Maintain history when switching mode

src/lib/components/JSONEditor.svelte

@@ -287,6 +287,9 @@
         case 'content':
           content = props[name] ?? contentDefault
           break
+        case 'selection':
+          selection = props[name] ?? selectionDefault
+          break
         case 'readOnly':
           readOnly = props[name] ?? readOnlyDefault
           break
@@ -527,7 +530,7 @@
     {#key instanceId}
       <JSONEditorRoot
         bind:this={refJSONEditorRoot}
-        {mode}
+        externalMode={mode}
         {content}
         {selection}
         {readOnly}

src/lib/components/modals/JSONEditorModal.svelte

@@ -245,7 +245,7 @@
         <div class="jse-modal-inline-editor">
           <JSONEditorRoot
             bind:this={refEditor}
-            mode={currentState.mode}
+            externalMode={currentState.mode}
             content={currentState.content}
             selection={currentState.selection}
             {readOnly}

src/lib/components/modals/TransformModal.svelte

@@ -17,6 +17,8 @@
   import TreeMode from '../modes/treemode/TreeMode.svelte'
   import type {
     Content,
+    HistoryItem,
+    History,
     JSONParser,
     JSONPathParser,
     OnChangeQueryLanguage,
@@ -31,6 +33,7 @@
   import { readonlyProxy } from '$lib/utils/readonlyProxy.js'
   import Modal from './Modal.svelte'
   import { onMount } from 'svelte'
+  import { createHistoryInstance } from '$lib/logic/history'
 
   const debug = createDebug('jsoneditor:TransformModal')
 
@@ -60,6 +63,12 @@
 
   let refQueryInput: HTMLTextAreaElement
 
+  const historyInstance = createHistoryInstance<HistoryItem>({
+    onChange: (updatedHistory) => (history = updatedHistory)
+  })
+
+  let history: History<HistoryItem> = historyInstance.get()
+
   let selectedJson: unknown | undefined
   $: selectedJson = readonlyProxy(getIn(json, rootPath))
   let selectedContent: Content
@@ -316,6 +325,7 @@
                 <TreeMode
                   externalContent={selectedContent}
                   externalSelection={undefined}
+                  {history}
                   readOnly={true}
                   mainMenuBar={false}
                   navigationBar={false}
@@ -331,6 +341,8 @@
                   onChange={noop}
                   onChangeMode={noop}
                   onSelect={noop}
+                  onUndo={noop}
+                  onRedo={noop}
                   onFocus={noop}
                   onBlur={noop}
                   onSortModal={noop}
@@ -351,6 +363,7 @@
                 <TreeMode
                   externalContent={previewContent}
                   externalSelection={undefined}
+                  {history}
                   readOnly={true}
                   mainMenuBar={false}
                   navigationBar={false}
@@ -366,6 +379,8 @@
                   onChange={noop}
                   onChangeMode={noop}
                   onSelect={noop}
+                  onUndo={noop}
+                  onRedo={noop}
                   onFocus={noop}
                   onBlur={noop}
                   onSortModal={noop}

src/lib/components/modes/JSONEditorRoot.svelte

@@ -3,6 +3,8 @@
     Content,
     ContentErrors,
     ContextMenuItem,
+    HistoryItem,
+    History,
     JSONEditorSelection,
     JSONParser,
     JSONPatchResult,
@@ -26,23 +28,26 @@
     OnSortModal,
     OnTransformModal,
     TransformModalOptions,
-    Validator
+    Validator,
+    ModeHistoryItem
   } from '$lib/types'
   import { Mode } from '$lib/types.js'
   import TextMode from './textmode/TextMode.svelte'
   import TableMode from './tablemode/TableMode.svelte'
   import TreeMode from './treemode/TreeMode.svelte'
   import type { JSONPatchDocument, JSONPath } from 'immutable-json-patch'
-  import { isMenuSpace } from '$lib/typeguards.js'
+  import { isMenuSpace, isModeHistoryItem } from '$lib/typeguards.js'
   import { cloneDeep } from 'lodash-es'
+  import { createHistoryInstance } from '$lib/logic/history'
+  import { createDebug } from '$lib/utils/debug'
 
   export let content: Content
   export let selection: JSONEditorSelection | undefined
 
   export let readOnly: boolean
   export let indentation: number | string
   export let tabSize: number
-  export let mode: Mode
+  export let externalMode: Mode
   export let mainMenuBar: boolean
   export let navigationBar: boolean
   export let statusBar: boolean
@@ -75,6 +80,75 @@
   let refTableMode: TableMode | undefined
   let refTextMode: TextMode | undefined
 
+  const debug = createDebug('jsoneditor:JSONEditorRoot')
+
+  const historyInstance = createHistoryInstance<HistoryItem>({
+    onChange: (updatedHistory) => (history = updatedHistory)
+  })
+
+  let history: History<HistoryItem> = historyInstance.get()
+
+  let mode = externalMode
+
+  function applyExternalMode(externalMode: Mode) {
+    if (externalMode === mode) {
+      return
+    }
+
+    const item: ModeHistoryItem = {
+      type: 'mode',
+      undo: { mode, selection: undefined },
+      redo: { mode: externalMode, selection: undefined }
+    }
+
+    if (mode === 'text' && refTextMode) {
+      // flush pending changes before adding a new history item
+      refTextMode.flush()
+    }
+
+    debug('add history item', item)
+    history.add(item)
+
+    mode = externalMode
+  }
+
+  $: applyExternalMode(externalMode)
+
+  function handleUndo(item: HistoryItem | undefined) {
+    if (isModeHistoryItem(item)) {
+      mode = item.undo.mode // important to prevent a new history item from being created
+
+      // find the selection of the previous history item (if any), and use that as initial selection
+      const items = history.items()
+      const index = items.findIndex((i) => i === item)
+      const prevItem = index !== -1 ? items[index - 1] : undefined
+      debug('handleUndo', { index, item, items, prevItem })
+      if (prevItem) {
+        selection = prevItem.redo.selection
+      }
+
+      onChangeMode(mode)
+    }
+  }
+
+  function handleRedo(item: HistoryItem | undefined) {
+    if (isModeHistoryItem(item)) {
+      // prevent a new history item from being created
+      mode = item.redo.mode
+
+      // find the selection of the next history item (if any), and use that as initial selection
+      const items = history.items()
+      const index = items.findIndex((i) => i === item)
+      const nextItem = index !== -1 ? items[index + 1] : undefined
+      debug('handleRedo', { index, item, items, nextItem })
+      if (nextItem) {
+        selection = nextItem.undo.selection
+      }
+
+      onChangeMode(mode)
+    }
+  }
+
   let modeMenuItems: MenuItem[]
   $: modeMenuItems = [
     {
@@ -268,6 +342,7 @@
     bind:this={refTextMode}
     externalContent={content}
     externalSelection={selection}
+    {history}
     {readOnly}
     {indentation}
     {tabSize}
@@ -279,8 +354,10 @@
     {validator}
     {validationParser}
     {onChange}
-    {onSelect}
     {onChangeMode}
+    {onSelect}
+    onUndo={handleUndo}
+    onRedo={handleRedo}
     {onError}
     {onFocus}
     {onBlur}
@@ -293,6 +370,7 @@
     bind:this={refTableMode}
     externalContent={content}
     externalSelection={selection}
+    {history}
     {readOnly}
     {mainMenuBar}
     {escapeControlCharacters}
@@ -306,6 +384,8 @@
     {onChange}
     {onChangeMode}
     {onSelect}
+    onUndo={handleUndo}
+    onRedo={handleRedo}
     {onRenderValue}
     {onFocus}
     {onBlur}
@@ -321,6 +401,7 @@
     bind:this={refTreeMode}
     externalContent={content}
     externalSelection={selection}
+    {history}
     {readOnly}
     {indentation}
     {mainMenuBar}
@@ -336,6 +417,8 @@
     {onChange}
     {onChangeMode}
     {onSelect}
+    onUndo={handleUndo}
+    onRedo={handleRedo}
     {onRenderValue}
     {onClassName}
     {onFocus}