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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package containers
import (
"fmt"
"io"
"sort"
"strings"
"testing"
"github.com/stretchr/testify/require"
"golang.org/x/exp/constraints"
)
func (t *RBTree[K, V]) ASCIIArt() string {
var out strings.Builder
t.root.asciiArt(&out, "", "", "")
return out.String()
}
func (node *RBNode[V]) String() string {
switch {
case node == nil:
return "nil"
case node.Color == Red:
return fmt.Sprintf("R(%v)", node.Value)
default:
return fmt.Sprintf("B(%v)", node.Value)
}
}
func (node *RBNode[V]) asciiArt(w io.Writer, u, m, l string) {
if node == nil {
fmt.Fprintf(w, "%snil\n", m)
return
}
node.Right.asciiArt(w, u+" ", u+" ,--", u+" | ")
if node.Color == Red {
fmt.Fprintf(w, "%s%v\n", m, node)
} else {
fmt.Fprintf(w, "%s%v\n", m, node)
}
node.Left.asciiArt(w, l+" | ", l+" `--", l+" ")
}
func checkRBTree[K constraints.Ordered, V any](t *testing.T, expectedSet map[K]struct{}, tree *RBTree[NativeOrdered[K], V]) {
// 1. Every node is either red or black
// 2. The root is black.
require.Equal(t, Black, tree.root.getColor())
// 3. Every nil is black.
// 4. If a node is red, then both its children are black.
require.NoError(t, tree.Walk(func(node *RBNode[V]) error {
if node.getColor() == Red {
require.Equal(t, Black, node.Left.getColor())
require.Equal(t, Black, node.Right.getColor())
}
return nil
}))
// 5. For each node, all simple paths from the node to
// descendent leaves contain the same number of black
// nodes.
var walkCnt func(node *RBNode[V], cnt int, leafFn func(int))
walkCnt = func(node *RBNode[V], cnt int, leafFn func(int)) {
if node.getColor() == Black {
cnt++
}
if node == nil {
leafFn(cnt)
return
}
walkCnt(node.Left, cnt, leafFn)
walkCnt(node.Right, cnt, leafFn)
}
require.NoError(t, tree.Walk(func(node *RBNode[V]) error {
var cnts []int
walkCnt(node, 0, func(cnt int) {
cnts = append(cnts, cnt)
})
for i := range cnts {
if cnts[0] != cnts[i] {
require.Truef(t, false, "node %v: not all leafs have same black-count: %v", node.Value, cnts)
break
}
}
return nil
}))
// expected contents
expectedOrder := make([]K, 0, len(expectedSet))
for k := range expectedSet {
expectedOrder = append(expectedOrder, k)
node := tree.Lookup(NativeOrdered[K]{Val: k})
require.NotNil(t, tree, node)
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 *RBNode[V]) error {
actOrder = append(actOrder, tree.KeyFn(node.Value).Val)
return nil
}))
require.Equal(t, expectedOrder, actOrder)
}
func FuzzRBTree(f *testing.F) {
Ins := uint8(0b0100_0000)
Del := uint8(0)
f.Add([]uint8{})
f.Add([]uint8{Ins | 5, Del | 5})
f.Add([]uint8{Ins | 5, Del | 6})
f.Add([]uint8{Del | 6})
f.Add([]uint8{ // CLRS Figure 14.4
Ins | 1,
Ins | 2,
Ins | 5,
Ins | 7,
Ins | 8,
Ins | 11,
Ins | 14,
Ins | 15,
Ins | 4,
})
f.Fuzz(func(t *testing.T, dat []uint8) {
tree := &RBTree[NativeOrdered[uint8], uint8]{
KeyFn: func(x uint8) NativeOrdered[uint8] {
return NativeOrdered[uint8]{Val: x}
},
}
set := make(map[uint8]struct{})
checkRBTree(t, set, tree)
t.Logf("\n%s\n", tree.ASCIIArt())
for _, b := range dat {
ins := (b & 0b0100_0000) != 0
val := (b & 0b0011_1111)
if ins {
t.Logf("Insert(%v)", val)
tree.Insert(val)
set[val] = struct{}{}
t.Logf("\n%s\n", tree.ASCIIArt())
node := tree.Lookup(NativeOrdered[uint8]{Val: val})
require.NotNil(t, node)
require.Equal(t, val, node.Value)
} else {
t.Logf("Delete(%v)", val)
tree.Delete(NativeOrdered[uint8]{Val: val})
delete(set, val)
t.Logf("\n%s\n", tree.ASCIIArt())
require.Nil(t, tree.Lookup(NativeOrdered[uint8]{Val: val}))
}
checkRBTree(t, set, tree)
}
})
}
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