add TagWriter

lua/u/buffer.lua

@@ -1,5 +1,5 @@
 local Range = require 'u.range'
-local Renderer = require 'u.renderer'
+local Renderer = require 'u.renderer'.Renderer
 
 ---@class Buffer
 ---@field buf number

lua/u/renderer.lua

@@ -1,10 +1,25 @@
 local utils = require 'u.utils'
 
+local M = {}
+
 --- @alias Tag { kind: 'tag'; name: string, attributes: table<string, unknown>, children: Tree }
 --- @alias Node nil | boolean | string | Tag
 --- @alias Tree Node | Node[]
 local TagMetaTable = {}
 
+--- @param name string
+--- @param attributes? table<string, any>
+--- @param children? Node | Node[]
+--- @return Tag
+function M.h(name, attributes, children)
+  return setmetatable({
+    kind = 'tag',
+    name = name,
+    attributes = attributes or {},
+    children = children,
+  }, TagMetaTable)
+end
+
 --------------------------------------------------------------------------------
 -- Renderer class
 --------------------------------------------------------------------------------
@@ -18,20 +33,7 @@ local TagMetaTable = {}
 --- @field curr { lines: string[]; extmarks: RendererExtmark[] }
 local Renderer = {}
 Renderer.__index = Renderer
-
+M.Renderer = Renderer
---- function h(name: string, attributes: table<string, unknown>, children: Node | Node[]): Node
---- @param name string
---- @param attributes? table<string, any>
---- @param children? Node | Node[]
---- @return Tag
-function Renderer.h(name, attributes, children)
-  return setmetatable({
-    kind = 'tag',
-    name = name,
-    attributes = attributes or {},
-    children = children,
-  }, TagMetaTable)
-end
 
 --- @param x any
 --- @return boolean
@@ -383,4 +385,48 @@ function Renderer:get_pos_infos(pos0)
   return matching_tags
 end
 
-return Renderer
+--------------------------------------------------------------------------------
+-- TagWriter class
+--------------------------------------------------------------------------------
+
+--- @class TagWriter
+--- @field private nodes Node[]
+local TagWriter = {}
+TagWriter.__index = TagWriter
+M.TagWriter = TagWriter
+
+function TagWriter.new()
+  local self = setmetatable({ nodes = {} }, TagWriter)
+  return self
+end
+
+--- @param nodes Tree
+--- @return TagWriter
+function TagWriter:put(nodes)
+  table.insert(self.nodes, nodes)
+  return self
+end
+
+--- @param name string
+--- @param attributes? table<string, any>
+--- @param children? Node | Node[]
+--- @return TagWriter
+function TagWriter:put_h(name, attributes, children)
+  local tag = M.h(name, attributes, children)
+  table.insert(self.nodes, tag)
+  return self
+end
+
+--- @param fn fun(TagWriter): any
+--- @return TagWriter
+function TagWriter:nest(fn)
+  local nested_writer = TagWriter.new()
+  fn(nested_writer)
+  table.insert(self.nodes, nested_writer.nodes)
+  return self
+end
+
+--- @return Tree
+function TagWriter:tree() return self.nodes end
+
+return M