Add a .String() method

2 files changed, 27 insertions, 0 deletions

diff --git a/deque.go b/deque.go
index e267eba..4eec0e6 100644
--- a/deque.go
+++ b/deque.go
@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"iter"
 	"slices"
+	"strings"
 )
 
 // Deque is a double-ended queue. The zero value is ready for use.
@@ -190,3 +191,17 @@ func (q *Deque[T]) PopAll() iter.Seq[T] {
 		}
 	}
 }
+
+// String displays the deque as a string, using fmt.Sprint to show each element.
+func (q *Deque[T]) String() string {
+	buf := new(strings.Builder)
+	buf.WriteString("[")
+	for i := range len(q.buf) {
+		if i > 0 {
+			buf.WriteString(" ")
+		}
+		fmt.Fprint(buf, q.buf[:cap(q.buf)][q.toPhysicalIdx(i)])
+	}
+	buf.WriteString("]")
+	return buf.String()
+}
diff --git a/deque_test.go b/deque_test.go
index d3ea63c..27ae232 100644
--- a/deque_test.go
+++ b/deque_test.go
@@ -285,3 +285,15 @@ func TestPopAll(t *testing.T) {
 		})
 	}
 }
+
+func TestString(t *testing.T) {
+	t.Parallel()
+
+	in := []int{1, 2, 3, 4, 5}
+	q := From(in)
+	const want = "[1 2 3 4 5]"
+	got := q.String()
+	if got != want {
+		t.Errorf("%d: String() = %q, want %q", in, got, want)
+	}
+}