add accumulator

src/rule/collection/skip.rs

@@ -41,8 +41,9 @@ where
         let mut remains = target.into_iterator();
         let mut result = VecDeque::new();
         let (mut is_valid, mut message) = (true, String::new());
+        let mut accumlator = None;
         for (i, item) in remains.by_ref().enumerate() {
-            if OPTION::should_skip(i, &item) {
+            if OPTION::should_skip(i, &item, accumlator.as_mut()) {
                 result.push_back(item);
                 continue;
             }

src/rule/collection/skip/option.rs

@@ -6,5 +6,10 @@ pub use skip_first::SkipFirst;
 
 pub trait SkipOption {
     type Item;
-    fn should_skip(i: usize, item: &Self::Item) -> bool;
+    type Accumulator;
+    fn should_skip(
+        i: usize,
+        item: &Self::Item,
+        accumulator: Option<&mut Self::Accumulator>,
+    ) -> bool;
 }

src/rule/collection/skip/option/no_skip.rs

@@ -6,7 +6,8 @@ pub struct NoSkip<T> {
 
 impl<ITEM> SkipOption for NoSkip<ITEM> {
     type Item = ITEM;
-    fn should_skip(_: usize, _: &Self::Item) -> bool {
+    type Accumulator = ();
+    fn should_skip(_: usize, _: &Self::Item, _: Option<&mut Self::Accumulator>) -> bool {
         false
     }
 }

src/rule/collection/skip/option/skip_first.rs

@@ -6,7 +6,8 @@ pub struct SkipFirst<ITEM> {
 
 impl<ITEM> SkipOption for SkipFirst<ITEM> {
     type Item = ITEM;
-    fn should_skip(i: usize, _: &Self::Item) -> bool {
+    type Accumulator = ();
+    fn should_skip(i: usize, _: &Self::Item, _: Option<&mut Self::Accumulator>) -> bool {
         i == 0
     }
 }