更改：添加 slice 接口，为 BreakLine 事件提供准备

src/common/signal.ts

@@ -1,4 +1,9 @@
-import { Accessor, Setter, Signal, createSignal as solid_createSignal } from "solid-js";
+import {
+  Accessor,
+  Setter,
+  Signal,
+  createSignal as solid_createSignal,
+} from "solid-js";
 
 export class WrappedSignal<T> {
   get: Accessor<T>;
@@ -31,4 +36,4 @@ export class EmitterSignal {
 
 export function createEmitterSignal() {
   return new EmitterSignal();
-}
+}

src/components/base/mix_editor/Area.ts

@@ -6,8 +6,10 @@ import { BlockSavedData, InlineSavedData, InlineTagSavedData } from "./save";
 import { WrappedSignal } from "@/common/signal";
 
 export interface BaseArea {
+  /** 切割当前区域。 */
+  slice(from: number, to: number): MaybePromise<this>;
   /** 生成保存数据。 */
-  save: () => MaybePromise<any>;
+  save(): MaybePromise<any>;
 
   /** 获取子区域数量。 */
   children_count(): number;

src/components/base/mix_editor/event/BreakLine.ts

@@ -2,12 +2,11 @@ import { MaybePromise } from "@/common/async";
 import { Area } from "../Area";
 import { BaseEvent } from "../event";
 import { Selection } from "../selection";
+import { find_index_in_parent_area } from "../utils/area";
 
 export type BreakLineEventCommand =
   | {
       type: "break";
-      /** 输入的结束位置。 */
-      to: number;
     }
   | {
       type: "no_break";
@@ -17,17 +16,53 @@ export const BreakLineEventCommand = {
   /** 不接受断行。 */
   no_break: { type: "no_break" } satisfies BreakLineEventCommand,
   /** 接受断行，并把光标移动到指定位置。 */
-  break: (to: number) => ({ type: "break", to } satisfies BreakLineEventCommand),
+  break: { type: "break" } satisfies BreakLineEventCommand,
 };
 
 /** 输入事件。 */
 export interface BreakLineEvent extends BaseEvent {
   event_type: "break_line";
-  /** 输入的位置。 */
+  /** 要断行的位置。 */
   to: number;
+  /** 是否从子节点进入。 */
+  from_child: boolean;
 }
 
 export type BreakLineEventPair = {
   event: BreakLineEvent;
   result: MaybePromise<BreakLineEventCommand>;
-};
+};
+
+export async function handle_break_line_event_command(
+  selection: Selection,
+  curr_area: Area,
+  command: BreakLineEventCommand | void,
+  to: number
+) {
+  let break_points: [Area, number][] = [[curr_area, to]];
+  while (true) {
+    command ??= BreakLineEventCommand.no_break;
+
+    if (command.type === "no_break") {
+      // 1. 自顶向下，切割每个区域的后半区域（不含要被切割的区域）
+      // 2. 自底向上，将自身补到上级的开头
+      // 3. 自顶向下，递归删除被切割的区域
+    } else if (command.type === "break") {
+      // 让父节点处理
+      const context = selection.editor.get_context(curr_area);
+      if (!context?.parent) return;
+
+      const index_in_parent = find_index_in_parent_area(
+        curr_area,
+        context.parent
+      );
+
+      curr_area = context.parent;
+      command = await curr_area.handle_event?.<BreakLineEventPair>({
+        event_type: "break_line",
+        to: index_in_parent,
+        from_child: true,
+      });
+    }
+  }
+}

src/components/base/mix_editor/plugins/paragraph.tsx

@@ -155,6 +155,16 @@ export class ParagraphBlock<TInline extends Inline<any, any>>
 {
   area_type = "block" as const;
   type = "paragraph" as const;
+  slice(from: number, to: number): this {
+    return new ParagraphBlock(
+      {
+        inlines: createSignal(this.data.inlines.get().slice(from, to), {
+          equals: false,
+        }),
+      },
+      this.editor
+    ) as this;
+  }
   async save() {
     return create_BlockSaveData(this.type, {
       inlines: await save_inlines(this.data.inlines.get()),

src/components/base/mix_editor/plugins/text.tsx

@@ -107,6 +107,12 @@ export class TextInline
   area_type = "inline" as const;
   type = "text" as const;
   data: { value: WrappedSignal<string>; tags: WrappedSignal<InlineTag[]> };
+  slice(from: number, to: number) {
+    return new TextInline(
+      { value: this.data.value.get().slice(from, to) },
+      this.editor
+    ) as this;
+  }
   async save() {
     return create_InlineSaveData(
       this.type,

src/components/base/mix_editor/root.ts

@@ -102,6 +102,9 @@ export class RootArea implements Block<"root", {}> {
   area_type = "block" as const;
   type = "root" as const;
   data = {};
+  slice(from: number, to: number): this {
+    throw new Error("根区域的切割未实现。");
+  }
   save() {
     return {
       type: "root",

src/components/base/mix_editor/save.ts

@@ -101,6 +101,9 @@ export class LoadingErrorBlock
 {
   area_type = "block" as const;
   type = "loading_error" as const;
+  slice(from: number, to: number) {
+    return new LoadingErrorBlock(this.data) as this;
+  }
   save() {
     return this.data.original;
   }
@@ -129,6 +132,9 @@ export class LoadingErrorInline
 {
   area_type = "inline" as const;
   type = "loading_error" as const;
+  slice(from: number, to: number) {
+    return new LoadingErrorInline(this.data) as this;
+  }
   save() {
     return this.data.original;
   }

src/components/base/mix_editor/selection.ts

@@ -5,12 +5,10 @@ import {
   CaretMoveEnterEventPair,
   handle_caret_move_enter_event_command
 } from "./event/CaretMoveEnter";
-import { CombineEventPair } from "./event/Combine";
 import {
   DeleteEventPair,
   handle_delete_event_command
 } from "./event/Delete";
-import { EnterEventPair, handle_enter_result } from "./event/Enter";
 import { MixEditor } from "./MixEditor";
 
 export type SelectedAreaInfo = {
@@ -59,15 +57,6 @@ export class Selection {
     return this.selected.get();
   }
 
-  async enter(area: Area, to: number) {
-    const result = await area.handle_event?.<EnterEventPair>({
-      event_type: "enter",
-      to,
-    });
-
-    return await handle_enter_result(this, result, area, to);
-  }
-
   private async move(direction: "backward" | "forward") {
     const selected = this.selected.get();
     if (!selected) return;