Author: hlship
Date: Thu Jun 3 17:22:09 2010
New Revision: 951076
URL: http://svn.apache.org/viewvc?rev=951076&view=rev
Log:
Add F.iterate(), which builds a lazy Flow by repeatedly applying a function to
an initial value
Added:
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/LazyIterate.java
(with props)
Modified:
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/F.java
tapestry/tapestry5/trunk/tapestry-func/src/test/java/org/apache/tapestry5/func/RangeTests.java
Modified:
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/F.java
URL:
http://svn.apache.org/viewvc/tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/F.java?rev=951076&r1=951075&r2=951076&view=diff
==============================================================================
---
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/F.java
(original)
+++
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/F.java
Thu Jun 3 17:22:09 2010
@@ -271,4 +271,23 @@ public class F
{
return lazy(new LazySeries(start, delta));
}
+
+ /**
+ * Creates a lazy, infinte Flow consisting of the initial value, then the
result of passing
+ * the initial value through the Mapper, and so forth, which each step
value passed through the mapper
+ * to form the next step value.
+ */
+ public static <T> Flow<T> iterate(final T initial, final Mapper<T, T>
mapper)
+ {
+ assert mapper != null;
+
+ return F.lazy(new LazyFunction<T>()
+ {
+
+ public LazyContinuation<T> next()
+ {
+ return new LazyContinuation<T>(initial, new
LazyIterate<T>(initial, mapper));
+ }
+ });
+ }
}
Added:
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/LazyIterate.java
URL:
http://svn.apache.org/viewvc/tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/LazyIterate.java?rev=951076&view=auto
==============================================================================
---
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/LazyIterate.java
(added)
+++
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/LazyIterate.java
Thu Jun 3 17:22:09 2010
@@ -0,0 +1,38 @@
+// Copyright 2010 The Apache Software Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package org.apache.tapestry5.func;
+
+/**
+ * Continuously re-applies a function, represented as a {...@link Mapper}, to
a value.
+ */
+class LazyIterate<T> implements LazyFunction<T>
+{
+ private final T previousValue;
+
+ private final Mapper<T, T> mapper;
+
+ public LazyIterate(T previousValue, Mapper<T, T> mapper)
+ {
+ this.previousValue = previousValue;
+ this.mapper = mapper;
+ }
+
+ public LazyContinuation<T> next()
+ {
+ T current = mapper.map(previousValue);
+
+ return new LazyContinuation<T>(current, new LazyIterate<T>(current,
mapper));
+ }
+}
Propchange:
tapestry/tapestry5/trunk/tapestry-func/src/main/java/org/apache/tapestry5/func/LazyIterate.java
------------------------------------------------------------------------------
svn:eol-style = native
Modified:
tapestry/tapestry5/trunk/tapestry-func/src/test/java/org/apache/tapestry5/func/RangeTests.java
URL:
http://svn.apache.org/viewvc/tapestry/tapestry5/trunk/tapestry-func/src/test/java/org/apache/tapestry5/func/RangeTests.java?rev=951076&r1=951075&r2=951076&view=diff
==============================================================================
---
tapestry/tapestry5/trunk/tapestry-func/src/test/java/org/apache/tapestry5/func/RangeTests.java
(original)
+++
tapestry/tapestry5/trunk/tapestry-func/src/test/java/org/apache/tapestry5/func/RangeTests.java
Thu Jun 3 17:22:09 2010
@@ -52,4 +52,18 @@ public class RangeTests extends BaseFunc
assertFlowValues(series.filter(evenp).take(4), 2, 4, 6, 8);
}
+
+ @Test
+ public void iterate()
+ {
+ Mapper<Integer, Integer> times2 = new Mapper<Integer, Integer>()
+ {
+ public Integer map(Integer value)
+ {
+ return 2 * value;
+ }
+ };
+
+ assertFlowValues(F.iterate(1, times2).take(5), 1, 2, 4, 8, 16);
+ }
}
