dsv 0.13.0

dsv (Data Swiss Knife) — a high-performance CSV, Parquet, and JSONL CLI toolkit. Modern xsv fork with all 33 community PRs merged.
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use csv;

use crate::config::{Config, Delimiter};
use crate::select::SelectColumns;
use crate::CliResult;
use clap::Parser;

#[derive(Parser, Debug)]
pub struct Args {
    #[arg()]
    pub arg_selection: SelectColumns,
    #[arg()]
    pub arg_input: Option<String>,
    #[arg(short = 'o', long = "output", value_name = "file")]
    pub flag_output: Option<String>,
    #[arg(short = 'n', long = "no-headers")]
    pub flag_no_headers: bool,
    #[arg(short = 'd', long = "delimiter", value_name = "arg")]
    pub flag_delimiter: Option<Delimiter>,
}

pub fn run(args: &Args) -> CliResult<()> {
    let rconfig = Config::new(&args.arg_input)
        .delimiter(args.flag_delimiter)
        .no_headers(args.flag_no_headers)
        .select(args.arg_selection.clone());

    let mut rdr = rconfig.reader()?;
    let mut wtr = Config::new(&args.flag_output).writer()?;

    let headers = rdr.byte_headers()?.clone();
    let sel = rconfig.selection(&headers)?;

    if !rconfig.no_headers {
        wtr.write_record(sel.iter().map(|&i| &headers[i]))?;
    }
    let mut record = csv::ByteRecord::new();
    while rdr.read_byte_record(&mut record)? {
        wtr.write_record(sel.iter().map(|&i| &record[i]))?;
    }
    wtr.flush()?;
    Ok(())
}