requireShape helper methods

Signed-off-by: Ryan Nett <[email protected]>

Author: rnett

tensorflow-core-kotlin/tensorflow-core-kotlin-api/src/main/kotlin/org/tensorflow/OperandHelpers.kt

@@ -0,0 +1,42 @@
+/*
+  Copyright 2020 The TensorFlow Authors. All Rights Reserved.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ ==============================================================================
+ */
+package org.tensorflow
+
+import org.tensorflow.ndarray.Shape
+import org.tensorflow.ndarray.Shaped
+
+/**
+ * Require the [Shaped] object have a certain shape.
+ *
+ * Throws [IllegalStateException] on failure.
+ */
+public fun <T: Shaped> T.requireShape(shape: Shape): T = apply{
+    check(this.shape().isCompatibleWith(shape)){
+        "Shape ${this.shape()} is not compatible with the required shape $shape"
+    }
+}
+
+/**
+ * Require the [Shaped] object have a certain shape.
+ *
+ * Throws [IllegalStateException] on failure.
+ */
+public fun <T: Shaped> T.requireShape(vararg shape: Long): T = apply{
+    check(this.shape().isCompatibleWith(Shape.of(*shape))){
+        "Shape ${this.shape()} is not compatible with the required shape $shape"
+    }
+}