Merge branch 'runner'

10 files changed, 818 insertions, 389 deletions

diff --git a/script/core/completion/completion.lua b/script/core/completion/completion.lua
index d7c210c6..285f5bf2 100644
--- a/script/core/completion/completion.lua
+++ b/script/core/completion/completion.lua
@@ -1132,7 +1132,7 @@ local function checkTypingEnum(state, position, defs, str, results)
         or def.type == 'doc.type.integer'
         or def.type == 'doc.type.boolean' then
             enums[#enums+1] = {
-                label       = vm.viewObject(def),
+                label       = vm.viewObject(def, state.uri),
                 description = def.comment and def.comment.text,
                 kind        = define.CompletionItemKind.EnumMember,
             }
@@ -1427,7 +1427,7 @@ local function tryCallArg(state, position, results)
         or src.type == 'doc.type.integer'
         or src.type == 'doc.type.boolean' then
             enums[#enums+1] = {
-                label       = vm.viewObject(src),
+                label       = vm.viewObject(src, state.uri),
                 description = src.comment,
                 kind        = define.CompletionItemKind.EnumMember,
             }
diff --git a/script/core/diagnostics/need-check-nil.lua b/script/core/diagnostics/need-check-nil.lua
index 98fdfd08..56cb1eae 100644
--- a/script/core/diagnostics/need-check-nil.lua
+++ b/script/core/diagnostics/need-check-nil.lua
@@ -28,7 +28,7 @@ return function (uri, callback)
             return
         end
         local node = vm.compileNode(src)
-        if node:hasFalsy() then
+        if node:hasFalsy() and not vm.getInfer(src):hasType(uri, 'any') then
             callback {
                 start   = src.start,
                 finish  = src.finish,
diff --git a/script/core/hover/description.lua b/script/core/hover/description.lua
index 3fef1a21..c96aaae3 100644
--- a/script/core/hover/description.lua
+++ b/script/core/hover/description.lua
@@ -144,7 +144,7 @@ local function tryDocModule(source)
     return collectRequire('require', source.module, guide.getUri(source))
 end
 
-local function buildEnumChunk(docType, name)
+local function buildEnumChunk(docType, name, uri)
     if not docType then
         return nil
     end
@@ -175,7 +175,7 @@ local function buildEnumChunk(docType, name)
                 (enum.default    and '->')
             or  (enum.additional and '+>')
             or  ' |',
-            vm.viewObject(enum)
+            vm.viewObject(enum, uri)
         )
         if enum.comment then
             local first = true
@@ -199,6 +199,7 @@ local function getBindEnums(source, docGroup)
         return
     end
 
+    local uri = guide.getUri(source)
     local mark = {}
     local chunks = {}
     local returnIndex = 0
@@ -209,7 +210,7 @@ local function getBindEnums(source, docGroup)
                 goto CONTINUE
             end
             mark[name] = true
-            chunks[#chunks+1] = buildEnumChunk(doc.extends, name)
+            chunks[#chunks+1] = buildEnumChunk(doc.extends, name, uri)
         elseif doc.type == 'doc.return' then
             for _, rtn in ipairs(doc.returns) do
                 returnIndex = returnIndex + 1
@@ -218,7 +219,7 @@ local function getBindEnums(source, docGroup)
                     goto CONTINUE
                 end
                 mark[name] = true
-                chunks[#chunks+1] = buildEnumChunk(rtn, name)
+                chunks[#chunks+1] = buildEnumChunk(rtn, name, uri)
             end
         end
         ::CONTINUE::
diff --git a/script/vm/compiler.lua b/script/vm/compiler.lua
index 9b871553..0cbe2b7a 100644
--- a/script/vm/compiler.lua
+++ b/script/vm/compiler.lua
@@ -998,8 +998,7 @@ local compilerSwitch = util.switch()
 
         local hasMark = vm.getNode(source):getData 'hasDefined'
 
-        local runner = vm.createRunner(source)
-        runner:launch(function (src, node)
+        vm.launchRunner(source, function (src, node)
             if src.type == 'setlocal' then
                 if src.bindDocs then
                     for _, doc in ipairs(src.bindDocs) do
diff --git a/script/vm/infer.lua b/script/vm/infer.lua
index 712cff10..9bcd3963 100644
--- a/script/vm/infer.lua
+++ b/script/vm/infer.lua
@@ -417,7 +417,8 @@ function mt:viewClass()
 end
 
 ---@param source parser.object
+---@param uri uri
 ---@return string?
-function vm.viewObject(source)
-    return viewNodeSwitch(source.type, source, {}, guide.getUri(source))
+function vm.viewObject(source, uri)
+    return viewNodeSwitch(source.type, source, {}, uri)
 end
diff --git a/script/vm/node.lua b/script/vm/node.lua
index 6a86350a..5086f66d 100644
--- a/script/vm/node.lua
+++ b/script/vm/node.lua
@@ -2,6 +2,7 @@ local files    = require 'files'
 ---@class vm
 local vm       = require 'vm.vm'
 local ws       = require 'workspace.workspace'
+local guide    = require 'parser.guide'
 
 ---@type table<vm.object, vm.node>
 vm.nodeCache = {}
@@ -105,6 +106,18 @@ function mt:hasFalsy()
     return false
 end
 
+function mt:hasKnownType()
+    for _, c in ipairs(self) do
+        if c.type == 'global' and c.cate == 'type' then
+            return true
+        end
+        if guide.isLiteral(c) then
+            return true
+        end
+    end
+    return false
+end
+
 ---@return boolean
 function mt:isNullable()
     if self.optional then
@@ -152,6 +165,7 @@ function mt:setTruthy()
     if hasBoolean then
         self[#self+1] = vm.declareGlobal('type', 'true')
     end
+    return self
 end
 
 ---@return vm.node
@@ -174,12 +188,19 @@ function mt:setFalsy()
             hasBoolean = true
             table.remove(self, index)
             self[c] = nil
+            goto CONTINUE
+        end
+        if (c.type == 'global' and c.cate == 'type') then
+            table.remove(self, index)
+            self[c] = nil
+            goto CONTINUE
         end
         ::CONTINUE::
     end
     if hasBoolean then
         self[#self+1] = vm.declareGlobal('type', 'false')
     end
+    return self
 end
 
 ---@param name string
@@ -200,6 +221,7 @@ function mt:remove(name)
             self[c] = nil
         end
     end
+    return self
 end
 
 ---@param node vm.node
@@ -207,6 +229,14 @@ function mt:removeNode(node)
     for _, c in ipairs(node) do
         if c.type == 'global' and c.cate == 'type' then
             self:remove(c.name)
+        elseif c.type == 'nil' then
+            self:remove 'nil'
+        elseif c.type == 'boolean' then
+            if c[1] == true then
+                self:remove 'true'
+            else
+                self:remove 'false'
+            end
         end
     end
 end
diff --git a/script/vm/runner-bak.lua b/script/vm/runner-bak.lua
new file mode 100644
index 00000000..5535f0ca
--- /dev/null
+++ b/script/vm/runner-bak.lua
@@ -0,0 +1,444 @@
+---@class vm
+local vm        = require 'vm.vm'
+local guide     = require 'parser.guide'
+
+---@class vm.runner-bak
+---@field loc       parser.object
+---@field mainBlock parser.object
+---@field blocks    table<parser.object, true>
+---@field steps     vm.runner.step[]
+local mt = {}
+mt.__index = mt
+mt.index = 1
+
+---@class parser.object
+---@field _casts parser.object[]
+
+---@class vm.runner.step
+---@field type    'truthy' | 'falsy' | 'as' | 'add' | 'remove' | 'object' | 'save' | 'push' | 'merge' | 'cast'
+---@field pos     integer
+---@field order?  integer
+---@field node?   vm.node
+---@field object? parser.object
+---@field name?   string
+---@field cast?   parser.object
+---@field tag?    string
+---@field copy?   boolean
+---@field new?    boolean
+---@field ref1?   vm.runner.step
+---@field ref2?   vm.runner.step
+
+---@param filter    parser.object
+---@param outStep   vm.runner.step
+---@param blockStep vm.runner.step
+function mt:_compileNarrowByFilter(filter, outStep, blockStep)
+    if not filter then
+        return
+    end
+    if filter.type == 'paren' then
+        if filter.exp then
+            self:_compileNarrowByFilter(filter.exp, outStep, blockStep)
+        end
+        return
+    end
+    if filter.type == 'unary' then
+        if not filter.op
+        or not filter[1] then
+            return
+        end
+        if filter.op.type == 'not' then
+            local exp = filter[1]
+            if exp.type == 'getlocal' and exp.node == self.loc then
+                self.steps[#self.steps+1] = {
+                    type  = 'falsy',
+                    pos   = filter.finish,
+                    new   = true,
+                }
+                self.steps[#self.steps+1] = {
+                    type  = 'truthy',
+                    pos   = filter.finish,
+                    ref1  = outStep,
+                }
+            end
+        end
+    elseif filter.type == 'binary' then
+        if not filter.op
+        or not filter[1]
+        or not filter[2] then
+            return
+        end
+        if filter.op.type == 'and' then
+            local dummyStep = {
+                type  = 'save',
+                copy  = true,
+                ref1  = outStep,
+                pos   = filter.start - 1,
+            }
+            self.steps[#self.steps+1] = dummyStep
+            self:_compileNarrowByFilter(filter[1], dummyStep, blockStep)
+            self:_compileNarrowByFilter(filter[2], dummyStep, blockStep)
+        end
+        if filter.op.type == 'or' then
+            self:_compileNarrowByFilter(filter[1], outStep, blockStep)
+            local dummyStep = {
+                type  = 'push',
+                copy  = true,
+                ref1  = outStep,
+                pos   = filter.op.finish,
+            }
+            self.steps[#self.steps+1] = dummyStep
+            self:_compileNarrowByFilter(filter[2], outStep, dummyStep)
+            self.steps[#self.steps+1] = {
+                type  = 'push',
+                tag   = 'or reset',
+                ref1  = blockStep,
+                pos   = filter.finish,
+            }
+        end
+        if filter.op.type == '=='
+        or filter.op.type == '~=' then
+            local loc, exp
+            for i = 1, 2 do
+                loc = filter[i]
+                if loc.type == 'getlocal' and loc.node == self.loc then
+                    exp = filter[i % 2 + 1]
+                    break
+                end
+            end
+            if not loc or not exp then
+                return
+            end
+            if guide.isLiteral(exp) then
+                if filter.op.type == '==' then
+                    self.steps[#self.steps+1] = {
+                        type  = 'remove',
+                        name  = exp.type,
+                        pos   = filter.finish,
+                        ref1  = outStep,
+                    }
+                    self.steps[#self.steps+1] = {
+                        type  = 'as',
+                        name  = exp.type,
+                        pos   = filter.finish,
+                        new   = true,
+                    }
+                end
+                if filter.op.type == '~=' then
+                    self.steps[#self.steps+1] = {
+                        type  = 'as',
+                        name  = exp.type,
+                        pos   = filter.finish,
+                        ref1  = outStep,
+                    }
+                    self.steps[#self.steps+1] = {
+                        type  = 'remove',
+                        name  = exp.type,
+                        pos   = filter.finish,
+                        new   = true,
+                    }
+                end
+            end
+        end
+    else
+        if filter.type == 'getlocal' and filter.node == self.loc then
+            self.steps[#self.steps+1] = {
+                type  = 'truthy',
+                pos   = filter.finish,
+                new   = true,
+            }
+            self.steps[#self.steps+1] = {
+                type  = 'falsy',
+                pos   = filter.finish,
+                ref1  = outStep,
+            }
+        end
+    end
+end
+
+---@param block parser.object
+function mt:_compileBlock(block)
+    if self.blocks[block] then
+        return
+    end
+    self.blocks[block] = true
+    if block == self.mainBlock then
+        return
+    end
+
+    local parentBlock = guide.getParentBlock(block)
+    self:_compileBlock(parentBlock)
+
+    if block.type == 'if' then
+        ---@type vm.runner.step[]
+        local finals = {}
+        for i, childBlock in ipairs(block) do
+            local blockStep = {
+                type  = 'save',
+                tag   = 'block',
+                copy  = true,
+                pos   = childBlock.start,
+            }
+            local outStep = {
+                type  = 'save',
+                tag   = 'out',
+                copy  = true,
+                pos   = childBlock.start,
+            }
+            self.steps[#self.steps+1] = blockStep
+            self.steps[#self.steps+1] = outStep
+            self.steps[#self.steps+1] = {
+                type  = 'push',
+                ref1  = blockStep,
+                pos   = childBlock.start,
+            }
+            self:_compileNarrowByFilter(childBlock.filter, outStep, blockStep)
+            if  not childBlock.hasReturn
+            and not childBlock.hasGoTo
+            and not childBlock.hasBreak then
+                local finalStep = {
+                    type = 'save',
+                    pos  = childBlock.finish,
+                    tag  = 'final #' .. i,
+                }
+                finals[#finals+1] = finalStep
+                self.steps[#self.steps+1] = finalStep
+            end
+            self.steps[#self.steps+1] = {
+                type   = 'push',
+                tag    = 'reset child',
+                ref1   = outStep,
+                pos    = childBlock.finish,
+            }
+        end
+        self.steps[#self.steps+1] = {
+            type = 'push',
+            tag  = 'reset if',
+            pos  = block.finish,
+            copy = true,
+        }
+        for _, final in ipairs(finals) do
+            self.steps[#self.steps+1] = {
+                type = 'merge',
+                ref2 = final,
+                pos  = block.finish,
+            }
+        end
+    end
+
+    if block.type == 'function'
+    or block.type == 'while'
+    or block.type == 'loop'
+    or block.type == 'in'
+    or block.type == 'repeat'
+    or block.type == 'for' then
+        local savePoint = {
+            type = 'save',
+            copy = true,
+            pos  = block.start,
+        }
+        self.steps[#self.steps+1] = {
+            type  = 'push',
+            copy  = true,
+            pos   = block.start,
+        }
+        self.steps[#self.steps+1] = savePoint
+        self.steps[#self.steps+1] = {
+            type = 'push',
+            pos  = block.finish,
+            ref1 = savePoint,
+        }
+    end
+end
+
+---@return parser.object[]
+function mt:_getCasts()
+    local root = guide.getRoot(self.loc)
+    if not root._casts then
+        root._casts = {}
+        local docs = root.docs
+        for _, doc in ipairs(docs) do
+            if doc.type == 'doc.cast' and doc.loc then
+                root._casts[#root._casts+1] = doc
+            end
+        end
+    end
+    return root._casts
+end
+
+function mt:_preCompile()
+    local startPos  = self.loc.start
+    local finishPos = 0
+
+    for _, ref in ipairs(self.loc.ref) do
+        self.steps[#self.steps+1] = {
+            type   = 'object',
+            object = ref,
+            pos    = ref.range or ref.start,
+        }
+        if ref.start > finishPos then
+            finishPos = ref.start
+        end
+        local block = guide.getParentBlock(ref)
+        self:_compileBlock(block)
+    end
+
+    for i, step in ipairs(self.steps) do
+        if step.type ~= 'object' then
+            step.order = i
+        end
+    end
+
+    local casts = self:_getCasts()
+    for _, cast in ipairs(casts) do
+        if  cast.loc[1] == self.loc[1]
+        and cast.start > startPos
+        and cast.finish < finishPos
+        and guide.getLocal(self.loc, self.loc[1], cast.start) == self.loc then
+            self.steps[#self.steps+1] = {
+                type  = 'cast',
+                cast  = cast,
+                pos   = cast.start,
+            }
+        end
+    end
+
+    table.sort(self.steps, function (a, b)
+        if a.pos == b.pos then
+            return (a.order or 0) < (b.order or 0)
+        else
+            return a.pos < b.pos
+        end
+    end)
+end
+
+---@param loc  parser.object
+---@param node vm.node
+---@return vm.node
+local function checkAssert(loc, node)
+    local parent = loc.parent
+    if parent.type == 'binary' then
+        if parent.op and (parent.op.type == '~=' or parent.op.type == '==') then
+            local exp
+            for i = 1, 2 do
+                if parent[i] == loc then
+                    exp = parent[i % 2 + 1]
+                end
+            end
+            if exp and guide.isLiteral(exp) then
+                local callargs = parent.parent
+                if  callargs.type == 'callargs'
+                and callargs.parent.node.special == 'assert'
+                and callargs[1] == parent then
+                    if parent.op.type == '~=' then
+                        node:remove(exp.type)
+                    end
+                    if parent.op.type == '==' then
+                        node = vm.compileNode(exp)
+                    end
+                end
+            end
+        end
+    end
+    if  parent.type == 'callargs'
+    and parent.parent.node.special == 'assert'
+    and parent[1] == loc then
+        node:setTruthy()
+    end
+    return node
+end
+
+---@param callback    fun(src: parser.object, node: vm.node)
+function mt:launch(callback)
+    local topNode = vm.getNode(self.loc):copy()
+    for _, step in ipairs(self.steps) do
+        local node = step.ref1 and step.ref1.node or topNode
+        if     step.type == 'truthy' then
+            if step.new then
+                node = node:copy()
+                topNode = node
+            end
+            node:setTruthy()
+        elseif step.type == 'falsy' then
+            if step.new then
+                node = node:copy()
+                topNode = node
+            end
+            node:setFalsy()
+        elseif step.type == 'as' then
+            if step.new then
+                topNode = vm.createNode(vm.getGlobal('type', step.name))
+            else
+                node:clear()
+                node:merge(vm.getGlobal('type', step.name))
+            end
+        elseif step.type == 'add' then
+            if step.new then
+                node = node:copy()
+                topNode = node
+            end
+            node:merge(vm.getGlobal('type', step.name))
+        elseif step.type == 'remove' then
+            if step.new then
+                node = node:copy()
+                topNode = node
+            end
+            node:remove(step.name)
+        elseif step.type == 'object' then
+            topNode = callback(step.object, node) or node
+            if step.object.type == 'getlocal' then
+                topNode = checkAssert(step.object, node)
+            end
+        elseif step.type == 'save' then
+            if step.copy then
+                node = node:copy()
+            end
+            step.node = node
+        elseif step.type == 'push' then
+            if step.copy then
+                node = node:copy()
+            end
+            topNode = node
+        elseif step.type == 'merge' then
+            node:merge(step.ref2.node)
+        elseif step.type == 'cast' then
+            topNode = node:copy()
+            for _, cast in ipairs(step.cast.casts) do
+                if     cast.mode == '+' then
+                    if cast.optional then
+                        topNode:addOptional()
+                    end
+                    if cast.extends then
+                        topNode:merge(vm.compileNode(cast.extends))
+                    end
+                elseif cast.mode == '-' then
+                    if cast.optional then
+                        topNode:removeOptional()
+                    end
+                    if cast.extends then
+                        topNode:removeNode(vm.compileNode(cast.extends))
+                    end
+                else
+                    if cast.extends then
+                        topNode:clear()
+                        topNode:merge(vm.compileNode(cast.extends))
+                    end
+                end
+            end
+        end
+    end
+end
+
+---@param loc parser.object
+---@return vm.runner
+function vm.launchRunner(loc)
+    local self = setmetatable({
+        loc       = loc,
+        mainBlock = guide.getParentBlock(loc),
+        blocks    = {},
+        steps     = {},
+    }, mt)
+
+    self:_preCompile()
+
+    return self
+end
diff --git a/script/vm/runner.lua b/script/vm/runner.lua
index 9fe0f172..a9c38a87 100644
--- a/script/vm/runner.lua
+++ b/script/vm/runner.lua
@@ -2,257 +2,19 @@
 local vm        = require 'vm.vm'
 local guide     = require 'parser.guide'
 
+---@alias vm.runner.callback fun(src: parser.object, node: vm.node)
+
 ---@class vm.runner
----@field loc       parser.object
----@field mainBlock parser.object
----@field blocks    table<parser.object, true>
----@field steps     vm.runner.step[]
+---@field _loc      parser.object
+---@field _objs     parser.object[]
+---@field _callback vm.runner.callback
 local mt = {}
 mt.__index = mt
-mt.index = 1
-
----@class parser.object
----@field _casts parser.object[]
-
----@class vm.runner.step
----@field type    'truthy' | 'falsy' | 'as' | 'add' | 'remove' | 'object' | 'save' | 'push' | 'merge' | 'cast'
----@field pos     integer
----@field order?  integer
----@field node?   vm.node
----@field object? parser.object
----@field name?   string
----@field cast?   parser.object
----@field tag?    string
----@field copy?   boolean
----@field new?    boolean
----@field ref1?   vm.runner.step
----@field ref2?   vm.runner.step
-
----@param filter    parser.object
----@param outStep   vm.runner.step
----@param blockStep vm.runner.step
-function mt:_compileNarrowByFilter(filter, outStep, blockStep)
-    if not filter then
-        return
-    end
-    if filter.type == 'paren' then
-        if filter.exp then
-            self:_compileNarrowByFilter(filter.exp, outStep, blockStep)
-        end
-        return
-    end
-    if filter.type == 'unary' then
-        if not filter.op
-        or not filter[1] then
-            return
-        end
-        if filter.op.type == 'not' then
-            local exp = filter[1]
-            if exp.type == 'getlocal' and exp.node == self.loc then
-                self.steps[#self.steps+1] = {
-                    type  = 'falsy',
-                    pos   = filter.finish,
-                    new   = true,
-                }
-                self.steps[#self.steps+1] = {
-                    type  = 'truthy',
-                    pos   = filter.finish,
-                    ref1  = outStep,
-                }
-            end
-        end
-    elseif filter.type == 'binary' then
-        if not filter.op
-        or not filter[1]
-        or not filter[2] then
-            return
-        end
-        if filter.op.type == 'and' then
-            local dummyStep = {
-                type  = 'save',
-                copy  = true,
-                ref1  = outStep,
-                pos   = filter.start - 1,
-            }
-            self.steps[#self.steps+1] = dummyStep
-            self:_compileNarrowByFilter(filter[1], dummyStep, blockStep)
-            self:_compileNarrowByFilter(filter[2], dummyStep, blockStep)
-        end
-        if filter.op.type == 'or' then
-            self:_compileNarrowByFilter(filter[1], outStep, blockStep)
-            local dummyStep = {
-                type  = 'push',
-                copy  = true,
-                ref1  = outStep,
-                pos   = filter.op.finish,
-            }
-            self.steps[#self.steps+1] = dummyStep
-            self:_compileNarrowByFilter(filter[2], outStep, dummyStep)
-            self.steps[#self.steps+1] = {
-                type  = 'push',
-                tag   = 'or reset',
-                ref1  = blockStep,
-                pos   = filter.finish,
-            }
-        end
-        if filter.op.type == '=='
-        or filter.op.type == '~=' then
-            local loc, exp
-            for i = 1, 2 do
-                loc = filter[i]
-                if loc.type == 'getlocal' and loc.node == self.loc then
-                    exp = filter[i % 2 + 1]
-                    break
-                end
-            end
-            if not loc or not exp then
-                return
-            end
-            if guide.isLiteral(exp) then
-                if filter.op.type == '==' then
-                    self.steps[#self.steps+1] = {
-                        type  = 'remove',
-                        name  = exp.type,
-                        pos   = filter.finish,
-                        ref1  = outStep,
-                    }
-                    self.steps[#self.steps+1] = {
-                        type  = 'as',
-                        name  = exp.type,
-                        pos   = filter.finish,
-                        new   = true,
-                    }
-                end
-                if filter.op.type == '~=' then
-                    self.steps[#self.steps+1] = {
-                        type  = 'as',
-                        name  = exp.type,
-                        pos   = filter.finish,
-                        ref1  = outStep,
-                    }
-                    self.steps[#self.steps+1] = {
-                        type  = 'remove',
-                        name  = exp.type,
-                        pos   = filter.finish,
-                        new   = true,
-                    }
-                end
-            end
-        end
-    else
-        if filter.type == 'getlocal' and filter.node == self.loc then
-            self.steps[#self.steps+1] = {
-                type  = 'truthy',
-                pos   = filter.finish,
-                new   = true,
-            }
-            self.steps[#self.steps+1] = {
-                type  = 'falsy',
-                pos   = filter.finish,
-                ref1  = outStep,
-            }
-        end
-    end
-end
-
----@param block parser.object
-function mt:_compileBlock(block)
-    if self.blocks[block] then
-        return
-    end
-    self.blocks[block] = true
-    if block == self.mainBlock then
-        return
-    end
-
-    local parentBlock = guide.getParentBlock(block)
-    self:_compileBlock(parentBlock)
-
-    if block.type == 'if' then
-        ---@type vm.runner.step[]
-        local finals = {}
-        for i, childBlock in ipairs(block) do
-            local blockStep = {
-                type  = 'save',
-                tag   = 'block',
-                copy  = true,
-                pos   = childBlock.start,
-            }
-            local outStep = {
-                type  = 'save',
-                tag   = 'out',
-                copy  = true,
-                pos   = childBlock.start,
-            }
-            self.steps[#self.steps+1] = blockStep
-            self.steps[#self.steps+1] = outStep
-            self.steps[#self.steps+1] = {
-                type  = 'push',
-                ref1  = blockStep,
-                pos   = childBlock.start,
-            }
-            self:_compileNarrowByFilter(childBlock.filter, outStep, blockStep)
-            if  not childBlock.hasReturn
-            and not childBlock.hasGoTo
-            and not childBlock.hasBreak then
-                local finalStep = {
-                    type = 'save',
-                    pos  = childBlock.finish,
-                    tag  = 'final #' .. i,
-                }
-                finals[#finals+1] = finalStep
-                self.steps[#self.steps+1] = finalStep
-            end
-            self.steps[#self.steps+1] = {
-                type   = 'push',
-                tag    = 'reset child',
-                ref1   = outStep,
-                pos    = childBlock.finish,
-            }
-        end
-        self.steps[#self.steps+1] = {
-            type = 'push',
-            tag  = 'reset if',
-            pos  = block.finish,
-            copy = true,
-        }
-        for _, final in ipairs(finals) do
-            self.steps[#self.steps+1] = {
-                type = 'merge',
-                ref2 = final,
-                pos  = block.finish,
-            }
-        end
-    end
-
-    if block.type == 'function'
-    or block.type == 'while'
-    or block.type == 'loop'
-    or block.type == 'in'
-    or block.type == 'repeat'
-    or block.type == 'for' then
-        local savePoint = {
-            type = 'save',
-            copy = true,
-            pos  = block.start,
-        }
-        self.steps[#self.steps+1] = {
-            type  = 'push',
-            copy  = true,
-            pos   = block.start,
-        }
-        self.steps[#self.steps+1] = savePoint
-        self.steps[#self.steps+1] = {
-            type = 'push',
-            pos  = block.finish,
-            ref1 = savePoint,
-        }
-    end
-end
+mt._index = 1
 
 ---@return parser.object[]
 function mt:_getCasts()
-    local root = guide.getRoot(self.loc)
+    local root = guide.getRoot(self._loc)
     if not root._casts then
         root._casts = {}
         local docs = root.docs
@@ -265,180 +27,256 @@ function mt:_getCasts()
     return root._casts
 end
 
-function mt:_preCompile()
-    local startPos  = self.loc.start
+function mt:_collect()
+    local startPos  = self._loc.start
     local finishPos = 0
 
-    for _, ref in ipairs(self.loc.ref) do
-        self.steps[#self.steps+1] = {
-            type   = 'object',
-            object = ref,
-            pos    = ref.range or ref.start,
-        }
-        if ref.start > finishPos then
-            finishPos = ref.start
+    for _, ref in ipairs(self._loc.ref) do
+        if ref.type == 'getlocal'
+        or ref.type == 'setlocal' then
+            self._objs[#self._objs+1] = ref
+            if ref.start > finishPos then
+                finishPos = ref.start
+            end
         end
-        local block = guide.getParentBlock(ref)
-        self:_compileBlock(block)
     end
 
-    for i, step in ipairs(self.steps) do
-        if step.type ~= 'object' then
-            step.order = i
-        end
+    if #self._objs == 0 then
+        return
     end
 
     local casts = self:_getCasts()
     for _, cast in ipairs(casts) do
-        if  cast.loc[1] == self.loc[1]
+        if  cast.loc[1] == self._loc[1]
         and cast.start > startPos
         and cast.finish < finishPos
-        and guide.getLocal(self.loc, self.loc[1], cast.start) == self.loc then
-            self.steps[#self.steps+1] = {
-                type  = 'cast',
-                cast  = cast,
-                pos   = cast.start,
-            }
+        and guide.getLocal(self._loc, self._loc[1], cast.start) == self._loc then
+            self._objs[#self._objs+1] = cast
         end
     end
 
-    table.sort(self.steps, function (a, b)
-        if a.pos == b.pos then
-            return (a.order or 0) < (b.order or 0)
-        else
-            return a.pos < b.pos
-        end
+    table.sort(self._objs, function (a, b)
+        return (a.range or a.finish) < (b.range or b.start)
     end)
 end
 
----@param loc  parser.object
+
+---@param pos  integer
 ---@param node vm.node
 ---@return vm.node
-local function checkAssert(loc, node)
-    local parent = loc.parent
-    if parent.type == 'binary' then
-        if parent.op and (parent.op.type == '~=' or parent.op.type == '==') then
-            local exp
-            for i = 1, 2 do
-                if parent[i] == loc then
-                    exp = parent[i % 2 + 1]
-                end
-            end
-            if exp and guide.isLiteral(exp) then
-                local callargs = parent.parent
-                if  callargs.type == 'callargs'
-                and callargs.parent.node.special == 'assert'
-                and callargs[1] == parent then
-                    if parent.op.type == '~=' then
-                        node:remove(exp.type)
-                    end
-                    if parent.op.type == '==' then
-                        node = vm.compileNode(exp)
-                    end
-                end
-            end
+---@return parser.object?
+function mt:_fastWard(pos, node)
+    for i = self._index, #self._objs do
+        local obj = self._objs[i]
+        if (obj.range or obj.finish) > pos then
+            self._index = i
+            return node, obj
         end
-    end
-    if  parent.type == 'callargs'
-    and parent.parent.node.special == 'assert'
-    and parent[1] == loc then
-        node:setTruthy()
-    end
-    return node
-end
-
----@param callback    fun(src: parser.object, node: vm.node)
-function mt:launch(callback)
-    local topNode = vm.getNode(self.loc):copy()
-    for _, step in ipairs(self.steps) do
-        local node = step.ref1 and step.ref1.node or topNode
-        if     step.type == 'truthy' then
-            if step.new then
-                node = node:copy()
-                topNode = node
-            end
-            node:setTruthy()
-        elseif step.type == 'falsy' then
-            if step.new then
-                node = node:copy()
-                topNode = node
-            end
-            node:setFalsy()
-        elseif step.type == 'as' then
-            if step.new then
-                topNode = vm.createNode(vm.getGlobal('type', step.name))
-            else
-                node:clear()
-                node:merge(vm.getGlobal('type', step.name))
-            end
-        elseif step.type == 'add' then
-            if step.new then
-                node = node:copy()
-                topNode = node
-            end
-            node:merge(vm.getGlobal('type', step.name))
-        elseif step.type == 'remove' then
-            if step.new then
-                node = node:copy()
-                topNode = node
-            end
-            node:remove(step.name)
-        elseif step.type == 'object' then
-            topNode = callback(step.object, node) or node
-            if step.object.type == 'getlocal' then
-                topNode = checkAssert(step.object, node)
-            end
-        elseif step.type == 'save' then
-            if step.copy then
-                node = node:copy()
-            end
-            step.node = node
-        elseif step.type == 'push' then
-            if step.copy then
-                node = node:copy()
+        if obj.type == 'getlocal' then
+            self._callback(obj, node)
+        elseif obj.type == 'setlocal' then
+            local newNode = self._callback(obj, node)
+            if newNode then
+                node = newNode:copy()
             end
-            topNode = node
-        elseif step.type == 'merge' then
-            node:merge(step.ref2.node)
-        elseif step.type == 'cast' then
-            topNode = node:copy()
-            for _, cast in ipairs(step.cast.casts) do
+        elseif obj.type == 'doc.cast' then
+            node = node:copy()
+            for _, cast in ipairs(obj.casts) do
                 if     cast.mode == '+' then
                     if cast.optional then
-                        topNode:addOptional()
+                        node:addOptional()
                     end
                     if cast.extends then
-                        topNode:merge(vm.compileNode(cast.extends))
+                        node:merge(vm.compileNode(cast.extends))
                     end
                 elseif cast.mode == '-' then
                     if cast.optional then
-                        topNode:removeOptional()
+                        node:removeOptional()
                     end
                     if cast.extends then
-                        topNode:removeNode(vm.compileNode(cast.extends))
+                        node:removeNode(vm.compileNode(cast.extends))
                     end
                 else
                     if cast.extends then
-                        topNode:clear()
-                        topNode:merge(vm.compileNode(cast.extends))
+                        node:clear()
+                        node:merge(vm.compileNode(cast.extends))
                     end
                 end
             end
         end
     end
+    self._index = #self._objs + 1
+    return node, nil
+end
+
+---@param action   parser.object
+---@param topNode  vm.node
+---@param outNode? vm.node
+---@return vm.node
+function mt:_lookInto(action, topNode, outNode)
+    local set
+    local value = vm.getObjectValue(action)
+    if value then
+        set = action
+        action = value
+    end
+    if     action.type == 'function'
+    or     action.type == 'loop'
+    or     action.type == 'in'
+    or     action.type == 'repeat'
+    or     action.type == 'for' then
+        self:_launchBlock(action, topNode:copy())
+    elseif action.type == 'while' then
+        local blockNode, mainNode = self:_lookInto(action.filter, topNode:copy(), topNode:copy())
+        self:_fastWard(action.filter.finish, blockNode)
+        self:_launchBlock(action, blockNode:copy())
+        topNode = mainNode
+    elseif action.type == 'if' then
+        local hasElse
+        local mainNode = topNode:copy()
+        local blockNodes = {}
+        for _, subBlock in ipairs(action) do
+            local blockNode = mainNode:copy()
+            if subBlock.filter then
+                blockNode, mainNode = self:_lookInto(subBlock.filter, blockNode, mainNode)
+                self:_fastWard(subBlock.filter.finish, blockNode)
+            else
+                hasElse = true
+                mainNode:clear()
+            end
+            blockNode = self:_launchBlock(subBlock, blockNode:copy())
+            local neverReturn = subBlock.hasReturn
+                            or  subBlock.hasGoTo
+                            or  subBlock.hasBreak
+            if not neverReturn then
+                blockNodes[#blockNodes+1] = blockNode
+            end
+        end
+        if not hasElse and not topNode:hasKnownType() then
+            mainNode:merge(vm.declareGlobal('type', 'unknown'))
+        end
+        for _, blockNode in ipairs(blockNodes) do
+            mainNode:merge(blockNode)
+        end
+        topNode = mainNode
+    elseif action.type == 'getlocal' then
+        if action.node == self._loc then
+            topNode = self:_fastWard(action.finish, topNode)
+            topNode = topNode:copy():setTruthy()
+            if outNode then
+                outNode:setFalsy()
+            end
+        end
+    elseif action.type == 'unary' then
+        if not action[1] then
+            goto RETURN
+        end
+        if action.op.type == 'not' then
+            outNode = outNode or topNode:copy()
+            outNode, topNode = self:_lookInto(action[1], topNode, outNode)
+        end
+    elseif action.type == 'binary' then
+        if not action[1] or not action[2] then
+            goto RETURN
+        end
+        if     action.op.type == 'and' then
+            topNode = self:_lookInto(action[1], topNode)
+            topNode = self:_lookInto(action[2], topNode)
+        elseif action.op.type == 'or' then
+            outNode = outNode or topNode:copy()
+            local topNode1, outNode1 = self:_lookInto(action[1], topNode, outNode)
+            local topNode2, outNode2 = self:_lookInto(action[2], outNode1, outNode1:copy())
+            topNode = vm.createNode(topNode1, topNode2)
+            outNode = outNode2
+        elseif action.op.type == '=='
+        or     action.op.type == '~=' then
+            local loc, checker
+            for i = 1, 2 do
+                if action[i].type == 'getlocal' and action[i].node == self._loc then
+                    loc = action[i]
+                    checker = action[3-i] -- Copilot tells me use `3-i` instead of `i%2+1`
+                elseif action[2].type == 'getlocal' and action[2].node == self._loc then
+                    loc = action[3-i]
+                    checker = action[i]
+                end
+            end
+            if loc then
+                self:_fastWard(loc.finish, topNode)
+                if guide.isLiteral(checker) then
+                    local checkerNode = vm.compileNode(checker)
+                    if action.op.type == '==' then
+                        topNode = checkerNode
+                        if outNode then
+                            outNode:removeNode(topNode)
+                        end
+                    else
+                        topNode:removeNode(checkerNode)
+                        if outNode then
+                            outNode = checkerNode
+                        end
+                    end
+                end
+            end
+        end
+    elseif action.type == 'call' then
+        if action.node.special == 'assert' and action.args and action.args[1] then
+            topNode = self:_lookInto(action.args[1], topNode)
+        elseif action.args then
+            for _, arg in ipairs(action.args) do
+                self:_lookInto(arg, topNode)
+            end
+        end
+    elseif action.type == 'return' then
+        for _, rtn in ipairs(action) do
+            self:_lookInto(rtn, topNode)
+        end
+    end
+    ::RETURN::
+    topNode = self:_fastWard(action.finish, topNode)
+    if set then
+        topNode = self:_fastWard(set.range or set.finish, topNode)
+    end
+    return topNode, outNode
+end
+
+---@param block parser.object
+---@param node  vm.node
+---@return vm.node
+function mt:_launchBlock(block, node)
+    local topNode, top = self:_fastWard(block.start, node)
+    if not top then
+        return topNode
+    end
+    for _, action in ipairs(block) do
+        if (action.range or action.finish) < (top.range or top.finish) then
+            goto CONTINUE
+        end
+        topNode = self:_lookInto(action, topNode)
+        topNode, top = self:_fastWard(action.range or action.finish, topNode)
+        if not top then
+            return topNode
+        end
+        ::CONTINUE::
+    end
+    -- `x = function () end`: don't touch `x` in the end of function
+    topNode = self:_fastWard(block.finish - 1, topNode)
+    return topNode
 end
 
 ---@param loc parser.object
----@return vm.runner
-function vm.createRunner(loc)
+---@param callback vm.runner.callback
+function vm.launchRunner(loc, callback)
     local self = setmetatable({
-        loc       = loc,
-        mainBlock = guide.getParentBlock(loc),
-        blocks    = {},
-        steps     = {},
+        _loc      = loc,
+        _objs     = {},
+        _callback = callback,
     }, mt)
 
-    self:_preCompile()
+    self:_collect()
+
+    if #self._objs == 0 then
+        return
+    end
 
-    return self
+    self:_launchBlock(guide.getParentBlock(loc), vm.getNode(loc):copy())
 end
diff --git a/script/vm/sign.lua b/script/vm/sign.lua
index fe112bc2..5c17aa3d 100644
--- a/script/vm/sign.lua
+++ b/script/vm/sign.lua
@@ -111,7 +111,7 @@ function mt:resolve(uri, args, removeGeneric)
                     goto CONTINUE
                 end
             end
-            local view = vm.viewObject(obj)
+            local view = vm.viewObject(obj, uri)
             if view then
                 knownTypes[view] = true
             end
@@ -130,7 +130,7 @@ function mt:resolve(uri, args, removeGeneric)
             if argNode:hasFalsy() then
                 goto CONTINUE
             end
-            local view = vm.viewObject(n)
+            local view = vm.viewObject(n, uri)
             if knownTypes[view] then
                 goto CONTINUE
             end
diff --git a/test/type_inference/init.lua b/test/type_inference/init.lua
index 566e847a..efcc5fea 100644
--- a/test/type_inference/init.lua
+++ b/test/type_inference/init.lua
@@ -1813,6 +1813,17 @@ TEST 'integer' [[
 ---@type integer?
 local x
 
+if not x then
+    return
+end
+
+print(<?x?>)
+]]
+
+TEST 'integer' [[
+---@type integer?
+local x
+
 if xxx and x then
     print(<?x?>)
 end
@@ -2153,6 +2164,15 @@ print(<?x?>)
 ]]
 
 TEST 'integer' [[
+---@type integer?
+local x
+
+while x do
+    print(<?x?>)
+end
+]]
+
+TEST 'integer' [[
 ---@type fun():integer?
 local iter
 
@@ -2237,6 +2257,19 @@ local x
 print(<?x?>)
 ]]
 
+TEST 'unknown?' [[
+---@type string?
+local x
+
+if x then
+    return
+else
+    print(<?x?>)
+end
+
+print(x)
+]]
+
 TEST 'string' [[
 ---@type string?
 local x
@@ -2298,6 +2331,18 @@ end
 print(<?t?>)
 ]]
 
+TEST 'unknown?' [[
+---@type integer?
+local t
+
+if t then
+else
+    print(<?t?>)
+end
+
+print(t)
+]]
+
 TEST 'table|unknown' [[
 local function f()
     if x then
@@ -2375,3 +2420,74 @@ TEST '`1`|`true`' [[
 ---@type `1` | `true`
 local <?x?>
 ]]
+
+TEST 'function' [[
+local x
+
+function x() end
+
+print(<?x?>)
+]]
+
+TEST 'unknown' [[
+local x
+
+if x.field == 'haha' then
+    print(<?x?>)
+end
+]]
+
+TEST 'string' [[
+---@type string?
+local t
+
+if not t or xxx then
+    return
+end
+
+print(<?t?>)
+]]
+
+TEST 'table' [[
+---@type table|nil
+local t
+
+return function ()
+    if not t then
+        return
+    end
+    
+    print(<?t?>)
+end
+]]
+
+TEST 'table' [[
+---@type table|nil
+local t
+
+f(function ()
+    if not t then
+        return
+    end
+    
+    print(<?t?>)
+end)
+]]
+
+TEST 'table' [[
+---@type table?
+local t
+
+t = t or {}
+
+print(<?t?>)
+]]
+
+TEST 'unknown|nil' [[
+local x
+
+if x == nil then
+end
+
+print(<?x?>)
+]]