Support external context, heap and lcache (#1778)

JerryScript should support external context, heap and lcache,
so that it can have multiple instances and runtime configurable heap
size.

Related issue: 1746

JerryScript-DCO-1.0-Signed-off-by: Zidong Jiang zidong.jiang@intel.com

jerry-core/include/jerryscript-core.h

@@ -205,6 +205,11 @@ typedef void *(*jerry_user_context_init_t) (void);
  */
 typedef void (*jerry_user_context_deinit_t) (void *user_context_p);
 
+/**
+ * Function type for allocating buffer for JerryScript instance.
+ */
+typedef void *(*jerry_instance_alloc_t) (size_t size, void *cb_data_p);
+
 /**
  * Type information of a native pointer.
  */
@@ -213,6 +218,11 @@ typedef struct
   jerry_object_native_free_callback_t free_cb; /**< the free callback of the native pointer */
 } jerry_object_native_info_t;
 
+/**
+ * A forward declaration of the JerryScript instance structure.
+ */
+typedef struct jerry_instance_t jerry_instance_t;
+
 /**
  * General engine functions.
  */
@@ -403,6 +413,11 @@ jerry_value_t jerry_resolve_or_reject_promise (jerry_value_t promise, jerry_valu
 bool jerry_is_valid_utf8_string (const jerry_char_t *utf8_buf_p, jerry_size_t buf_size);
 bool jerry_is_valid_cesu8_string (const jerry_char_t *cesu8_buf_p, jerry_size_t buf_size);
 
+/*
+ * External context functions.
+ */
+jerry_instance_t *jerry_create_instance (uint32_t heap_size, jerry_instance_alloc_t alloc, void *cb_data_p);
+
 /**
  * Miscellaneous functions.
  */

jerry-core/include/jerryscript-port.h

@@ -126,6 +126,18 @@ bool jerry_port_get_time_zone (jerry_time_zone_t *tz_p);
  */
 double jerry_port_get_current_time (void);
 
+/**
+ * Get the current instance, which contains the current context, heap and other infomation.
+ * Each port should provide its own implementation of this interface.
+ *
+ *Note:
+ *    This port function will be called automatically by jerry-core
+ *    wnen JERRY_ENABLE_EXTERNAL_CONTEXT is defined. If not, this function will never be called.
+ *
+ * @return the pointer to the jerry instance.
+ */
+struct jerry_instance_t *jerry_port_get_current_instance (void);
+
 /**
  * @}
  */