Sort column counts

[tablify] / src / lib.rs

diff --git a/src/lib.rs b/src/lib.rs
index e90f66b37f2359542bad445064f86ea1ee2ec6ad..fcf5dc822e790b15b377e6c154669f6b07524c71 100644 (file)
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,5 @@
 #[cfg(test)]
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 #[cfg(test)]
 use std::io::BufRead;
 #[cfg(test)]
@@ -69,16 +69,21 @@ fn read_rows(input: impl std::io::Read) -> impl Iterator<Item = Result<RowInput,
 }
 
 #[cfg(test)]
-fn column_counts(rows: &[RowInput]) -> HashMap<String, usize> {
-    rows.iter()
-        .flat_map(|r| r.entries.iter())
-        .fold(HashMap::new(), |mut counts, e| {
-            counts
-                .entry(String::from(e))
-                .and_modify(|c| *c += 1)
+fn column_counts(rows: &[RowInput]) -> Vec<(usize, String)> {
+    let mut counts: Vec<_> = rows
+        .iter()
+        .flat_map(|r| r.entries.iter().collect::<HashSet<_>>().into_iter())
+        .fold(HashMap::new(), |mut cs, e| {
+            cs.entry(String::from(e))
+                .and_modify(|n| *n += 1)
                 .or_insert(1);
-            counts
+            cs
         })
+        .into_iter()
+        .map(|(col, n)| (n, col))
+        .collect();
+    counts.sort();
+    counts
 }
 
 pub fn tablify(_input: &impl std::io::Read) -> String {
@@ -191,7 +196,7 @@ mod tests {
                     .collect::<Result<Vec<_>, _>>()
                     .unwrap()
             ),
-            HashMap::from([(String::from("bar"), 1), (String::from("baz"), 1)])
+            vec![(1, String::from("bar")), (1, String::from("baz"))]
         );
         assert_eq!(
             column_counts(
@@ -199,7 +204,15 @@ mod tests {
                     .collect::<Result<Vec<_>, _>>()
                     .unwrap()
             ),
-            HashMap::from([(String::from("bar"), 1), (String::from("baz"), 2)])
+            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::<Result<Vec<_>, _>>()
+                    .unwrap()
+            ),
+            vec![(1, String::from("bar")), (2, String::from("baz"))]
         );
     }
 }