From 267074cd8107a4f2073af0eef12e83f3eaf76c49 Mon Sep 17 00:00:00 2001
From: Andrew Kaster <akaster@serenityos.org>
Date: Mon, 11 Sep 2023 16:32:13 -0600
Subject: [PATCH] LibWeb: Add {de}serialization steps for RegExpObjects

We skip serializing any of the internal state of the Regex<ECMA262>
object, because that state is all computable from the input pattern
and flags. If it turns out that this is really, really slow, we can add
some optimizations to serialize more of the regex parse result.
---
 .../StructuredClone-object-primitives.txt     |  1 +
 .../StructuredClone-object-primitives.html    |  1 +
 .../LibWeb/HTML/StructuredSerialize.cpp       | 24 ++++++++++++++++++-
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/Tests/LibWeb/Text/expected/HTML/StructuredClone-object-primitives.txt b/Tests/LibWeb/Text/expected/HTML/StructuredClone-object-primitives.txt
index d3eebbfa88..3955abadde 100644
--- a/Tests/LibWeb/Text/expected/HTML/StructuredClone-object-primitives.txt
+++ b/Tests/LibWeb/Text/expected/HTML/StructuredClone-object-primitives.txt
@@ -5,4 +5,5 @@ false
 This is a String object
 9007199254740991
 1692748800000
+/abc/gimsuy
 ERROR: DataCloneError: Cannot serialize Symbol
\ No newline at end of file
diff --git a/Tests/LibWeb/Text/input/HTML/StructuredClone-object-primitives.html b/Tests/LibWeb/Text/input/HTML/StructuredClone-object-primitives.html
index 512ef6c7e5..0ba2a843e5 100644
--- a/Tests/LibWeb/Text/input/HTML/StructuredClone-object-primitives.html
+++ b/Tests/LibWeb/Text/input/HTML/StructuredClone-object-primitives.html
@@ -8,6 +8,7 @@
         println(structuredClone(new String("This is a String object")));
         println(structuredClone(BigInt("0x1fffffffffffff")));
         println(structuredClone(Date.UTC(2023, 7, 23)));
+        println(structuredClone(/abc/gimsuy));
 
         try {
             structuredClone(Symbol("foo"));
diff --git a/Userland/Libraries/LibWeb/HTML/StructuredSerialize.cpp b/Userland/Libraries/LibWeb/HTML/StructuredSerialize.cpp
index 61f3ece718..96bb3b60e0 100644
--- a/Userland/Libraries/LibWeb/HTML/StructuredSerialize.cpp
+++ b/Userland/Libraries/LibWeb/HTML/StructuredSerialize.cpp
@@ -16,6 +16,7 @@
 #include <LibJS/Runtime/Date.h>
 #include <LibJS/Runtime/NumberObject.h>
 #include <LibJS/Runtime/PrimitiveString.h>
+#include <LibJS/Runtime/RegExpObject.h>
 #include <LibJS/Runtime/StringObject.h>
 #include <LibJS/Runtime/VM.h>
 #include <LibWeb/Bindings/ExceptionOrUtils.h>
@@ -67,6 +68,8 @@ enum ValueTag {
 
     DateObject,
 
+    RegExpObject,
+
     // TODO: Define many more types
 
     // This tag or higher are understood to be errors
@@ -171,7 +174,20 @@ public:
             m_serialized.append(bit_cast<u32*>(&date_value), 2);
         }
 
-        // 12 - 24: FIXME: Serialize other data types
+        // 12. Otherwise, if value has a [[RegExpMatcher]] internal slot, then set serialized to
+        //     { [[Type]]: "RegExp", [[RegExpMatcher]]: value.[[RegExpMatcher]], [[OriginalSource]]: value.[[OriginalSource]],
+        //       [[OriginalFlags]]: value.[[OriginalFlags]] }.
+        else if (value.is_object() && is<JS::RegExpObject>(value.as_object())) {
+            m_serialized.append(ValueTag::RegExpObject);
+            auto& regexp_object = static_cast<JS::RegExpObject&>(value.as_object());
+            // Note: A Regex<ECMA262> object is perfectly happy to be reconstructed with just the source+flags
+            //       In the future, we could optimize the work being done on the deserialize step by serializing
+            //       more of the internal state (the [[RegExpMatcher]] internal slot)
+            TRY(serialize_string(m_serialized, TRY_OR_THROW_OOM(m_vm, String::from_deprecated_string(regexp_object.pattern()))));
+            TRY(serialize_string(m_serialized, TRY_OR_THROW_OOM(m_vm, String::from_deprecated_string(regexp_object.flags()))));
+        }
+
+        // 13 - 24: FIXME: Serialize other data types
         else {
             return throw_completion(WebIDL::DataCloneError::create(*m_vm.current_realm(), "Unsupported type"_fly_string));
         }
@@ -301,6 +317,12 @@ public:
                 m_memory.append(JS::Date::create(*realm, value));
                 break;
             }
+            case ValueTag::RegExpObject: {
+                auto pattern = TRY(deserialize_string_primitive(m_vm, m_vector, position));
+                auto flags = TRY(deserialize_string_primitive(m_vm, m_vector, position));
+                m_memory.append(TRY(JS::regexp_create(m_vm, move(pattern), move(flags))));
+                break;
+            }
             default:
                 m_error = "Unsupported type"_fly_string;
                 break;