Documentation: Add submit rule example on how to implement 1+1=2
Adds an example that demonstrates how to write a submit-rule that
implements accumulative voting scores.
Bug: Issue 757
Change-Id: Ia36e29495b5cc77ea2254519f5485eb9f29154eb
diff --git a/Documentation/prolog-cookbook.txt b/Documentation/prolog-cookbook.txt
index 99773c6..105929a 100644
--- a/Documentation/prolog-cookbook.txt
+++ b/Documentation/prolog-cookbook.txt
@@ -638,6 +638,42 @@
remove_verified_category([H|T], [H|R]) :- remove_verified_category(T, R).
====
+Example 12: 1+1=2 Code-Review
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+In this example we introduce accumulative voting to determine if a change is
+submittable or not. We modify the standard Code-Review to be accumulative, and make the
+change submittable if the total score is 2 or higher.
+
+The code in this example is very similar to Example 8, with the addition of findall/3
+and gerrit:remove_label.
+The findall/3 embedded predicate is used to form a list of all objects that satisfy a
+specified Goal. In this example it is used to get a list of all the 'Code-Review' scores.
+gerrit:remove_label is a built-in helper that is implemented similarly to the
+'remove_verified_category' as seen in the previous example.
+
+.rules.pl
+[caption=""]
+====
+ sum_list([], 0).
+ sum_list([H | Rest], Sum) :- sum_list(Rest,Tmp), Sum is H + Tmp.
+
+ add_category_min_score(In, Category, Min, P) :-
+ findall(X, gerrit:commit_label(label(Category,X),R),Z),
+ sum_list(Z, Sum),
+ Sum >= Min, !,
+ P = [label(Category,ok(R)) | In].
+
+ add_category_min_score(In, Category,Min,P) :-
+ P = [label(Category,need(Min)) | In].
+
+ submit_rule(S) :-
+ gerrit:default_submit(X),
+ X =.. [submit | Ls],
+ gerrit:remove_label(Ls,label('Code-Review',_),NoCR),
+ add_category_min_score(NoCR,'Code-Review', 2, Labels),
+ S =.. [submit | Labels].
+====
+
GERRIT
------
Part of link:index.html[Gerrit Code Review]
