Implement async generators (#3916)

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

jerry-core/ecma/base/ecma-gc.c

@@ -404,6 +404,27 @@ ecma_gc_mark_executable_object (ecma_object_t *object_p) /**< object */
 {
   vm_executable_object_t *executable_object_p = (vm_executable_object_t *) object_p;
 
+  if (executable_object_p->extended_object.u.class_prop.extra_info & ECMA_ASYNC_GENERATOR_CALLED)
+  {
+    ecma_value_t task = executable_object_p->extended_object.u.class_prop.u.head;
+
+    while (!ECMA_IS_INTERNAL_VALUE_NULL (task))
+    {
+      ecma_async_generator_task_t *task_p;
+      task_p = ECMA_GET_INTERNAL_VALUE_POINTER (ecma_async_generator_task_t, task);
+
+      JERRY_ASSERT (ecma_is_value_object (task_p->promise));
+      ecma_gc_set_object_visited (ecma_get_object_from_value (task_p->promise));
+
+      if (ecma_is_value_object (task_p->operation_value))
+      {
+        ecma_gc_set_object_visited (ecma_get_object_from_value (task_p->operation_value));
+      }
+
+      task = task_p->next;
+    }
+  }
+
   if (!ECMA_EXECUTABLE_OBJECT_IS_SUSPENDED (executable_object_p->extended_object.u.class_prop.extra_info))
   {
     /* All objects referenced by running executable objects are strong roots,
@@ -584,6 +605,7 @@ ecma_gc_mark (ecma_object_t *object_p) /**< object to mark from */
 #endif /* ENABLED (JERRY_BUILTIN_CONTAINER) */
 #if ENABLED (JERRY_ESNEXT)
           case LIT_MAGIC_STRING_GENERATOR_UL:
+          case LIT_MAGIC_STRING_ASYNC_GENERATOR_UL:
           {
             ecma_gc_mark_executable_object (object_p);
             break;
@@ -850,6 +872,23 @@ ecma_gc_free_executable_object (ecma_object_t *object_p) /**< object */
 
   ecma_bytecode_deref ((ecma_compiled_code_t *) bytecode_header_p);
 
+  if (executable_object_p->extended_object.u.class_prop.extra_info & ECMA_ASYNC_GENERATOR_CALLED)
+  {
+    ecma_value_t task = executable_object_p->extended_object.u.class_prop.u.head;
+
+    while (!ECMA_IS_INTERNAL_VALUE_NULL (task))
+    {
+      ecma_async_generator_task_t *task_p;
+      task_p = ECMA_GET_INTERNAL_VALUE_POINTER (ecma_async_generator_task_t, task);
+
+      JERRY_ASSERT (ecma_is_value_object (task_p->promise));
+      ecma_free_value_if_not_object (task_p->operation_value);
+
+      task = task_p->next;
+      jmem_heap_free_block (task_p, sizeof (ecma_async_generator_task_t));
+    }
+  }
+
   if (executable_object_p->extended_object.u.class_prop.extra_info & ECMA_EXECUTABLE_OBJECT_COMPLETED)
   {
     return size;
@@ -1167,6 +1206,7 @@ ecma_gc_free_object (ecma_object_t *object_p) /**< object to free */
 #endif /* ENABLED (JERRY_BUILTIN_DATAVIEW) */
 #if ENABLED (JERRY_ESNEXT)
         case LIT_MAGIC_STRING_GENERATOR_UL:
+        case LIT_MAGIC_STRING_ASYNC_GENERATOR_UL:
         {
           ext_object_size = ecma_gc_free_executable_object (object_p);
           break;

jerry-core/ecma/base/ecma-globals.h

@@ -120,6 +120,7 @@ typedef enum
   ECMA_PARSE_FUNCTION_CONTEXT = (1u << 8), /**< function context is present (ECMA_PARSE_DIRECT_EVAL must be set) */
 
   ECMA_PARSE_GENERATOR_FUNCTION = (1u << 9), /**< generator function is parsed */
+  ECMA_PARSE_ASYNC_FUNCTION = (1u << 10), /**< async function is parsed */
 
   /* These flags are internally used by the parser. */
 #ifndef JERRY_NDEBUG
@@ -870,6 +871,7 @@ typedef struct
         ecma_value_t value; /**< value of the object (e.g. boolean, number, string, etc.) */
         uint32_t length; /**< length related property (e.g. length of ArrayBuffer) */
         ecma_value_t target; /**< [[ProxyTarget]] internal property */
+        ecma_value_t head; /**< points to the async generator task queue head item */
       } u;
     } class_prop;
 
@@ -1862,6 +1864,7 @@ typedef enum
   ECMA_EXECUTABLE_OBJECT_RUNNING = (1u << 1), /**< executable object is currently running */
   /* Generator specific flags. */
   ECMA_GENERATOR_ITERATE_AND_YIELD = (1u << 2), /**< the generator performs a yield* operation */
+  ECMA_ASYNC_GENERATOR_CALLED = (1u << 3), /**< the async generator was executed before */
 } ecma_executable_object_flags_t;
 
 /**
@@ -1870,6 +1873,23 @@ typedef enum
 #define ECMA_EXECUTABLE_OBJECT_IS_SUSPENDED(extra_info) \
   (!((extra_info) & (ECMA_EXECUTABLE_OBJECT_COMPLETED | ECMA_EXECUTABLE_OBJECT_RUNNING)))
 
+/**
+ * Enqueued task of an AsyncGenerator.
+ *
+ * An execution of a task has three steps:
+ *  1) Perform a next/throw/return operation
+ *  2) Resume the execution of the AsyncGenerator
+ *  3) Fulfill or reject a promise if the AsyncGenerator yielded a value
+ *     (these Promises are created by the AsyncGenerator itself)
+ */
+typedef struct
+{
+  ecma_value_t next; /**< points to the next task which will be performed after this task is completed */
+  ecma_value_t promise; /**< promise which will be fulfilled or rejected after this task is completed */
+  ecma_value_t operation_value; /**< value argument of the operation */
+  uint8_t operation_type; /**< type of operation (see ecma_async_generator_operation_type_t) */
+} ecma_async_generator_task_t;
+
 #endif /* ENABLED (JERRY_ESNEXT) */
 
 #if ENABLED (JERRY_BUILTIN_DATAVIEW)

jerry-core/ecma/base/ecma-helpers.h

@@ -127,13 +127,13 @@ typedef enum
  * Set an internal property value from pointer.
  */
 #define ECMA_SET_INTERNAL_VALUE_POINTER(field, pointer) \
-  (field) = ((ecma_value_t) pointer)
+  ((field) = ((ecma_value_t) pointer))
 
 /**
  * Set an internal property value from pointer. Pointer can be NULL.
  */
 #define ECMA_SET_INTERNAL_VALUE_ANY_POINTER(field, pointer) \
-  (field) = ((ecma_value_t) pointer)
+  ((field) = ((ecma_value_t) pointer))
 
 /**
  * Convert an internal property value to pointer.
@@ -147,6 +147,12 @@ typedef enum
 #define ECMA_GET_INTERNAL_VALUE_ANY_POINTER(type, field) \
   ((type *) field)
 
+/**
+ * Checks whether an internal property is NULL.
+ */
+#define ECMA_IS_INTERNAL_VALUE_NULL(field) \
+  ((field) == ((ecma_value_t) NULL))
+
 #else /* !ECMA_VALUE_CAN_STORE_UINTPTR_VALUE_DIRECTLY */
 
 /**
@@ -173,6 +179,12 @@ typedef enum
 #define ECMA_GET_INTERNAL_VALUE_ANY_POINTER(type, field) \
   ECMA_GET_POINTER (type, field)
 
+/**
+ * Checks whether an internal property is NULL.
+ */
+#define ECMA_IS_INTERNAL_VALUE_NULL(field) \
+  ((field) == ((ecma_value_t) JMEM_CP_NULL))
+
 #endif /* ECMA_VALUE_CAN_STORE_UINTPTR_VALUE_DIRECTLY */
 
 /**