Package org.apache.tapestry5.func

Interface FlowOperations<T,​FT>

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      FT concat​(Collection<? extends T> collection)
      Returns a new Flow with the elements in the collection appended to this Flow.
      int count()
      Returns the number of values in this flow.
      FT drop​(int length)
      Returns a new flow with the first elements omitted.
      FT each​(Worker<? super T> worker)
      Applies the worker to each element in the Flow, then returns the flow for further behaviors.
      FT filter​(Predicate<? super T> predicate)
      Filters values, keeping only values where the predicate is true, returning a new Flow with just the retained values.
      T first()
      Returns the first element in the Flow.
      boolean isEmpty()
      Returns true if the Flow contains no values.
      <A> A reduce​(Reducer<A,​T> reducer, A initial)
      Applies a Reducer to the values of the Flow.
      FT remove​(Predicate<? super T> predicate)
      Removes values where the predicate returns true, returning a new Flow with just the remaining values.
      FT removeNulls()
      Removes null elements from the flow (null tuples from a ZippedFlow), leaving just the non-null elements.
      FT rest()
      Returns a new Flow containing all but the first element in this flow.
      FT reverse()
      Returns a new flow with the same elements but in reverse order.
      FT sort​(Comparator<T> comparator)
      Sorts this flow using the comparator, forming a new flow.
      FT take​(int length)
      Returns a new flow containing just the first elements from this Flow.
      List<T> toList()
      Converts the Flow into an unmodifiable list of values.
      Set<T> toSet()
      Converts the Flow into an unmodifiable set of values.

    • Method Detail

      • filter

        FT filter​(Predicate<? super T> predicate)
        Filters values, keeping only values where the predicate is true, returning a new Flow with just the retained values.

      • remove

        FT remove​(Predicate<? super T> predicate)
        Removes values where the predicate returns true, returning a new Flow with just the remaining values.

      • each

        FT each​(Worker<? super T> worker)
        Applies the worker to each element in the Flow, then returns the flow for further behaviors. Each is a non-lazy operation; it will fully realize the values of the Flow.

      • toList

        List<T> toList()
        Converts the Flow into an unmodifiable list of values. This is a non-lazy operation that will fully realize the values of the Flow.

      • toSet

        Set<T> toSet()
        Converts the Flow into an unmodifiable set of values. This is a non-lazy operation that will fully realize the values of the Flow.

      • reverse

        FT reverse()
        Returns a new flow with the same elements but in reverse order.

      • isEmpty

        boolean isEmpty()
        Returns true if the Flow contains no values. This may realize the first value in the Flow.

      • first

        T first()
        Returns the first element in the Flow. Returns null for empty flows, but remember that null is a valid element within a flow, so use isEmpty() to determine if a flow is actually empty. The first element can be realized without realizing the full Flow.

      • rest

        FT rest()
        Returns a new Flow containing all but the first element in this flow. If this flow has only a single element, or is empty, this will return an empty Flow.

      • count

        int count()
        Returns the number of values in this flow. This forces the realization of much of the flow (i.e., because each value will need to be passed through any Predicates).

      • sort

        FT sort​(Comparator<T> comparator)
        Sorts this flow using the comparator, forming a new flow. This is a non-lazy operation; it will fully realize the elements of the Flow.

      • take

        FT take​(int length)
        Returns a new flow containing just the first elements from this Flow.
        Parameters:
        length - maximum number of values in the Flow

      • drop

        FT drop​(int length)
        Returns a new flow with the first elements omitted.
        Parameters:
        length - number of values to drop

      • concat

        FT concat​(Collection<? extends T> collection)
        Returns a new Flow with the elements in the collection appended to this Flow. This is a lazy operation. Note that the type of this method changed from List to Collection in Tapestry 5.4. This is considered a compatible change.
        Parameters:
        collection - collection of elements to be appended

      • reduce

        <A> A reduce​(Reducer<A,​T> reducer,
             A initial)
        Applies a Reducer to the values of the Flow. The Reducer is passed the initial value and the first element from the Flow. The result is captured as the accumulator and passed to the Reducer with the next value from the Flow, and so on. The final accumulator value is returned. If the flow is empty, the initial value is returned. Reducing is a non-lazy operation; it will fully realize the values of the Flow.

      • removeNulls

        FT removeNulls()
        Removes null elements from the flow (null tuples from a ZippedFlow), leaving just the non-null elements. This is a lazy operation.
        Since:
        5.3