use std::collections::{HashMap, HashSet};
use std::io::BufRead;
use std::iter::Iterator;
const HEADER: &str = "
";
const FOOTER: &str = "
";
#[derive(Debug, PartialEq, Eq, Hash)]
struct Entry(String);
#[derive(Debug, PartialEq, Eq)]
struct RowInput {
label: String,
entries: Vec,
}
struct Reader>> {
input: std::iter::Enumerate,
row: Option,
}
impl>> Reader {
fn new(input: Input) -> Self {
Self {
input: input.enumerate(),
row: None,
}
}
}
impl>> Iterator for Reader {
type Item = Result;
fn next(&mut self) -> Option {
loop {
match self
.input
.next()
.map(|(n, r)| (n, r.map(|line| String::from(line.trim_end()))))
{
None => return Ok(std::mem::take(&mut self.row)).transpose(),
Some((_, Err(e))) => return Some(Err(e)),
Some((_, Ok(line))) if line.is_empty() && self.row.is_some() => {
return Ok(std::mem::take(&mut self.row)).transpose()
}
Some((_, Ok(line))) if line.is_empty() => {}
Some((n, Ok(line))) if line.starts_with(' ') => match &mut self.row {
None => {
return Some(Err(std::io::Error::other(format!(
"{}: Entry with no header",
n + 1
))))
}
Some(ref mut row) => row.entries.push(Entry(String::from(line.trim()))),
},
Some((_, Ok(line))) => {
let prev = std::mem::take(&mut self.row);
self.row = Some(RowInput {
label: line,
entries: vec![],
});
if prev.is_some() {
return Ok(prev).transpose();
}
}
}
}
}
}
fn read_rows(input: impl std::io::Read) -> impl Iterator- > {
Reader::new(std::io::BufReader::new(input).lines())
}
fn column_counts(rows: &[RowInput]) -> Vec<(usize, String)> {
let mut counts: Vec<_> = rows
.iter()
.flat_map(|r| r.entries.iter().collect::>().into_iter())
.fold(HashMap::new(), |mut cs, e| {
cs.entry(String::from(&e.0))
.and_modify(|n| *n += 1)
.or_insert(1);
cs
})
.into_iter()
.map(|(col, n)| (n, col))
.collect();
counts.sort();
counts
}
/// # Errors
///
/// Will return `Err` if
/// * there's an i/o error while reading `input`
/// * the log has invalid syntax:
/// * an indented line with no preceding non-indented line
pub fn tablify(input: impl std::io::Read) -> Result {
let rows = read_rows(input).collect::, _>>()?;
let _columns = column_counts(&rows);
Ok(String::from(HEADER) + "Hello, world!" + FOOTER)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_read_rows() {
assert_eq!(
read_rows(&b"foo"[..]).flatten().collect::>(),
vec![RowInput {
label: String::from("foo"),
entries: vec![]
}]
);
assert_eq!(
read_rows(&b"bar"[..]).flatten().collect::>(),
vec![RowInput {
label: String::from("bar"),
entries: vec![]
}]
);
assert_eq!(
read_rows(&b"foo\nbar\n"[..]).flatten().collect::>(),
vec![
RowInput {
label: String::from("foo"),
entries: vec![]
},
RowInput {
label: String::from("bar"),
entries: vec![]
}
]
);
assert_eq!(
read_rows(&b"foo\n bar\n"[..]).flatten().collect::>(),
vec![RowInput {
label: String::from("foo"),
entries: vec![Entry(String::from("bar"))]
}]
);
assert_eq!(
read_rows(&b"foo\n bar\n baz\n"[..])
.flatten()
.collect::>(),
vec![RowInput {
label: String::from("foo"),
entries: vec![Entry(String::from("bar")), Entry(String::from("baz"))]
}]
);
assert_eq!(
read_rows(&b"foo\n\nbar\n"[..])
.flatten()
.collect::>(),
vec![
RowInput {
label: String::from("foo"),
entries: vec![]
},
RowInput {
label: String::from("bar"),
entries: vec![]
}
]
);
assert_eq!(
read_rows(&b"foo\n \nbar\n"[..])
.flatten()
.collect::>(),
vec![
RowInput {
label: String::from("foo"),
entries: vec![]
},
RowInput {
label: String::from("bar"),
entries: vec![]
}
]
);
assert_eq!(
read_rows(&b"foo \n bar \n"[..])
.flatten()
.collect::>(),
vec![RowInput {
label: String::from("foo"),
entries: vec![Entry(String::from("bar"))]
}]
);
let bad = read_rows(&b" foo"[..]).next().unwrap();
assert!(bad.is_err());
assert!(format!("{bad:?}").contains("1: Entry with no header"));
let bad2 = read_rows(&b"foo\n\n bar"[..]).nth(1).unwrap();
assert!(bad2.is_err());
assert!(format!("{bad2:?}").contains("3: Entry with no header"));
}
#[test]
fn test_column_counts() {
assert_eq!(
column_counts(
&read_rows(&b"foo\n bar\n baz\n"[..])
.collect::, _>>()
.unwrap()
),
vec![(1, String::from("bar")), (1, String::from("baz"))]
);
assert_eq!(
column_counts(
&read_rows(&b"foo\n bar\n baz\nquux\n baz"[..])
.collect::, _>>()
.unwrap()
),
vec![(1, String::from("bar")), (2, String::from("baz"))]
);
assert_eq!(
column_counts(
&read_rows(&b"foo\n bar\n bar\n baz\n bar\nquux\n baz"[..])
.collect::, _>>()
.unwrap()
),
vec![(1, String::from("bar")), (2, String::from("baz"))]
);
}
}