xiaokang/
lib.rs

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//! # My Crate
//!
//! `my_crate` is a collection of utilities to make performing certain
//! calculations more convenient.
use std::fs;
use std::env;
use std::error::Error;


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);
    }
    return Ok(());
}

pub struct Config {
    pub query: String,
    pub filename: String,
    pub case_sensitive: bool,
}

impl Config {
    pub fn new(mut args: std::env::Args) -> Result<Config, &'static str> {
        args.next();
        let query = match args.next() {
            Some(args) => args,
            None => return Err("Didn't get a query string")
        };
        let filename = match args.next() {
            Some(args) => args,
            None => return Err("Didn't get a file name")
        };
        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();

        return Ok(Config{query, filename, case_sensitive});
    }
}



/// Adds one to the number given.
///
/// # Examples
///
/// ```
/// let arg = 5;
/// let answer = my_crate::add_one(arg);
///
/// assert_eq!(6, answer);
/// ```

pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents.lines()
    .filter(|line| line.contains(query))
    .collect()
}
pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let query = query.to_lowercase();

    contents.lines()
    .filter(|line| line.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))
    }
    #[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)
        );
    }
}