java.lang.Object

cloud.opencode.base.functional.optics.Lens<S,A>

Type Parameters:: S - source/whole type - 源/整体类型; A - target/part type - 目标/部分类型

public final class Lens<S,A> extends Object

Lens - Functional lens for immutable data access and modification Lens - 用于不可变数据访问和修改的函数式透镜

A lens provides a way to focus on a part of a data structure, allowing both reading and functional updating of that part. Particularly useful for nested immutable data structures like records.

透镜提供了一种聚焦数据结构某部分的方式，允许读取和函数式更新该部分。对于嵌套的不可变数据结构（如 record）特别有用。

Features | 主要功能:

Get: read a part of a structure - 获取: 读取结构的一部分
Set: create a copy with modified part - 设置: 创建带修改部分的副本
Modify: transform a part - 修改: 转换一部分
Compose: combine lenses - 组合: 组合透镜

Usage Examples | 使用示例:

// Define a lens for Person.name
Lens<Person, String> nameLens = Lens.of(
    Person::name,
    (person, name) -> new Person(name, person.age())
);

// Read value
String name = nameLens.get(person);

// Create modified copy
Person updated = nameLens.set(person, "Alice");

// Transform value
Person upperCased = nameLens.modify(person, String::toUpperCase);

// Compose lenses for nested access
Lens<Company, String> ceoNameLens = companyToPersonLens.andThen(nameLens);

// Record lens example
record Address(String city, String street) {}
record Person(String name, Address address) {}

Lens<Person, Address> addressLens = Lens.of(
    Person::address,
    (p, addr) -> new Person(p.name(), addr)
);

Lens<Address, String> cityLens = Lens.of(
    Address::city,
    (addr, city) -> new Address(city, addr.street())
);

// Compose to access nested field
Lens<Person, String> personCityLens = addressLens.andThen(cityLens);
Person moved = personCityLens.set(person, "New York");

Laws | 透镜定律:

Get-Set: set(s, get(s)) == s - 获取-设置: set(s, get(s)) == s
Set-Get: get(set(s, a)) == a - 设置-获取: get(set(s, a)) == a
Set-Set: set(set(s, a), b) == set(s, b) - 设置-设置: set(set(s, a), b) == set(s, b)

Performance | 性能特性:

Get: O(1) - 获取: O(1)
Set: O(1) (assuming O(1) copy) - 设置: O(1) (假设 O(1) 复制)
Compose: O(depth) for nested access - 组合: O(深度) 用于嵌套访问

Security | 安全性:

Thread-safe: Yes (immutable) - 线程安全: 是 (不可变)
Null-safe: Depends on getter/setter - 空值安全: 取决于 getter/setter

Since:

JDK 25, opencode-base-functional V1.0.0

Author:

Leon Soo www.LeonSoo.com

See Also:

Method Summary

Modifier and Type

Method

Description

<B> Lens<S,B>

andThen(Lens<A,B> other)

Compose with another lens (this lens first, then other) 与另一个透镜组合（先应用此透镜，然后应用其他）

OptionalLens<S,A>

asOptional()

Convert to an OptionalLens 转换为 OptionalLens

<T> Lens<T,A>

compose(Lens<T,S> other)

Compose with another lens (other lens first, then this) 与另一个透镜组合（先应用其他，然后应用此透镜）

static <S,A> Lens<S,A>

forRecord(Function<S,A> getter, BiFunction<S,A,S> constructor)

Create a lens for a record component 为 record 组件创建透镜

A

get(S source)

Get the focused value from the source 从源获取聚焦的值

Function<S,A>

getter()

Get the getter function 获取 getter 函数

static <S> Lens<S,S>

identity()

Create an identity lens 创建恒等透镜

UnaryOperator<S>

modifier(UnaryOperator<A> modifier)

Create a modifier function for this lens 为此透镜创建修改器函数

S

modify(S source, UnaryOperator<A> modifier)

Modify the focused value using a function 使用函数修改聚焦的值

static <S,A> Lens<S,A>

of(Function<S,A> getter, BiFunction<S,A,S> setter)

Create a lens from getter and setter 从 getter 和 setter 创建透镜

S

set(S source, A value)

Set the focused value, returning a new source 设置聚焦的值，返回新的源

BiFunction<S,A,S>

setter()

Get the setter function 获取 setter 函数

String

toString()

Methods inherited from class Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Details
- of
  
  public static <S,A> Lens<S,A> of(Function<S,A> getter, BiFunction<S,A,S> setter)
  
  Create a lens from getter and setter 从 getter 和 setter 创建透镜
  
  Type Parameters:
  
  S - source/whole type - 源/整体类型
  
  A - target/part type - 目标/部分类型
  
  Parameters:
  
  getter - function to get the part - 获取部分的函数
  
  setter - function to set the part (returns new whole) - 设置部分的函数（返回新整体）
  
  Returns:
  
  lens
- identity
  
  public static <S> Lens<S,S> identity()
  
  Create an identity lens 创建恒等透镜
  
  Type Parameters:
  
  S - type - 类型
  
  Returns:
  
  identity lens
- get
  
  public A get(S source)
  
  Get the focused value from the source 从源获取聚焦的值
  
  Parameters:
  
  source - the source structure - 源结构
  
  Returns:
  
  the focused part
- set
  
  public S set(S source, A value)
  
  Set the focused value, returning a new source 设置聚焦的值，返回新的源
  
  Parameters:
  
  source - the source structure - 源结构
  
  value - the new value - 新值
  
  Returns:
  
  new source with updated part
- modify
  
  public S modify(S source, UnaryOperator<A> modifier)
  
  Modify the focused value using a function 使用函数修改聚焦的值
  
  Parameters:
  
  source - the source structure - 源结构
  
  modifier - function to modify the value - 修改值的函数
  
  Returns:
  
  new source with modified part
- modifier
  
  public UnaryOperator<S> modifier(UnaryOperator<A> modifier)
  
  Create a modifier function for this lens 为此透镜创建修改器函数
  
  Parameters:
  
  modifier - function to modify the value - 修改值的函数
  
  Returns:
  
  function that modifies source
- andThen
  
  public <B> Lens<S,B> andThen(Lens<A,B> other)
  
  Compose with another lens (this lens first, then other) 与另一个透镜组合（先应用此透镜，然后应用其他）
  Creates a lens that focuses on a part of the part.
  
  创建聚焦于部分的部分的透镜。
  
  Type Parameters:
  
  B - deeper target type - 更深的目标类型
  
  Parameters:
  
  other - lens to compose with - 要组合的透镜
  
  Returns:
  
  composed lens
- compose
  
  public <T> Lens<T,A> compose(Lens<T,S> other)
  
  Compose with another lens (other lens first, then this) 与另一个透镜组合（先应用其他，然后应用此透镜）
  
  Type Parameters:
  
  T - outer source type - 外部源类型
  
  Parameters:
  
  other - lens to compose with - 要组合的透镜
  
  Returns:
  
  composed lens
- asOptional
  
  public OptionalLens<S,A> asOptional()
  
  Convert to an OptionalLens 转换为 OptionalLens
  
  Returns:
  
  optional lens
- getter
  
  public Function<S,A> getter()
  
  Get the getter function 获取 getter 函数
  
  Returns:
  
  getter function
- setter
  
  public BiFunction<S,A,S> setter()
  
  Get the setter function 获取 setter 函数
  
  Returns:
  
  setter function
- forRecord
  
  public static <S,A> Lens<S,A> forRecord(Function<S,A> getter, BiFunction<S,A,S> constructor)
  
  Create a lens for a record component 为 record 组件创建透镜
  Helper for creating lenses for record fields.
  
  为 record 字段创建透镜的辅助方法。
  
  Type Parameters:
  
  S - record type - record 类型
  
  A - component type - 组件类型
  
  Parameters:
  
  getter - record component accessor - record 组件访问器
  
  constructor - record constructor with updated field - 带更新字段的 record 构造器
  
  Returns:
  
  lens for record component
- toString
  
  public String toString()
  
  Overrides:
  
  toString in class Object

Class Lens<S,A>

Method Summary

Methods inherited from class Object

Method Details

of

identity

get

set

modify

modifier

andThen

compose

asOptional

getter

setter

forRecord

toString