Void merge strategy.

josephburnett · Apr 25, 2022 · 1c36706 · 1c36706
1 parent e20ae8e
commit 1c36706
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Showing 2 changed files with 23 additions and 3 deletions.
diff --git a/lib/void.go b/lib/void.go
@@ -71,16 +71,29 @@ func (v voidNode) Patch(d Diff) (JsonNode, error) {
 }
 
 func (v voidNode) patch(pathBehind, pathAhead path, oldValues, newValues []JsonNode, strategy patchStrategy) (JsonNode, error) {
- if len(pathAhead) != 0 {
+ if !pathAhead.isLeaf() {
  return patchErrExpectColl(v, pathBehind[len(pathBehind)-1])
  }
  if len(oldValues) > 1 || len(newValues) > 1 {
  return patchErrNonSetDiff(oldValues, newValues, pathBehind)
  }
  oldValue := singleValue(oldValues)
  newValue := singleValue(newValues)
- if !v.Equals(oldValue) {
- return patchErrExpectValue(oldValue, v, pathBehind)
+ switch strategy {
+ case mergePatchStrategy:
+ if !isVoid(oldValue) {
+ return patchErrMergeWithOldValue(pathBehind, oldValue)
+ }
+ if isNull(newValue) {
+ // Null deletes a node
+ return voidNode{}, nil
+ }
+ case strictPatchStrategy:
+ if !v.Equals(oldValue) {
+ return patchErrExpectValue(oldValue, v, pathBehind)
+ }
+ default:
+ return patchErrUnsupportedPatchStrategy(pathBehind, strategy)
  }
  return newValue, nil
 }
diff --git a/lib/void_test.go b/lib/void_test.go
@@ -49,6 +49,13 @@ func TestVoidPatch(t *testing.T) {
  checkPatch(ctx, `1`, ``,
  `@ []`,
  `- 1`)
+ checkPatch(ctx, ``, `1`,
+ `@ [["merge"]]`,
+ `+ 1`)
+ // Null deletes a node
+ checkPatch(ctx, ``, ``,
+ `@ [["merge"]]`,
+ `+ null`)
 }
 
 func TestVoidPatchError(t *testing.T) {