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-rw-r--r--src/slices/slices.go26
-rw-r--r--src/slices/slices_test.go46
2 files changed, 72 insertions, 0 deletions
diff --git a/src/slices/slices.go b/src/slices/slices.go
index 1a837c53c1..ea1dea573c 100644
--- a/src/slices/slices.go
+++ b/src/slices/slices.go
@@ -109,6 +109,32 @@ func Delete[S ~[]E, E any](s S, i, j int) S {
return append(s[:i], s[j:]...)
}
+// DeleteFunc removes any elements from s for which del returns true,
+// returning the modified slice.
+// DeleteFunc modifies the contents of the slice s;
+// it does not create a new slice.
+// When DeleteFunc removes m elements, it might not modify the elements
+// s[len(s)-m:len(s)]. If those elements contain pointers you might consider
+// zeroing those elements so that objects they reference can be garbage
+// collected.
+func DeleteFunc[S ~[]E, E any](s S, del func(E) bool) S {
+ // Don't start copying elements until we find one to delete.
+ for i, v := range s {
+ if del(v) {
+ j := i
+ for i++; i < len(s); i++ {
+ v = s[i]
+ if !del(v) {
+ s[j] = v
+ j++
+ }
+ }
+ return s[:j]
+ }
+ }
+ return s
+}
+
// Replace replaces the elements s[i:j] by the given v, and returns the
// modified slice. Replace panics if s[i:j] is not a valid slice of s.
func Replace[S ~[]E, E any](s S, i, j int, v ...E) S {
diff --git a/src/slices/slices_test.go b/src/slices/slices_test.go
index 80efb34fc8..720e731ddf 100644
--- a/src/slices/slices_test.go
+++ b/src/slices/slices_test.go
@@ -304,6 +304,52 @@ func TestDelete(t *testing.T) {
}
}
+var deleteFuncTests = []struct {
+ s []int
+ fn func(int) bool
+ want []int
+}{
+ {
+ nil,
+ func(int) bool { return true },
+ nil,
+ },
+ {
+ []int{1, 2, 3},
+ func(int) bool { return true },
+ nil,
+ },
+ {
+ []int{1, 2, 3},
+ func(int) bool { return false },
+ []int{1, 2, 3},
+ },
+ {
+ []int{1, 2, 3},
+ func(i int) bool { return i > 2 },
+ []int{1, 2},
+ },
+ {
+ []int{1, 2, 3},
+ func(i int) bool { return i < 2 },
+ []int{2, 3},
+ },
+ {
+ []int{10, 2, 30},
+ func(i int) bool { return i >= 10 },
+ []int{2},
+ },
+}
+
+func TestDeleteFunc(t *testing.T) {
+ for i, test := range deleteFuncTests {
+ copy := Clone(test.s)
+ if got := DeleteFunc(copy, test.fn); !Equal(got, test.want) {
+ t.Errorf("DeleteFunc case %d: got %v, want %v", i, got, test.want)
+ }
+ }
+}
+
func panics(f func()) (b bool) {
defer func() {
if x := recover(); x != nil {