Add gcd() and lcm() function

core/src/main/java/me/fourteendoggo/mathexpressionparser/symbol/BuiltinSymbols.java

@@ -87,7 +87,7 @@ public static void init(ExecutionEnv env) {
                 return Math.round(ctx.getDouble(0));
             }
             double value = ctx.getDouble(0);
-            int places = ctx.getBoundedInt(1, 0, Integer.MAX_VALUE);
+            int places = ctx.getInt(1);
             double factor = Utility.getPowerOfTen(places);
 
             return Math.round(value * factor) / factor;
@@ -104,5 +104,15 @@ public static void init(ExecutionEnv env) {
                 throw new SyntaxException(e.getMessage());
             }
         });
+        env.insertFunction("gcd", 2, ctx -> {
+            int a = ctx.getInt(0);
+            int b = ctx.getInt(1);
+            return Utility.gcd(a, b);
+        });
+        env.insertFunction("lcm", 2, ctx -> {
+            int a = ctx.getInt(0);
+            int b = ctx.getInt(1);
+            return Utility.lcm(a, b);
+        });
     }
 }

core/src/main/java/me/fourteendoggo/mathexpressionparser/utils/Utility.java

@@ -60,4 +60,37 @@ public static boolean isValidArgument(int c) {
     public static boolean isBetweenBrackets(int c) {
         return c != ')';
     }
+
+    public static int gcd(int a, int b) {
+        if (a < 0) a = -a;
+        if (b < 0) b = -b;
+        if (a < b) { // force a >= b
+            int tmp = a;
+            a = b;
+            b = tmp;
+        }
+
+        while (b != 0) {
+            int tmp = b;
+            b = a % b;
+            a = tmp;
+        }
+        return a;
+    }
+
+    private static int fastUnsignedGcd(int a, int b) {
+        while (b != 0) {
+            int tmp = b;
+            b = a % b;
+            a = tmp;
+        }
+        return a;
+    }
+
+    public static int lcm(int a, int b) {
+        if (b == 0) return 0;
+        if (a < 0) a = -a;
+        if (b < 0) b = -b;
+        return a / fastUnsignedGcd(a, b) * b;
+    }
 }

core/src/test/resources/negative-input.csv

@@ -65,4 +65,9 @@ max(0)
 "min(1,-.)"
 "sin(1,,)"
 "sin(1,,2)"
-pi1
+pi1
+gcd()
+"gcd(1,)"
+"gcd(1.5, 3)"
+"gcd(3.5, 1.2)"
+"lcm(-3/2, 1)"

core/src/test/resources/positive-input.csv

@@ -136,3 +136,24 @@ pi,pi
 "xnor(0, 1)",0
 "xnor(1, 0)",0
 "xnor(1, 1)",1
+"gcd(10, 5)",5
+"gcd(25, 5)",5
+"gcd(30, 15)",15
+"gcd(30, 9)",3
+"gcd(29, 43)",1
+"gcd(461952, 116298)",18
+"gcd(24826148, 45296490)",526
+"gcd(0, 0)",0
+"gcd(12, 0)",12
+"gcd(0, 9)",9
+"lcm(15, 20)",60
+"lcm(10, 5)",10
+"lcm(5, 7)",35
+"lcm(1, 0)",0
+"lcm(2, 0)",0
+"lcm(0, 0)",0
+"lcm(2, -3)",6
+"lcm(-2, -2)",2
+"gcd(-24, 18)",6
+"gcd(-30, -9)",3
+"gcd(25, -5)",5