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#[macro_use] extern crate easy_csv_derive; extern crate csv; pub trait CSVParsable<T> { fn parse_header<R: std::io::Read>(reader: &mut csv::Reader<R>) -> Vec<usize>; fn parse_row<R: std::io::Read>( reader: &mut csv::StringRecords<R>, col_indices: &Vec<usize>) -> Option<T>; } pub struct CSVIterator<'a, T, R> where T: CSVParsable<T>, R: 'a, R: std::io::Read { records: csv::StringRecords<'a, R>, col_indices: Vec<usize>, _marker: std::marker::PhantomData<T> } impl<'a, T, R> CSVIterator<'a, T, R> where T: CSVParsable<T>, R: 'a, R: std::io::Read { pub fn new(mut reader: &'a mut csv::Reader<R>) -> Self { let col_indices = T::parse_header(&mut reader); CSVIterator { records: reader.records::<'a>(), col_indices: col_indices, _marker: std::marker::PhantomData::<T> {} } } } impl<'a, T, R> Iterator for CSVIterator<'a, T, R> where T: CSVParsable<T>, R: std::io::Read { type Item=T; fn next(&mut self) -> Option<Self::Item> { T::parse_row(&mut self.records, &self.col_indices) } } #[test] fn test() { #[derive(Debug,CSVParsable,PartialEq)] struct Record { a: u32, b: i32 } let mut rdr = csv::Reader::from_file("./test_input/test.csv").unwrap(); let iter = CSVIterator::<Record,_>::new(&mut rdr); let res : Vec<Record> = iter.collect(); assert_eq!(res, vec![Record { a: 2, b: -3 }]); }