From f1e8040bc33e9057bd7a756a09c431c3f0d86226 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Tue, 12 Jul 2022 23:52:37 -0600
Subject: Add an `Ordered` interface for the Cmp method, have rbtree use it

---
 lib/rbtree/rbtree.go      | 15 ++++-----------
 lib/rbtree/rbtree_test.go | 22 +++++++++++++---------
 2 files changed, 17 insertions(+), 20 deletions(-)

(limited to 'lib/rbtree')

diff --git a/lib/rbtree/rbtree.go b/lib/rbtree/rbtree.go
index 0353e75..575a9ca 100644
--- a/lib/rbtree/rbtree.go
+++ b/lib/rbtree/rbtree.go
@@ -7,7 +7,7 @@ package rbtree
 import (
 	"fmt"
 
-	"golang.org/x/exp/constraints"
+	"git.lukeshu.com/btrfs-progs-ng/lib/util"
 )
 
 type Color bool
@@ -32,7 +32,7 @@ func (node *Node[V]) getColor() Color {
 	return node.Color
 }
 
-type Tree[K constraints.Ordered, V any] struct {
+type Tree[K util.Ordered[K], V any] struct {
 	KeyFn func(V) K
 	root  *Node[V]
 }
@@ -104,14 +104,7 @@ func (node *Node[V]) search(fn func(V) int) (exact, nearest *Node[V]) {
 func (t *Tree[K, V]) exactKey(key K) func(V) int {
 	return func(val V) int {
 		valKey := t.KeyFn(val)
-		switch {
-		case key < valKey:
-			return -1
-		case key > valKey:
-			return 1
-		default: // key == valKey:
-			return 0
-		}
+		return key.Cmp(valKey)
 	}
 }
 
@@ -282,7 +275,7 @@ func (t *Tree[K, V]) Insert(val V) {
 	}
 	if parent == nil {
 		t.root = node
-	} else if key < t.KeyFn(parent.Value) {
+	} else if key.Cmp(t.KeyFn(parent.Value)) < 0 {
 		parent.Left = node
 	} else {
 		parent.Right = node
diff --git a/lib/rbtree/rbtree_test.go b/lib/rbtree/rbtree_test.go
index 9e9a734..999eb6f 100644
--- a/lib/rbtree/rbtree_test.go
+++ b/lib/rbtree/rbtree_test.go
@@ -10,9 +10,11 @@ import (
 
 	"github.com/stretchr/testify/require"
 	"golang.org/x/exp/constraints"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/util"
 )
 
-func checkTree[K constraints.Ordered, V any](t *testing.T, expectedSet map[K]struct{}, tree *Tree[K, V]) {
+func checkTree[K constraints.Ordered, V any](t *testing.T, expectedSet map[K]struct{}, tree *Tree[util.NativeOrdered[K], V]) {
 	// 1. Every node is either red or black
 
 	// 2. The root is black.
@@ -62,16 +64,16 @@ func checkTree[K constraints.Ordered, V any](t *testing.T, expectedSet map[K]str
 	expectedOrder := make([]K, 0, len(expectedSet))
 	for k := range expectedSet {
 		expectedOrder = append(expectedOrder, k)
-		node := tree.Lookup(k)
+		node := tree.Lookup(util.NativeOrdered[K]{Val: k})
 		require.NotNil(t, tree, node)
-		require.Equal(t, k, tree.KeyFn(node.Value))
+		require.Equal(t, k, tree.KeyFn(node.Value).Val)
 	}
 	sort.Slice(expectedOrder, func(i, j int) bool {
 		return expectedOrder[i] < expectedOrder[j]
 	})
 	actOrder := make([]K, 0, len(expectedSet))
 	require.NoError(t, tree.Walk(func(node *Node[V]) error {
-		actOrder = append(actOrder, tree.KeyFn(node.Value))
+		actOrder = append(actOrder, tree.KeyFn(node.Value).Val)
 		return nil
 	}))
 	require.Equal(t, expectedOrder, actOrder)
@@ -100,8 +102,10 @@ func FuzzTree(f *testing.F) {
 	})
 
 	f.Fuzz(func(t *testing.T, dat []uint8) {
-		tree := &Tree[uint8, uint8]{
-			KeyFn: func(x uint8) uint8 { return x },
+		tree := &Tree[util.NativeOrdered[uint8], uint8]{
+			KeyFn: func(x uint8) util.NativeOrdered[uint8] {
+				return util.NativeOrdered[uint8]{Val: x}
+			},
 		}
 		set := make(map[uint8]struct{})
 		checkTree(t, set, tree)
@@ -114,15 +118,15 @@ func FuzzTree(f *testing.F) {
 				tree.Insert(val)
 				set[val] = struct{}{}
 				t.Logf("\n%s\n", tree.ASCIIArt())
-				node := tree.Lookup(val)
+				node := tree.Lookup(util.NativeOrdered[uint8]{Val: val})
 				require.NotNil(t, node)
 				require.Equal(t, val, node.Value)
 			} else {
 				t.Logf("Delete(%v)", val)
-				tree.Delete(val)
+				tree.Delete(util.NativeOrdered[uint8]{Val: val})
 				delete(set, val)
 				t.Logf("\n%s\n", tree.ASCIIArt())
-				require.Nil(t, tree.Lookup(val))
+				require.Nil(t, tree.Lookup(util.NativeOrdered[uint8]{Val: val}))
 			}
 			checkTree(t, set, tree)
 		}
-- 
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