cleanup

14 files changed, 381 insertions, 430 deletions

diff --git a/script/vm/compiler.lua b/script/vm/compiler.lua
index 2af4f61f..3c0a2dcb 100644
--- a/script/vm/compiler.lua
+++ b/script/vm/compiler.lua
@@ -2,10 +2,8 @@ local guide      = require 'parser.guide'
 local util       = require 'utility'
 local localID    = require 'vm.local-id'
 local globalMgr  = require 'vm.global-manager'
-local nodeMgr    = require 'vm.node'
 local signMgr    = require 'vm.sign'
 local config     = require 'config'
-local union      = require 'vm.union'
 local genericMgr = require 'vm.generic'
 local rpath      = require 'workspace.require-path'
 local files      = require 'files'
@@ -112,7 +110,7 @@ local searchFieldSwitch = util.switch()
             local fieldKey = field.name
             if fieldKey.type == 'doc.type' then
                 local fieldNode = vm.compileNode(fieldKey)
-                for fn in nodeMgr.eachObject(fieldNode) do
+                for fn in fieldNode:eachObject() do
                     if fn.type == 'global' and fn.cate == 'type' then
                         if key == nil
                         or fn.name == 'any'
@@ -237,7 +235,7 @@ local function getObjectSign(source)
             for _, arg in ipairs(source.args) do
                 local argNode = vm.compileNode(arg)
                 if arg.optional then
-                    argNode = nodeMgr.addOptional(argNode)
+                    argNode:addOptional()
                 end
                 source._sign:addSign(argNode)
             end
@@ -257,7 +255,7 @@ local function getObjectSign(source)
             for _, arg in ipairs(source.args) do
                 local argNode = vm.compileNode(arg.extends)
                 if arg.optional then
-                    argNode = nodeMgr.addOptional(argNode)
+                    argNode:addOptional()
                 end
                 source._sign:addSign(argNode)
             end
@@ -296,16 +294,17 @@ function vm.getReturnOfFunction(func, index)
     end
 end
 
+---@return vm.node
 local function getReturnOfSetMetaTable(args)
     local tbl  = args[1]
     local mt   = args[2]
-    local node = union()
+    local node = vm.createNode()
     if tbl then
         node:merge(vm.compileNode(tbl))
     end
     if mt then
         vm.compileByParentNode(mt, '__index', function (src)
-            for n in nodeMgr.eachObject(vm.compileNode(src)) do
+            for n in vm.compileNode(src):eachObject() do
                 if n.type == 'global'
                 or n.type == 'local'
                 or n.type == 'table'
@@ -318,6 +317,7 @@ local function getReturnOfSetMetaTable(args)
     return node
 end
 
+---@return vm.node?
 local function getReturn(func, index, args)
     if func.special == 'setmetatable' then
         if not args then
@@ -369,29 +369,27 @@ local function getReturn(func, index, args)
         return vm.compileNode(ast)
     end
     local node = vm.compileNode(func)
-    ---@type vm.union
+    ---@type vm.node?
     local result
-    if node then
-        for cnode in nodeMgr.eachObject(node) do
-            if cnode.type == 'function'
-            or cnode.type == 'doc.type.function' then
-                local returnObject = vm.getReturnOfFunction(cnode, index)
-                local returnNode   = vm.compileNode(returnObject)
-                if returnNode then
-                    for rnode in nodeMgr.eachObject(returnNode) do
-                        if rnode.type == 'generic' then
-                            returnNode = rnode:resolve(guide.getUri(func), args)
-                            break
-                        end
+    for cnode in node:eachObject() do
+        if cnode.type == 'function'
+        or cnode.type == 'doc.type.function' then
+            local returnObject = vm.getReturnOfFunction(cnode, index)
+            local returnNode   = vm.compileNode(returnObject)
+            if returnNode then
+                for rnode in returnNode:eachObject() do
+                    if rnode.type == 'generic' then
+                        returnNode = rnode:resolve(guide.getUri(func), args)
+                        break
                     end
                 end
-                if returnNode then
-                    for rnode in nodeMgr.eachObject(returnNode) do
-                        -- TODO: narrow type
-                        if rnode.type ~= 'doc.generic.name' then
-                            result = result or union()
-                            result:merge(rnode)
-                        end
+            end
+            if returnNode then
+                for rnode in returnNode:eachObject() do
+                    -- TODO: narrow type
+                    if rnode.type ~= 'doc.generic.name' then
+                        result = result or vm.createNode()
+                        result:merge(rnode)
                     end
                 end
             end
@@ -408,7 +406,7 @@ local function bindDocs(source)
         local doc = docs[i]
         if doc.type == 'doc.type' then
             if not isParam then
-                nodeMgr.setNode(source, vm.compileNode(doc))
+                vm.setNode(source, vm.compileNode(doc))
                 return true
             end
         end
@@ -417,13 +415,13 @@ local function bindDocs(source)
             or (source._globalNode and guide.isSet(source))
             or source.type == 'tablefield'
             or source.type == 'tableindex' then
-                nodeMgr.setNode(source, vm.compileNode(doc))
+                vm.setNode(source, vm.compileNode(doc))
                 return true
             end
         end
         if doc.type == 'doc.param' then
             if isParam and source[1] == doc.param[1] then
-                nodeMgr.setNode(source, vm.compileNode(doc))
+                vm.setNode(source, vm.compileNode(doc))
                 return true
             end
         end
@@ -438,7 +436,7 @@ local function bindDocs(source)
             if not ast then
                 return nil
             end
-            nodeMgr.setNode(source, vm.compileNode(ast))
+            vm.setNode(source, vm.compileNode(ast))
             return true
         end
     end
@@ -455,14 +453,14 @@ local function compileByLocalID(source)
         if src.bindDocs then
             if bindDocs(src) then
                 hasMarkDoc = true
-                nodeMgr.setNode(source, vm.compileNode(src))
+                vm.setNode(source, vm.compileNode(src))
             end
         end
     end
     for _, src in ipairs(sources) do
         if src.value then
             if not hasMarkDoc or guide.isLiteral(src.value) then
-                nodeMgr.setNode(source, vm.compileNode(src.value))
+                vm.setNode(source, vm.compileNode(src.value))
             end
         end
     end
@@ -477,11 +475,12 @@ function vm.compileByParentNode(source, key, pushResult)
         return
     end
     local suri = guide.getUri(source)
-    for node in nodeMgr.eachObject(parentNode) do
+    for node in parentNode:eachObject() do
         searchFieldSwitch(node.type, suri, node, key, pushResult)
     end
 end
 
+---@return vm.node?
 local function selectNode(source, list, index)
     if not list then
         return nil
@@ -508,14 +507,17 @@ local function selectNode(source, list, index)
     local result
     if exp.type == 'call' then
         result = getReturn(exp.node, index, exp.args)
+        if not result then
+            return nil
+        end
     else
         result = vm.compileNode(exp)
     end
     if source.type == 'function.return' then
         -- remove any for returns
-        local rtnNode = union()
+        local rtnNode = vm.createNode()
         local hasKnownType
-        for n in nodeMgr.eachObject(result) do
+        for n in result:eachObject() do
             if guide.isLiteral(n) then
                 hasKnownType = true
                 rtnNode:merge(n)
@@ -533,9 +535,11 @@ local function selectNode(source, list, index)
         if not hasKnownType then
             rtnNode:merge(globalMgr.getGlobal('type', 'unknown'))
         end
-        return nodeMgr.setNode(source, rtnNode)
+        vm.setNode(source, rtnNode)
+        return rtnNode
     end
-    return nodeMgr.setNode(source, result)
+    vm.setNode(source, result)
+    return result
 end
 
 ---@param source parser.object
@@ -583,6 +587,9 @@ local function compileCallArgNode(arg, call, callNode, fixIndex, myIndex)
     if call.args then
         for i = 1, 2 do
             local eventArg = call.args[i + fixIndex]
+            if not eventArg then
+                break
+            end
             eventMap = vm.getLiterals(eventArg)
             if eventMap then
                 eventIndex = i
@@ -591,27 +598,29 @@ local function compileCallArgNode(arg, call, callNode, fixIndex, myIndex)
         end
     end
 
-    for n in nodeMgr.eachObject(callNode) do
+    for n in callNode:eachObject() do
         if n.type == 'function' then
             local farg = getFuncArg(n, myIndex)
-            for fn in nodeMgr.eachObject(vm.compileNode(farg)) do
+            for fn in vm.compileNode(farg):eachObject() do
                 if isValidCallArgNode(arg, fn) then
-                    nodeMgr.setNode(arg, fn)
+                    vm.setNode(arg, fn)
                 end
             end
         end
         if n.type == 'doc.type.function' then
-            local argNode = vm.compileNode(n.args[eventIndex])
-            local event = argNode and argNode[1]
-            if not event
-            or not eventMap
-            or myIndex <= eventIndex
-            or event.type ~= 'doc.type.string'
-            or eventMap[event[1]] then
-                local farg = getFuncArg(n, myIndex)
-                for fn in nodeMgr.eachObject(vm.compileNode(farg)) do
-                    if isValidCallArgNode(arg, fn) then
-                        nodeMgr.setNode(arg, fn)
+            if n.args[eventIndex] then
+                local argNode = vm.compileNode(n.args[eventIndex])
+                local event = argNode and argNode[1]
+                if not event
+                or not eventMap
+                or myIndex <= eventIndex
+                or event.type ~= 'doc.type.string'
+                or eventMap[event[1]] then
+                    local farg = getFuncArg(n, myIndex)
+                    for fn in vm.compileNode(farg):eachObject() do
+                        if isValidCallArgNode(arg, fn) then
+                            vm.setNode(arg, fn)
+                        end
                     end
                 end
             end
@@ -641,7 +650,7 @@ function vm.compileCallArg(arg, call, index)
         callNode = vm.compileNode(call.args[1])
         compileCallArgNode(arg, call, callNode, fixIndex, index - fixIndex)
     end
-    return nodeMgr.getNode(arg)
+    return vm.getNode(arg)
 end
 
 local compilerSwitch = util.switch()
@@ -654,11 +663,11 @@ local compilerSwitch = util.switch()
     : case 'doc.type.table'
     : case 'doc.type.array'
     : call(function (source)
-        nodeMgr.setNode(source, source)
+        vm.setNode(source, source)
     end)
     : case 'table'
     : call(function (source)
-        nodeMgr.setNode(source, source)
+        vm.setNode(source, source)
 
         if source.parent.type == 'callargs' then
             local call = source.parent.parent
@@ -672,17 +681,17 @@ local compilerSwitch = util.switch()
         or source.parent.type == 'tableindex'
         or source.parent.type == 'setfield'
         or source.parent.type == 'setindex' then
-            nodeMgr.setNode(source, vm.compileNode(source.parent))
+            vm.setNode(source, vm.compileNode(source.parent))
         end
     end)
     : case 'function'
     : call(function (source)
-        nodeMgr.setNode(source, source)
+        vm.setNode(source, source)
 
         if source.bindDocs then
             for _, doc in ipairs(source.bindDocs) do
                 if doc.type == 'doc.overload' then
-                    nodeMgr.setNode(source, vm.compileNode(doc))
+                    vm.setNode(source, vm.compileNode(doc))
                 end
             end
         end
@@ -695,12 +704,11 @@ local compilerSwitch = util.switch()
     end)
     : case 'paren'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.exp))
+        vm.setNode(source, vm.compileNode(source.exp))
     end)
     : case 'local'
     : call(function (source)
-        --localMgr.declareLocal(source)
-        nodeMgr.setNode(source, source)
+        vm.setNode(source, source)
         local hasMarkDoc
         if source.bindDocs then
             hasMarkDoc = bindDocs(source)
@@ -708,14 +716,14 @@ local compilerSwitch = util.switch()
         local hasMarkParam
         if source.dummy and not hasMarkDoc then
             hasMarkParam = true
-            nodeMgr.setNode(source, vm.compileNode(source.method.node))
+            vm.setNode(source, vm.compileNode(source.method.node))
         end
         if source.value then
             if not hasMarkDoc or guide.isLiteral(source.value) then
                 if source.value and source.value.type == 'table' then
-                    nodeMgr.setNode(source, source.value)
+                    vm.setNode(source, source.value)
                 else
-                    nodeMgr.setNode(source, vm.compileNode(source.value))
+                    vm.setNode(source, vm.compileNode(source.value))
                 end
             end
         end
@@ -726,9 +734,9 @@ local compilerSwitch = util.switch()
             for _, ref in ipairs(source.ref) do
                 if ref.type == 'setlocal' then
                     if ref.value and ref.value.type == 'table' then
-                        nodeMgr.setNode(source, ref.value)
+                        vm.setNode(source, ref.value)
                     else
-                        nodeMgr.setNode(source, vm.compileNode(ref.value))
+                        vm.setNode(source, vm.compileNode(ref.value))
                     end
                 end
             end
@@ -742,25 +750,25 @@ local compilerSwitch = util.switch()
             local setfield = source.parent.parent.parent
             if setfield.type == 'setfield' then
                 hasMarkParam = true
-                nodeMgr.setNode(source, vm.compileNode(setfield.node))
+                vm.setNode(source, vm.compileNode(setfield.node))
             end
         end
         if source.parent.type == 'funcargs' and not hasMarkDoc and not hasMarkParam then
             local func = source.parent.parent
             local funcNode = vm.compileNode(func)
             local hasDocArg
-            for n in nodeMgr.eachObject(funcNode) do
+            for n in funcNode:eachObject() do
                 if n.type == 'doc.type.function' then
                     for index, arg in ipairs(n.args) do
                         if func.args[index] == source then
-                            nodeMgr.setNode(source, vm.compileNode(arg))
+                            vm.setNode(source, vm.compileNode(arg))
                             hasDocArg = true
                         end
                     end
                 end
             end
             if not hasDocArg then
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'any'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'any'))
             end
         end
         -- for x in ... do
@@ -770,13 +778,13 @@ local compilerSwitch = util.switch()
 
         -- for x = ... do
         if source.parent.type == 'loop' then
-            nodeMgr.setNode(source, globalMgr.getGlobal('type', 'integer'))
+            vm.setNode(source, globalMgr.getGlobal('type', 'integer'))
         end
     end)
     : case 'setlocal'
     : case 'getlocal'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.node), true)
+        vm.setNode(source, vm.compileNode(source.node), true)
     end)
     : case 'setfield'
     : case 'setmethod'
@@ -790,7 +798,7 @@ local compilerSwitch = util.switch()
         vm.compileByParentNode(source.node, key, function (src)
             if src.type == 'doc.type.field'
             or src.type == 'doc.field' then
-                nodeMgr.setNode(source, vm.compileNode(src))
+                vm.setNode(source, vm.compileNode(src))
             end
         end)
     end)
@@ -809,10 +817,12 @@ local compilerSwitch = util.switch()
         if type(key) == 'table' then
             local uri = guide.getUri(source)
             local value = vm.getTableValue(uri, vm.compileNode(source.node), key)
-            nodeMgr.setNode(source, value)
+            if value then
+                vm.setNode(source, value)
+            end
         else
             vm.compileByParentNode(source.node, key, function (src)
-                nodeMgr.setNode(source, vm.compileNode(src))
+                vm.setNode(source, vm.compileNode(src))
             end)
         end
     end)
@@ -825,7 +835,7 @@ local compilerSwitch = util.switch()
         vm.compileByParentNode(source.node, key, function (src)
             if src.type == 'doc.type.field'
             or src.type == 'doc.field' then
-                nodeMgr.setNode(source, vm.compileNode(src))
+                vm.setNode(source, vm.compileNode(src))
             end
         end)
     end)
@@ -836,7 +846,7 @@ local compilerSwitch = util.switch()
         end
         local key = guide.getKeyName(source)
         vm.compileByParentNode(source.node, key, function (src)
-            nodeMgr.setNode(source, vm.compileNode(src))
+            vm.setNode(source, vm.compileNode(src))
         end)
     end)
     : case 'tablefield'
@@ -850,27 +860,27 @@ local compilerSwitch = util.switch()
         if source.value then
             if not hasMarkDoc or guide.isLiteral(source.value) then
                 if source.value and source.value.type == 'table' then
-                    nodeMgr.setNode(source, source.value)
+                    vm.setNode(source, source.value)
                 else
-                    nodeMgr.setNode(source, vm.compileNode(source.value))
+                    vm.setNode(source, vm.compileNode(source.value))
                 end
             end
         end
 
         if not hasMarkDoc then
             vm.compileByParentNode(source.parent, guide.getKeyName(source), function (src)
-                nodeMgr.setNode(source, vm.compileNode(src))
+                vm.setNode(source, vm.compileNode(src))
             end)
         end
     end)
     : case 'field'
     : case 'method'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.parent))
+        vm.setNode(source, vm.compileNode(source.parent))
     end)
     : case 'tableexp'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.value))
+        vm.setNode(source, vm.compileNode(source.value))
     end)
     : case 'function.return'
     : call(function (source)
@@ -891,9 +901,9 @@ local compilerSwitch = util.switch()
                                 end)
                             end
                             if hasGeneric then
-                                nodeMgr.setNode(source, genericMgr(rtn, sign))
+                                vm.setNode(source, genericMgr(rtn, sign))
                             else
-                                nodeMgr.setNode(source, vm.compileNode(rtn))
+                                vm.setNode(source, vm.compileNode(rtn))
                             end
                         end
                     end
@@ -910,7 +920,7 @@ local compilerSwitch = util.switch()
     : call(function (source)
         if source.returns then
             for _, rtn in ipairs(source.returns) do
-                nodeMgr.setNode(source, vm.compileNode(rtn[1]))
+                vm.setNode(source, vm.compileNode(rtn[1]))
             end
         end
     end)
@@ -922,22 +932,22 @@ local compilerSwitch = util.switch()
             if not node then
                 return
             end
-            for n in nodeMgr.eachObject(node) do
+            for n in node:eachObject() do
                 if  n.type == 'global'
                 and n.cate == 'type'
                 and n.name == '...' then
                     return
                 end
             end
-            nodeMgr.setNode(source, node)
+            vm.setNode(source, node)
         end
         if vararg.type == 'varargs' then
-            nodeMgr.setNode(source, vm.compileNode(vararg))
+            vm.setNode(source, vm.compileNode(vararg))
         end
     end)
     : case 'varargs'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.node))
+        vm.setNode(source, vm.compileNode(source.node))
     end)
     : case 'call'
     : call(function (source)
@@ -945,14 +955,14 @@ local compilerSwitch = util.switch()
         if not node then
             return
         end
-        for n in nodeMgr.eachObject(node) do
+        for n in node:eachObject() do
             if  n.type == 'global'
             and n.cate == 'type'
             and n.name == '...' then
                 return
             end
         end
-        nodeMgr.setNode(source, node)
+        vm.setNode(source, node)
     end)
     : case 'in'
     : call(function (source)
@@ -972,31 +982,33 @@ local compilerSwitch = util.switch()
         if source.keys then
             for i, loc in ipairs(source.keys) do
                 local node = getReturn(source._iterator, i, source._iterArgs)
-                nodeMgr.setNode(loc, node)
+                if node then
+                    vm.setNode(loc, node)
+                end
             end
         end
     end)
     : case 'doc.type'
     : call(function (source)
         for _, typeUnit in ipairs(source.types) do
-            nodeMgr.setNode(source, vm.compileNode(typeUnit))
+            vm.setNode(source, vm.compileNode(typeUnit))
         end
     end)
     : case 'doc.type.integer'
     : case 'doc.type.string'
     : case 'doc.type.boolean'
     : call(function (source)
-        nodeMgr.setNode(source, source)
+        vm.setNode(source, source)
     end)
     : case 'doc.generic.name'
     : call(function (source)
-        nodeMgr.setNode(source, source)
+        vm.setNode(source, source)
     end)
     : case 'doc.type.name'
     : call(function (source)
         if source.signs then
             local uri = guide.getUri(source)
-            nodeMgr.setNode(source, source)
+            vm.setNode(source, source)
             local global = globalMgr.getGlobal('type', source[1])
             for _, set in ipairs(global:getSets(uri)) do
                 if set.type == 'doc.class' then
@@ -1005,7 +1017,7 @@ local compilerSwitch = util.switch()
                             if ext.type == 'doc.type.table' then
                                 if ext._generic then
                                     local resolved = ext._generic:resolve(uri, source.signs)
-                                    nodeMgr.setNode(source, resolved)
+                                    vm.setNode(source, resolved)
                                 end
                             end
                         end
@@ -1014,7 +1026,7 @@ local compilerSwitch = util.switch()
                 if set.type == 'doc.alias' then
                     if set.extends._generic then
                         local resolved = set.extends._generic:resolve(uri, source.signs)
-                        nodeMgr.setNode(source, resolved)
+                        vm.setNode(source, resolved)
                     end
                 end
             end
@@ -1022,23 +1034,23 @@ local compilerSwitch = util.switch()
     end)
     : case 'doc.class.name'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.parent))
+        vm.setNode(source, vm.compileNode(source.parent))
     end)
     : case 'doc.field'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.extends))
+        vm.setNode(source, vm.compileNode(source.extends))
     end)
     : case 'doc.type.field'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.extends))
+        vm.setNode(source, vm.compileNode(source.extends))
     end)
     : case 'doc.param'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.extends))
+        vm.setNode(source, vm.compileNode(source.extends))
     end)
     : case 'doc.vararg'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.vararg))
+        vm.setNode(source, vm.compileNode(source.vararg))
     end)
     : case '...'
     : call(function (source)
@@ -1051,45 +1063,45 @@ local compilerSwitch = util.switch()
         end
         for _, doc in ipairs(func.bindDocs) do
             if doc.type == 'doc.vararg' then
-                nodeMgr.setNode(source, vm.compileNode(doc))
+                vm.setNode(source, vm.compileNode(doc))
             end
             if doc.type == 'doc.param' and doc.param[1] == '...' then
-                nodeMgr.setNode(source, vm.compileNode(doc))
+                vm.setNode(source, vm.compileNode(doc))
             end
         end
     end)
     : case 'doc.overload'
     : call(function (source)
-        nodeMgr.setNode(source, vm.compileNode(source.overload))
+        vm.setNode(source, vm.compileNode(source.overload))
     end)
     : case 'doc.see.name'
     : call(function (source)
         local type = globalMgr.getGlobal('type', source[1])
         if type then
-            nodeMgr.setNode(source, vm.compileNode(type))
+            vm.setNode(source, vm.compileNode(type))
         end
     end)
     : case 'doc.type.arg'
     : call(function (source)
         if source.extends then
-            nodeMgr.setNode(source, vm.compileNode(source.extends))
+            vm.setNode(source, vm.compileNode(source.extends))
         else
-            nodeMgr.setNode(source, globalMgr.getGlobal('type', 'any'))
+            vm.setNode(source, globalMgr.getGlobal('type', 'any'))
         end
     end)
     : case 'generic'
     : call(function (source)
-        nodeMgr.setNode(source, source)
+        vm.setNode(source, source)
     end)
     : case 'unary'
     : call(function (source)
         if source.op.type == 'not' then
             local result = vm.test(source[1])
             if result == nil then
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'boolean'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'boolean'))
                 return
             else
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'boolean',
                     start  = source.start,
                     finish = source.finish,
@@ -1100,16 +1112,16 @@ local compilerSwitch = util.switch()
             end
         end
         if source.op.type == '#' then
-            nodeMgr.setNode(source, globalMgr.getGlobal('type', 'integer'))
+            vm.setNode(source, globalMgr.getGlobal('type', 'integer'))
             return
         end
         if source.op.type == '-' then
             local v = vm.getNumber(source[1])
             if v == nil then
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'number'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'number'))
                 return
             else
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'number',
                     start  = source.start,
                     finish = source.finish,
@@ -1122,10 +1134,10 @@ local compilerSwitch = util.switch()
         if source.op.type == '~' then
             local v = vm.getInteger(source[1])
             if v == nil then
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'integer'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'integer'))
                 return
             else
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'integer',
                     start  = source.start,
                     finish = source.finish,
@@ -1141,11 +1153,11 @@ local compilerSwitch = util.switch()
         if source.op.type == 'and' then
             local r1 = vm.test(source[1])
             if r1 == true then
-                nodeMgr.setNode(source, vm.compileNode(source[2]))
+                vm.setNode(source, vm.compileNode(source[2]))
                 return
             end
             if r1 == false then
-                nodeMgr.setNode(source, vm.compileNode(source[1]))
+                vm.setNode(source, vm.compileNode(source[1]))
                 return
             end
             return
@@ -1153,11 +1165,11 @@ local compilerSwitch = util.switch()
         if source.op.type == 'or' then
             local r1 = vm.test(source[1])
             if r1 == true then
-                nodeMgr.setNode(source, vm.compileNode(source[1]))
+                vm.setNode(source, vm.compileNode(source[1]))
                 return
             end
             if r1 == false then
-                nodeMgr.setNode(source, vm.compileNode(source[2]))
+                vm.setNode(source, vm.compileNode(source[2]))
                 return
             end
             return
@@ -1165,10 +1177,10 @@ local compilerSwitch = util.switch()
         if source.op.type == '==' then
             local result = vm.equal(source[1], source[2])
             if result == nil then
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'boolean'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'boolean'))
                 return
             else
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'boolean',
                     start  = source.start,
                     finish = source.finish,
@@ -1181,10 +1193,10 @@ local compilerSwitch = util.switch()
         if source.op.type == '~=' then
             local result = vm.equal(source[1], source[2])
             if result == nil then
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'boolean'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'boolean'))
                 return
             else
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'boolean',
                     start  = source.start,
                     finish = source.finish,
@@ -1198,7 +1210,7 @@ local compilerSwitch = util.switch()
             local a = vm.getInteger(source[1])
             local b = vm.getInteger(source[2])
             if a and b then
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'integer',
                     start  = source.start,
                     finish = source.finish,
@@ -1207,7 +1219,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'integer'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'integer'))
                 return
             end
         end
@@ -1215,7 +1227,7 @@ local compilerSwitch = util.switch()
             local a = vm.getInteger(source[1])
             local b = vm.getInteger(source[2])
             if a and b then
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'integer',
                     start  = source.start,
                     finish = source.finish,
@@ -1224,7 +1236,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'integer'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'integer'))
                 return
             end
         end
@@ -1232,7 +1244,7 @@ local compilerSwitch = util.switch()
             local a = vm.getInteger(source[1])
             local b = vm.getInteger(source[2])
             if a and b then
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'integer',
                     start  = source.start,
                     finish = source.finish,
@@ -1241,7 +1253,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'integer'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'integer'))
                 return
             end
         end
@@ -1249,7 +1261,7 @@ local compilerSwitch = util.switch()
             local a = vm.getInteger(source[1])
             local b = vm.getInteger(source[2])
             if a and b then
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'integer',
                     start  = source.start,
                     finish = source.finish,
@@ -1258,7 +1270,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'integer'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'integer'))
                 return
             end
         end
@@ -1266,7 +1278,7 @@ local compilerSwitch = util.switch()
             local a = vm.getInteger(source[1])
             local b = vm.getInteger(source[2])
             if a and b then
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'integer',
                     start  = source.start,
                     finish = source.finish,
@@ -1275,7 +1287,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'integer'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'integer'))
                 return
             end
         end
@@ -1284,7 +1296,7 @@ local compilerSwitch = util.switch()
             local b = vm.getNumber(source[2])
             if a and b then
                 local result = a + b
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = math.type(result) == 'integer' and 'integer' or 'number',
                     start  = source.start,
                     finish = source.finish,
@@ -1293,7 +1305,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'number'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'number'))
                 return
             end
         end
@@ -1302,7 +1314,7 @@ local compilerSwitch = util.switch()
             local b = vm.getNumber(source[2])
             if a and b then
                 local result = a - b
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = math.type(result) == 'integer' and 'integer' or 'number',
                     start  = source.start,
                     finish = source.finish,
@@ -1311,7 +1323,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'number'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'number'))
                 return
             end
         end
@@ -1320,7 +1332,7 @@ local compilerSwitch = util.switch()
             local b = vm.getNumber(source[2])
             if a and b then
                 local result = a * b
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = math.type(result) == 'integer' and 'integer' or 'number',
                     start  = source.start,
                     finish = source.finish,
@@ -1329,7 +1341,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'number'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'number'))
                 return
             end
         end
@@ -1337,7 +1349,7 @@ local compilerSwitch = util.switch()
             local a = vm.getNumber(source[1])
             local b = vm.getNumber(source[2])
             if a and b then
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'number',
                     start  = source.start,
                     finish = source.finish,
@@ -1346,7 +1358,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'number'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'number'))
                 return
             end
         end
@@ -1355,7 +1367,7 @@ local compilerSwitch = util.switch()
             local b = vm.getNumber(source[2])
             if a and b then
                 local result = a % b
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = math.type(result) == 'integer' and 'integer' or 'number',
                     start  = source.start,
                     finish = source.finish,
@@ -1364,7 +1376,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'number'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'number'))
                 return
             end
         end
@@ -1372,7 +1384,7 @@ local compilerSwitch = util.switch()
             local a = vm.getNumber(source[1])
             local b = vm.getNumber(source[2])
             if a and b then
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'number',
                     start  = source.start,
                     finish = source.finish,
@@ -1381,7 +1393,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'number'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'number'))
                 return
             end
         end
@@ -1390,7 +1402,7 @@ local compilerSwitch = util.switch()
             local b = vm.getNumber(source[2])
             if a and b and b ~= 0 then
                 local result = a // b
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = math.type(result) == 'integer' and 'integer' or 'number',
                     start  = source.start,
                     finish = source.finish,
@@ -1399,7 +1411,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'number'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'number'))
                 return
             end
         end
@@ -1427,7 +1439,7 @@ local compilerSwitch = util.switch()
                         end
                     end
                 end
-                nodeMgr.setNode(source, {
+                vm.setNode(source, {
                     type   = 'string',
                     start  = source.start,
                     finish = source.finish,
@@ -1436,7 +1448,7 @@ local compilerSwitch = util.switch()
                 })
                 return
             else
-                nodeMgr.setNode(source, globalMgr.getGlobal('type', 'string'))
+                vm.setNode(source, globalMgr.getGlobal('type', 'string'))
                 return
             end
         end
@@ -1451,13 +1463,13 @@ end
 local function compileByGlobal(uri, source)
     uri = uri or guide.getUri(source)
     if source.type == 'global' then
-        nodeMgr.setNode(source, source)
+        vm.setNode(source, source)
         if source.cate == 'variable' then
             local hasMarkDoc
             for _, set in ipairs(source:getSets(uri)) do
                 if set.bindDocs then
                     if bindDocs(set) then
-                        nodeMgr.setNode(source, vm.compileNode(set))
+                        vm.setNode(source, vm.compileNode(set))
                         hasMarkDoc = true
                     end
                 end
@@ -1465,7 +1477,7 @@ local function compileByGlobal(uri, source)
             for _, set in ipairs(source:getSets(uri)) do
                 if set.value then
                     if not hasMarkDoc or guide.isLiteral(set.value) then
-                        nodeMgr.setNode(source, vm.compileNode(set.value))
+                        vm.setNode(source, vm.compileNode(set.value))
                     end
                 end
             end
@@ -1477,7 +1489,7 @@ local function compileByGlobal(uri, source)
                         for _, ext in ipairs(set.extends) do
                             if ext.type == 'doc.type.table' then
                                 if not ext._generic then
-                                    nodeMgr.setNode(source, vm.compileNode(ext))
+                                    vm.setNode(source, vm.compileNode(ext))
                                 end
                             end
                         end
@@ -1485,7 +1497,7 @@ local function compileByGlobal(uri, source)
                 end
                 if set.type == 'doc.alias' then
                     if not set.extends._generic then
-                        nodeMgr.setNode(source, vm.compileNode(set.extends))
+                        vm.setNode(source, vm.compileNode(set.extends))
                     end
                 end
             end
@@ -1493,7 +1505,7 @@ local function compileByGlobal(uri, source)
         return
     end
     if source._globalNode then
-        nodeMgr.setNode(source, vm.compileNode(source._globalNode, uri))
+        vm.setNode(source, vm.compileNode(source._globalNode, uri))
         return
     end
 end
@@ -1509,7 +1521,9 @@ function vm.resumeCache()
     pauseCacheCount = pauseCacheCount - 1
     if pauseCacheCount == 0 then
         for source in pairs(originCacheKeys) do
-            nodeMgr.nodeCache[source] = originCacheValues[source]
+            if originCacheValues[source] then
+                vm.setNode(source, originCacheValues[source], true)
+            end
             originCacheKeys[source]   = nil
             originCacheValues[source] = nil
         end
@@ -1521,23 +1535,22 @@ end
 ---@return vm.node
 function vm.compileNode(source, uri)
     if not source then
-        return false
+        error('Can not compile nil node')
     end
-    if nodeMgr.nodeCache[source] ~= nil then
-        return nodeMgr.nodeCache[source]
+    local cache = vm.getNode(source)
+    if cache ~= nil then
+        return cache
     end
 
     local pauseCache = pauseCacheCount > 0
     if pauseCache and not originCacheKeys[source] then
         originCacheKeys[source]   = true
-        originCacheValues[source] = nodeMgr.nodeCache[source]
+        originCacheValues[source] = cache
     end
 
-    nodeMgr.nodeCache[source] = false
+    vm.setNode(source, vm.createNode(), true)
     compileByGlobal(uri, source)
     compileByNode(source)
 
-    --localMgr.subscribeLocal(source, source._node)
-
-    return nodeMgr.nodeCache[source]
+    return vm.getNode(source)
 end
diff --git a/script/vm/def.lua b/script/vm/def.lua
index 40dcc9f0..9efb3e90 100644
--- a/script/vm/def.lua
+++ b/script/vm/def.lua
@@ -4,7 +4,6 @@ local util      = require 'utility'
 local guide     = require 'parser.guide'
 local localID   = require 'vm.local-id'
 local globalMgr = require 'vm.global-manager'
-local nodeMgr   = require 'vm.node'
 
 local simpleSwitch
 
@@ -145,7 +144,7 @@ local nodeSwitch = util.switch()
         end
         local uri = guide.getUri(source)
         local key = guide.getKeyName(source)
-        for pn in nodeMgr.eachObject(parentNode) do
+        for pn in parentNode:eachObject() do
             searchFieldSwitch(pn.type, uri, pn, key, pushResult)
         end
     end)
@@ -163,7 +162,7 @@ local nodeSwitch = util.switch()
             return
         end
         local uri = guide.getUri(source)
-        for pn in nodeMgr.eachObject(parentNode) do
+        for pn in parentNode:eachObject() do
             searchFieldSwitch(pn.type, uri, pn, source[1], pushResult)
         end
     end)
@@ -200,7 +199,7 @@ local function searchByNode(source, pushResult)
         return
     end
     local suri = guide.getUri(source)
-    for n in nodeMgr.eachObject(node) do
+    for n in node:eachObject() do
         if n.type == 'global' then
             for _, set in ipairs(n:getSets(suri)) do
                 pushResult(set)
diff --git a/script/vm/generic.lua b/script/vm/generic.lua
index 37d2bd13..b3981ff8 100644
--- a/script/vm/generic.lua
+++ b/script/vm/generic.lua
@@ -1,5 +1,3 @@
-local nodeMgr = require 'vm.node'
-local union   = require 'vm.union'
 local vm      = require 'vm.vm'
 
 ---@class parser.object
@@ -14,7 +12,7 @@ mt.type = 'generic'
 
 ---@param source    parser.object
 ---@param resolved? table<string, vm.node>
----@return parser.object | vm.union
+---@return parser.object | vm.node
 local function cloneObject(source, resolved)
     if not resolved then
         return source
@@ -28,7 +26,9 @@ local function cloneObject(source, resolved)
             parent = source.parent,
             [1]    = source[1],
         }
-        nodeMgr.setNode(newName, resolved[key], true)
+        if resolved[key] then
+            vm.setNode(newName, resolved[key], true)
+        end
         return newName
     end
     if source.type == 'doc.type' then
@@ -118,8 +118,8 @@ end
 function mt:resolve(uri, args)
     local resolved  = self.sign:resolve(uri, args)
     local protoNode = vm.compileNode(self.proto)
-    local result = union()
-    for nd in nodeMgr.eachObject(protoNode) do
+    local result = vm.createNode()
+    for nd in protoNode:eachObject() do
         local clonedNode = vm.compileNode(cloneObject(nd, resolved))
         result:merge(clonedNode)
     end
diff --git a/script/vm/global-manager.lua b/script/vm/global-manager.lua
index dffc5c73..3f48197f 100644
--- a/script/vm/global-manager.lua
+++ b/script/vm/global-manager.lua
@@ -3,6 +3,8 @@ local guide         = require 'parser.guide'
 local globalBuilder = require 'vm.global'
 local signMgr       = require 'vm.sign'
 local genericMgr    = require 'vm.generic'
+---@class vm
+local vm            = require 'vm.vm'
 
 ---@class parser.object
 ---@field _globalNode vm.global
@@ -145,6 +147,7 @@ local compilerGlobalSwitch = util.switch()
         end
     end)
     : case 'doc.class'
+    ---@param source parser.object
     : call(function (source)
         local uri  = guide.getUri(source)
         local name = guide.getKeyName(source)
@@ -155,7 +158,7 @@ local compilerGlobalSwitch = util.switch()
         if source.signs then
             source._sign = signMgr()
             for _, sign in ipairs(source.signs) do
-                source._sign:addSign(sign)
+                source._sign:addSign(vm.compileNode(sign))
             end
             if source.extends then
                 for _, ext in ipairs(source.extends) do
@@ -177,7 +180,7 @@ local compilerGlobalSwitch = util.switch()
         if source.signs then
             source._sign = signMgr()
             for _, sign in ipairs(source.signs) do
-                source._sign:addSign(sign)
+                source._sign:addSign(vm.compileNode(sign))
             end
             source.extends._generic = genericMgr(source.extends, source._sign)
         end
diff --git a/script/vm/infer.lua b/script/vm/infer.lua
index ffd6f292..71da6317 100644
--- a/script/vm/infer.lua
+++ b/script/vm/infer.lua
@@ -1,8 +1,6 @@
 local util     = require 'utility'
-local nodeMgr  = require 'vm.node'
 local config   = require 'config'
 local guide    = require 'parser.guide'
-local union    = require 'vm.union'
 local vm       = require 'vm.vm'
 
 ---@class vm.infer-manager
@@ -163,17 +161,14 @@ function m.getInfer(source)
     if not node then
         return m.NULL
     end
-    -- TODO: more cache?
-    if node.type == 'vm.union' and node.lastInfer then
+    if node.lastInfer then
         return node.lastInfer
     end
     local infer = setmetatable({
         node  = node,
         uri   = guide.getUri(source),
     }, mt)
-    if node.type == 'vm.union' then
-        node.lastInfer = infer
-    end
+    node.lastInfer = infer
 
     return infer
 end
@@ -203,7 +198,7 @@ end
 
 function mt:_eraseAlias()
     local expandAlias = config.get(self.uri, 'Lua.hover.expandAlias')
-    for n in nodeMgr.eachObject(self.node) do
+    for n in self.node:eachObject() do
         if n.type == 'global' and n.cate == 'type' then
             for _, set in ipairs(n:getSets(self.uri)) do
                 if set.type == 'doc.alias' then
@@ -250,7 +245,7 @@ function mt:_computeViews()
 
     self.views = {}
 
-    for n in nodeMgr.eachObject(self.node) do
+    for n in self.node:eachObject() do
         local view = viewNodeSwitch(n.type, n, self)
         if view then
             self.views[view] = true
@@ -329,7 +324,7 @@ function mt:merge(other)
     end
 
     local infer = setmetatable({
-        node  = union(self.node, other.node),
+        node  = vm.createNode(self.node, other.node),
         uri   = self.uri,
     }, mt)
 
@@ -343,7 +338,7 @@ function mt:viewLiterals()
     end
     local mark     = {}
     local literals = {}
-    for n in nodeMgr.eachObject(self.node) do
+    for n in self.node:eachObject() do
         if n.type == 'string'
         or n.type == 'number'
         or n.type == 'integer'
@@ -369,7 +364,7 @@ function mt:viewClass()
     end
     local mark  = {}
     local class = {}
-    for n in nodeMgr.eachObject(self.node) do
+    for n in self.node:eachObject() do
         if n.type == 'global' and n.cate == 'type' then
             local name = n.name
             if not mark[name] then
diff --git a/script/vm/init.lua b/script/vm/init.lua
index 5d32bf28..0058c698 100644
--- a/script/vm/init.lua
+++ b/script/vm/init.lua
@@ -1,11 +1,12 @@
 local vm = require 'vm.vm'
-require 'vm.manager'
 require 'vm.compiler'
 require 'vm.value'
+require 'vm.node'
 require 'vm.def'
 require 'vm.ref'
 require 'vm.field'
 require 'vm.doc'
 require 'vm.type'
 require 'vm.library'
+require 'vm.manager'
 return vm
diff --git a/script/vm/local-manager.lua b/script/vm/local-manager.lua
index 9ffee344..2baabed4 100644
--- a/script/vm/local-manager.lua
+++ b/script/vm/local-manager.lua
@@ -26,10 +26,11 @@ end
 ---@param source parser.object
 ---@param node   vm.node
 function m.subscribeLocal(source, node)
+    -- TODO: need delete
     if not node then
         return
     end
-    if node.type == 'vm.union' then
+    if node.type == 'vm.node' then
         node:subscribeLocal(source)
         return
     end
diff --git a/script/vm/manager.lua b/script/vm/manager.lua
index 67e8cc38..c9103ff9 100644
--- a/script/vm/manager.lua
+++ b/script/vm/manager.lua
@@ -3,6 +3,8 @@ local files          = require 'files'
 local globalManager  = require 'vm.global-manager'
 local localManager = require 'vm.local-manager'
 
+---@alias vm.object parser.object | vm.global | vm.generic
+
 ---@class vm.state
 local m = {}
 for uri in files.eachFile() do
diff --git a/script/vm/node.lua b/script/vm/node.lua
index 9f998181..6106d3e1 100644
--- a/script/vm/node.lua
+++ b/script/vm/node.lua
@@ -1,106 +1,177 @@
-local union      = require 'vm.union'
-local files      = require 'files'
-
----@alias vm.node vm.union
----@alias vm.object parser.object | vm.global | vm.generic
-
----@class vm.node-manager
-local m = {}
-
-local DUMMY_FUNCTION = function () end
+local files    = require 'files'
+local localMgr = require 'vm.local-manager'
+---@class vm
+local vm       = require 'vm.vm'
 
 ---@type table<vm.object, vm.node>
-m.nodeCache = {}
+vm.nodeCache = {}
 
----@param a vm.node
----@param b vm.node
-function m.mergeNode(a, b)
-    if not b then
-        return a
-    end
-    if not a then
-        return b
-    end
-    return union(a, b)
-end
+---@class vm.node
+local mt = {}
+mt.__index   = mt
+mt.type      = 'vm.node'
+mt.optional  = nil
+mt.lastInfer = nil
 
----@param source vm.object
 ---@param node vm.node | vm.object
----@param cover? boolean
-function m.setNode(source, node, cover)
-    if cover then
-        m.nodeCache[source] = node
-        return
-    end
+function mt:merge(node)
     if not node then
         return
     end
-    local me = m.nodeCache[source]
-    if not me then
-        if node.type == 'vm.union' then
-            m.nodeCache[source] = node
-        else
-            m.nodeCache[source] = union(node)
+    if node.type == 'vm.node' then
+        for _, c in ipairs(node) do
+            if not self[c] then
+                self[c]       = true
+                self[#self+1] = c
+            end
+        end
+        if node:isOptional() then
+            self.optional = true
+        end
+    else
+        if not self[node] then
+            self[node]    = true
+            self[#self+1] = node
         end
-        return
     end
-    m.nodeCache[source] = union(me, node)
 end
 
----@return vm.node?
-function m.getNode(source)
-    return m.nodeCache[source]
+---@return vm.node
+function mt:copy()
+    return vm.createNode(self)
+end
+
+---@return boolean
+function mt:isEmpty()
+    return #self == 0
+end
+
+---@param source parser.object
+function mt:subscribeLocal(source)
+    -- TODO: need delete
+    for _, c in ipairs(self) do
+        localMgr.subscribeLocal(source, c)
+    end
 end
 
----@param node vm.node?
 ---@return vm.node
-function m.addOptional(node)
-    if not node or node.type ~= 'vm.union' then
-        node = union(node)
+function mt:addOptional()
+    if self:isOptional() then
+        return self
     end
-    node = node:addOptional()
-    return node
+    self.optional = true
+    return self
 end
 
----@param node vm.node?
----@return vm.union?
-function m.removeOptional(node)
-    if not node then
-        return node
+---@return vm.node
+function mt:removeOptional()
+    self.optional = nil
+    if not self:isOptional() then
+        return self
     end
-    if node.type ~= 'vm.union' then
-        node = union(node)
+    local newNode = vm.createNode()
+    for _, n in ipairs(self) do
+        if n.type == 'nil' then
+            goto CONTINUE
+        end
+        if n.type == 'boolean' and n[1] == false then
+            goto CONTINUE
+        end
+        if n.type == 'doc.type.boolean' and n[1] == false then
+            goto CONTINUE
+        end
+        if n.type == 'false' then
+            goto CONTINUE
+        end
+        newNode[#newNode+1] = n
+        ::CONTINUE::
     end
-    node = node:removeOptional()
-    return node
+    newNode.optional = false
+    return newNode
+end
+
+---@return boolean
+function mt:isOptional()
+    if self.optional ~= nil then
+        return self.optional
+    end
+    for _, c in ipairs(self) do
+        if c.type == 'nil' then
+            self.optional = true
+            return true
+        end
+        if c.type == 'boolean' then
+            if c[1] == false then
+                self.optional = true
+                return true
+            end
+        end
+        if c.type == 'false' then
+            self.optional = true
+            return true
+        end
+    end
+    self.optional = false
+    return false
 end
 
 ---@return fun():vm.object
-function m.eachObject(node)
+function mt:eachObject()
+    local i = 0
+    return function ()
+        i = i + 1
+        return self[i]
+    end
+end
+
+---@param source vm.object
+---@param node vm.node | vm.object
+---@param cover? boolean
+function vm.setNode(source, node, cover)
     if not node then
-        return DUMMY_FUNCTION
+        error('Can not set nil node')
     end
-    if node.type == 'vm.union' then
-        return node:eachNode()
+    if cover then
+        vm.nodeCache[source] = node
+        return
     end
-    local first = true
-    return function ()
-        if first then
-            first = false
-            return node
+    local me = vm.nodeCache[source]
+    if not me then
+        if node.type == 'vm.node' then
+            vm.nodeCache[source] = node
+        else
+            vm.nodeCache[source] = vm.createNode(node)
         end
-        return nil
+        return
     end
+    vm.nodeCache[source] = vm.createNode(me, node)
+end
+
+---@return vm.node?
+function vm.getNode(source)
+    return vm.nodeCache[source]
 end
 
-function m.clearNodeCache()
-    m.nodeCache = {}
+function vm.clearNodeCache()
+    vm.nodeCache = {}
+end
+
+---@param a? vm.node | vm.object
+---@param b? vm.node | vm.object
+---@return vm.node
+function vm.createNode(a, b)
+    local node = setmetatable({}, mt)
+    if a then
+        node:merge(a)
+    end
+    if b then
+        node:merge(b)
+    end
+    return node
 end
 
 files.watch(function (ev, uri)
     if ev == 'version' then
-        m.clearNodeCache()
+        vm.clearNodeCache()
     end
 end)
-
-return m
diff --git a/script/vm/ref.lua b/script/vm/ref.lua
index e8192c72..360d979e 100644
--- a/script/vm/ref.lua
+++ b/script/vm/ref.lua
@@ -4,7 +4,6 @@ local util      = require 'utility'
 local guide     = require 'parser.guide'
 local localID   = require 'vm.local-id'
 local globalMgr = require 'vm.global-manager'
-local nodeMgr   = require 'vm.node'
 local files     = require 'files'
 local await     = require 'await'
 local progress  = require 'progress'
@@ -271,7 +270,7 @@ local function searchByNode(source, pushResult)
         return
     end
     local uri = guide.getUri(source)
-    for n in nodeMgr.eachObject(node) do
+    for n in node:eachObject() do
         if n.type == 'global' then
             for _, get in ipairs(n:getGets(uri)) do
                 pushResult(get)
diff --git a/script/vm/sign.lua b/script/vm/sign.lua
index 2fac9528..5b97f2b9 100644
--- a/script/vm/sign.lua
+++ b/script/vm/sign.lua
@@ -1,5 +1,4 @@
 local guide         = require 'parser.guide'
-local nodeMgr       = require 'vm.node'
 local vm            = require 'vm.vm'
 
 ---@class vm.sign
@@ -31,19 +30,19 @@ function mt:resolve(uri, args)
             local key = typeUnit[1]
             if typeUnit.literal then
                 -- 'number' -> `T`
-                for n in nodeMgr.eachObject(node) do
+                for n in node:eachObject() do
                     if n.type == 'string' then
                         local type = globalMgr.declareGlobal('type', n[1], guide.getUri(n))
-                        resolved[key] = nodeMgr.mergeNode(type, resolved[key])
+                        resolved[key] = vm.createNode(type, resolved[key])
                     end
                 end
             else
                 -- number -> T
-                resolved[key] = nodeMgr.mergeNode(node, resolved[key])
+                resolved[key] = vm.createNode(node, resolved[key])
             end
         end
         if typeUnit.type == 'doc.type.array' then
-            for n in nodeMgr.eachObject(node) do
+            for n in node:eachObject() do
                 if n.type == 'doc.type.array' then
                     -- number[] -> T[]
                     resolve(typeUnit.node, vm.compileNode(n.node))
@@ -80,11 +79,11 @@ function mt:resolve(uri, args)
         if not sign then
             break
         end
-        for n in nodeMgr.eachObject(sign) do
+        for n in sign:eachObject() do
             local argNode = vm.compileNode(arg)
             if argNode then
                 if sign.optional then
-                    argNode = nodeMgr.removeOptional(argNode)
+                    argNode:removeOptional()
                 end
                 resolve(n, argNode)
             end
diff --git a/script/vm/type.lua b/script/vm/type.lua
index 46cc3946..5c8a8088 100644
--- a/script/vm/type.lua
+++ b/script/vm/type.lua
@@ -1,6 +1,4 @@
-local nodeMgr   = require 'vm.node'
 local globalMgr = require 'vm.global-manager'
-local union     = require 'vm.union'
 ---@class vm
 local vm        = require 'vm.vm'
 
@@ -11,10 +9,10 @@ local vm        = require 'vm.vm'
 ---@return boolean
 function vm.isSubType(uri, child, parent, mark)
     if type(parent) == 'string' then
-        parent = globalMgr.getGlobal('type', parent)
+        parent = vm.createNode(globalMgr.getGlobal('type', parent))
     end
     if type(child) == 'string' then
-        child = globalMgr.getGlobal('type', child)
+        child = vm.createNode(globalMgr.getGlobal('type', child))
     end
 
     if not child or not parent then
@@ -22,33 +20,33 @@ function vm.isSubType(uri, child, parent, mark)
     end
 
     mark = mark or {}
-    for childNode in nodeMgr.eachObject(child) do
-        if childNode.type ~= 'global'
-        or childNode.cate ~= 'type' then
+    for obj in child:eachObject() do
+        if obj.type ~= 'global'
+        or obj.cate ~= 'type' then
             goto CONTINUE_CHILD
         end
-        if mark[childNode.name] then
+        if mark[obj.name] then
             return false
         end
-        mark[childNode.name] = true
-        for parentNode in nodeMgr.eachObject(parent) do
+        mark[obj.name] = true
+        for parentNode in parent:eachObject() do
             if parentNode.type ~= 'global'
             or parentNode.cate ~= 'type' then
                 goto CONTINUE_PARENT
             end
-            if parentNode.name == 'any' or childNode.name == 'any' then
+            if parentNode.name == 'any' or obj.name == 'any' then
                 return true
             end
 
-            if parentNode.name == childNode.name then
+            if parentNode.name == obj.name then
                 return true
             end
 
-            for _, set in ipairs(childNode:getSets(uri)) do
+            for _, set in ipairs(obj:getSets(uri)) do
                 if set.type == 'doc.class' and set.extends then
                     for _, ext in ipairs(set.extends) do
                         if  ext.type == 'doc.extends.name'
-                        and vm.isSubType(uri, ext[1], parentNode, mark) then
+                        and vm.isSubType(uri, ext[1], parentNode.name, mark) then
                             return true
                         end
                     end
@@ -56,7 +54,7 @@ function vm.isSubType(uri, child, parent, mark)
                 if set.type == 'doc.alias' and set.extends then
                     for _, ext in ipairs(set.extends.types) do
                         if  ext.type == 'doc.type.name'
-                        and vm.isSubType(uri, ext[1], parentNode, mark) then
+                        and vm.isSubType(uri, ext[1], parentNode.name, mark) then
                             return true
                         end
                     end
@@ -73,10 +71,10 @@ end
 ---@param uri uri
 ---@param tnode vm.node
 ---@param knode vm.node
----@return vm.union?
+---@return vm.node?
 function vm.getTableValue(uri, tnode, knode)
-    local result = union()
-    for tn in nodeMgr.eachObject(tnode) do
+    local result = vm.createNode()
+    for tn in tnode:eachObject() do
         if tn.type == 'doc.type.table' then
             for _, field in ipairs(tn.fields) do
                 if vm.isSubType(uri, vm.compileNode(field.name), knode) then
@@ -114,10 +112,10 @@ end
 ---@param uri uri
 ---@param tnode vm.node
 ---@param vnode vm.node
----@return vm.union?
+---@return vm.node?
 function vm.getTableKey(uri, tnode, vnode)
-    local result = union()
-    for tn in nodeMgr.eachObject(tnode) do
+    local result = vm.createNode()
+    for tn in tnode:eachObject() do
         if tn.type == 'doc.type.table' then
             for _, field in ipairs(tn.fields) do
                 if vm.isSubType(uri, vm.compileNode(field.extends), vnode) then
diff --git a/script/vm/union.lua b/script/vm/union.lua
deleted file mode 100644
index f816952a..00000000
--- a/script/vm/union.lua
+++ /dev/null
@@ -1,129 +0,0 @@
-local localMgr = require 'vm.local-manager'
-
----@class vm.union
-local mt = {}
-mt.__index   = mt
-mt.type      = 'vm.union'
-mt.optional  = nil
-mt.lastInfer = nil
-
----@param me   vm.node
----@param node vm.node
----@return vm.union
-local function createUnion(me, node)
-    local union = setmetatable({}, mt)
-    union:merge(me)
-    union:merge(node)
-    return union
-end
-
----@param node vm.node
-function mt:merge(node)
-    if not node then
-        return
-    end
-    if node.type == 'vm.union' then
-        for _, c in ipairs(node) do
-            if not self[c] then
-                self[c]       = true
-                self[#self+1] = c
-            end
-        end
-        if node:isOptional() then
-            self.optional = true
-        end
-    else
-        if not self[node] then
-            self[node]    = true
-            self[#self+1] = node
-        end
-    end
-end
-
----@return vm.node
-function mt:copy()
-    return createUnion(self, nil)
-end
-
----@return boolean
-function mt:isEmpty()
-    return #self == 0
-end
-
----@param source parser.object
-function mt:subscribeLocal(source)
-    for _, c in ipairs(self) do
-        localMgr.subscribeLocal(source, c)
-    end
-end
-
-function mt:eachNode()
-    local i = 0
-    return function ()
-        i = i + 1
-        return self[i]
-    end
-end
-
----@return vm.union
-function mt:addOptional()
-    if self:isOptional() then
-        return self
-    end
-    self.optional = true
-    return self
-end
-
----@return vm.union
-function mt:removeOptional()
-    self.optional = nil
-    if not self:isOptional() then
-        return self
-    end
-    -- copy union
-    local newUnion = createUnion()
-    for _, n in ipairs(self) do
-        if n.type == 'nil' then
-            goto CONTINUE
-        end
-        if n.type == 'boolean' then
-            if n[1] == false then
-                goto CONTINUE
-            end
-        end
-        if n.type == 'false' then
-            goto CONTINUE
-        end
-        newUnion[#newUnion+1] = n
-        ::CONTINUE::
-    end
-    newUnion.optional = false
-    return newUnion
-end
-
----@return boolean
-function mt:isOptional()
-    if self.optional ~= nil then
-        return self.optional
-    end
-    for _, c in ipairs(self) do
-        if c.type == 'nil' then
-            self.optional = true
-            return true
-        end
-        if c.type == 'boolean' then
-            if c[1] == false then
-                self.optional = true
-                return true
-            end
-        end
-        if c.type == 'false' then
-            self.optional = true
-            return true
-        end
-    end
-    self.optional = false
-    return false
-end
-
-return createUnion
diff --git a/script/vm/value.lua b/script/vm/value.lua
index 00912820..5810f8da 100644
--- a/script/vm/value.lua
+++ b/script/vm/value.lua
@@ -1,4 +1,3 @@
-local nodeMgr  = require 'vm.node'
 local guide    = require 'parser.guide'
 ---@class vm
 local vm       = require 'vm.vm'
@@ -8,7 +7,7 @@ local vm       = require 'vm.vm'
 function vm.test(source)
     local node = vm.compileNode(source)
     local hasTrue, hasFalse
-    for n in nodeMgr.eachObject(node) do
+    for n in node:eachObject() do
         if n.type == 'boolean' then
             if n[1] == true then
                 hasTrue = true
@@ -81,14 +80,14 @@ function vm.equal(a, b)
     local nodeA = vm.compileNode(a)
     local nodeB = vm.compileNode(b)
     local mapA = {}
-    for obj in nodeMgr.eachObject(nodeA) do
+    for obj in nodeA:eachObject() do
         local unique = getUnique(obj)
         if not unique then
             return nil
         end
         mapA[unique] = true
     end
-    for obj in nodeMgr.eachObject(nodeB) do
+    for obj in nodeB:eachObject() do
         local unique = getUnique(obj)
         if not unique then
             return nil
@@ -105,7 +104,7 @@ end
 function vm.getInteger(v)
     local node = vm.compileNode(v)
     local result
-    for n in nodeMgr.eachObject(node) do
+    for n in node:eachObject() do
         if n.type == 'integer' then
             if result then
                 return nil
@@ -133,7 +132,7 @@ end
 function vm.getString(v)
     local node = vm.compileNode(v)
     local result
-    for n in nodeMgr.eachObject(node) do
+    for n in node:eachObject() do
         if n.type == 'string' then
             if result then
                 return nil
@@ -153,7 +152,7 @@ end
 function vm.getNumber(v)
     local node = vm.compileNode(v)
     local result
-    for n in nodeMgr.eachObject(node) do
+    for n in node:eachObject() do
         if n.type == 'number'
         or n.type == 'integer' then
             if result then
@@ -174,7 +173,7 @@ end
 function vm.getBoolean(v)
     local node = vm.compileNode(v)
     local result
-    for n in nodeMgr.eachObject(node) do
+    for n in node:eachObject() do
         if n.type == 'boolean' then
             if result then
                 return nil
@@ -194,7 +193,7 @@ end
 function vm.getLiterals(v)
     local map
     local node = vm.compileNode(v)
-    for n in nodeMgr.eachObject(node) do
+    for n in node:eachObject() do
         local literal
         if n.type == 'boolean'
         or n.type == 'string'