From 9676500addbcc5974bf81f7b3726230d26f5c1a5 Mon Sep 17 00:00:00 2001
From: Zoltan Herczeg <zherczeg.u-szeged@partner.samsung.com>
Date: Fri, 18 Dec 2020 10:58:48 +0100
Subject: [PATCH] Implement get proxy target (#4367)

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com
---
 docs/02.API-REFERENCE.md              | 56 +++++++++++++++++++++++++++
 jerry-core/api/jerry.c                | 34 ++++++++++++++++
 jerry-core/include/jerryscript-core.h |  5 +++
 tests/unit-core/test-proxy.c          | 20 ++++++++++
 4 files changed, 115 insertions(+)

diff --git a/docs/02.API-REFERENCE.md b/docs/02.API-REFERENCE.md
index d26f27c8c..f51041d88 100644
--- a/docs/02.API-REFERENCE.md
+++ b/docs/02.API-REFERENCE.md
@@ -4494,6 +4494,62 @@ main (void)
 - [jerry_get_bigint_size_in_digits](#jerry_get_bigint_size_in_digits)
 
 
+# Functions for Proxy objects
+
+These APIs all depend on build option (`JERRY_BUILTIN_PROXY`).
+
+## jerry_get_proxy_target
+
+**Summary**
+
+Gets the target object of a Proxy object
+
+*Notes*:
+- This API depends on a build option (`JERRY_BUILTIN_PROXY`) and can be checked
+  in runtime with the `JERRY_FEATURE_PROXY` feature enum value,
+  see: [jerry_is_feature_enabled](#jerry_is_feature_enabled).
+- The es.next profile enables this by default.
+
+
+**Prototype**
+
+```c
+jerry_value_t
+jerry_get_proxy_target (jerry_value_t proxy_value)
+```
+
+- `proxy_value` - Proxy object value
+- return value
+  - type error - if proxy_value is not a Proxy object
+  - target object - otherwise
+
+*New in version [[NEXT_RELEASE]]*.
+
+**Example**
+
+```c
+{
+  jerry_value_t target = jerry_create_object ();
+  jerry_value_t handler = jerry_create_object ();
+  jerry_value_t proxy = jerry_create_proxy (target, handler);
+
+  jerry_release_value (target);
+  jerry_release_value (handler);
+
+  target = jerry_get_proxy_target (proxy);
+
+  // ... usage of the target
+
+  jerry_release_value (target);
+  jerry_release_value (proxy);
+}
+```
+
+**See also**
+
+- [jerry_create_proxy](#jerry_create_proxy)
+
+
 # Acquire and release API values
 
 ## jerry_acquire_value
diff --git a/jerry-core/api/jerry.c b/jerry-core/api/jerry.c
index 1b56eff54..99f15fafb 100644
--- a/jerry-core/api/jerry.c
+++ b/jerry-core/api/jerry.c
@@ -4337,6 +4337,40 @@ jerry_get_bigint_digits (jerry_value_t value, /**< BigInt value */
 #endif /* ENABLED (JERRY_BUILTIN_BIGINT) */
 } /* jerry_get_bigint_digits */
 
+/**
+ * Get the target object of a Proxy object
+ *
+ * @return type error - if proxy_value is not a Proxy object
+ *         target object - otherwise
+ */
+jerry_value_t
+jerry_get_proxy_target (jerry_value_t proxy_value) /**< proxy value */
+{
+  jerry_assert_api_available ();
+
+#if ENABLED (JERRY_BUILTIN_PROXY)
+  if (ecma_is_value_object (proxy_value))
+  {
+    ecma_object_t *object_p = ecma_get_object_from_value (proxy_value);
+
+    if (ECMA_OBJECT_IS_PROXY (object_p))
+    {
+      ecma_proxy_object_t *proxy_object_p = (ecma_proxy_object_t *) object_p;
+
+      if (!ecma_is_value_null (proxy_object_p->target))
+      {
+        ecma_ref_object (ecma_get_object_from_value (proxy_object_p->target));
+      }
+      return proxy_object_p->target;
+    }
+  }
+#else /* !ENABLED (JERRY_BUILTIN_PROXY) */
+  JERRY_UNUSED (proxy_value);
+#endif /* ENABLED (JERRY_BUILTIN_PROXY) */
+
+  return jerry_throw (ecma_raise_type_error (ECMA_ERR_MSG ("Passed value is not a proxy object")));
+} /* jerry_get_proxy_target */
+
 /**
  * Validate UTF-8 string
  *
diff --git a/jerry-core/include/jerryscript-core.h b/jerry-core/include/jerryscript-core.h
index 780f41532..e9265a4f1 100644
--- a/jerry-core/include/jerryscript-core.h
+++ b/jerry-core/include/jerryscript-core.h
@@ -723,6 +723,11 @@ jerry_value_t jerry_realm_set_this (jerry_value_t realm_value, jerry_value_t thi
 uint32_t jerry_get_bigint_size_in_digits (jerry_value_t value);
 void jerry_get_bigint_digits (jerry_value_t value, uint64_t *digits_p, uint32_t size, bool *sign_p);
 
+/**
+ * Proxy functions.
+ */
+jerry_value_t jerry_get_proxy_target (jerry_value_t proxy_value);
+
 /**
  * Input validator functions.
  */
diff --git a/tests/unit-core/test-proxy.c b/tests/unit-core/test-proxy.c
index fb0e344ee..6346387a7 100644
--- a/tests/unit-core/test-proxy.c
+++ b/tests/unit-core/test-proxy.c
@@ -272,6 +272,26 @@ main (void)
     jerry_release_value (property);
   }
 
+  target = jerry_create_object ();
+  handler = jerry_create_object ();
+  proxy = jerry_create_proxy (target, handler);
+  jerry_release_value (handler);
+
+  {
+    jerry_value_t res = jerry_get_proxy_target (proxy);
+    TEST_ASSERT (res == target);
+    jerry_release_value (res);
+
+    res = jerry_get_proxy_target (target);
+    TEST_ASSERT (jerry_value_is_error (res));
+    res = jerry_get_value_from_error (res, true);
+    TEST_ASSERT (jerry_get_error_type (res) == JERRY_ERROR_TYPE);
+    jerry_release_value (res);
+  }
+
+  jerry_release_value (proxy);
+  jerry_release_value (target);
+
   jerry_cleanup ();
   return 0;
 } /* main */