Bug in Row implementation with regex matching

[antmelon]

Performing a row filter with a regex that does not exist in CSV file will panic and crash

impl Row {
    pub fn subset(&self, indices: &[usize]) -> Row {
        let mut subfields = vec![];
        for i in indices {
            subfields.push(self.fields.get(*i).unwrap().clone());
        }
        Row {
            record_num: self.record_num,
            fields: subfields,
        }
    }

    fn empty() -> Row {
        Row {
            record_num: 0,
            fields: vec![],
        }
    }
}

the for loop in subset will try to unwrap a None value and crash

[YS-L]

The subset method is intended for filtering columns rather than rows. The indices used are generated here:

csvlens/src/view.rs

Lines 41 to 51 in 29e46af

	let mut indices = vec![];
	let mut filtered_headers: Vec<String> = vec![];
	for (i, header) in headers.iter().enumerate() {
	if pattern.is_match(header) {
	indices.push(i);
	filtered_headers.push(header.clone());
	}
	}
	let disabled_because_no_match;
	if indices.is_empty() {
	indices = (0..headers.len()).collect();

This logic ensures the indices are always valid.

Applying a row filter doesn't trigger these code paths. Have you been able to reproduce the panic? Sharing a traceback could help identify any underlying cause.

[antmelon]

The issue happens when there are rows with different numbers of columns.
foo.csv

When filtering on a column that is present for all rows, there are no issues. When filtering on a column that is either out of bounds of some rows, or not present in any, the following error is received:

thread 'main' panicked at /home/alongo/.cargo/registry/src/index.crates.io-6f17d22bba15001f/csvlens-0.10.1/src/csv.rs:96:48:
called `Option::unwrap()` on a `None` value
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: core::option::unwrap_failed
   4: csvlens::csv::Row::subset
   5: csvlens::view::RowsView::do_get_rows
   6: csvlens::view::RowsView::set_columns_filter
   7: csvlens::app::App::set_columns_filter
   8: csvlens::app::App::main_loop
   9: csvlens::runner::AppRunner::run
  10: csvlens::runner::run_csvlens
  11: csvlens::main

The change made in #112 resolves this issue and allows filtering on all columns. If the column is not present in any row, it functions as normal and continues to show all columns