init

2026-01-06 17:31:56 +08:00
commit 210d948353
21 changed files with 4215 additions and 0 deletions
@@ -0,0 +1,155 @@
+// 简单文本操作的实现
+import { v4 as uuidv4 } from 'uuid';
+
+export abstract class SimpleTextOperation {
+  id: string = uuidv4();
+  abstract toString(): string;
+  abstract equals(other: SimpleTextOperation): boolean;
+  abstract apply(doc: string): string;
+
+  static transform(a: SimpleTextOperation, b: SimpleTextOperation): [SimpleTextOperation, SimpleTextOperation] {
+    if (a instanceof Noop || b instanceof Noop) {
+      return [a, b];
+    }
+
+    if (a instanceof Insert && b instanceof Insert) {
+      if (a.position < b.position || (a.position === b.position && a.str < b.str)) {
+        return [a, new Insert(b.str, b.position + a.str.length)];
+      }
+      if (a.position > b.position || (a.position === b.position && a.str > b.str)) {
+        return [new Insert(a.str, a.position + b.str.length), b];
+      }
+      return [noop, noop];
+    }
+
+    if (a instanceof Insert && b instanceof Delete) {
+      if (a.position <= b.position) {
+        return [a, new Delete(b.count, b.position + a.str.length)];
+      }
+      if (a.position >= b.position + b.count) {
+        return [new Insert(a.str, a.position - b.count), b];
+      }
+      // 这里，我们必须删除操作 a 插入的字符串。
+      // 这不能保留操作 a 的意图，但这是获得有效转换函数的唯一方法。
+      return [noop, new Delete(b.count + a.str.length, b.position)];
+    }
+
+    if (a instanceof Delete && b instanceof Insert) {
+      if (a.position >= b.position) {
+        return [new Delete(a.count, a.position + b.str.length), b];
+      }
+      if (a.position + a.count <= b.position) {
+        return [a, new Insert(b.str, b.position - a.count)];
+      }
+      // 与上面相同的问题。我们必须删除操作 b 中插入的字符串。
+      return [new Delete(a.count + b.str.length, a.position), noop];
+    }
+
+    if (a instanceof Delete && b instanceof Delete) {
+      if (a.position === b.position) {
+        if (a.count === b.count) {
+          return [noop, noop];
+        } else if (a.count < b.count) {
+          return [noop, new Delete(b.count - a.count, b.position)];
+        }
+        return [new Delete(a.count - b.count, a.position), noop];
+      }
+      if (a.position < b.position) {
+        if (a.position + a.count <= b.position) {
+          return [a, new Delete(b.count, b.position - a.count)];
+        }
+        if (a.position + a.count >= b.position + b.count) {
+          return [new Delete(a.count - b.count, a.position), noop];
+        }
+        return [
+          new Delete(b.position - a.position, a.position),
+          new Delete(b.position + b.count - (a.position + a.count), a.position)
+        ];
+      }
+      if (a.position > b.position) {
+        if (a.position >= b.position + b.count) {
+          return [new Delete(a.count, a.position - b.count), b];
+        }
+        if (a.position + a.count <= b.position + b.count) {
+          return [noop, new Delete(b.count - a.count, b.position)];
+        }
+        return [
+          new Delete(a.position + a.count - (b.position + b.count), b.position),
+          new Delete(a.position - b.position, b.position)
+        ];
+      }
+    }
+
+    throw new Error('Unsupported operation types for transformation');
+  }
+}
+
+// 在文档的从零开始的位置 `position` 插入字符串 `str`
+export class Insert extends SimpleTextOperation {
+  public str: string;
+  public position: number;
+
+  constructor(str: string, position: number) {
+    super();
+    this.str = str;
+    this.position = position;
+  }
+
+  toString(): string {
+    return 'Insert(' + JSON.stringify(this.str) + ', ' + this.position + ')';
+  }
+
+  equals(other: SimpleTextOperation): boolean {
+    return other instanceof Insert &&
+      this.str === other.str &&
+      this.position === other.position;
+  }
+
+  apply(doc: string): string {
+    return doc.slice(0, this.position) + this.str + doc.slice(this.position);
+  }
+}
+
+// 在文档的从零开始的位置 `position` 删除 `count` 个字符
+export class Delete extends SimpleTextOperation {
+  public count: number;
+  public position: number;
+
+  constructor(count: number, position: number) {
+    super();
+    this.count = count;
+    this.position = position;
+  }
+
+  toString(): string {
+    return 'Delete(' + this.count + ', ' + this.position + ')';
+  }
+
+  equals(other: SimpleTextOperation): boolean {
+    return other instanceof Delete &&
+      this.count === other.count &&
+      this.position === other.position;
+  }
+
+  apply(doc: string): string {
+    return doc.slice(0, this.position) + doc.slice(this.position + this.count);
+  }
+}
+
+// 不执行任何操作的操作。这对于转换两个删除相同字符的结果是必需的
+export class Noop extends SimpleTextOperation {
+  toString(): string {
+    return 'Noop()';
+  }
+
+  equals(other: SimpleTextOperation): boolean {
+    return other instanceof Noop;
+  }
+
+  apply(doc: string): string {
+    return doc;
+  }
+}
+
+const noop = new Noop();
+