From d6f4838f0593560e82be1ee62ef311a2cea8b879 Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Wed, 9 Aug 2017 11:51:12 -0700
Subject: [PATCH] Add a random function.

---
 .../nwapw/abacus/plugin/StandardPlugin.java   | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/main/java/org/nwapw/abacus/plugin/StandardPlugin.java b/src/main/java/org/nwapw/abacus/plugin/StandardPlugin.java
index 4f3f370..fdd3674 100755
--- a/src/main/java/org/nwapw/abacus/plugin/StandardPlugin.java
+++ b/src/main/java/org/nwapw/abacus/plugin/StandardPlugin.java
@@ -242,6 +242,20 @@ public class StandardPlugin extends Plugin {
             return OP_CARET.getFunction().apply(params[0], ((new NaiveNumber(0.5)).promoteTo(params[0].getClass())));
         }
     };
+    /**
+     * Gets a random number smaller or equal to the given number's integer value.
+     */
+    public static final Function FUNCTION_RAND_INT = new Function() {
+        @Override
+        protected boolean matchesParams(NumberInterface[] params) {
+            return params.length == 1;
+        }
+
+        @Override
+        protected NumberInterface applyInternal(NumberInterface[] params) {
+            return fromInt(params[0].getClass(), (int) Math.round(Math.random() * params[0].floor().intValue()));
+        }
+    };
     /**
      * The implementation for double-based naive numbers.
      */
@@ -572,6 +586,8 @@ public class StandardPlugin extends Plugin {
         registerFunction("csc", functionCsc);
         registerFunction("cot", functionCot);
 
+        registerFunction("random_int", FUNCTION_RAND_INT);
+
         registerDocumentation(new Documentation("abs", "Absolute Value", "Finds the distance " +
                 "from zero of a number.", "Given a number, this function finds the distance form " +
                 "zero of a number, effectively turning negative numbers into positive ones.\n\n" +
@@ -600,6 +616,12 @@ public class StandardPlugin extends Plugin {
                 "in radians.", "", DocumentationType.FUNCTION));
         registerDocumentation(new Documentation("cot", "Cotangent", "Computes the cotangent of the given angle, " +
                 "in radians.", "", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("random_int", "Random Integer", "Generates a random integer [0, n].",
+                "Generates a pseudorandom number using the standard JVM random mechanism, keeping it less than or " +
+                        "equal to the given number.\n\n" +
+                        "Example: random_int(5) -> 4\n" +
+                        "random_int(5) -> 3\n" +
+                        "random_int(5) -> 3\n", DocumentationType.FUNCTION));
     }
 
     @Override