Add ConfigMemorySize type

Not used at all yet, and with no unit conversions supported.

config/src/main/java/com/typesafe/config/ConfigMemorySize.java

@@ -0,0 +1,49 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
+package com.typesafe.config;
+
+/**
+ * An immutable class representing an amount of memory.  Use
+ * static factory methods such as {@link
+ * ConfigMemorySize#ofBytes(long)} to create instances.
+ */
+public final class ConfigMemorySize {
+    private final long bytes;
+
+    private ConfigMemorySize(long bytes) {
+        if (bytes < 0)
+            throw new IllegalArgumentException("Attempt to construct ConfigMemorySize with negative number: " + bytes);
+        this.bytes = bytes;
+    }
+
+    /** Constructs a ConfigMemorySize representing the given
+     * number of bytes.
+     */
+    public static ConfigMemorySize ofBytes(long bytes) {
+        return new ConfigMemorySize(bytes);
+    }
+
+    /** Gets the size in bytes.
+     */
+    public long toBytes() {
+        return bytes;
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (other instanceof ConfigMemorySize) {
+            return ((ConfigMemorySize)other).bytes == this.bytes;
+        } else {
+            return false;
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        // in Java 8 this can become Long.hashCode(bytes)
+        return Long.valueOf(bytes).hashCode();
+    }
+
+}
+

config/src/test/scala/com/typesafe/config/impl/ConfigMemorySizeTest.scala

@@ -0,0 +1,25 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
+package com.typesafe.config.impl
+
+import org.junit.Assert._
+import org.junit._
+import com.typesafe.config.ConfigMemorySize
+
+class ConfigMemorySizeTest extends TestUtils {
+
+  @Test
+  def testEquals() {
+    assertTrue("Equal ConfigMemorySize are equal",
+               ConfigMemorySize.ofBytes(10).equals(ConfigMemorySize.ofBytes(10)))
+    assertTrue("Different ConfigMemorySize are not equal",
+               !ConfigMemorySize.ofBytes(10).equals(ConfigMemorySize.ofBytes(11)))
+  }
+
+  @Test
+  def testToUnits() {
+    val kilobyte = ConfigMemorySize.ofBytes(1024)
+    assertEquals(1024, kilobyte.toBytes)
+  }
+}