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From dawidwys <...@git.apache.org>
Subject [GitHub] flink pull request #3624: [FLINK-6197] [cep] Add support for iterative condi...
Date Tue, 28 Mar 2017 08:59:53 GMT
Github user dawidwys commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3624#discussion_r108367951
  
    --- Diff: docs/dev/libs/cep.md ---
    @@ -124,13 +124,70 @@ val start : Pattern[Event, _] = Pattern.begin("start")
     </div>
     </div>
     
    -Each state must have an unique name to identify the matched events later on.
    +Each state must have a unique name to identify the matched events later on.
     Additionally, we can specify a filter condition for the event to be accepted as the start
event via the `where` method.
    +These filtering conditions can be either an `IterativeCondition` or a `SimpleCondition`.

    +
    +**Iterative Conditions:** This type of conditions can iterate over the previously accepted
elements in the pattern and 
    +decide to accept a new element or not, based on some statistic over those elements. 
    +
    +Below is the code for an iterative condition that accepts elements whose name start with
"foo" and for which, the sum 
    +of the prices of the previously accepted elements for a state named "middle", plus the
price of the current event, do 
    +not exceed the value of 5.0. Iterative condition can be very powerful, especially in
combination with quantifiers, e.g.
    +`oneToMany` or `zeroToMany`.
    +
    +<div class="codetabs" markdown="1">
    +<div data-lang="java" markdown="1">
    +{% highlight java %}
    +start.where(new IterativeCondition<SubEvent>() {
    +    @Override
    +    public boolean filter(SubEvent value, Context<SubEvent> ctx) throws Exception
{
    +        if (!value.getName().startsWith("foo")) {
    +            return false;
    +        }
    +        
    +        double sum = 0.0;
    +        for (Event event : ctx.getEventsForPattern("middle")) {
    +            sum += event.getPrice();
    +        }
    +        sum += value.getPrice();
    +        return Double.compare(sum, 5.0) < 0;
    +    }
    +});
    +{% endhighlight %}
    +</div>
    +
    +<div data-lang="scala" markdown="1">
    +{% highlight scala %}
    +start.where(
    --- End diff --
    
    I just meant I would expect scala version of `Iterable` in scala code. Not the java version.


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