Dump non-zero len and cap for applicable types.

Closes #16.

1 files changed, 26 insertions, 0 deletions

diff --git a/spew/dump.go b/spew/dump.go
index 3d57306..02d4c9d 100644
--- a/spew/dump.go
+++ b/spew/dump.go
@@ -270,6 +270,32 @@ func (d *dumpState) dump(v reflect.Value) {
 	}
 	d.ignoreNextType = false
 
+	// Display length and capacity if the built-in len and cap functions
+	// work with the value's kind and the len/cap itself is non-zero.
+	valueLen, valueCap := 0, 0
+	switch v.Kind() {
+	case reflect.Array, reflect.Slice, reflect.Chan:
+		valueLen, valueCap = v.Len(), v.Cap()
+	case reflect.Map, reflect.String:
+		valueLen = v.Len()
+	}
+	if valueLen != 0 || valueCap != 0 {
+		d.w.Write(openParenBytes)
+		if valueLen != 0 {
+			d.w.Write(lenEqualsBytes)
+			printInt(d.w, int64(valueLen), 10)
+		}
+		if valueCap != 0 {
+			if valueLen != 0 {
+				d.w.Write(spaceBytes)
+			}
+			d.w.Write(capEqualsBytes)
+			printInt(d.w, int64(valueCap), 10)
+		}
+		d.w.Write(closeParenBytes)
+		d.w.Write(spaceBytes)
+	}
+
 	// Call Stringer/error interfaces if they exist and the handle methods flag
 	// is enabled
 	if !d.cs.DisableMethods {