Add minigrep example

minigrep/src/lib.rs

@@ -0,0 +1,101 @@
+use std::env;
+use std::error::Error;
+use std::fs;
+
+pub struct Config {
+    pub query: String,
+    pub filename: String,
+    pub case_sensitive: bool,
+}
+
+impl Config {
+    pub fn new(args: &[String]) -> Result<Config, &'static str> {
+        if args.len() < 3 {
+            return Err("Not enough arguments");
+        }
+
+        let query = args[1].clone();
+        let filename = args[2].clone();
+
+        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();
+
+        Ok(Config {
+            query,
+            filename,
+            case_sensitive,
+        })
+    }
+}
+
+pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
+    let contents = fs::read_to_string(config.filename)?;
+
+    let results = if config.case_sensitive {
+        search(&config.query, &contents)
+    } else {
+        search_case_insensitive(&config.query, &contents)
+    };
+
+    for line in results {
+        println!("{}", line);
+    }
+
+    Ok(())
+}
+
+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 query = query.to_lowercase();
+    let mut results = Vec::new();
+
+    for line in contents.lines() {
+        if line.to_lowercase().contains(&query) {
+            results.push(line);
+        }
+    }
+
+    results
+}
+
+#[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)
+        );
+    }
+}

minigrep/src/main.rs

@@ -0,0 +1,21 @@
+use std::env;
+use std::process;
+
+use minigrep::Config;
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    let config = Config::new(&args).unwrap_or_else(|err| {
+        eprintln!("Problem parsing arguments: {}", err);
+        process::exit(1);
+    });
+
+    println!("Searching for {}", config.query);
+    println!("In file {}", config.filename);
+
+    if let Err(e) = minigrep::run(config) {
+        eprintln!("Application error: {}", e);
+
+        process::exit(1);
+    }
+}