better elvis + throw

+added run {}

docs/tutorial.md

@@ -225,6 +225,19 @@ It works much like `also`, but is executed in the context of the source object:
     assertEquals(p, Point(2,3))
     >>> void
 
+## run
+
+Executes a block after it returning the value passed by the block. for example, can be used with elvis operator:
+
+    var someVar = null
+    val result = someVar ?: run {
+      someVar = 121
+      "reset"
+    }
+    assertEquals("reset", result)
+    assertEquals(121, someVar)
+    >>> void
+
 ## Math
 
 It is rather simple, like everywhere else:
@@ -1311,6 +1324,7 @@ See [math functions](math.md). Other general purpose functions are:
 | flow {}                                      | create flow sequence, see [parallelism]                    |
 | delay, launch, yield                         | see [parallelism]                                          |
 | cached(builder)                              | remembers builder() on first invocation and return it then |
+| let, also, apply, run                        | see above, flow controls                                   |
 
 
 # Built-in constants

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Compiler.kt

@@ -376,6 +376,11 @@ class Compiler(
 
                         }
 
+                        "throw" -> {
+                            val s = parseThrowStatement()
+                            operand = Accessor { s.execute(it).asReadonly }
+                        }
+
                         else -> operand?.let { left ->
                             // selector: <lvalue>, '.' , <id>
                             // we replace operand with selector code, that

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/Obj.kt

@@ -315,6 +315,9 @@ open class Obj {
                 args.firstAndOnly().callOn(copy(Arguments(thisObj)))
                 thisObj
             }
+            addFn("run") {
+                args.firstAndOnly().callOn(this)
+            }
             addFn("getAt") {
                 requireExactCount(1)
                 thisObj.getAt(this, requiredArg<Obj>(0))

lynglib/src/commonTest/kotlin/ScriptTest.kt

@@ -2961,5 +2961,25 @@ class ScriptTest {
         """.trimIndent())
     }
 
+    @Test
+    fun testElvisAndThrow() = runTest {
+        eval("""
+            val x = assertThrows {
+                null ?: throw "test" + "x"
+            }
+            assertEquals( "testx", x.message)
+        """.trimIndent())
+    }
+
+    @Test
+    fun testElvisAndRunThrow() = runTest {
+        eval("""
+            val x = assertThrows {
+                null ?: run { throw "testx" }
+            }
+            assertEquals( "testx", x.message)
+        """.trimIndent())
+    }
+
 
 }