ecpp17cc.rs

//! ```cargo
//! [dependencies]
//! clap = "2"
//! csv = "0.15"
//! error-chain = "0.11"
//! ```

#[macro_use] extern crate clap;
extern crate csv;
#[macro_use] extern crate error_chain;

use std::io;

error_chain! {
    foreign_links {
        Io(io::Error);
        Csv(csv::Error);
    }
}

quick_main!(|| -> Result<i32> {
    let matches = clap_app! { ecpp17ccrs =>
        (author: "Steve Klabnik, Alex Burka")
        (about: "Expressive C++17 Coding Challenge -- in Rust!")

        (@arg INPUT: +required "Input CSV file")
        (@arg COL: +required "Column to replace")
        (@arg REP: +required "Replacement value")
        (@arg OUTPUT: +required "Output CSV file")
    }.get_matches();

    let filename = matches.value_of("INPUT").unwrap();
    let column_name = matches.value_of("COL").unwrap();
    let replacement = matches.value_of("REP").unwrap();
    let output_filename = matches.value_of("OUTPUT").unwrap();

    let mut input = csv::Reader::from_file(filename)?;
    let mut output = csv::Writer::from_file(output_filename)?;

    let headers = input.headers()?;
    if headers.is_empty() {
        bail!("input file missing");
    }
    let col_to_replace = headers.iter()
                                .position(|e| e == column_name)
                                .ok_or("column name doesn't exist in the input file")?;
    output.encode(headers)?;
    for row in input.records() {
        let mut row = row?;
        row[col_to_replace] = replacement.into();
        output.encode(row)?;
    }

    Ok(0)
});