complated all feature mini-grep

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "minigrep"
+version = "0.1.0"

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?
+Are you nobody, too?
+Then there's a pair of us - don't tell!
+They'd banish us, you know.
+
+How dreary to be somebody!
+How public, like a frog
+To tell your name the livelong day
+To an admiring bog!

src/lib.rs

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+use std::error::Error;
+use std::{env, fs};
+pub struct Config {
+    query: String,
+    file_path: String,
+    ignore_case: bool,
+}
+impl Config {
+    // Create a new Result<Config>,
+    // parse config from args 's iter.
+    pub fn build(mut args: impl Iterator<Item = String>) -> Result<Config, &'static str> {
+        args.next();
+        let query = match args.next() {
+            Some(args) => args,
+            None => return Err("Please provide a query string"),
+        };
+        let file_path = match args.next() {
+            Some(args) => args,
+            None => return Err("Please provide a file path")
+        };
+        let ignore_case = env::var("IGNORE_CASE").is_ok();
+        Ok(Config {
+            query,
+            file_path,
+            ignore_case,
+        })
+    }
+}
+pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
+    // println!("Query: {}", config.query);
+    // println!("File path: {}", config.file_path);
+    // Read the file,if it not exists, return an error(Box<dyn Error>)
+    let contents = fs::read_to_string(config.file_path)?;
+    let result = if config.ignore_case {
+        search_case_insensitive(&config.query, &contents)
+    } else {
+        search(&config.query, &contents)
+    };
+    for line in result {
+        println!("{line}")
+    }
+    // print!("File contents: \n{}", contents);
+    Ok(())
+}
+fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+    // let mut results = Vec::new();
+    // for line in contents.lines() {
+    //     if line.contains(query) {
+    //         results.push(line);
+    //     }
+    // }
+    // results
+    contents.lines()
+    .filter(|line| line.contains(query))
+    .collect()
+}
+fn search_case_insensitive<'a>(query: &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 case_sensitive() {
+        let query = "duct";
+        let contents = "\
+Rust:
+safe, fast, productive.
+Pick three.
+Duct tape.";
+
+        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
+    }
+
+    #[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 std::env as ENV;
+use std::process;
+fn main() {
+    println!("-------------Grep Cli Tool-------------");
+    println!("Usage : grep <query> <file_path>");
+    println!("------------------End------------------");
+    // let config = minigrep::Config::new(ENV::args());
+    let config = minigrep::Config::build(ENV::args()).unwrap_or_else(|err| {
+        eprintln!("Problem parsing arguments: {err}");
+        process::exit(1);
+    });
+    if let Err(e) = minigrep::run(config) {
+        println!("Application error: {}", e);
+        process::exit(1);
+    };
+}