feat: added support for an empty string

demo/components/Playground.tsx

@@ -46,7 +46,7 @@
 
 const b = block('playground');
 const fileUploadHandler: FileUploadHandler = async (file) => {
     console.info('[Playground] Uploading file: ' + file.name);
     await randomDelay(1000, 3000);
     return {url: URL.createObjectURL(file)};
 };
@@ -63,6 +63,7 @@
     allowHTML?: boolean;
     settingsVisible?: boolean;
     initialEditor?: MarkdownEditorMode;
+    preserveEmptyRows?: boolean;
     breaks?: boolean;
     linkify?: boolean;
     linkifyTlds?: string | string[];
@@ -101,8 +102,8 @@
     >;
 
 logger.setLogger({
     metrics: console.info,
     action: (data) => console.info(`Action: ${data.action}`, data),
     ...console,
 });
 
@@ -115,6 +116,7 @@
         allowHTML,
         breaks,
         linkify,
+        preserveEmptyRows,
         linkifyTlds,
         sanitizeHtml,
         prepareRawMarkup,
@@ -147,7 +149,7 @@
     }, [mdRaw]);
 
     const renderPreview = useCallback<RenderPreview>(
         ({getValue, md, directiveSyntax}) => (
             <SplitModePreview
                 getValue={getValue}
                 allowHTML={md.html}
@@ -219,6 +221,7 @@
             experimental: {
                 ...experimental,
                 directiveSyntax,
+                preserveEmptyRows: preserveEmptyRows,
             },
             prepareRawMarkup: prepareRawMarkup
                 ? (value) => '**prepare raw markup**\n\n' + value
@@ -271,14 +274,14 @@
             setEditorMode(mode);
         }
         const onToolbarAction = ({id, editorMode: type}: ToolbarActionData) => {
             console.info(`The '${id}' action is performed in the ${type}-editor.`);
         };
         function onChangeSplitModeEnabled({splitModeEnabled}: {splitModeEnabled: boolean}) {
             props.onChangeSplitModeEnabled?.(splitModeEnabled);
             console.info(`Split mode enabled: ${splitModeEnabled}`);
         }
         function onChangeToolbarVisibility({visible}: {visible: boolean}) {
             console.info('Toolbar visible: ' + visible);
         }
 
         mdEditor.on('cancel', onCancel);
@@ -298,7 +301,7 @@
             mdEditor.off('change-split-mode-enabled', onChangeSplitModeEnabled);
             mdEditor.off('change-toolbar-visibility', onChangeToolbarVisibility);
         };
     }, [mdEditor]);
 
     return (
         <div className={b()}>

src/bundle/Editor.ts

@@ -4,6 +4,9 @@ import {EditorView as CMEditorView} from '@codemirror/view';
 import {TextSelection} from 'prosemirror-state';
 import {EditorView as PMEditorView} from 'prosemirror-view';
 
+import {TransformFn} from 'src/core/markdown/ProseMirrorTransformer';
+
+import {getAutocompleteConfig} from '../../src/markup/codemirror/autocomplete';
 import type {CommonEditor, MarkupString} from '../common';
 import {
     type ActionStorage,
@@ -124,6 +127,7 @@ export type EditorOptions = Pick<
     renderStorage: ReactRenderStorage;
     preset: EditorPreset;
     directiveSyntax: DirectiveSyntaxContext;
+    pmTransformers: TransformFn[];
 };
 
 /** @internal */
@@ -139,6 +143,8 @@ export class EditorImpl extends SafeEventEmitter<EventMapInt> implements EditorI
     #markupConfig: MarkupConfig;
     #escapeConfig?: EscapeConfig;
     #mdOptions: Readonly<MarkdownEditorMdOptions>;
+    #pmTransformers: TransformFn[] = [];
+    #preserveEmptyRows: boolean;
 
     readonly #preset: EditorPreset;
     #extensions?: WysiwygEditorOptions['extensions'];
@@ -248,6 +254,7 @@ export class EditorImpl extends SafeEventEmitter<EventMapInt> implements EditorI
                 mdPreset,
                 initialContent: this.#markup,
                 extensions: this.#extensions,
+                pmTransformers: this.#pmTransformers,
                 allowHTML: this.#mdOptions.html,
                 linkify: this.#mdOptions.linkify,
                 linkifyTlds: this.#mdOptions.linkifyTlds,
@@ -279,7 +286,12 @@ export class EditorImpl extends SafeEventEmitter<EventMapInt> implements EditorI
                     extensions: this.#markupConfig.extensions,
                     disabledExtensions: this.#markupConfig.disabledExtensions,
                     keymaps: this.#markupConfig.keymaps,
-                    yfmLangOptions: {languageData: this.#markupConfig.languageData},
+                    preserveEmptyRows: this.#preserveEmptyRows,
+                    yfmLangOptions: {
+                        languageData: getAutocompleteConfig({
+                            preserveEmptyRows: this.#preserveEmptyRows,
+                        }).concat(this.#markupConfig?.languageData || []),
+                    },
                     autocompletion: this.#markupConfig.autocompletion,
                     directiveSyntax: this.directiveSyntax,
                     receiver: this,
@@ -330,6 +342,7 @@ export class EditorImpl extends SafeEventEmitter<EventMapInt> implements EditorI
         this.#markup = initial.markup ?? '';
 
         this.#preset = opts.preset ?? 'full';
+        this.#pmTransformers = opts.pmTransformers;
         this.#mdOptions = md;
         this.#extensions = wysiwygConfig.extensions;
         this.#markupConfig = {...opts.markupConfig};
@@ -342,6 +355,7 @@ export class EditorImpl extends SafeEventEmitter<EventMapInt> implements EditorI
         );
         this.#directiveSyntax = opts.directiveSyntax;
         this.#enableNewImageSizeCalculation = Boolean(experimental.enableNewImageSizeCalculation);
+        this.#preserveEmptyRows = experimental.preserveEmptyRows || false;
         this.#prepareRawMarkup = experimental.prepareRawMarkup;
         this.#escapeConfig = wysiwygConfig.escapeConfig;
         this.#beforeEditorModeChange = experimental.beforeEditorModeChange;

src/bundle/config/action-names.ts

@@ -20,6 +20,7 @@ const names = [
     'heading4',
     'heading5',
     'heading6',
+    'emptyRow',
     /** @deprecated use horizontalRule */
     'horizontalrule',
     'horizontalRule',

src/bundle/types.ts

@@ -104,6 +104,12 @@ export type MarkdownEditorExperimentalOptions = {
      * Default value is 'disabled'.
      */
     directiveSyntax?: DirectiveSyntaxOption;
+    /**
+     * If we need support for empty strings
+     *
+     * @default false
+     */
+    preserveEmptyRows?: boolean;
 };
 
 export type MarkdownEditorMarkupConfig = {

src/bundle/useMarkdownEditor.ts

@@ -1,6 +1,7 @@
 import {useLayoutEffect, useMemo} from 'react';
 
 import type {Extension} from '../core';
+import {getPMTransformers} from '../core/markdown/ProseMirrorTransformer/getTransformers';
 import {ReactRenderStorage} from '../extensions';
 import {logger} from '../logger';
 import {DirectiveSyntaxContext} from '../utils/directive';
@@ -33,6 +34,7 @@ export function useMarkdownEditor<T extends object = {}>(
         } = props;
 
         const breaks = md.breaks ?? props.breaks;
+        const preserveEmptyRows = experimental.preserveEmptyRows;
         const preset: MarkdownEditorPreset = props.preset ?? 'full';
         const renderStorage = new ReactRenderStorage();
         const uploadFile = handlers.uploadFile ?? props.fileUploadHandler;
@@ -41,6 +43,10 @@ export function useMarkdownEditor<T extends object = {}>(
             props.needToSetDimensionsForUploadedImages;
         const enableNewImageSizeCalculation = experimental.enableNewImageSizeCalculation;
 
+        const pmTransformers = getPMTransformers({
+            emptyRowTransformer: preserveEmptyRows,
+        });
+
         const directiveSyntax = new DirectiveSyntaxContext(experimental.directiveSyntax);
 
         const extensions: Extension = (builder) => {
@@ -59,6 +65,7 @@ export function useMarkdownEditor<T extends object = {}>(
                     editor.emit('submit', null);
                     return true;
                 },
+                preserveEmptyRows: preserveEmptyRows,
                 placeholderOptions: wysiwygConfig.placeholderOptions,
                 mdBreaks: breaks,
                 fileUploadHandler: uploadFile,
@@ -72,11 +79,13 @@ export function useMarkdownEditor<T extends object = {}>(
                 }
             }
         };
+
         return new EditorImpl({
             ...props,
             preset,
             renderStorage,
             directiveSyntax,
+            pmTransformers,
             md: {
                 ...md,
                 breaks,

src/bundle/wysiwyg-preset.ts

@@ -26,6 +26,7 @@ export type BundlePresetOptions = ExtensionsOptions &
     EditorModeKeymapOptions & {
         preset: MarkdownEditorPreset;
         mdBreaks?: boolean;
+        preserveEmptyRows?: boolean;
         fileUploadHandler?: FileUploadHandler;
         placeholderOptions?: WysiwygPlaceholderOptions;
         /**
@@ -81,6 +82,7 @@ export const BundlePreset: ExtensionAuto<BundlePresetOptions> = (builder, opts)
                     ? value()
                     : value ?? i18nPlaceholder('doc_empty');
             },
+            preserveEmptyRows: opts.preserveEmptyRows,
             ...opts.baseSchema,
         },
     };

src/core/Editor.ts

@@ -7,6 +7,7 @@ import type {CommonEditor, ContentHandler, MarkupString} from '../common';
 import type {ActionsManager} from './ActionsManager';
 import {WysiwygContentHandler} from './ContentHandler';
 import {ExtensionsManager} from './ExtensionsManager';
+import {TransformFn} from './markdown/ProseMirrorTransformer';
 import type {ActionStorage} from './types/actions';
 import type {Extension} from './types/extension';
 import type {Parser} from './types/parser';
@@ -30,6 +31,7 @@ export type WysiwygEditorOptions = {
     mdPreset?: PresetName;
     allowHTML?: boolean;
     linkify?: boolean;
+    pmTransformers?: TransformFn[];
     linkifyTlds?: string | string[];
     escapeConfig?: EscapeConfig;
     /** Call on any state change (move cursor, change selection, etc...) */
@@ -74,6 +76,7 @@ export class WysiwygEditor implements CommonEditor, ActionStorage {
         allowHTML,
         mdPreset,
         linkify,
+        pmTransformers,
         linkifyTlds,
         escapeConfig,
         onChange,
@@ -92,6 +95,7 @@ export class WysiwygEditor implements CommonEditor, ActionStorage {
             // "breaks" option only affects the renderer, but not the parser
             mdOpts: {html: allowHTML, linkify, breaks: true, preset: mdPreset},
             linkifyTlds,
+            pmTransformers,
         });
 
         const state = EditorState.create({

src/core/ExtensionsManager.ts

@@ -6,6 +6,7 @@ import {ExtensionBuilder} from './ExtensionBuilder';
 import {ParserTokensRegistry} from './ParserTokensRegistry';
 import {SchemaSpecRegistry} from './SchemaSpecRegistry';
 import {SerializerTokensRegistry} from './SerializerTokensRegistry';
+import {TransformFn} from './markdown/ProseMirrorTransformer';
 import type {ActionSpec} from './types/actions';
 import type {
     Extension,
@@ -24,6 +25,7 @@ type ExtensionsManagerParams = {
 type ExtensionsManagerOptions = {
     mdOpts?: MarkdownIt.Options & {preset?: PresetName};
     linkifyTlds?: string | string[];
+    pmTransformers?: TransformFn[];
 };
 
 export class ExtensionsManager {
@@ -38,6 +40,8 @@ export class ExtensionsManager {
     #nodeViewCreators = new Map<string, (deps: ExtensionDeps) => NodeViewConstructor>();
     #markViewCreators = new Map<string, (deps: ExtensionDeps) => MarkViewConstructor>();
 
+    #pmTransformers: TransformFn[] = [];
+
     #mdForMarkup: MarkdownIt;
     #mdForText: MarkdownIt;
     #extensions: Extension;
@@ -62,6 +66,10 @@ export class ExtensionsManager {
             this.#mdForText.linkify.tlds(options.linkifyTlds, true);
         }
 
+        if (options.pmTransformers) {
+            this.#pmTransformers = options.pmTransformers;
+        }
+
         // TODO: add prefilled context
         this.#builder = new ExtensionBuilder();
     }
@@ -118,8 +126,16 @@ export class ExtensionsManager {
         this.#deps = {
             schema,
             actions: new ActionsManager(),
-            markupParser: this.#parserRegistry.createParser(schema, this.#mdForMarkup),
-            textParser: this.#parserRegistry.createParser(schema, this.#mdForText),
+            markupParser: this.#parserRegistry.createParser(
+                schema,
+                this.#mdForMarkup,
+                this.#pmTransformers,
+            ),
+            textParser: this.#parserRegistry.createParser(
+                schema,
+                this.#mdForText,
+                this.#pmTransformers,
+            ),
             serializer: this.#serializerRegistry.createSerializer(),
         };
     }

src/core/ParserTokensRegistry.ts

@@ -2,6 +2,7 @@ import type MarkdownIt from 'markdown-it';
 import type {Schema} from 'prosemirror-model';
 
 import {MarkdownParser} from './markdown/MarkdownParser';
+import {TransformFn} from './markdown/ProseMirrorTransformer';
 import type {Parser, ParserToken} from './types/parser';
 
 export class ParserTokensRegistry {
@@ -12,7 +13,7 @@ export class ParserTokensRegistry {
         return this;
     }
 
-    createParser(schema: Schema, tokenizer: MarkdownIt): Parser {
-        return new MarkdownParser(schema, tokenizer, this.#tokens);
+    createParser(schema: Schema, tokenizer: MarkdownIt, pmTransformers: TransformFn[]): Parser {
+        return new MarkdownParser(schema, tokenizer, this.#tokens, pmTransformers);
     }
 }

src/core/markdown/Markdown.test.ts

@@ -14,23 +14,28 @@ import {MarkdownSerializer} from './MarkdownSerializer';
 
 const {schema} = builder;
 schema.nodes['hard_break'].spec.isBreak = true;
-const parser: Parser = new MarkdownParser(schema, new MarkdownIt('commonmark'), {
-    paragraph: {type: 'block', name: 'paragraph'},
-    heading: {
-        type: 'block',
-        name: 'heading',
-        getAttrs: (tok) => ({level: Number(tok.tag.slice(1))}),
+const parser: Parser = new MarkdownParser(
+    schema,
+    new MarkdownIt('commonmark'),
+    {
+        paragraph: {type: 'block', name: 'paragraph'},
+        heading: {
+            type: 'block',
+            name: 'heading',
+            getAttrs: (tok) => ({level: Number(tok.tag.slice(1))}),
+        },
+        list_item: {type: 'block', name: 'list_item'},
+        bullet_list: {type: 'block', name: 'bullet_list'},
+        ordered_list: {type: 'block', name: 'ordered_list'},
+        hardbreak: {type: 'node', name: 'hard_break'},
+        fence: {type: 'block', name: 'code_block', noCloseToken: true},
+
+        em: {type: 'mark', name: 'em'},
+        strong: {type: 'mark', name: 'strong'},
+        code_inline: {type: 'mark', name: 'code', noCloseToken: true},
     },
-    list_item: {type: 'block', name: 'list_item'},
-    bullet_list: {type: 'block', name: 'bullet_list'},
-    ordered_list: {type: 'block', name: 'ordered_list'},
-    hardbreak: {type: 'node', name: 'hard_break'},
-    fence: {type: 'block', name: 'code_block', noCloseToken: true},
-
-    em: {type: 'mark', name: 'em'},
-    strong: {type: 'mark', name: 'strong'},
-    code_inline: {type: 'mark', name: 'code', noCloseToken: true},
-});
+    [],
+);
 const serializer = new MarkdownSerializer(
     {
         text: ((state, node) => {

src/core/markdown/MarkdownParser.test.ts

@@ -7,11 +7,16 @@ import type {Parser} from '../types/parser';
 import {MarkdownParser} from './MarkdownParser';
 
 const md = MarkdownIt('commonmark', {html: false, breaks: true});
-const testParser: Parser = new MarkdownParser(schema, md, {
-    blockquote: {name: 'blockquote', type: 'block', ignore: true},
-    paragraph: {type: 'block', name: 'paragraph'},
-    softbreak: {type: 'node', name: 'hard_break'},
-});
+const testParser: Parser = new MarkdownParser(
+    schema,
+    md,
+    {
+        blockquote: {name: 'blockquote', type: 'block', ignore: true},
+        paragraph: {type: 'block', name: 'paragraph'},
+        softbreak: {type: 'node', name: 'hard_break'},
+    },
+    [],
+);
 
 function parseWith(parser: Parser) {
     return (text: string, node: Node) => {

src/core/markdown/MarkdownParser.ts

@@ -6,6 +6,8 @@ import {Mark, MarkType, Node, NodeType, Schema} from 'prosemirror-model';
 import {logger} from '../../logger';
 import type {Parser, ParserToken} from '../types/parser';
 
+import {ProseMirrorTransformer, TransformFn} from './ProseMirrorTransformer';
+
 type TokenAttrs = {[name: string]: unknown};
 
 const openSuffix = '_open';
@@ -22,12 +24,19 @@ export class MarkdownParser implements Parser {
     marks: readonly Mark[];
     tokens: Record<string, ParserToken>;
     tokenizer: MarkdownIt;
-
-    constructor(schema: Schema, tokenizer: MarkdownIt, tokens: Record<string, ParserToken>) {
+    pmTransformers: TransformFn[];
+
+    constructor(
+        schema: Schema,
+        tokenizer: MarkdownIt,
+        tokens: Record<string, ParserToken>,
+        pmTransformers: TransformFn[],
+    ) {
         this.schema = schema;
         this.marks = Mark.none;
         this.tokens = tokens;
         this.tokenizer = tokenizer;
+        this.pmTransformers = pmTransformers;
     }
 
     validateLink(url: string): boolean {
@@ -69,7 +78,9 @@ export class MarkdownParser implements Parser {
                 doc = this.closeNode();
             } while (this.stack.length);
 
-            return (doc || this.schema.topNodeType.createAndFill()) as Node;
+            const pmTransformer = new ProseMirrorTransformer(this.pmTransformers);
+
+            return doc ? pmTransformer.transform(doc) : this.schema.topNodeType.createAndFill()!;
         } finally {
             logger.metrics({component: 'parser', event: 'parse', duration: Date.now() - time});
         }

src/core/markdown/ProseMirrorTransformer/emptyRowTransformer.ts

@@ -0,0 +1,8 @@
+import {TransformFn} from './index';
+
+export const transformEmptyParagraph: TransformFn = (node) => {
+    if (node.type !== 'paragraph') return;
+    if (node.content?.length !== 1) return;
+    if (node.content[0]?.type !== 'text') return;
+    if (node.content[0].text === String.fromCharCode(160)) delete node.content;
+};