Добавлен std::default

src/main/java/com/annimon/ownlang/modules/std/std.java

@@ -26,6 +26,7 @@ public final class std implements Module {
         Functions.set("thread", new std_thread());
         Functions.set("sync", new std_sync());
         Functions.set("try", new std_try());
+        Functions.set("default", new std_default());
 
         // Numbers
         Functions.set("toHexString", NumberFunctions::toHexString);

src/main/java/com/annimon/ownlang/modules/std/std_default.java

@@ -0,0 +1,38 @@
+package com.annimon.ownlang.modules.std;
+
+import com.annimon.ownlang.lib.Arguments;
+import com.annimon.ownlang.lib.ArrayValue;
+import com.annimon.ownlang.lib.Function;
+import com.annimon.ownlang.lib.MapValue;
+import com.annimon.ownlang.lib.Types;
+import com.annimon.ownlang.lib.Value;
+
+public final class std_default implements Function {
+
+    @Override
+    public Value execute(Value... args) {
+        Arguments.check(2, args.length);
+        if (isEmpty(args[0])) {
+            return args[1];
+        }
+        return args[0];
+    }
+
+    private boolean isEmpty(Value value) {
+        if (value == null || value.raw() == null) {
+            return true;
+        }
+        switch (value.type()) {
+            case Types.NUMBER:
+                return (value.asInt() == 0);
+            case Types.STRING:
+                return (value.asString().isEmpty());
+            case Types.ARRAY:
+                return ((ArrayValue) value).size() == 0;
+            case Types.MAP:
+                return ((MapValue) value).size() == 0;
+            default:
+                return false;
+        }
+    }
+}

src/test/resources/modules/std/default.own

@@ -0,0 +1,19 @@
+use "std"
+
+def testDefaultNumber() {
+  assertEquals(123, default(0, 123))
+}
+
+def testDefaultString() {
+  assertEquals("123", default("", "123"))
+}
+
+def testDefaultNull() {
+  use "java"
+  assertEquals("not null", default(null, "not null"))
+}
+
+def testOperatorOverloading() {
+  def `?:`(a, b) = default(a, b)
+  assertEquals("not null", "" ?: "not null")
+}