Simple utilities to track and compute averages and maximums

I use these when reading in PSML column data. The average length and
maximum length of a column are passed as configuration to the table that
displays the data. A rendered column will use no more than the column
maximum number of cells, and if that number of cells is not
available (e.g. on a narrower terminal), then the width of the column
will be determined by the column's average in proportion to the other
displayed columns' averages or rendered widths.

pcap/utils.go

@@ -0,0 +1,48 @@
+// Copyright 2019-2021 Graham Clark. All rights reserved.  Use of this source
+// code is governed by the MIT license that can be found in the LICENSE
+// file.
+
+package pcap
+
+import (
+	"github.com/gcla/gowid/gwutil"
+)
+
+//======================================================================
+
+type averageTracker struct {
+	count uint64
+	total uint64
+}
+
+func (a averageTracker) average() gwutil.IntOption {
+	if a.count == 0 {
+		return gwutil.NoneInt()
+	}
+	return gwutil.SomeInt(int(a.total / a.count))
+}
+
+func (a *averageTracker) update(more int) {
+	a.count += 1
+	a.total += uint64(more)
+}
+
+type maxTracker struct {
+	cur int
+}
+
+func (a maxTracker) max() int {
+	return a.cur
+}
+
+func (a *maxTracker) update(candidate int) {
+	if candidate > a.cur {
+		a.cur = candidate
+	}
+}
+
+//======================================================================
+// Local Variables:
+// mode: Go
+// fill-column: 78
+// End: