🎨 Support arm64 version in Microsoft Store https://github.com/siyuan-note/siyuan/issues/15836

Signed-off-by: Daniel <845765@qq.com>

app/appx/AppxManifest-arm64.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--suppress XmlUnusedNamespaceDeclaration -->
+<Package
+        xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
+        xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
+        xmlns:desktop="http://schemas.microsoft.com/appx/manifest/desktop/windows10"
+        xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities">
+    <!-- use single quotes to avoid double quotes escaping in the publisher value  -->
+    <Identity Name="89C2A984.SiYuan"
+              ProcessorArchitecture="arm64"
+              Publisher="CN=087C656E-C1D9-42D8-8807-CED45A74FC0F"
+              Version="3.3.2.0"/>
+    <Properties>
+        <DisplayName>SiYuan</DisplayName>
+        <PublisherDisplayName>云南链滴科技有限公司</PublisherDisplayName>
+        <Description>Refactor your thinking</Description>
+        <Logo>assets\StoreLogo.png</Logo>
+    </Properties>
+    <Resources>
+        <Resource Language="en-US"/>
+        <Resource Language="zh-CN"/>
+    </Resources>
+    <Dependencies>
+        <TargetDeviceFamily Name="Windows.Desktop" MinVersion="10.0.14316.0" MaxVersionTested="10.0.14316.0"/>
+    </Dependencies>
+    <Capabilities>
+        <rescap:Capability Name="runFullTrust"/>
+    </Capabilities>
+    <Applications>
+        <Application Id="SiYuan" Executable="app\SiYuan.exe" EntryPoint="Windows.FullTrustApplication">
+            <uap:VisualElements
+                    BackgroundColor="transparent"
+                    DisplayName="SiYuan"
+                    Square150x150Logo="assets\Square150x150Logo.png"
+                    Square44x44Logo="assets\Square44x44Logo.png"
+                    Description="Refactor your thinking">
+
+                <uap:DefaultTile Wide310x150Logo="assets\Wide310x150Logo.png"/>
+
+            </uap:VisualElements>
+
+            <Extensions>
+                <uap:Extension Category="windows.protocol">
+                    <uap:Protocol Name="siyuan"/>
+                </uap:Extension>
+            </Extensions>
+        </Application>
+    </Applications>
+</Package>

app/package.json

@@ -18,7 +18,6 @@
     "build:export": "webpack --mode production --config webpack.export.js",
     "gen:types": "tsc -d",
     "start": "NODE_ENV=development electron ./electron/main.js",
-    "dist-appx": "ELECTRON_MIRROR=https://npmmirror.com/mirrors/electron/ electron-builder --config electron-appx-builder.yml",
     "dist": "ELECTRON_MIRROR=https://npmmirror.com/mirrors/electron/ electron-builder --config electron-builder.yml --publish=never",
     "dist-arm64": "ELECTRON_MIRROR=https://npmmirror.com/mirrors/electron/ electron-builder --arm64 --config electron-builder-arm64.yml --publish=never",
     "dist-darwin": "ELECTRON_MIRROR=https://npmmirror.com/mirrors/electron/ electron-builder --mac --config electron-builder-darwin.yml --publish=never",

app/src/protyle/breadcrumb/index.ts

@@ -58,7 +58,7 @@ export class Breadcrumb {
 <span class="protyle-breadcrumb__space"></span>
 <button class="protyle-breadcrumb__icon fn__none ariaLabel" aria-label="${updateHotkeyTip(window.siyuan.config.keymap.editor.general.exitFocus.custom)}" data-type="exit-focus">${window.siyuan.languages.exitFocus}</button>
 ${padHTML}
-<button class="block__icon fn__flex-center ariaLabel${window.siyuan.config.readonly ? " fn__none" : ""}" aria-label="${window.siyuan.languages.lockEdit}" data-type="readonly"><svg><use xlink:href="#iconUnlock"></use></svg></button>
+<button class="block__icon fn__flex-center ariaLabel${window.siyuan.config.readonly ? " fn__none" : ""}" aria-label="${window.siyuan.languages.lockEdit}" data-type="readonly" data-subtype="unlock"><svg><use xlink:href="#iconUnlock"></use></svg></button>
 <button class="block__icon fn__flex-center ariaLabel" data-type="doc" aria-label="${isMac() ? window.siyuan.languages.gutterTip2 : window.siyuan.languages.gutterTip2.replace("⇧", "Shift+")}"><svg><use xlink:href="#iconFile"></use></svg></button>
 <button class="block__icon fn__flex-center ariaLabel" data-type="more" aria-label="${window.siyuan.languages.more}"><svg><use xlink:href="#iconMore"></use></svg></button>
 <button class="block__icon fn__flex-center fn__none ariaLabel" data-type="context" aria-label="${window.siyuan.languages.context}"><svg><use xlink:href="#iconAlignCenter"></use></svg></button>`;

app/src/protyle/gutter/index.ts

@@ -1802,15 +1802,6 @@ export class Gutter {
                 transferBlockRef(id);
             }
         }
-        window.siyuan.menus.menu.append(new MenuItem({
-            id: "jumpToParentNext",
-            label: window.siyuan.languages.jumpToParentNext,
-            accelerator: window.siyuan.config.keymap.editor.general.jumpToParentNext.custom,
-            click() {
-                hideElements(["select"], protyle);
-                jumpToParent(protyle, nodeElement, "next");
-            }
-        }).element);
         window.siyuan.menus.menu.append(new MenuItem({
             id: "jumpToParentPrev",
             label: window.siyuan.languages.jumpToParentPrev,
@@ -1820,6 +1811,15 @@ export class Gutter {
                 jumpToParent(protyle, nodeElement, "previous");
             }
         }).element);
+        window.siyuan.menus.menu.append(new MenuItem({
+            id: "jumpToParentNext",
+            label: window.siyuan.languages.jumpToParentNext,
+            accelerator: window.siyuan.config.keymap.editor.general.jumpToParentNext.custom,
+            click() {
+                hideElements(["select"], protyle);
+                jumpToParent(protyle, nodeElement, "next");
+            }
+        }).element);
         window.siyuan.menus.menu.append(new MenuItem({
             id: "jumpToParent",
             label: window.siyuan.languages.jumpToParent,

app/src/protyle/render/av/render.ts

@@ -761,6 +761,7 @@ export const refreshAV = (protyle: IProtyle, operation: IOperation) => {
                 const attrElement = document.querySelector(`.b3-dialog--open[data-key="${Constants.DIALOG_ATTR}"] .custom-attr > [data-av-id="${avID}"]`) as HTMLElement;
                 if (attrElement) {
                     // 更新属性面板
+                    attrElement.removeAttribute("data-rendering");
                     renderAVAttribute(attrElement.parentElement, attrElement.dataset.nodeId, protyle);
                 } else {
                     if (operation.action === "insertAttrViewBlock" && operation.context?.ignoreTip !== "true") {

app/src/protyle/util/onGet.ts

@@ -368,8 +368,10 @@ export const disabledProtyle = (protyle: IProtyle) => {
         item.setAttribute("draggable", "false");
     });
     if (protyle.breadcrumb) {
-        protyle.breadcrumb.element.parentElement.querySelector('[data-type="readonly"] use').setAttribute("xlink:href", "#iconLock");
-        protyle.breadcrumb.element.parentElement.querySelector('[data-type="readonly"]').setAttribute("aria-label", window.siyuan.config.editor.readOnly ? window.siyuan.languages.tempUnlock : window.siyuan.languages.unlockEdit);
+        const readonlyButton = protyle.breadcrumb.element.parentElement.querySelector('[data-type="readonly"]');
+        readonlyButton.querySelector("use").setAttribute("xlink:href", "#iconLock");
+        readonlyButton.setAttribute("aria-label", window.siyuan.config.editor.readOnly ? window.siyuan.languages.tempUnlock : window.siyuan.languages.unlockEdit);
+        readonlyButton.setAttribute("data-subtype", "lock");
         const undoElement = protyle.breadcrumb.element.parentElement.querySelector('[data-type="undo"]');
         if (undoElement && !undoElement.classList.contains("fn__none")) {
             undoElement.classList.add("fn__none");
@@ -426,8 +428,10 @@ export const enableProtyle = (protyle: IProtyle) => {
         }
     });
     if (protyle.breadcrumb) {
-        protyle.breadcrumb.element.parentElement.querySelector('[data-type="readonly"] use').setAttribute("xlink:href", "#iconUnlock");
-        protyle.breadcrumb.element.parentElement.querySelector('[data-type="readonly"]').setAttribute("aria-label", window.siyuan.config.editor.readOnly ? window.siyuan.languages.cancelTempUnlock : window.siyuan.languages.lockEdit);
+        const readonlyButton = protyle.breadcrumb.element.parentElement.querySelector('[data-type="readonly"]');
+        readonlyButton.querySelector("use").setAttribute("xlink:href", "#iconUnlock");
+        readonlyButton.setAttribute("aria-label", window.siyuan.config.editor.readOnly ? window.siyuan.languages.cancelTempUnlock : window.siyuan.languages.lockEdit);
+        readonlyButton.setAttribute("data-subtype", "unlock");
         const undoElement = protyle.breadcrumb.element.parentElement.querySelector('[data-type="undo"]');
         if (undoElement && undoElement.classList.contains("fn__none")) {
             undoElement.classList.remove("fn__none");

kernel/av/av.go

@@ -221,6 +221,10 @@ type View struct {
 	GroupSort    int        `json:"groupSort"`           // 分组排序值，用于手动排序
 }
 
+func (view *View) IsGroupView() bool {
+	return nil != view.Group && "" != view.Group.Field
+}
+
 // GetGroupValue 获取分组视图的分组值。
 func (view *View) GetGroupValue() string {
 	if nil == view.GroupVal {
@@ -270,7 +274,7 @@ func (view *View) RemoveGroupByID(groupID string) {
 
 // GetGroupKey 获取分组视图的分组字段。
 func (view *View) GetGroupKey(attrView *AttributeView) (ret *Key) {
-	if nil == view.Group || "" == view.Group.Field {
+	if !view.IsGroupView() {
 		return
 	}
 
@@ -295,6 +299,7 @@ type LayoutType string
 const (
 	LayoutTypeTable   LayoutType = "table"   // 属性视图类型 - 表格
 	LayoutTypeGallery LayoutType = "gallery" // 属性视图类型 - 卡片
+	LayoutTypeKanban  LayoutType = "kanban"  // 属性视图类型 - 看板
 )
 
 const (
@@ -530,6 +535,15 @@ func SaveAttributeView(av *AttributeView) (err error) {
 		}
 	}
 
+	// 清理渲染回填值
+	for _, kv := range av.KeyValues {
+		for i := len(kv.Values) - 1; i >= 0; i-- {
+			if kv.Values[i].IsRenderAutoFill {
+				kv.Values = append(kv.Values[:i], kv.Values[i+1:]...)
+			}
+		}
+	}
+
 	var data []byte
 	if util.UseSingleLineSave {
 		data, err = gulu.JSON.MarshalJSON(av)

kernel/av/layout_kanban.go

@@ -0,0 +1,149 @@
+// SiYuan - Refactor your thinking
+// Copyright (c) 2020-present, b3log.org
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package av
+
+import (
+	"github.com/88250/lute/ast"
+)
+
+// LayoutKanban 描述了看板视图的结构。
+type LayoutKanban struct {
+	*BaseLayout
+
+	GroupFields []*ViewKanbanField `json:"field"` // 字段
+}
+
+func NewLayoutKanban() *LayoutKanban {
+	return &LayoutKanban{
+		BaseLayout: &BaseLayout{
+			Spec:     0,
+			ID:       ast.NewNodeID(),
+			ShowIcon: true,
+		},
+	}
+}
+
+// ViewKanbanField 描述了看板字段的结构。
+type ViewKanbanField struct {
+	*BaseField
+}
+
+// Kanban 描述了看板视图实例的结构。
+type Kanban struct {
+	*BaseInstance
+
+	Fields    []*KanbanField `json:"fields"`   // 卡片字段
+	Cards     []*KanbanCard  `json:"cards"`    // 卡片
+	CardCount int            `json:"rowCount"` // 总卡片数
+}
+
+// KanbanCard 描述了看板实例卡片的结构。
+type KanbanCard struct {
+	ID     string              `json:"id"`     // 卡片 ID
+	Values []*KanbanFieldValue `json:"values"` // 卡片字段值
+}
+
+// KanbanField 描述了看板实例字段的结构。
+type KanbanField struct {
+	*BaseInstanceField
+}
+
+// KanbanFieldValue 描述了卡片字段实例值的结构。
+type KanbanFieldValue struct {
+	*BaseValue
+}
+
+func (card *KanbanCard) GetID() string {
+	return card.ID
+}
+
+func (card *KanbanCard) GetBlockValue() (ret *Value) {
+	for _, v := range card.Values {
+		if KeyTypeBlock == v.ValueType {
+			ret = v.Value
+			break
+		}
+	}
+	return
+}
+
+func (card *KanbanCard) GetValues() (ret []*Value) {
+	ret = []*Value{}
+	for _, v := range card.Values {
+		ret = append(ret, v.Value)
+	}
+	return
+}
+
+func (card *KanbanCard) GetValue(keyID string) (ret *Value) {
+	for _, value := range card.Values {
+		if nil != value.Value && keyID == value.Value.KeyID {
+			ret = value.Value
+			break
+		}
+	}
+	return
+}
+
+func (kanban *Kanban) GetItems() (ret []Item) {
+	ret = []Item{}
+	for _, card := range kanban.Cards {
+		ret = append(ret, card)
+	}
+	return
+}
+
+func (kanban *Kanban) SetItems(items []Item) {
+	kanban.Cards = []*KanbanCard{}
+	for _, item := range items {
+		kanban.Cards = append(kanban.Cards, item.(*KanbanCard))
+	}
+}
+
+func (kanban *Kanban) CountItems() int {
+	return len(kanban.Cards)
+}
+
+func (kanban *Kanban) GetFields() (ret []Field) {
+	ret = []Field{}
+	for _, field := range kanban.Fields {
+		ret = append(ret, field)
+	}
+	return ret
+}
+
+func (kanban *Kanban) GetField(id string) (ret Field, fieldIndex int) {
+	for i, field := range kanban.Fields {
+		if field.ID == id {
+			return field, i
+		}
+	}
+	return nil, -1
+}
+
+func (kanban *Kanban) GetValue(itemID, keyID string) (ret *Value) {
+	for _, card := range kanban.Cards {
+		if card.ID == itemID {
+			return card.GetValue(keyID)
+		}
+	}
+	return nil
+}
+
+func (kanban *Kanban) GetType() LayoutType {
+	return LayoutTypeKanban
+}

kernel/av/value.go

@@ -57,6 +57,8 @@ type Value struct {
 	Checkbox *ValueCheckbox `json:"checkbox,omitempty"`
 	Relation *ValueRelation `json:"relation,omitempty"`
 	Rollup   *ValueRollup   `json:"rollup,omitempty"`
+
+	IsRenderAutoFill bool `json:"-"` // 标识是否是渲染阶段自动填充的值，保存数据的时候要删掉
 }
 
 func (value *Value) SetUpdatedAt(mills int64) {

kernel/model/attribute_view.go

@@ -101,7 +101,7 @@ func GetAttrViewAddingBlockDefaultValues(avID, viewID, groupID, previousBlockID,
 		return
 	}
 
-	if 1 > len(view.Filters) && nil == view.Group {
+	if 1 > len(view.Filters) && !view.IsGroupView() {
 		// 没有过滤条件也没有分组条件时忽略
 		return
 	}
@@ -128,7 +128,7 @@ func GetAttrViewAddingBlockDefaultValues(avID, viewID, groupID, previousBlockID,
 func getAttrViewAddingBlockDefaultValues(attrView *av.AttributeView, view, groupView *av.View, previousItemID, addingItemID string) (ret map[string]*av.Value) {
 	ret = map[string]*av.Value{}
 
-	if 1 > len(view.Filters) && nil == view.Group {
+	if 1 > len(view.Filters) && !view.IsGroupView() {
 		// 没有过滤条件也没有分组条件时忽略
 		return
 	}
@@ -533,7 +533,7 @@ func foldAttrViewGroup(avID, blockID, groupID string, folded bool) (err error) {
 		return err
 	}
 
-	if nil == view.Group {
+	if !view.IsGroupView() {
 		return
 	}
 
@@ -1032,7 +1032,7 @@ func AppendAttributeViewDetachedBlocksWithValues(avID string, blocksValues [][]*
 			v.IsDetached = true
 			v.CreatedAt = now
 			v.UpdatedAt = now
-
+			v.IsRenderAutoFill = false
 			keyValues.Values = append(keyValues.Values, v)
 
 			if av.KeyTypeSelect == v.Type || av.KeyTypeMSelect == v.Type {
@@ -1725,7 +1725,7 @@ func GetBlockAttributeViewKeys(nodeID string) (ret []*BlockAttributeViewKeys) {
 }
 
 func genAttrViewGroups(view *av.View, attrView *av.AttributeView) {
-	if nil == view.Group {
+	if !view.IsGroupView() {
 		return
 	}
 
@@ -1969,7 +1969,7 @@ type GroupState struct {
 
 func getAttrViewGroupStates(view *av.View) (groupStates map[string]*GroupState) {
 	groupStates = map[string]*GroupState{}
-	if nil == view.Group {
+	if !view.IsGroupView() {
 		return
 	}
 
@@ -2329,6 +2329,7 @@ func updateAttributeViewColRelation(operation *Operation) (err error) {
 							destVal.Relation = &av.ValueRelation{}
 						}
 						destVal.UpdatedAt = now
+						destVal.IsRenderAutoFill = false
 					}
 					destVal.Relation.BlockIDs = append(destVal.Relation.BlockIDs, srcVal.BlockID)
 					destVal.Relation.BlockIDs = gulu.Str.RemoveDuplicatedElem(destVal.Relation.BlockIDs)
@@ -3145,12 +3146,19 @@ func addAttributeViewBlock(now int64, avID, dbBlockID, viewID, groupID, previous
 	// The database date field supports filling the current time by default https://github.com/siyuan-note/siyuan/issues/10823
 	for _, keyValues := range attrView.KeyValues {
 		if av.KeyTypeDate == keyValues.Key.Type && nil != keyValues.Key.Date && keyValues.Key.Date.AutoFillNow {
-			if nil == keyValues.GetValue(addingItemID) { // 避免覆盖已有值（可能前面已经通过过滤或者分组条件填充了值）
+			val := keyValues.GetValue(addingItemID)
+			if nil == val { // 避免覆盖已有值（可能前面已经通过过滤或者分组条件填充了值）
 				dateVal := &av.Value{
 					ID: ast.NewNodeID(), KeyID: keyValues.Key.ID, BlockID: addingItemID, Type: av.KeyTypeDate, IsDetached: isDetached, CreatedAt: now, UpdatedAt: now + 1000,
 					Date: &av.ValueDate{Content: now, IsNotEmpty: true},
 				}
 				keyValues.Values = append(keyValues.Values, dateVal)
+			} else {
+				if val.IsRenderAutoFill {
+					val.CreatedAt, val.UpdatedAt = now, now+1000
+					val.Date.Content, val.Date.IsNotEmpty = now, true
+					val.IsRenderAutoFill = false
+				}
 			}
 		}
 	}
@@ -3230,11 +3238,13 @@ func fillDefaultValue(attrView *av.AttributeView, view, groupView *av.View, prev
 
 		existingVal := keyValues.GetValue(addingItemID)
 		if nil == existingVal {
+			newValue.IsRenderAutoFill = false
 			keyValues.Values = append(keyValues.Values, newValue)
 		} else {
 			newValueRaw := newValue.GetValByType(keyValues.Key.Type)
 			if av.KeyTypeBlock != existingVal.Type || (av.KeyTypeBlock == existingVal.Type && existingVal.IsDetached) {
 				// 非主键的值直接覆盖，主键的值只覆盖非绑定块
+				existingVal.IsRenderAutoFill = false
 				existingVal.SetValByType(keyValues.Key.Type, newValueRaw)
 			}
 		}

kernel/model/attribute_view_render.go

@@ -177,7 +177,7 @@ func renderAttributeViewGroups(viewable av.Viewable, attrView *av.AttributeView,
 }
 
 func hideEmptyGroupViews(view *av.View, viewable av.Viewable) {
-	if nil == view.Group {
+	if !view.IsGroupView() {
 		return
 	}
 
@@ -343,14 +343,14 @@ func sortGroupsBySelectOption(view *av.View, groupKey *av.Key) {
 }
 
 func isGroupByDate(view *av.View) bool {
-	if nil == view.Group {
+	if !view.IsGroupView() {
 		return false
 	}
 	return av.GroupMethodDateDay == view.Group.Method || av.GroupMethodDateWeek == view.Group.Method || av.GroupMethodDateMonth == view.Group.Method || av.GroupMethodDateYear == view.Group.Method || av.GroupMethodDateRelative == view.Group.Method
 }
 
 func isGroupByTemplate(attrView *av.AttributeView, view *av.View) bool {
-	if nil == view.Group {
+	if !view.IsGroupView() {
 		return false
 	}
 

kernel/model/block.go

@@ -234,6 +234,22 @@ func GetBlockSiblingID(id string) (parent, previous, next string) {
 				next = flb.ID
 			}
 		}
+
+		if "" == previous && "" == next && nil != current {
+			parent = current.ID
+			if nil != current.Previous {
+				previous = current.Previous.ID
+				if flb := treenode.FirstChildBlock(current.Previous); nil != flb {
+					previous = flb.ID
+				}
+			}
+			if nil != current.Next {
+				next = current.Next.ID
+				if flb := treenode.FirstChildBlock(current.Next); nil != flb {
+					next = flb.ID
+				}
+			}
+		}
 		return
 	}
 

kernel/sql/av.go

@@ -624,6 +624,7 @@ func fillAttributeViewKeyValues(attrView *av.AttributeView, collection av.Collec
 				}
 			}
 			if !exist {
+				val.IsRenderAutoFill = true
 				keyValues.Values = append(keyValues.Values, val)
 			}
 		}

scripts/win-build.bat

@@ -14,9 +14,9 @@ if errorlevel 1 (
 cd ..
 
 echo 'Cleaning Builds'
-del /S /Q /F app\build 1>nul
-del /S /Q /F app\kernel 1>nul
-del /S /Q /F app\kernel-arm64 1>nul
+rmdir /S /Q app\build 1>nul
+rmdir /S /Q app\kernel 1>nul
+rmdir /S /Q app\kernel-arm64 1>nul
 
 echo 'Building Kernel'
 @REM the C compiler "gcc" is necessary https://sourceforge.net/projects/mingw-w64/files/mingw-w64/
@@ -68,4 +68,13 @@ cd ..
 echo 'Building Appx'
 echo 'Building Appx should be disabled if you do not need it. Not configured correctly will lead to build failures'
 cd . > app\build\win-unpacked\resources\ms-store
-electron-windows-store --input-directory app\build\win-unpacked --output-directory app\build\ --package-version 1.0.0.0 --package-name SiYuan --manifest app\appx\AppxManifest.xml --assets app\appx\assets\ --make-pri true
+call electron-windows-store --input-directory app\build\win-unpacked --output-directory app\build\ --package-version 1.0.0.0 --package-name SiYuan --manifest app\appx\AppxManifest.xml --assets app\appx\assets\ --make-pri true
+
+rmdir /S /Q app\build\pre-appx 1>nul
+
+echo 'Building Appx arm64'
+echo 'Building Appx arm64 should be disabled if you do not need it. Not configured correctly will lead to build failures'
+cd . > app\build\win-arm64-unpacked\resources\ms-store
+call electron-windows-store --input-directory app\build\win-arm64-unpacked --output-directory app\build\ --package-version 1.0.0.0 --package-name SiYuan-arm64 --manifest app\appx\AppxManifest-arm64.xml --assets app\appx\assets\ --make-pri true
+
+rmdir /S /Q app\build\pre-appx 1>nul