Make Tetris sample more readable, add config reader. (JetBrains#1773)

samples/tetris/src/main/kotlin/Config.kt

@@ -0,0 +1,55 @@
+/**
+ * Copyright 2010-2018 JetBrains s.r.o.
+ *
+ * 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 tetris
+
+import platform.posix.*
+import kotlinx.cinterop.*
+
+object Config {
+    var width: Int = 10
+        private set
+    var height: Int = 20
+        private set
+    var startLevel = 0
+        private set
+
+    init {
+        val file = fopen("config.txt", "r")
+        if (file != null) {
+            try {
+                memScoped {
+                    val bufferLength = 2 * 1024
+                    val buffer = allocArray<ByteVar>(bufferLength)
+                    while (true) {
+                        val nextLine = fgets(buffer, bufferLength, file)?.toKString()
+                        if (nextLine == null || nextLine.isEmpty()) break
+                        val records = nextLine.split('=')
+                        if (records.size != 2) continue
+                        val key = records[0].trim()
+                        val value = records[1].trim()
+                        when (key) {
+                            "width" -> width = value.toInt()
+                            "height" -> height = value.toInt()
+                            "startLevel" -> startLevel = value.toInt()
+                        }
+                    }
+                }
+            } finally {
+                fclose(file)
+            }
+        }
+    }
+}