LibJS: Make AssignmentExpression assign through a Reference

Reference now has assign(Interpreter&, Value) which is used to write
transparently through a Reference into whatever location it refers to.

2 files changed, 53 insertions, 0 deletions

diff --git a/Libraries/LibJS/Runtime/Reference.cpp b/Libraries/LibJS/Runtime/Reference.cpp
new file mode 100644
index 0000000000..13402cdc9d
--- /dev/null
+++ b/Libraries/LibJS/Runtime/Reference.cpp
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibJS/Interpreter.h>
+#include <LibJS/Runtime/Reference.h>
+#include <LibJS/Runtime/Object.h>
+
+namespace JS {
+
+void Reference::assign(Interpreter& interpreter, Value value)
+{
+    // NOTE: The caller is responsible for doing an exception check after assign().
+
+    ASSERT(!is_unresolvable());
+
+    if (is_local_variable()) {
+        interpreter.set_variable(m_name.to_string(), value);
+        return;
+    }
+
+    auto* object = base().to_object(interpreter.heap());
+    if (!object)
+        return;
+
+    object->put(m_name, value);
+}
+
+}
diff --git a/Libraries/LibJS/Runtime/Reference.h b/Libraries/LibJS/Runtime/Reference.h
index 2cad110497..81b1701496 100644
--- a/Libraries/LibJS/Runtime/Reference.h
+++ b/Libraries/LibJS/Runtime/Reference.h
@@ -71,6 +71,8 @@ public:
         return m_local_variable;
     }
 
+    void assign(Interpreter&, Value);
+
 private:
     Value m_base { js_undefined() };
     PropertyName m_name;