mapper_once_demo/
mapper_once_demo.rs

1/*******************************************************************************
2 *
3 *    Copyright (c) 2025.
4 *    3-Prism Co. Ltd.
5 *
6 *    All rights reserved.
7 *
8 ******************************************************************************/
9
10use prism3_function::{BoxMapperOnce, FnMapperOnceOps, MapperOnce};
11
12fn main() {
13    println!("=== MapperOnce 演示 ===\n");
14
15    // 1. 基本的 BoxMapperOnce
16    println!("1. 基本的 BoxMapperOnce");
17    let parse = BoxMapperOnce::new(|s: String| s.parse::<i32>().unwrap_or(0));
18    let result = parse.apply_once("42".to_string());
19    println!("   解析 '42': {}", result);
20
21    // 2. identity mapper
22    println!("\n2. Identity Mapper");
23    let identity = BoxMapperOnce::<i32, i32>::identity();
24    let result = identity.apply_once(42);
25    println!("   identity(42): {}", result);
26
27    // 3. constant mapper
28    println!("\n3. Constant Mapper");
29    let constant = BoxMapperOnce::constant("hello");
30    let result = constant.apply_once(123);
31    println!("   constant(123): {}", result);
32
33    // 4. and_then 组合
34    println!("\n4. and_then 组合");
35    let add_one = BoxMapperOnce::new(|x: i32| x + 1);
36    let double = |x: i32| x * 2;
37    let composed = add_one.and_then(double);
38    let result = composed.apply_once(5);
39    println!("   (5 + 1) * 2 = {}", result);
40
41    // 5. compose 组合
42    println!("\n5. compose 组合");
43    let double = BoxMapperOnce::new(|x: i32| x * 2);
44    let add_one = |x: i32| x + 1;
45    let composed = double.compose(add_one);
46    let result = composed.apply_once(5);
47    println!("   double(5 + 1) = {}", result);
48
49    // 6. 条件映射
50    println!("\n6. 条件映射");
51    let double = BoxMapperOnce::new(|x: i32| x * 2);
52    let conditional = double.when(|x: &i32| *x > 0).or_else(|x: i32| -x);
53    let result1 = conditional.apply_once(5);
54    println!("   条件(5 > 0): double(5) = {}", result1);
55
56    let double2 = BoxMapperOnce::new(|x: i32| x * 2);
57    let conditional2 = double2.when(|x: &i32| *x > 0).or_else(|x: i32| -x);
58    let result2 = conditional2.apply_once(-5);
59    println!("   条件(-5 > 0): negate(-5) = {}", result2);
60
61    // 7. 管道操作
62    println!("\n7. 管道操作");
63    let add_one = BoxMapperOnce::new(|x: i32| x + 1);
64    let pipeline = add_one.and_then(|x| x * 2).and_then(|x| x - 3);
65    let result = pipeline.apply_once(5);
66    println!("   ((5 + 1) * 2) - 3 = {}", result);
67
68    // 8. 闭包扩展方法
69    println!("\n8. 闭包扩展方法 (FnMapperOnceOps)");
70    let parse = |s: String| s.parse::<i32>().unwrap_or(0);
71    let double = |x: i32| x * 2;
72    let composed = parse.and_then(double);
73    let result = composed.apply_once("21".to_string());
74    println!("   parse('21') * 2 = {}", result);
75
76    // 9. 类型转换
77    println!("\n9. 类型转换");
78    let to_string = BoxMapperOnce::new(|x: i32| x.to_string());
79    let add_suffix = to_string.and_then(|s| format!("{}_suffix", s));
80    let result = add_suffix.apply_once(42);
81    println!("   42.to_string() + '_suffix' = {}", result);
82
83    // 10. 消费所有权
84    println!("\n10. 消费所有权");
85    let vec = vec![1, 2, 3, 4, 5];
86    let sum = BoxMapperOnce::new(|v: Vec<i32>| v.iter().sum::<i32>());
87    let result = sum.apply_once(vec);
88    println!("   sum([1,2,3,4,5]) = {}", result);
89
90    println!("\n=== MapperOnce 演示完成 ===");
91}
mapper_once_demo/mapper_once_demo.rs

mapper_once_demo/
mapper_once_demo.rs
