dsc order collection window

Author: Benito

jsonpatch.go

@@ -109,35 +109,63 @@ func CreatePatch(a, b []byte) ([]Operation, error) {
 			keysOriginal[k] = true
 		}
 
-		if len(modified) == len(original) {
-			// very specific case of a moving window of collections in ascending order
-			diffCount := 0
+		if len(modified) == len(original) && len(original) > 2 {
+			// moving window of collections in ascending order
+			diffAsc := 0
 			length := len(modified) - 1
 			for key := range modified {
 				// first element of the original cant be found in the modified
 				if key < length && string(original[0]) == string(modified[key]) {
-					diffCount++
+					diffAsc++
 					break
 				}
 				// last element of the modified cant be found in the original
 				if key > 0 && string(modified[length]) == string(original[key]) {
-					diffCount++
+					diffAsc++
 					break
 				}
-				// other then first original and last modified all elements are the same
+				// other than the first original and last modified all elements are the same
 				if key < length && string(original[key+1]) != string(modified[key]) {
-					diffCount++
+					diffAsc++
 					break
 				}
 			}
 
-			if diffCount == 0 {
+			if diffAsc == 0 {
 				pFirst := makePath(path, 0)
 				pLast := makePath(path, length)
 				patch = append([]Operation{NewPatch("add", pLast, modified[0])}, patch...)
 				patch = append([]Operation{NewPatch("remove", pFirst, nil)}, patch...)
 				return patch, nil
 			}
+
+			// moving window of collections in descending order
+			diffDsc := 0
+			for key := range modified {
+				// first element of the modified cant be found in the original
+				if key < length && string(modified[0]) == string(original[key]) {
+					diffDsc++
+					break
+				}
+				// last element of the original cant be found in the modified
+				if key > 0 && string(original[length]) == string(modified[key]) {
+					diffDsc++
+					break
+				}
+				// other than the first modified and last original all elements are the same
+				if key < length && string(modified[key+1]) != string(original[key]) {
+					diffDsc++
+					break
+				}
+			}
+
+			if diffDsc == 0 {
+				pFirst := makePath(path, 0)
+				pLast := makePath(path, length+1)
+				patch = append([]Operation{NewPatch("remove", pLast, nil)}, patch...)
+				patch = append([]Operation{NewPatch("add", pFirst, modified[0])}, patch...)
+				return patch, nil
+			}
 		}
 
 		for key, bv := range modified {

jsonpatch_simple_test.go

@@ -20,7 +20,7 @@ var empty = `{}`
 var collection = `[{"created":1564944548180294000,"updated":0,"index":"15b7ccc66f7878a8","data":"eyJuYW1lIjoibmFtZTEifQ=="},{"created":1564944548172292600,"updated":0,"index":"15b7ccc66efe6194","data":"eyJuYW1lIjoibmFtZTAifQ=="}]`
 var emptyCollection = `[]`
 
-var collectionWindowBefore = `[{
+var collectionWindowAscBefore = `[{
 	"test":"1"
 },
 {
@@ -30,7 +30,7 @@ var collectionWindowBefore = `[{
 	"test":"3"
 }]`
 
-var collectionWindowAfter = `[{
+var collectionWindowAscAfter = `[{
 	"test":"2"
 },
 {
@@ -40,15 +40,35 @@ var collectionWindowAfter = `[{
 	"test":"4"
 }]`
 
+var collectionWindowDscBefore = `[{
+	"test":"3"
+},
+{
+	"test":"2"
+},
+{
+	"test":"1"
+}]`
+
+var collectionWindowDscAfter = `[{
+	"test":"4"
+},
+{
+	"test":"3"
+},
+{
+	"test":"2"
+}]`
+
 func TestMultipleRemove(t *testing.T) {
 	patch, e := CreatePatch([]byte(collection), []byte(emptyCollection))
 	assert.NoError(t, e)
 	assert.Equal(t, len(patch), 2, "the patch should be the same lenght as the collection")
 	assert.Equal(t, patch[0].Path, "/1", "the patch should have descending order by path")
 }
 
-func TestCollectionWindowMove(t *testing.T) {
-	patch, e := CreatePatch([]byte(collectionWindowBefore), []byte(collectionWindowAfter))
+func TestCollectionWindowAscMove(t *testing.T) {
+	patch, e := CreatePatch([]byte(collectionWindowAscBefore), []byte(collectionWindowAscAfter))
 	assert.NoError(t, e)
 	assert.Equal(t, 2, len(patch), "the patch should have one insert and one remove")
 	assert.Equal(t, "remove", patch[0].Operation, "the patch should remove the first position")
@@ -57,6 +77,16 @@ func TestCollectionWindowMove(t *testing.T) {
 	assert.Equal(t, "/2", patch[1].Path, "the patch should have descending order by path")
 }
 
+func TestCollectionWindowDscMove(t *testing.T) {
+	patch, e := CreatePatch([]byte(collectionWindowDscBefore), []byte(collectionWindowDscAfter))
+	assert.NoError(t, e)
+	assert.Equal(t, 2, len(patch), "the patch should have one insert and one remove")
+	assert.Equal(t, "add", patch[0].Operation, "the patch should remove the first position")
+	assert.Equal(t, "/0", patch[0].Path, "the patch should have descending order by path")
+	assert.Equal(t, "remove", patch[1].Operation, "the patch should add on the last position")
+	assert.Equal(t, "/3", patch[1].Path, "the patch should have descending order by path")
+}
+
 func TestOneNullReplace(t *testing.T) {
 	patch, e := CreatePatch([]byte(simplef), []byte(simpleG))
 	assert.NoError(t, e)