如何基于Rust实现文本搜索minigrep

minigrep
├── Cargo.lock
├── Cargo.toml
├── output.txt
├── poem.txt
├── src
    ├── lib.rs
    └── main.rs

use std::{env, process};
use std::io::stdin;
use minigrep::Config;
fn main() {
    let args: Vec<String> = env::args().collect();
    if args.len() == 1 {
        // 如果没输入查询参数，就循环等待用户的输入
        loop {
            println!("请输入要查询的字符串：");
            // 等待用户输入
            let mut input = String::new();
            stdin().read_line(&mut input).expect("无法读取");
            let mut args = input.split_whitespace();
            let mut a = String::new();
            let query = args.next().unwrap_or_else(|| {
                println!("请输入有效的查询字符串");
                stdin().read_line(&mut a);
                &a.as_str().trim()
            });
            if(":q".eq(query.clone())){
                println!("程序退出");
                process::exit(1);
            }
            let mut a = String::new();
            let file_path = args.next().unwrap_or_else(|| {
                println!("请输入文件路径：");
                stdin().read_line(&mut a);
                &a.as_str().trim()
            });
            let config1 = Config { query: query.to_string(), file_path: file_path.to_string(), ignore_case: true };
            if let Err(e) = minigrep::run(config1) {
                eprintln!("程序出错：{e}");
            }
        }
    } else {
        // 启动时的入参
        let config = Config::build(env::args()).unwrap_or_else(|err| {
            eprintln!("程序解析 参数异常 {err}");
            process::exit(1);
        });
        println!("search for {}", config.query);
        println!("in file {}", config.file_path);
        if let Err(e) = minigrep::run(config) {
            eprintln!("程序出错：{e}");
            process::exit(1);
        }
    }
}

use std::error::Error;
use std::{env, fs};
// 查询业务逻辑
pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    if let Ok(contents) = fs::read_to_string(config.file_path){
        let lines = if config.ignore_case {
            search_case_insensitive(&config.query, &contents)
        } else {
            search(&config.query, &contents)
        };
        println!("查询到的结果：");
        for line in lines {
            println!("{line}")
        }
        Ok(())
    }else {
        Err(Box::from("未查询到文件"))
    }
}
// 配置实体
pub struct Config {
    pub query: String,
    pub file_path: String,
    pub ignore_case:bool,
}
impl Config {
    // 构建配置实体
    pub fn build(mut args: impl Iterator<Item =String>) -> Result<Config, &'static str> {
        let _programeName = args.next();
        let query = match args.next() {
            Some(query) => query,
            None => return Err("未获取到 要查询的 字符串参数"),
        };
        let file_path = match args.next() {
            Some(file_path) => file_path,
            None => return Err("未获取到文件路径"),
        };
        // 从环境变量中找到是否包含 IGNORE_CASE
        let ignore_case =  env::var("IGNORE_CASE").is_ok();
        Ok(Config { query, file_path ,ignore_case})
    }
}
// 对参数解析
fn parse_config(args: &[String]) -> Config {
    let query = args[1].clone();
    let file_path = args[2].clone();
    let ignore_case =  env::var("IGNORE_CASE").is_ok();
    Config { query, file_path ,ignore_case}
}
// 大小写敏感查询
pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents
        .lines()
        .filter(|line| line.contains(query))
        .collect()
}
// 忽略大小写查询
pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents
        .lines()
        .filter(|line| line.to_lowercase().contains(&query.to_lowercase()))
        .collect()
}
// 测试模块
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn one_result() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";
        assert_eq!(vec!["safe, fast, productive."], search(query, contents))
    }
    #[test]
    fn test_case_insensitive() {
        let query = "RusT";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";
        assert_eq!(vec!["Rust:"], search_case_insensitive(query, contents))
    }
}