From 2f54da4d4344181c5fd6a22b1f03713601ae748e Mon Sep 17 00:00:00 2001
From: Shiming Zhang <wzshiming@foxmail.com>
Date: Thu, 10 Nov 2022 19:19:44 +0800
Subject: [PATCH] Add String

---
 llrb/llrb_string.go      | 74 ++++++++++++++++++++++++++++++++++++++++
 llrb/llrb_string_test.go | 32 +++++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100644 llrb/llrb_string.go
 create mode 100644 llrb/llrb_string_test.go

diff --git a/llrb/llrb_string.go b/llrb/llrb_string.go
new file mode 100644
index 0000000..836dec3
--- /dev/null
+++ b/llrb/llrb_string.go
@@ -0,0 +1,74 @@
+package llrb
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+)
+
+func (t *LLRB) String() string {
+	buf := bytes.NewBuffer(nil)
+	fprintNodes(buf, t.root, edges{}, edgeRoot)
+	return buf.String()
+}
+
+func fprintNodes(wr io.Writer, n *Node, pre edges, edge edge) {
+	if n == nil {
+		return
+	}
+
+	{
+		es := edgeSpace
+		if edge == edgeRight {
+			es = edgeLink
+		}
+		fprintNodes(wr, n.Left, append(pre, es), edgeLeft)
+	}
+
+	fmt.Fprintf(wr, "%s %v\n", append(pre, edge), n.Item)
+
+	{
+		es := edgeSpace
+		if edge == edgeLeft {
+			es = edgeLink
+		}
+		fprintNodes(wr, n.Right, append(pre, es), edgeRight)
+	}
+}
+
+type edges []edge
+
+func (e edges) String() string {
+	buf := make([]rune, 0, len(e))
+	for _, v := range e {
+		buf = append(buf, []rune(v.String())...)
+	}
+	return string(buf)
+}
+
+type edge uint
+
+const (
+	_ = edge(iota)
+	edgeSpace
+	edgeLink
+	edgeRoot
+	edgeLeft
+	edgeRight
+)
+
+var edgeMap = map[edge]string{
+	edgeSpace: `  `,
+	edgeLink:  ` │`,
+	edgeRoot:  `───`,
+	edgeLeft:  ` ┌─`,
+	edgeRight: ` └─`,
+}
+
+func (e edge) String() string {
+	v, ok := edgeMap[e]
+	if ok {
+		return v
+	}
+	return ""
+}
diff --git a/llrb/llrb_string_test.go b/llrb/llrb_string_test.go
new file mode 100644
index 0000000..29e3790
--- /dev/null
+++ b/llrb/llrb_string_test.go
@@ -0,0 +1,32 @@
+package llrb
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestString(t *testing.T) {
+	tree := New()
+	for i := 0; i != 10; i++ {
+		tree.InsertNoReplace(Int(i))
+	}
+
+	want := `
+     ┌─ 0
+   ┌─ 1
+   │ └─ 2
+─── 3
+   │   ┌─ 4
+   │ ┌─ 5
+   │ │ └─ 6
+   └─ 7
+     │ ┌─ 8
+     └─ 9
+`
+	want = want[1:]
+	got := tree.String()
+	if got != want {
+		t.Errorf("the output is not expected")
+		fmt.Printf("got:\n%s\nwant:\n%s\n", got, want)
+	}
+}