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working limit impl

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This commit is contained in:
Yadunand Prem 2022-11-02 11:08:41 +08:00
parent 8fd82c39ea
commit 852f48d522
1 changed files with 57 additions and 49 deletions
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106
Lab8/cs2030s/fp/InfiniteList.java
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@ -16,48 +16,6 @@ public class InfiniteList<T> {
return result; return result;
} }
private static class End extends InfiniteList<Object> {
private End() {
super(null, null);
}
@Override
public Object head() {
throw new NoSuchElementException();
}
@Override
public InfiniteList<Object> tail() {
throw new NoSuchElementException();
}
@Override
public boolean isEnd() {
return true;
}
@Override
public String toString() {
return "-";
}
@Override
public InfiniteList<Object> limit(long n) {
return InfiniteList.end();
}
@Override
public InfiniteList<Object> filter(Immutator<Boolean, ? super Object> pred) {
return InfiniteList.end();
}
@Override
public <R> InfiniteList<R> map(Immutator<? extends R, ? super Object> f) {
return InfiniteList.end();
}
}
private InfiniteList(Memo<Actually<T>> head, Memo<InfiniteList<T>> tail) { private InfiniteList(Memo<Actually<T>> head, Memo<InfiniteList<T>> tail) {
this.head = head; this.head = head;
this.tail = tail; this.tail = tail;
@ -102,16 +60,20 @@ public class InfiniteList<T> {
return InfiniteList.end(); return InfiniteList.end();
} }
Memo<Actually<T>> head = this.head; /*
* next tail ->
* get the current tail
* check if actually.err(). If actually.err() then return limit(n). If ok()
* return limit - 1
*/
Memo<InfiniteList<T>> tail = Memo.from(() -> { Memo<InfiniteList<T>> tail = Memo.from(() -> {
InfiniteList<T> tempTail = this.tail.get(); if (this.head.get().unless(null) == null) {
if (tempTail.head.get().unless(null) == null) { return this.tail.get().limit(n);
return tempTail.limit(n);
} }
return tempTail.limit(n - 1); return this.tail.get().limit(n - 1);
}); });
return new InfiniteList<>(head, tail); return new InfiniteList<>(this.head, tail);
} }
public InfiniteList<T> takeWhile(Immutator<Boolean, ? super T> pred) { public InfiniteList<T> takeWhile(Immutator<Boolean, ? super T> pred) {
@ -145,5 +107,51 @@ public class InfiniteList<T> {
return false; return false;
} }
// Add your End class here... private static class End extends InfiniteList<Object> {
private End() {
super(null, null);
}
@Override
public Object head() {
throw new NoSuchElementException();
}
@Override
public InfiniteList<Object> tail() {
throw new NoSuchElementException();
}
@Override
public boolean isEnd() {
return true;
}
@Override
public String toString() {
return "-";
}
@Override
public InfiniteList<Object> limit(long n) {
return InfiniteList.end();
}
@Override
public InfiniteList<Object> filter(Immutator<Boolean, ? super Object> pred) {
return InfiniteList.end();
}
@Override
public <R> InfiniteList<R> map(Immutator<? extends R, ? super Object> f) {
return InfiniteList.end();
}
@Override
public List<Object> toList() {
return List.of();
}
}
} }