WIP: sort entries by full path name before compare

compare.go

@@ -3,6 +3,7 @@ package mtree
 import (
 	"encoding/json"
 	"fmt"
+	"sort"
 	"strconv"
 )
 
@@ -348,6 +349,7 @@ func Compare(thisDh, thatDh *DirectoryHierarchy, keys []Keyword) ([]InodeDelta,
 
 	// First, iterate over the old hierarchy. If nil, pretend it's empty.
 	if thisDh != nil {
+		sort.Sort(byName(thisDh.Entries))
 		for _, e := range thisDh.Entries {
 			if e.Type == RelativeType || e.Type == FullType {
 				path, err := e.Path()
@@ -370,6 +372,7 @@ func Compare(thisDh, thatDh *DirectoryHierarchy, keys []Keyword) ([]InodeDelta,
 
 	// Then, iterate over the new hierarchy. If nil, pretend it's empty.
 	if thatDh != nil {
+		sort.Sort(byName(thatDh.Entries))
 		for _, e := range thatDh.Entries {
 			if e.Type == RelativeType || e.Type == FullType {
 				path, err := e.Path()

entry.go

@@ -14,6 +14,33 @@ func (bp byPos) Len() int           { return len(bp) }
 func (bp byPos) Less(i, j int) bool { return bp[i].Pos < bp[j].Pos }
 func (bp byPos) Swap(i, j int)      { bp[i], bp[j] = bp[j], bp[i] }
 
+type byName []Entry
+
+func (bp byName) Len() int { return len(bp) }
+func (bp byName) Less(i, j int) bool {
+	var iParent string
+	var jParent string
+	var err error
+	if bp[i].Parent != nil {
+		iParent, err = bp[i].Parent.Path()
+		if err != nil {
+			return false
+		}
+	}
+	iName := filepath.Clean(filepath.Join(iParent, bp[i].Name))
+
+	if bp[j].Parent != nil {
+		jParent, err = bp[j].Parent.Path()
+		if err != nil {
+			return false
+		}
+	}
+	jName := filepath.Clean(filepath.Join(jParent, bp[j].Name))
+
+	return iName < jName
+}
+func (bp byName) Swap(i, j int) { bp[i], bp[j] = bp[j], bp[i] }
+
 // Entry is each component of content in the mtree spec file
 type Entry struct {
 	Parent     *Entry   // up