Added int min, int max and ord monoid. Added FingerTree empty and int max for pqueue's

mperry · mperry · commit b947a4fbd033 · 2016-06-02T22:44:40.000+10:00
diff --git a/core/src/main/java/fj/Monoid.java b/core/src/main/java/fj/Monoid.java
@@ -401,6 +401,10 @@ public static <A> Monoid<IO<A>> ioMonoid(final Monoid <A> ma) {
     return monoid(Semigroup.ioSemigroup(ma.semigroup()), IOFunctions.unit(ma.zero()));
   }
 
+  public static final Monoid<Integer> intMaxMonoid = monoid(Semigroup.intMaximumSemigroup, Integer.MIN_VALUE);
+
+  public static final Monoid<Integer> intMinMonoid = monoid(Semigroup.intMinimumSemigroup, Integer.MAX_VALUE);
+
   /**
    * A monoid for the Unit value.
    */
@@ -416,4 +420,8 @@ public static <A> Monoid<Set<A>> setMonoid(final Ord<A> o) {
     return monoid(Semigroup.setSemigroup(), Set.empty(o));
   }
 
+  public static <A> Monoid<A> ordMonoid(Ord<A> o, A zero) {
+    return monoid(o.max, zero);
+  }
+
 }
diff --git a/core/src/main/java/fj/data/fingertrees/FingerTree.java b/core/src/main/java/fj/data/fingertrees/FingerTree.java
@@ -5,6 +5,7 @@
 import fj.data.Seq;
 
 import static fj.Monoid.intAdditionMonoid;
+import static fj.Monoid.intMaxMonoid;
 
 /**
  * Provides 2-3 finger trees, a functional representation of persistent sequences supporting access to the ends in
@@ -96,8 +97,8 @@ public final <B> FingerTree<V, A> filter(final F<A, Boolean> f) {
   public final boolean isEmpty() {
     return this instanceof Empty;
   }
-
-  final Measured<V, A> measured() {
+  
+  public final Measured<V, A> measured() {
     return m;
   }
 
@@ -225,7 +226,15 @@ public final P3<FingerTree<V, A>, A, FingerTree<V, A>> split1(final F<V, Boolean
     public abstract int length();
 
     public static <A> FingerTree<Integer, A> emptyIntAddition() {
-        return mkTree(FingerTree.<Integer, A>measured(intAdditionMonoid, Function.constant(1))).empty();
+      return empty(intAdditionMonoid, Function.constant(1));
     }
 
+  public static <V, A> FingerTree<V, A> empty(Monoid<V> m, F<A, V> f) {
+    return FingerTree.mkTree(measured(m, f)).empty();
+  }
+
+  public static <A> FingerTree<Integer, P2<Integer, A>> emptyIntMax() {
+    return empty(intMaxMonoid, (P2<Integer, A> p) -> p._1());
+  }
+
 }

Original file line number	Diff line number	Diff line change
`@@ -401,6 +401,10 @@ public static <A> Monoid<IO<A>> ioMonoid(final Monoid <A> ma) {`
`401`	`401`	`return monoid(Semigroup.ioSemigroup(ma.semigroup()), IOFunctions.unit(ma.zero()));`
`402`	`402`	`}`
`403`	`403`
	`404`	`+ public static final Monoid<Integer> intMaxMonoid = monoid(Semigroup.intMaximumSemigroup, Integer.MIN_VALUE);`
	`405`	`+`
	`406`	`+ public static final Monoid<Integer> intMinMonoid = monoid(Semigroup.intMinimumSemigroup, Integer.MAX_VALUE);`
	`407`	`+`
`404`	`408`	`/**`
`405`	`409`	`* A monoid for the Unit value.`
`406`	`410`	`*/`
`@@ -416,4 +420,8 @@ public static <A> Monoid<Set<A>> setMonoid(final Ord<A> o) {`
`416`	`420`	`return monoid(Semigroup.setSemigroup(), Set.empty(o));`
`417`	`421`	`}`
`418`	`422`
	`423`	`+ public static <A> Monoid<A> ordMonoid(Ord<A> o, A zero) {`
	`424`	`+ return monoid(o.max, zero);`
	`425`	`+ }`
	`426`	`+`
`419`	`427`	`}`