minigrep-dalingtao 0.1.1

//!
//! This mod implement grep main logic
//! 

use std::fs;
use std::error::Error;

pub struct Config<'a> {
    pattern: &'a String, 
    filename: &'a String,
}

#[derive(Debug)]
#[derive(PartialEq)]
pub struct Row {
    row: String,
    row_num: usize
}

impl Row {
    pub fn new(row: String, row_num: usize) -> Self {
        Row{row, row_num}
    }
}
impl ToString for Row {
    fn to_string(&self) -> String {
        format!("{} : {}", self.row_num, self.row)
    }
}

impl<'a> Config<'a> {
    pub fn new(pattern: &'a String, filename: &'a String) -> Self {
        Config { pattern, filename }
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = dbg!(fs::read_to_string(config.filename)?);
    let rows = filter(config.pattern, &contents);
    for row in rows.iter() {
        println!("{}", row.to_string());
    }
    Ok(())
}

///
/// process content and filter out all the rows with specified pattern
/// 
/// # Examples
/// 
/// ```
/// let ans = minigrep_dalingtao::filter(&"123".to_string(), &"123\r\n456".to_string());
/// assert_eq!(vec![minigrep_dalingtao::Row::new("123".to_string(), 0)], ans);
/// ```
/// 
pub fn filter(pattern: &String, content: &String) -> Vec<Row> {
    let res: Vec<Row> = content.split("\r\n").enumerate().filter(|(index, row)| {
        row.contains(pattern)
    })
    .map(|(index, row)| { Row::new(row.to_string(), index) })
    .collect();
    res
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn filter_test() {
        let ret = filter(&"human".to_string(), &"I'm a human\r\nI will never die".to_string());
        assert_eq!(ret, vec![Row{row_num: 0, row: "I'm a human".to_string()}]);
    }
}