repl: help command

compiler/cli/src/org/jetbrains/jet/cli/jvm/repl/ReplFromTerminal.java

@@ -85,7 +85,8 @@ public class ReplFromTerminal {
 
     private void doRun() {
         try {
-            System.out.println("Kotlin");
+            System.out.println("Kotlin interactive shell");
+            System.out.println("Type :help for help");
             while (true) {
                 boolean next = one();
                 if (!next) {
@@ -109,6 +110,11 @@ public class ReplFromTerminal {
             if (line == null) {
                 return false;
             }
+
+            if (line.startsWith(":")) {
+                return oneCommand(line.substring(1));
+            }
+
             Object value = getReplInterpreter().eval(line);
             System.out.println(value);
             return true;
@@ -118,6 +124,20 @@ public class ReplFromTerminal {
         }
     }
 
+    private boolean oneCommand(@NotNull String command) {
+        if (command.equals("help")) {
+            System.out.println("This is Kotlin REPL help");
+            System.out.println("Available commands are:");
+            System.out.println(":help                   show this help");
+            return true;
+        }
+        else {
+            System.out.println("Unknown command");
+            System.out.println("Type :help for help");
+            return true;
+        }
+    }
+
     public static void run(@NotNull Disposable disposable, @NotNull CompilerDependencies compilerDependencies) {
         new ReplFromTerminal(disposable, compilerDependencies).doRun();
     }