diff --git a/__tests__/CalcChain.test.ts b/__tests__/CalcChain.test.ts
index acd52887..4b69ec55 100644
--- a/__tests__/CalcChain.test.ts
+++ b/__tests__/CalcChain.test.ts
@@ -1,4 +1,4 @@
-import { CalcChain } from '../src/CalcChain';
+import { CalcChain } from '../src';
 
 describe('Calc', function () {
   test('Calc', () => {
diff --git a/__tests__/StateTool.test.ts b/__tests__/StateTool.test.ts
new file mode 100644
index 00000000..397f6b41
--- /dev/null
+++ b/__tests__/StateTool.test.ts
@@ -0,0 +1,52 @@
+import { expectError, expectType } from './object/common.test';
+import { StateTool } from '../src';
+
+describe('StateTool', () => {
+  enum Color {
+    RED,
+    BLUE,
+    GREEN,
+  }
+  it('is', () => {
+    const state = new StateTool(Color.RED);
+    expect(state.is(Color.RED)).toBe(true);
+    expect(state.is(Color.GREEN)).toBe(false);
+    // @ts-expect-error
+    expectError(state.is('green'));
+  });
+  it('in', () => {
+    const state = new StateTool(Color.BLUE);
+    expect(state.in(Color.BLUE, Color.RED, Color.GREEN)).toBe(true);
+    expect(state.in(Color.RED, Color.GREEN)).toBe(false);
+    // @ts-expect-error
+    expectError(state.in('green'));
+  });
+  it('set', () => {
+    const state = new StateTool(Color.RED);
+    expect(state.is(Color.RED)).toBe(true);
+    expect(state.is(Color.GREEN)).toBe(false);
+    state.value = Color.GREEN;
+    expect(state.is(Color.GREEN)).toBe(true);
+    // @ts-expect-error
+    expectError((state.value = 5));
+  });
+  it('is, no default', () => {
+    const state = new StateTool<Color | null>(null);
+    expect(state.in(Color.BLUE, Color.RED, Color.GREEN)).toBe(false);
+    expect(state.value === null).toBe(true);
+    // @ts-expect-error
+    expectError(state.is('green'));
+  });
+  it('value type', () => {
+    const state = new StateTool<Color | void>(void 0);
+    state.value = Color.RED;
+    state.value = undefined;
+    expectType<Color | void>(state.value);
+
+    const state2 = new StateTool(Color.RED);
+    state2.value = Color.GREEN;
+    // @ts-expect-error
+    state2.value = undefined;
+    expectType<Color>(state2.value);
+  });
+});
diff --git a/__tests__/object/common.test.ts b/__tests__/object/common.test.ts
index 30141fd7..1446d261 100644
--- a/__tests__/object/common.test.ts
+++ b/__tests__/object/common.test.ts
@@ -2,7 +2,7 @@ import * as cm from '../../src/object/common';
 import * as arr from '../../src/array';
 import { forEachNum } from '../../src';
 
-function expectType<T>(_value: T) {}
+export function expectType<T>(_value: T) {}
 
 export function expectError<T>(_value: T) {}
 
diff --git a/src/CalcChain.ts b/src/class/CalcChain.ts
similarity index 97%
rename from src/CalcChain.ts
rename to src/class/CalcChain.ts
index c16134ba..cf48c92a 100644
--- a/src/CalcChain.ts
+++ b/src/class/CalcChain.ts
@@ -1,4 +1,4 @@
-import { divide, minus, times, strip, plus } from './number';
+import { divide, minus, times, strip, plus } from '../number';
 
 /**
  * 链式计算
diff --git a/src/class/StateTool.ts b/src/class/StateTool.ts
new file mode 100644
index 00000000..71fcd71a
--- /dev/null
+++ b/src/class/StateTool.ts
@@ -0,0 +1,46 @@
+/**
+ * 状态工具
+ *
+ * 一个简单的状态判断封装，
+ * 主要是写代码时总要把状态从===判断改成[state1,state2,...].includes(state),
+ * 而封装后，我只要把 is 方法改为 in 然后添加参数就行，
+ * 而且 in 方法预设的类型约束比现写数组的要好(可能要再写一遍约束)
+ *
+ *  @example
+ *  enum Color {
+ *     RED,
+ *     BLUE,
+ *     GREEN,
+ *  }
+ *
+ *  const state = new StateTool(Color.RED);
+ *  state.is(Color.RED); // return true
+ *  state.in(Color.BLUE, Color.RED, Color.GREEN) // return true
+ *
+ *  state.value = Color.GREEN;
+ *  state.is(Color.GREEN); // return true
+ *  state.value // Color.GREEN
+ *
+ *  // 必须指定类型
+ *  const state2 = new StateTool<Color | null>(null);
+ *  state2.value // null
+ *  state2.value = Color.RED;
+ */
+export class StateTool<T> {
+  constructor(private state: T) {}
+
+  in(...status: T[]): boolean {
+    return status.includes(this.state);
+  }
+  is(state: T): boolean {
+    return this.state === state;
+  }
+  // 为什么不直接在构造函数内把参数设置为 public value: T
+  // 是因为后续如果要继承这个类给 set 或者 get 加个过滤的话，就要另外起一个名字，不够灵活
+  set value(state: T) {
+    this.state = state;
+  }
+  get value(): T {
+    return this.state;
+  }
+}
diff --git a/src/class/index.ts b/src/class/index.ts
new file mode 100644
index 00000000..10bf5c65
--- /dev/null
+++ b/src/class/index.ts
@@ -0,0 +1,2 @@
+export * from './CalcChain';
+export * from './StateTool';
diff --git a/src/coordinate/getRotatePoint.ts b/src/coordinate/getRotatePoint.ts
index 2d8d151e..34427178 100644
--- a/src/coordinate/getRotatePoint.ts
+++ b/src/coordinate/getRotatePoint.ts
@@ -1,5 +1,5 @@
 import type { Point } from '@tool-pack/types';
-import { CalcChain } from '../CalcChain';
+import { CalcChain } from '../class';
 
 /**
  * 根据半径与角度获取对应坐标点
diff --git a/src/index.ts b/src/index.ts
index 4335d94a..08359baa 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -6,7 +6,6 @@ export * from './object';
 export * from './promise';
 export * from './time';
 export * from './common';
-export * from './CalcChain';
 export * from './coordinate';
 export * from './random';
 export * from './color';
@@ -16,3 +15,4 @@ export * from './bezier';
 export * from './generator';
 export * from './array-buffer';
 export * from './base64';
+export * from './class';
diff --git a/src/index.typedoc.ts b/src/index.typedoc.ts
index f4a98e46..2d100c9f 100644
--- a/src/index.typedoc.ts
+++ b/src/index.typedoc.ts
@@ -36,9 +36,9 @@ export * as Time from './time';
  */
 export * as Clone from './clone';
 /**
- * 计算链工具函数
+ * 各种工具类
  */
-export * as CalcChain from './CalcChain';
+export * as Classes from './class';
 /**
  * 坐标系相关的工具函数
  */