From f126b8b618a88d0161dbbc7da74d65abc2380c7b Mon Sep 17 00:00:00 2001
From: Calvin Kim <calvin@kcalvinalvin.info>
Date: Wed, 11 May 2022 17:58:23 +0900
Subject: [PATCH] Move to sort.Sort from slices.Sort

Most of the sorts that are being used are very basic and can be done
with the std lib. There's now only one call to the slices package in the
library, making it easier to switch over to a different library as the
slices package is subject to change.
---
 accumulator.go | 6 ++----
 prove.go       | 7 +++----
 utils.go       | 4 +---
 utils_test.go  | 3 ++-
 4 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/accumulator.go b/accumulator.go
index b4d3c758..9a190144 100644
--- a/accumulator.go
+++ b/accumulator.go
@@ -4,8 +4,6 @@ import (
 	"encoding/hex"
 	"fmt"
 	"sort"
-
-	"golang.org/x/exp/slices"
 )
 
 // Pollard is a representation of the utreexo forest using a collection of
@@ -163,7 +161,7 @@ func (p *Pollard) calculateNewRoot(node *polNode) *polNode {
 
 // remove removes all the positions that are passed in.
 func (p *Pollard) remove(dels []uint64) error {
-	slices.Sort(dels)
+	sort.Slice(dels, func(a, b int) bool { return dels[a] < dels[b] })
 
 	totalRows := treeRows(p.numLeaves)
 	dels = deTwin(dels, totalRows)
@@ -332,7 +330,7 @@ func (p *Pollard) undoEmptyRoots(numAdds uint64, origDels []uint64) error {
 	copy(dels, origDels)
 
 	// Sort before detwining.
-	slices.Sort(dels)
+	sort.Slice(dels, func(a, b int) bool { return dels[a] < dels[b] })
 	dels = deTwin(dels, treeRows(p.numLeaves))
 	for i := len(dels) - 1; i >= 0; i-- {
 		del := dels[i]
diff --git a/prove.go b/prove.go
index 4f5bcc65..06f94462 100644
--- a/prove.go
+++ b/prove.go
@@ -4,8 +4,6 @@ import (
 	"encoding/hex"
 	"fmt"
 	"sort"
-
-	"golang.org/x/exp/slices"
 )
 
 // Proof is the inclusion-proof for multiple leaves.
@@ -37,7 +35,8 @@ type Proof struct {
 func (p *Proof) ToString() string {
 	targs := make([]uint64, len(p.Targets))
 	copy(targs, p.Targets)
-	slices.Sort(targs)
+	sort.Slice(targs, func(a, b int) bool { return targs[a] < targs[b] })
+
 	s := fmt.Sprintf("%d targets: ", len(targs))
 	for _, t := range targs {
 		s += fmt.Sprintf("%d ", t)
@@ -80,7 +79,7 @@ func (p *Pollard) Prove(hashes []Hash) (Proof, error) {
 	// locality or performance.
 	sortedTargets := make([]uint64, len(proof.Targets))
 	copy(sortedTargets, proof.Targets)
-	slices.Sort(sortedTargets)
+	sort.Slice(sortedTargets, func(a, b int) bool { return sortedTargets[a] < sortedTargets[b] })
 
 	// Get the positions of all the hashes that are needed to prove the targets
 	proofPositions := proofPositions(sortedTargets, p.numLeaves, treeRows(p.numLeaves))
diff --git a/utils.go b/utils.go
index 2ebff1e7..18d18ebb 100644
--- a/utils.go
+++ b/utils.go
@@ -6,8 +6,6 @@ import (
 	"fmt"
 	"math/bits"
 	"sort"
-
-	"golang.org/x/exp/slices"
 )
 
 // parentHash returns the hash of the left and right hashes passed in.
@@ -380,7 +378,7 @@ func proofPositions(targets []uint64, numLeaves uint64, forestRows uint8) []uint
 		rowTargs := extractRow(targets, forestRows, row)
 
 		rowTargs = append(rowTargs, nextTargets...)
-		slices.Sort(rowTargs)
+		sort.Slice(rowTargs, func(a, b int) bool { return rowTargs[a] < rowTargs[b] })
 
 		// Reset nextTargets
 		nextTargets = nextTargets[:0]
diff --git a/utils_test.go b/utils_test.go
index 9def5f54..1e0d5671 100644
--- a/utils_test.go
+++ b/utils_test.go
@@ -3,6 +3,7 @@ package utreexo
 import (
 	"fmt"
 	"math/rand"
+	"sort"
 	"testing"
 	"time"
 
@@ -71,7 +72,7 @@ func TestDeTwinRand(t *testing.T) {
 			dels = append(dels, randNum)
 		}
 
-		slices.Sort(dels)
+		sort.Slice(dels, func(a, b int) bool { return dels[a] < dels[b] })
 		origDels := make([]uint64, len(dels))
 		copy(origDels, dels)