Merge pull request #1411 from jqnatividad/count-optimize-width

`count`: optimize `--width` option

src/cmd/count.rs

@@ -92,17 +92,27 @@ fn count_input(
     let mut rdr = conf.reader()?;
     let mut count = 0_u64;
     let mut max_width = 0_usize;
-    let mut record_numfields = 0_usize;
+    let mut record_numdelimiters = 0_usize;
     let mut record = csv::ByteRecord::new();
 
     if compute_width {
         let mut curr_width;
+
+        // read the first record to get the number of delimiters
+        // and the width of the first record
+        rdr.read_byte_record(&mut record)?;
+        max_width = record.as_slice().len();
+        count = 1;
+
+        // number of delimiters is number of fields minus 1
+        // we subtract 1 because the last field doesn't have a delimiter
+        record_numdelimiters = record.len().saturating_sub(1);
+
         while rdr.read_byte_record(&mut record)? {
             count += 1;
 
             curr_width = record.as_slice().len();
             if curr_width > max_width {
-                record_numfields = record.len();
                 max_width = curr_width;
             }
         }
@@ -111,7 +121,7 @@ fn count_input(
             count += 1;
         }
     }
-    // record_numfields is a count of the delimiters
+    // record_numdelimiters is a count of the delimiters
     // which we also want to count when returning width
-    Ok((count, max_width + record_numfields))
+    Ok((count, max_width + record_numdelimiters))
 }

tests/test_count.rs

@@ -26,16 +26,18 @@ fn count_width() {
     wrk.create_indexed(
         "in.csv",
         vec![
-            svec!["letter", "number"],
-            svec!["alpha", "13"],
-            svec!["beta", "24"],
+            svec!["letter", "number", "flag"],
+            svec!["alphabetic", "13", "true"],
+            svec!["beta", "24", "false"],
+            svec!["gamma", "37.1", "true"],
+            svec!("delta", "42.5", "false"),
         ],
     );
     let mut cmd = wrk.command("count");
     cmd.arg("--width").arg("in.csv");
 
     let got: String = wrk.stdout(&mut cmd);
-    let expected = "2;9";
+    let expected = "4;18";
     assert_eq!(got, expected.to_string());
 }