From ed8b5d835ddf07777ad781313bb7ed38e5fa41e8 Mon Sep 17 00:00:00 2001
From: Thomas Goyne <tg@realm.io>
Date: Wed, 20 Jun 2018 14:42:52 -0700
Subject: [PATCH] Eliminate some copies when reading strings from node

---
 src/node/node_string.hpp | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/node/node_string.hpp b/src/node/node_string.hpp
index dabe9d07..fe54781a 100644
--- a/src/node/node_string.hpp
+++ b/src/node/node_string.hpp
@@ -30,16 +30,35 @@ class String<node::Types> {
   public:
     String(const char* s) : m_str(s) {}
     String(const std::string &s) : m_str(s) {}
-    String(const v8::Local<v8::String> &s) : m_str(*Nan::Utf8String(s)) {}
+    String(const v8::Local<v8::String> &s);
     String(v8::Local<v8::String> &&s) : String(s) {}
 
-    operator std::string() const {
+    operator std::string() const& {
         return m_str;
     }
+    operator std::string() && {
+        return std::move(m_str);
+    }
     operator v8::Local<v8::String>() const {
         return Nan::New(m_str).ToLocalChecked();
     }
 };
 
+inline String<node::Types>::String(const v8::Local<v8::String> &s) {
+    if (s.IsEmpty() || s->Length() == 0) {
+        return;
+    }
+    if (s->IsOneByte()) {
+        m_str.resize(s->Length());
+    }
+    else {
+        // Length is in UCS-2 code units, which can take up to 3 bytes each to encode
+        m_str.resize(3 * s->Length());
+    }
+    const int flags = v8::String::NO_NULL_TERMINATION | v8::String::REPLACE_INVALID_UTF8;
+    auto length = s->WriteUtf8(&m_str[0], m_str.size(), 0, flags);
+    m_str.resize(length);
+}
+
 } // js
 } // realm