From 0717705f15e2bbcc6ffd3f86fa8c65ade2f4aafe Mon Sep 17 00:00:00 2001
From: Ilya Gorbunov <ilya.a.gorbunov@yandex.ru>
Date: Fri, 27 Mar 2015 14:27:25 +0300
Subject: [PATCH] Add requireNotNull with lazy message.

---
 .../stdlib/src/kotlin/util/Preconditions.kt     | 17 ++++++++++++++++-
 libraries/stdlib/test/PreconditionsTest.kt      | 15 +++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/libraries/stdlib/src/kotlin/util/Preconditions.kt b/libraries/stdlib/src/kotlin/util/Preconditions.kt
index bb28bcb9303..340a593bb12 100644
--- a/libraries/stdlib/src/kotlin/util/Preconditions.kt
+++ b/libraries/stdlib/src/kotlin/util/Preconditions.kt
@@ -41,6 +41,21 @@ public fun <T:Any> requireNotNull(value: T?, message: Any = "Required value was
     }
 }
 
+/**
+ * Throws an [IllegalArgumentException] with the result of calling [lazyMessage] if the [value] is null. Otherwise
+ * returns the not null value.
+ *
+ * @sample test.collections.PreconditionsTest.requireNotNullWithLazyMessage
+ */
+public fun <T:Any> requireNotNull(value: T?, lazyMessage: () -> Any): T {
+    if (value == null) {
+        val message = lazyMessage()
+        throw IllegalArgumentException(message.toString())
+    } else {
+        return value
+    }
+}
+
 /**
  * Throws an [IllegalStateException] with an optional [message] if the [value] is false.
  *
@@ -65,7 +80,7 @@ public inline fun check(value: Boolean, lazyMessage: () -> Any): Unit {
 }
 
 /**
- * Throws an [IllegalArgumentException] with the given [message] if the [value] is null. Otherwise
+ * Throws an [IllegalStateException] with the given [message] if the [value] is null. Otherwise
  * returns the not null value.
  *
  * @sample test.collections.PreconditionsTest.checkNotNull
diff --git a/libraries/stdlib/test/PreconditionsTest.kt b/libraries/stdlib/test/PreconditionsTest.kt
index 9bc75893d81..9e4a7f99614 100644
--- a/libraries/stdlib/test/PreconditionsTest.kt
+++ b/libraries/stdlib/test/PreconditionsTest.kt
@@ -84,6 +84,21 @@ class PreconditionsTest() {
         }
     }
 
+    test fun requireNotNullWithLazyMessage() {
+        val error = failsWith(javaClass<IllegalArgumentException>()) {
+            val obj: Any? = null
+            requireNotNull(obj) { "Message" }
+        }
+        assertEquals("Message", error.getMessage())
+
+        var lazyCalled: Boolean = false
+        requireNotNull("not null") {
+            lazyCalled = true
+            "Message"
+        }
+        assertFalse(lazyCalled, "Message is not evaluated if the condition is met")
+    }
+
     test fun checkNotNull() {
         val s1: String? = "S1"
         val r1: String = checkNotNull(s1)