Add mini_grep: like-grep util for terminal

mini_grep/src/lib.rs

@@ -0,0 +1,101 @@
+use std::env;
+use std::error::Error;
+use std::fs;
+
+pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
+    let contents = fs::read_to_string(&config.file_name)?;
+
+    let results = if config.case_sensitive {
+        search(&config.query, &contents)
+    } else {
+        search_case_insensitive(&config.query, &contents)
+    };
+
+    if results.len() == 0 {
+        eprintln!("Can't find anything.");
+    }
+
+    for line in results {
+        println!("{}", line);
+    }
+
+    Ok(())
+}
+
+pub struct Config {
+    pub query: String,
+    pub file_name: String,
+    pub case_sensitive: bool,
+}
+
+impl Config {
+    pub fn new(args: &[String]) -> Result<Config, &str> {
+        if args.len() < 3 {
+            return Err("No enoght arguments!");
+        }
+
+        let query = args[1].clone();
+        let file_name = args[2].clone();
+        let case_sensitive = env::var("CASE_SENSITIVE").is_err();
+
+        Ok(Config {
+            query: query,
+            file_name: file_name,
+            case_sensitive: case_sensitive,
+        })
+    }
+}
+
+pub 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
+}
+
+pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+    let mut results = Vec::new();
+
+    for line in contents.lines() {
+        if line.to_lowercase().contains(&query.to_lowercase()) {
+            results.push(line);
+        }
+    }
+
+    results
+}
+
+#[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 case_insensitive() {
+        let query = "rUsT";
+        let contents = "\
+Rust:
+safe, fast, productive.
+Trust me.";
+
+        assert_eq!(
+            vec!["Rust:", "Trust me."],
+            search_case_insensitive(query, contents)
+        );
+    }
+}

mini_grep/src/main.rs

@@ -1,3 +1,18 @@
+use std::env;
+use std::process;
+
+use mini_grep::Config;
+
 fn main() {
-    println!("Hello, world!");
+    let args: Vec<String> = env::args().collect();
+
+    let config = Config::new(&args).unwrap_or_else(|err| {
+        eprintln!("Problem parsing arguments: {}", err);
+        process::exit(1);
+    });
+
+    if let Err(e) = mini_grep::run(config) {
+        eprintln!("Application error: {}", e);
+        process::exit(1);
+    }
 }