+		self:indent(indentstring)
 	end
-	self:indent(indentstring)
 
 	-- (possibly) keep user-set opts.
 	if self.merge_child_ext_opts then