From 3b344d6d721ecc45a96da00d2189c0d73f62d70b Mon Sep 17 00:00:00 2001
From: Deukhoofd <deukhoofd@gmail.com>
Date: Sun, 28 Jul 2019 12:33:14 +0200
Subject: [PATCH] Improve performance of cloning StringEvalValue

---
 src/Evaluator/EvalValues/StringEvalValue.hpp | 21 ++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/Evaluator/EvalValues/StringEvalValue.hpp b/src/Evaluator/EvalValues/StringEvalValue.hpp
index 77857e9..41d28ee 100644
--- a/src/Evaluator/EvalValues/StringEvalValue.hpp
+++ b/src/Evaluator/EvalValues/StringEvalValue.hpp
@@ -10,12 +10,16 @@ using namespace std;
 
 namespace Porygon::Evaluation {
     class StringEvalValue : public EvalValue {
-        u16string _value;
+        shared_ptr<u16string> _value;
         size_t _hash;
-    public:
-        explicit StringEvalValue(u16string s) : _value(move(s)){
-            _hash = Utilities::HashedString::ConstHash(_value.c_str());
+        explicit StringEvalValue(shared_ptr<u16string> s) : _value(move(s)){
+            _hash = Utilities::HashedString::ConstHash(_value->c_str());
         }
+    public:
+        explicit StringEvalValue(const u16string& s) : _value(make_shared<u16string>(s)){
+            _hash = Utilities::HashedString::ConstHash(_value->c_str());
+        }
+
 
         [[nodiscard]]
         inline TypeClass GetTypeClass() const final {
@@ -30,7 +34,7 @@ namespace Porygon::Evaluation {
 
         [[nodiscard]]
         inline u16string EvaluateString() const final {
-            return _value;
+            return *_value.get();
         }
 
         [[nodiscard]]
@@ -41,7 +45,7 @@ namespace Porygon::Evaluation {
         EvalValue* IndexValue(const EvalValue *val) const final {
             // Porygon is 1-indexed, so we convert to that.
             auto l = val->EvaluateInteger() - 1;
-            return new StringEvalValue(u16string(1, _value[l]));
+            return new StringEvalValue(u16string(1, (*_value)[l]));
         }
 
         [[nodiscard]]
@@ -55,9 +59,10 @@ namespace Porygon::Evaluation {
                 throw EvaluationException("Binary operation not supported for strings.");
             }
             std::basic_ostringstream<char16_t> stringStream;
-            stringStream << _value;
+            stringStream << *_value;
             stringStream << b->EvaluateString();
-            return new StringEvalValue(stringStream.str());
+            auto str = stringStream.str();
+            return new StringEvalValue(str);
         }
     };
 }