first commit

.gitignore

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+/target

Cargo.toml

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+[package]
+name = "minigrep"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

poem.txt

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+I'm nobody! Who are you?
+我啥也不是，你呢？
+Are you nobody, too?
+牛逼如你也是无名之辈吗？
+Then there's a pair of us - don't tell!
+那我们就是天生一对，嘘！别说话！
+They'd banish us, you know.
+你知道，我们不属于这里。
+How dreary to be somebody!
+因为这里属于没劲的大人物！
+How public, like a frog
+他们就像青蛙一样呱噪，
+To tell your name the livelong day
+成天将自己的大名
+To an admiring bog!
+传遍整个无聊的沼泽！

src/lib.rs

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+use std::{env, error::Error, fs};
+
+// 命令行参数
+// 聚合配置变量到结构体中
+pub struct Config<'a> {
+    query: &'a str,
+    file_path: &'a str,
+    ignore_case: bool,
+}
+
+impl<'a> Config<'a> {
+    pub fn build(args: &'a [String]) -> Result<Self, &'static str> {
+        if args.len() < 3 {
+            return Err("not enough arguments");
+        }
+
+        let query = &args[1];
+        let file_path = &args[2];
+        let ignore_case = env::var("IGNORE_CASE").is_ok();
+
+        Ok(Self {
+            query,
+            file_path,
+            ignore_case,
+        })
+    }
+}
+
+pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
+    let contents = fs::read_to_string(config.file_path)?;
+
+    let iter = if config.ignore_case {
+        search_case_insensitive(config.query, &contents)
+    } else {
+        search(config.query, &contents)
+    };
+
+    iter.into_iter().for_each(|line| println!("{line}"));
+
+    Ok(())
+}
+
+pub fn search<'a>(query: &'a str, contents: &'a str) -> Vec<&'a str> {
+    contents
+        .lines()
+        .filter(|line| line.contains(query))
+        .collect()
+}
+
+pub fn search_case_insensitive<'a>(query: &'a str, contents: &'a str) -> Vec<&'a str> {
+    let query = query.to_lowercase();
+    contents
+        .lines()
+        .filter(|line| line.to_lowercase().contains(&query))
+        .collect()
+}
+
+#[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));
+    }
+
+    // 大小写敏感的测试用例
+    #[test]
+    fn case_sensitive() {
+        let query = "duct";
+        let contents = "\
+Rust:
+safe, fast, productive.
+Pick three.
+Duct tape.";
+
+        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
+    }
+
+    // 大小写不敏感的测试用例
+    #[test]
+    fn case_insensitive() {
+        let query = "rUsT";
+        let contents = "\
+Rust:
+safe, fast, productive.
+Pick three.
+Trust me.
+        ";
+
+        assert_eq!(
+            vec!["Rust:", "Trust me."],
+            search_case_insensitive(query, contents)
+        );
+    }
+}

src/main.rs

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+use minigrep::{Config, run};
+use std::env;
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    let config = Config::build(&args).unwrap_or_else(|err| {
+        println!("Problem parse arguments: {err}");
+        std::process::exit(1);
+    });
+
+    if let Err(err) = run(config) {
+        eprintln!("Application error: {err}");
+        std::process::exit(1);
+    }
+}