use std::collections::HashSet;
use csv;
use config::{Config, Delimiter};
use select::SelectColumns;
use util;
use CliResult;
static USAGE: &str = "
Deduplicate the rows of a CSV file. Runs in O(n) time, consuming O(c) memory, c being
the distinct number of row identities.
If your file is already sorted on the deduplication selection, use the -S/--sorted flag
to run in O(1) memory instead.
Usage:
xan dedup [options] [<input>]
xan dedup --help
dedup options:
-s, --select <arg> Select a subset of columns to on which to deduplicate.
See 'xan select --help' for the format details.
-S, --sorted Use if you know your file is already sorted on the deduplication
selection to avoid storing unique values in memory.
Common options:
-h, --help Display this message
-o, --output <file> Write output to <file> instead of stdout.
-n, --no-headers When set, the first row will not be evaled
as headers.
-d, --delimiter <arg> The field delimiter for reading CSV data.
Must be a single character. [default: ,]
";
#[derive(Deserialize)]
struct Args {
arg_input: Option<String>,
flag_select: SelectColumns,
flag_no_headers: bool,
flag_output: Option<String>,
flag_delimiter: Option<Delimiter>,
flag_sorted: bool,
}
type DeduplicationKey = Vec<Vec<u8>>;
pub fn run(argv: &[&str]) -> CliResult<()> {
let args: Args = util::get_args(USAGE, argv)?;
let rconf = Config::new(&args.arg_input)
.delimiter(args.flag_delimiter)
.no_headers(args.flag_no_headers)
.select(args.flag_select);
let mut rdr = rconf.reader()?;
let sel = rconf.selection(rdr.byte_headers()?)?;
let mut wtr = Config::new(&args.flag_output).writer()?;
rconf.write_headers(&mut rdr, &mut wtr)?;
let mut record = csv::ByteRecord::new();
if !args.flag_sorted {
let mut already_seen = HashSet::<DeduplicationKey>::new();
while rdr.read_byte_record(&mut record)? {
let key = sel.collect(&record);
if already_seen.insert(key) {
wtr.write_byte_record(&record)?;
}
}
} else {
let mut current: Option<DeduplicationKey> = None;
while rdr.read_byte_record(&mut record)? {
let key = sel.collect(&record);
match current {
None => {
wtr.write_byte_record(&record)?;
current = Some(key);
}
Some(current_key) if current_key != key => {
wtr.write_byte_record(&record)?;
current = Some(key);
}
_ => (),
};
}
}
Ok(wtr.flush()?)
}