csvsc 2.2.1

Build processing chains for CSV files
Documentation 
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use crate::{Headers, RowStream, RowResult, Error};

pub struct FilterCol<I, F> {
    iter: I,
    f: F,
    colname: String,
    headers: Headers,
}

impl<I, F> FilterCol<I, F>
where
    I: RowStream,
    F: Fn(&str) -> bool,
{
    pub fn new(
        iter: I,
        colname: String,
        f: F,
    ) -> Result<FilterCol<I, F>, Error> {
        let headers = iter.headers().clone();

        if !headers.contains_key(&colname) {
            return Err(Error::ColumnNotFound(colname));
        }

        Ok(FilterCol {
            iter,
            f,
            colname,
            headers,
        })
    }
}

pub struct IntoIter<I, F> {
    iter: I,
    f: F,
    colname: String,
    headers: Headers,
}

impl<I, F> Iterator for IntoIter<I, F>
where
    I: Iterator<Item = RowResult>,
    F: Fn(&str) -> bool,
{
    type Item = RowResult;

    fn next(&mut self) -> Option<Self::Item> {
        for rs in self.iter.by_ref() {
            match rs {
                Ok(row) => if let Some(val) = self.headers.get_field(&row, &self.colname) {
                    if (self.f)(val) {
                        return Some(Ok(row));
                    }
                } else {
                    return Some(Err(Error::ColumnNotFound(self.colname.clone())));
                }
                Err(e) => return Some(Err(e)),
            }
        }

        None
    }
}

impl<I, F> IntoIterator for FilterCol<I, F>
where
    I: RowStream,
    F: Fn(&str) -> bool,
{
    type Item = RowResult;

    type IntoIter = IntoIter<I::IntoIter, F>;

    fn into_iter(self) -> Self::IntoIter {
        Self::IntoIter {
            iter: self.iter.into_iter(),
            f: self.f,
            colname: self.colname,
            headers: self.headers,
        }
    }
}

impl<I, F> RowStream for FilterCol<I, F>
where
    I: RowStream,
    F: Fn(&str) -> bool,
{
    fn headers(&self) -> &Headers {
        &self.headers
    }
}

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

    use crate::{Row, MockStream, error};

    #[test]
    fn test_filter() {
        let iter = MockStream::from_rows(
            vec![
                Ok(Row::from(vec!["a", "b"])),
                Ok(Row::from(vec!["1", "2"])),
                Ok(Row::from(vec!["2", "7"])),
                Err(error::Error::InconsistentHeaders),
                Ok(Row::from(vec!["1", "1"])),
                Ok(Row::from(vec!["2", "9"])),
            ]
            .into_iter(),
        )
        .unwrap();

        let mut r = FilterCol::new(iter, "b".into(), |value| {
            value.parse::<i32>().unwrap() > 2
        }).unwrap()
            .into_iter();

        assert!(r.next().unwrap().is_ok());
        assert!(r.next().unwrap().is_err());
        assert!(r.next().unwrap().is_ok());
        assert!(r.next().is_none());
    }
}