From a5a15673dee7ef1ba98f2af14785e41ffec367f9 Mon Sep 17 00:00:00 2001
From: Mislav Bradac <mislav.bradac@memgraph.io>
Date: Mon, 13 Mar 2017 15:55:48 +0100
Subject: [PATCH] TypedValue getters return references

Reviewers: buda

Reviewed By: buda

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D113
---
 src/query/backend/cpp/typed_value.cpp | 558 ++++++++++++++------------
 src/query/backend/cpp/typed_value.hpp |  72 ++--
 2 files changed, 346 insertions(+), 284 deletions(-)

diff --git a/src/query/backend/cpp/typed_value.cpp b/src/query/backend/cpp/typed_value.cpp
index 63cc4ce9c..279ea0714 100644
--- a/src/query/backend/cpp/typed_value.cpp
+++ b/src/query/backend/cpp/typed_value.cpp
@@ -1,58 +1,58 @@
 #include "query/backend/cpp/typed_value.hpp"
 
-#include <fmt/format.h>
 #include <cmath>
+#include <fmt/format.h>
 #include <iostream>
 #include <memory>
 
 #include "utils/assert.hpp"
 
-TypedValue::TypedValue(const PropertyValue& value) {
+TypedValue::TypedValue(const PropertyValue &value) {
   switch (value.type()) {
-    case PropertyValue::Type::Null:
-      type_ = Type::Null;
-      return;
-    case PropertyValue::Type::Bool:
-      type_ = Type::Bool;
-      bool_v = value.Value<bool>();
-      return;
-    case PropertyValue::Type::Int:
-      type_ = Type::Int;
-      int_v = value.Value<int64_t>();
-      return;
-    case PropertyValue::Type::Double:
-      type_ = Type::Double;
-      double_v = value.Value<double>();
-    case PropertyValue::Type::String:
-      type_ = Type::String;
-      new (&string_v) std::string(value.Value<std::string>());
-    case PropertyValue::Type::List:
-      type_ = Type::List;
-      auto vec = value.Value<std::vector<PropertyValue>>();
-      new (&list_v) std::vector<TypedValue>(vec.begin(), vec.end());
-      return;
+  case PropertyValue::Type::Null:
+    type_ = Type::Null;
+    return;
+  case PropertyValue::Type::Bool:
+    type_ = Type::Bool;
+    bool_v = value.Value<bool>();
+    return;
+  case PropertyValue::Type::Int:
+    type_ = Type::Int;
+    int_v = value.Value<int64_t>();
+    return;
+  case PropertyValue::Type::Double:
+    type_ = Type::Double;
+    double_v = value.Value<double>();
+  case PropertyValue::Type::String:
+    type_ = Type::String;
+    new (&string_v) std::string(value.Value<std::string>());
+  case PropertyValue::Type::List:
+    type_ = Type::List;
+    auto vec = value.Value<std::vector<PropertyValue>>();
+    new (&list_v) std::vector<TypedValue>(vec.begin(), vec.end());
+    return;
   }
   permanent_fail("Unsupported type");
 }
 
 TypedValue::operator PropertyValue() const {
   switch (type_) {
-    case TypedValue::Type::Null:
-      return PropertyValue::Null;
-    case TypedValue::Type::Bool:
-      return PropertyValue(bool_v);
-    case TypedValue::Type::Int:
-      return PropertyValue(int_v);
-    case TypedValue::Type::Double:
-      return PropertyValue(double_v);
-    case TypedValue::Type::String:
-      return PropertyValue(string_v);
-    case TypedValue::Type::List:
-      return PropertyValue(
-          std::vector<PropertyValue>(list_v.begin(), list_v.end()));
-    default:
-      throw TypedValueException(
-          "Unsupported conversion from TypedValue to PropertyValue");
+  case TypedValue::Type::Null:
+    return PropertyValue::Null;
+  case TypedValue::Type::Bool:
+    return PropertyValue(bool_v);
+  case TypedValue::Type::Int:
+    return PropertyValue(int_v);
+  case TypedValue::Type::Double:
+    return PropertyValue(double_v);
+  case TypedValue::Type::String:
+    return PropertyValue(string_v);
+  case TypedValue::Type::List:
+    return PropertyValue(
+        std::vector<PropertyValue>(list_v.begin(), list_v.end()));
+  default:
+    throw TypedValueException(
+        "Unsupported conversion from TypedValue to PropertyValue");
   }
 }
 
@@ -61,32 +61,28 @@ TypedValue::operator PropertyValue() const {
 // Other solution would be to add additional overloads for references, for
 // example Value<string&>.
 // Value extraction template instantiations
-template <>
-bool TypedValue::Value<bool>() const {
+template <> const bool &TypedValue::Value<bool>() const {
   if (type_ != TypedValue::Type::Bool) {
     throw TypedValueException("Incompatible template param and type");
   }
   return bool_v;
 }
 
-template <>
-int64_t TypedValue::Value<int64_t>() const {
+template <> const int64_t &TypedValue::Value<int64_t>() const {
   if (type_ != TypedValue::Type::Int) {
     throw TypedValueException("Incompatible template param and type");
   }
   return int_v;
 }
 
-template <>
-double TypedValue::Value<double>() const {
+template <> const double &TypedValue::Value<double>() const {
   if (type_ != TypedValue::Type::Double) {
     throw TypedValueException("Incompatible template param and type");
   }
   return double_v;
 }
 
-template <>
-std::string TypedValue::Value<std::string>() const {
+template <> const std::string &TypedValue::Value<std::string>() const {
   if (type_ != TypedValue::Type::String) {
     throw TypedValueException("Incompatible template param and type");
   }
@@ -94,7 +90,8 @@ std::string TypedValue::Value<std::string>() const {
 }
 
 template <>
-std::vector<TypedValue> TypedValue::Value<std::vector<TypedValue>>() const {
+const std::vector<TypedValue> &
+TypedValue::Value<std::vector<TypedValue>>() const {
   if (type_ != TypedValue::Type::List) {
     throw TypedValueException("Incompatible template param and type");
   }
@@ -102,7 +99,7 @@ std::vector<TypedValue> TypedValue::Value<std::vector<TypedValue>>() const {
 }
 
 template <>
-std::map<std::string, TypedValue>
+std::map<std::string, TypedValue> const &
 TypedValue::Value<std::map<std::string, TypedValue>>() const {
   if (type_ != TypedValue::Type::Map) {
     throw TypedValueException("Incompatible template param and type");
@@ -110,159 +107,222 @@ TypedValue::Value<std::map<std::string, TypedValue>>() const {
   return map_v;
 }
 
-template <>
-VertexAccessor TypedValue::Value<VertexAccessor>() const {
+template <> const VertexAccessor &TypedValue::Value<VertexAccessor>() const {
   if (type_ != TypedValue::Type::Vertex) {
     throw TypedValueException("Incompatible template param and type");
   }
   return vertex_v;
 }
 
-template <>
-EdgeAccessor TypedValue::Value<EdgeAccessor>() const {
+template <> const EdgeAccessor &TypedValue::Value<EdgeAccessor>() const {
   if (type_ != TypedValue::Type::Edge) {
     throw TypedValueException("Incompatible template param and type");
   }
   return edge_v;
 }
 
-template <>
-Path TypedValue::Value<Path>() const {
+template <> const Path &TypedValue::Value<Path>() const {
   if (type_ != TypedValue::Type::Path) {
     throw TypedValueException("Incompatible template param and type");
   }
   return path_v;
 }
 
-TypedValue::TypedValue(const TypedValue& other) : type_(other.type_) {
+template <> bool &TypedValue::Value<bool>() {
+  if (type_ != TypedValue::Type::Bool) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return bool_v;
+}
+
+template <> int64_t &TypedValue::Value<int64_t>() {
+  if (type_ != TypedValue::Type::Int) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return int_v;
+}
+
+template <> double &TypedValue::Value<double>() {
+  if (type_ != TypedValue::Type::Double) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return double_v;
+}
+
+template <> std::string &TypedValue::Value<std::string>() {
+  if (type_ != TypedValue::Type::String) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return string_v;
+}
+
+template <>
+std::vector<TypedValue> &TypedValue::Value<std::vector<TypedValue>>() {
+  if (type_ != TypedValue::Type::List) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return list_v;
+}
+
+template <>
+std::map<std::string, TypedValue> &
+TypedValue::Value<std::map<std::string, TypedValue>>() {
+  if (type_ != TypedValue::Type::Map) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return map_v;
+}
+
+template <> VertexAccessor &TypedValue::Value<VertexAccessor>() {
+  if (type_ != TypedValue::Type::Vertex) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return vertex_v;
+}
+
+template <> EdgeAccessor &TypedValue::Value<EdgeAccessor>() {
+  if (type_ != TypedValue::Type::Edge) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return edge_v;
+}
+
+template <> Path &TypedValue::Value<Path>() {
+  if (type_ != TypedValue::Type::Path) {
+    throw TypedValueException("Incompatible template param and type");
+  }
+  return path_v;
+}
+
+TypedValue::TypedValue(const TypedValue &other) : type_(other.type_) {
   switch (other.type_) {
-    case TypedValue::Type::Null:
-      return;
-    case TypedValue::Type::Bool:
-      this->bool_v = other.bool_v;
-      return;
-    case Type::Int:
-      this->int_v = other.int_v;
-      return;
-    case Type::Double:
-      this->double_v = other.double_v;
-      return;
-    case TypedValue::Type::String:
-      new (&string_v) std::string(other.string_v);
-      return;
-    case Type::List:
-      new (&list_v) std::vector<TypedValue>(other.list_v);
-      return;
-    case Type::Map:
-      new (&map_v) std::map<std::string, TypedValue>(other.map_v);
-      return;
-    case Type::Vertex:
-      new (&vertex_v) VertexAccessor(other.vertex_v);
-      return;
-    case Type::Edge:
-      new (&edge_v) EdgeAccessor(other.edge_v);
-      return;
-    case Type::Path:
-      new (&path_v) Path(other.path_v);
+  case TypedValue::Type::Null:
+    return;
+  case TypedValue::Type::Bool:
+    this->bool_v = other.bool_v;
+    return;
+  case Type::Int:
+    this->int_v = other.int_v;
+    return;
+  case Type::Double:
+    this->double_v = other.double_v;
+    return;
+  case TypedValue::Type::String:
+    new (&string_v) std::string(other.string_v);
+    return;
+  case Type::List:
+    new (&list_v) std::vector<TypedValue>(other.list_v);
+    return;
+  case Type::Map:
+    new (&map_v) std::map<std::string, TypedValue>(other.map_v);
+    return;
+  case Type::Vertex:
+    new (&vertex_v) VertexAccessor(other.vertex_v);
+    return;
+  case Type::Edge:
+    new (&edge_v) EdgeAccessor(other.edge_v);
+    return;
+  case Type::Path:
+    new (&path_v) Path(other.path_v);
   }
   permanent_fail("Unsupported TypedValue::Type");
 }
 
-std::ostream& operator<<(std::ostream& os, const TypedValue::Type type) {
+std::ostream &operator<<(std::ostream &os, const TypedValue::Type type) {
   switch (type) {
-    case TypedValue::Type::Null:
-      return os << "null";
-    case TypedValue::Type::Bool:
-      return os << "bool";
-    case TypedValue::Type::Int:
-      return os << "int";
-    case TypedValue::Type::Double:
-      return os << "double";
-    case TypedValue::Type::String:
-      return os << "string";
-    case TypedValue::Type::List:
-      return os << "list";
-    case TypedValue::Type::Map:
-      return os << "map";
-    case TypedValue::Type::Vertex:
-      return os << "vertex";
-    case TypedValue::Type::Edge:
-      return os << "edge";
-    case TypedValue::Type::Path:
-      return os << "path";
+  case TypedValue::Type::Null:
+    return os << "null";
+  case TypedValue::Type::Bool:
+    return os << "bool";
+  case TypedValue::Type::Int:
+    return os << "int";
+  case TypedValue::Type::Double:
+    return os << "double";
+  case TypedValue::Type::String:
+    return os << "string";
+  case TypedValue::Type::List:
+    return os << "list";
+  case TypedValue::Type::Map:
+    return os << "map";
+  case TypedValue::Type::Vertex:
+    return os << "vertex";
+  case TypedValue::Type::Edge:
+    return os << "edge";
+  case TypedValue::Type::Path:
+    return os << "path";
   }
   permanent_fail("Unsupported TypedValue::Type");
 }
 
-std::ostream& operator<<(std::ostream& os, const TypedValue& value) {
+std::ostream &operator<<(std::ostream &os, const TypedValue &value) {
   switch (value.type_) {
-    case TypedValue::Type::Null:
-      return os << "Null";
-    case TypedValue::Type::Bool:
-      return os << (value.Value<bool>() ? "true" : "false");
-    case TypedValue::Type::Int:
-      return os << value.Value<int64_t>();
-    case TypedValue::Type::Double:
-      return os << value.Value<double>();
-    case TypedValue::Type::String:
-      return os << value.Value<std::string>();
-    case TypedValue::Type::List:
-      os << "[";
-      for (const auto& x : value.Value<std::vector<TypedValue>>()) {
-        os << x << ",";
-      }
-      return os << "]";
-    case TypedValue::Type::Map:
-      os << "{";
-      for (const auto& x : value.Value<std::map<std::string, TypedValue>>()) {
-        os << x.first << ": " << x.second << ",";
-      }
-      return os << "}";
-    case TypedValue::Type::Vertex:
-      return os << value.Value<VertexAccessor>();
-    case TypedValue::Type::Edge:
-      return os << value.Value<EdgeAccessor>();
-    case TypedValue::Type::Path:
-      return os << value.Value<Path>();
+  case TypedValue::Type::Null:
+    return os << "Null";
+  case TypedValue::Type::Bool:
+    return os << (value.Value<bool>() ? "true" : "false");
+  case TypedValue::Type::Int:
+    return os << value.Value<int64_t>();
+  case TypedValue::Type::Double:
+    return os << value.Value<double>();
+  case TypedValue::Type::String:
+    return os << value.Value<std::string>();
+  case TypedValue::Type::List:
+    os << "[";
+    for (const auto &x : value.Value<std::vector<TypedValue>>()) {
+      os << x << ",";
+    }
+    return os << "]";
+  case TypedValue::Type::Map:
+    os << "{";
+    for (const auto &x : value.Value<std::map<std::string, TypedValue>>()) {
+      os << x.first << ": " << x.second << ",";
+    }
+    return os << "}";
+  case TypedValue::Type::Vertex:
+    return os << value.Value<VertexAccessor>();
+  case TypedValue::Type::Edge:
+    return os << value.Value<EdgeAccessor>();
+  case TypedValue::Type::Path:
+    return os << value.Value<Path>();
   }
   permanent_fail("Unsupported PropertyValue::Type");
 }
 
-TypedValue& TypedValue::operator=(const TypedValue& other) {
+TypedValue &TypedValue::operator=(const TypedValue &other) {
   // set the type of this
   this->~TypedValue();
   type_ = other.type_;
 
   if (this != &other) {
     switch (other.type_) {
-      case TypedValue::Type::Null:
-      case TypedValue::Type::Bool:
-        this->bool_v = other.bool_v;
-        return *this;
-      case TypedValue::Type::Int:
-        this->int_v = other.int_v;
-        return *this;
-      case TypedValue::Type::Double:
-        this->double_v = other.double_v;
-        return *this;
-      case TypedValue::Type::String:
-        new (&string_v) std::string(other.string_v);
-        return *this;
-      case TypedValue::Type::List:
-        new (&list_v) std::vector<TypedValue>(other.list_v);
-        return *this;
-      case TypedValue::Type::Map:
-        new (&map_v) std::map<std::string, TypedValue>(other.map_v);
-        return *this;
-      case TypedValue::Type::Vertex:
-        new (&vertex_v) VertexAccessor(other.vertex_v);
-        return *this;
-      case TypedValue::Type::Edge:
-        new (&edge_v) EdgeAccessor(other.edge_v);
-        return *this;
-      case TypedValue::Type::Path:
-        new (&path_v) Path(other.path_v);
-        return *this;
+    case TypedValue::Type::Null:
+    case TypedValue::Type::Bool:
+      this->bool_v = other.bool_v;
+      return *this;
+    case TypedValue::Type::Int:
+      this->int_v = other.int_v;
+      return *this;
+    case TypedValue::Type::Double:
+      this->double_v = other.double_v;
+      return *this;
+    case TypedValue::Type::String:
+      new (&string_v) std::string(other.string_v);
+      return *this;
+    case TypedValue::Type::List:
+      new (&list_v) std::vector<TypedValue>(other.list_v);
+      return *this;
+    case TypedValue::Type::Map:
+      new (&map_v) std::map<std::string, TypedValue>(other.map_v);
+      return *this;
+    case TypedValue::Type::Vertex:
+      new (&vertex_v) VertexAccessor(other.vertex_v);
+      return *this;
+    case TypedValue::Type::Edge:
+      new (&edge_v) EdgeAccessor(other.edge_v);
+      return *this;
+    case TypedValue::Type::Path:
+      new (&path_v) Path(other.path_v);
+      return *this;
     }
   }
   permanent_fail("Unsupported TypedValue::Type");
@@ -272,38 +332,38 @@ const TypedValue TypedValue::Null = TypedValue();
 
 TypedValue::~TypedValue() {
   switch (type_) {
-    // destructor for primitive types does nothing
-    case Type::Null:
-    case Type::Bool:
-    case Type::Int:
-    case Type::Double:
-      return;
+  // destructor for primitive types does nothing
+  case Type::Null:
+  case Type::Bool:
+  case Type::Int:
+  case Type::Double:
+    return;
 
-    // we need to call destructors for non primitive types since we used
-    // placement new
-    case Type::String:
-      // Clang fails to compile ~std::string. It seems it is a bug in some
-      // versions of clang. using namespace std statement solves the issue.
-      using namespace std;
-      string_v.~string();
-      return;
-    case Type::List:
-      using namespace std;
-      list_v.~vector<TypedValue>();
-      return;
-    case Type::Map:
-      using namespace std;
-      map_v.~map<std::string, TypedValue>();
-      return;
-    case Type::Vertex:
-      vertex_v.~VertexAccessor();
-      return;
-    case Type::Edge:
-      edge_v.~EdgeAccessor();
-      return;
-    case Type::Path:
-      path_v.~Path();
-      return;
+  // we need to call destructors for non primitive types since we used
+  // placement new
+  case Type::String:
+    // Clang fails to compile ~std::string. It seems it is a bug in some
+    // versions of clang. using namespace std statement solves the issue.
+    using namespace std;
+    string_v.~string();
+    return;
+  case Type::List:
+    using namespace std;
+    list_v.~vector<TypedValue>();
+    return;
+  case Type::Map:
+    using namespace std;
+    map_v.~map<std::string, TypedValue>();
+    return;
+  case Type::Vertex:
+    vertex_v.~VertexAccessor();
+    return;
+  case Type::Edge:
+    edge_v.~EdgeAccessor();
+    return;
+  case Type::Path:
+    path_v.~Path();
+    return;
   }
   permanent_fail("Unsupported TypedValue::Type");
 }
@@ -315,19 +375,19 @@ TypedValue::~TypedValue() {
  * @param value
  * @return
  */
-double ToDouble(const TypedValue& value) {
+double ToDouble(const TypedValue &value) {
   switch (value.type()) {
-    case TypedValue::Type::Int:
-      return (double)value.Value<int64_t>();
-    case TypedValue::Type::Double:
-      return value.Value<double>();
-    default:
-      throw TypedValueException(
-          "Unsupported TypedValue::Type conversion to double");
+  case TypedValue::Type::Int:
+    return (double)value.Value<int64_t>();
+  case TypedValue::Type::Double:
+    return value.Value<double>();
+  default:
+    throw TypedValueException(
+        "Unsupported TypedValue::Type conversion to double");
   }
 }
 
-TypedValue operator<(const TypedValue& a, const TypedValue& b) {
+TypedValue operator<(const TypedValue &a, const TypedValue &b) {
   if (a.type() == TypedValue::Type::Bool || b.type() == TypedValue::Type::Bool)
     throw TypedValueException("Invalid 'less' operand types({} + {})", a.type(),
                               b.type());
@@ -356,7 +416,7 @@ TypedValue operator<(const TypedValue& a, const TypedValue& b) {
 
 // TODO: 2 = "2" -> false, I don't think this is handled correctly at the
 // moment.
-TypedValue operator==(const TypedValue& a, const TypedValue& b) {
+TypedValue operator==(const TypedValue &a, const TypedValue &b) {
   if (a.type() == TypedValue::Type::Null || b.type() == TypedValue::Type::Null)
     return TypedValue::Null;
 
@@ -370,7 +430,8 @@ TypedValue operator==(const TypedValue& a, const TypedValue& b) {
       // can compare list_v-s directly.
       auto list1 = a.Value<std::vector<TypedValue>>();
       auto list2 = b.Value<std::vector<TypedValue>>();
-      if (list1.size() != list2.size()) return false;
+      if (list1.size() != list2.size())
+        return false;
       for (int i = 0; i < (int)list1.size(); ++i) {
         if (!(list1[i] == list2[i]).Value<bool>()) {
           return false;
@@ -417,15 +478,15 @@ TypedValue operator==(const TypedValue& a, const TypedValue& b) {
   }
 }
 
-TypedValue operator!(const TypedValue& a) {
+TypedValue operator!(const TypedValue &a) {
   switch (a.type()) {
-    case TypedValue::Type::Null:
-      return TypedValue::Null;
-    case TypedValue::Type::Bool:
-      return TypedValue(!a.Value<bool>());
-    default:
-      throw TypedValueException("Invalid logical not operand type (!{})",
-                                a.type());
+  case TypedValue::Type::Null:
+    return TypedValue::Null;
+  case TypedValue::Type::Bool:
+    return TypedValue(!a.Value<bool>());
+  default:
+    throw TypedValueException("Invalid logical not operand type (!{})",
+                              a.type());
   }
 }
 
@@ -435,32 +496,32 @@ TypedValue operator!(const TypedValue& a) {
  * @param value a value.
  * @return A string.
  */
-std::string ValueToString(const TypedValue& value) {
+std::string ValueToString(const TypedValue &value) {
   switch (value.type()) {
-    case TypedValue::Type::String:
-      return value.Value<std::string>();
-    case TypedValue::Type::Int:
-      return std::to_string(value.Value<int64_t>());
-    case TypedValue::Type::Double:
-      return fmt::format("{}", value.Value<double>());
-    // unsupported situations
-    default:
-      throw TypedValueException(
-          "Unsupported TypedValue::Type conversion to string");
+  case TypedValue::Type::String:
+    return value.Value<std::string>();
+  case TypedValue::Type::Int:
+    return std::to_string(value.Value<int64_t>());
+  case TypedValue::Type::Double:
+    return fmt::format("{}", value.Value<double>());
+  // unsupported situations
+  default:
+    throw TypedValueException(
+        "Unsupported TypedValue::Type conversion to string");
   }
 }
 
-TypedValue operator-(const TypedValue& a) {
+TypedValue operator-(const TypedValue &a) {
   switch (a.type()) {
-    case TypedValue::Type::Null:
-      return TypedValue::Null;
-    case TypedValue::Type::Int:
-      return -a.Value<int64_t>();
-    case TypedValue::Type::Double:
-      return -a.Value<double>();
-    default:
-      throw TypedValueException("Invalid unary minus operand type (-{})",
-                                a.type());
+  case TypedValue::Type::Null:
+    return TypedValue::Null;
+  case TypedValue::Type::Int:
+    return -a.Value<int64_t>();
+  case TypedValue::Type::Double:
+    return -a.Value<double>();
+  default:
+    throw TypedValueException("Invalid unary minus operand type (-{})",
+                              a.type());
   }
 }
 
@@ -475,13 +536,14 @@ TypedValue operator-(const TypedValue& a) {
  *  @param op_name Name of the operation, used only for exception description,
  *  if raised.
  */
-inline void EnsureArithmeticallyOk(const TypedValue& a, const TypedValue& b,
-                                   bool string_ok, const std::string& op_name) {
+inline void EnsureArithmeticallyOk(const TypedValue &a, const TypedValue &b,
+                                   bool string_ok, const std::string &op_name) {
   if (a.type() == TypedValue::Type::Bool || b.type() == TypedValue::Type::Bool)
     throw TypedValueException("Invalid {} operand types {}, {}", op_name,
                               a.type(), b.type());
 
-  if (string_ok) return;
+  if (string_ok)
+    return;
 
   if (a.type() == TypedValue::Type::String ||
       b.type() == TypedValue::Type::String)
@@ -489,14 +551,14 @@ inline void EnsureArithmeticallyOk(const TypedValue& a, const TypedValue& b,
                               a.type(), b.type());
 }
 
-TypedValue operator+(const TypedValue& a, const TypedValue& b) {
+TypedValue operator+(const TypedValue &a, const TypedValue &b) {
   if (a.type() == TypedValue::Type::Null || b.type() == TypedValue::Type::Null)
     return TypedValue::Null;
 
   if (a.type() == TypedValue::Type::List ||
       b.type() == TypedValue::Type::List) {
     std::vector<TypedValue> list;
-    auto append_list = [&list](const TypedValue& v) {
+    auto append_list = [&list](const TypedValue &v) {
       if (v.type() == TypedValue::Type::List) {
         auto list2 = v.Value<std::vector<TypedValue>>();
         list.insert(list.end(), list2.begin(), list2.end());
@@ -525,7 +587,7 @@ TypedValue operator+(const TypedValue& a, const TypedValue& b) {
   }
 }
 
-TypedValue operator-(const TypedValue& a, const TypedValue& b) {
+TypedValue operator-(const TypedValue &a, const TypedValue &b) {
   EnsureArithmeticallyOk(a, b, false, "subtraction");
 
   if (a.type() == TypedValue::Type::Null || b.type() == TypedValue::Type::Null)
@@ -540,7 +602,7 @@ TypedValue operator-(const TypedValue& a, const TypedValue& b) {
   }
 }
 
-TypedValue operator/(const TypedValue& a, const TypedValue& b) {
+TypedValue operator/(const TypedValue &a, const TypedValue &b) {
   EnsureArithmeticallyOk(a, b, false, "division");
 
   if (a.type() == TypedValue::Type::Null || b.type() == TypedValue::Type::Null)
@@ -555,7 +617,7 @@ TypedValue operator/(const TypedValue& a, const TypedValue& b) {
   }
 }
 
-TypedValue operator*(const TypedValue& a, const TypedValue& b) {
+TypedValue operator*(const TypedValue &a, const TypedValue &b) {
   EnsureArithmeticallyOk(a, b, false, "multiplication");
 
   if (a.type() == TypedValue::Type::Null || b.type() == TypedValue::Type::Null)
@@ -570,7 +632,7 @@ TypedValue operator*(const TypedValue& a, const TypedValue& b) {
   }
 }
 
-TypedValue operator%(const TypedValue& a, const TypedValue& b) {
+TypedValue operator%(const TypedValue &a, const TypedValue &b) {
   EnsureArithmeticallyOk(a, b, false, "modulo");
 
   if (a.type() == TypedValue::Type::Null || b.type() == TypedValue::Type::Null)
@@ -585,13 +647,13 @@ TypedValue operator%(const TypedValue& a, const TypedValue& b) {
   }
 }
 
-inline bool IsLogicallyOk(const TypedValue& a) {
+inline bool IsLogicallyOk(const TypedValue &a) {
   return a.type() == TypedValue::Type::Bool ||
          a.type() == TypedValue::Type::Null;
 }
 
 // TODO: Fix bugs in && and ||. null or true -> true; false and null -> false
-TypedValue operator&&(const TypedValue& a, const TypedValue& b) {
+TypedValue operator&&(const TypedValue &a, const TypedValue &b) {
   if (IsLogicallyOk(a) && IsLogicallyOk(b)) {
     if (a.type() == TypedValue::Type::Null ||
         b.type() == TypedValue::Type::Null) {
@@ -605,7 +667,7 @@ TypedValue operator&&(const TypedValue& a, const TypedValue& b) {
   }
 }
 
-TypedValue operator||(const TypedValue& a, const TypedValue& b) {
+TypedValue operator||(const TypedValue &a, const TypedValue &b) {
   if (IsLogicallyOk(a) && IsLogicallyOk(b)) {
     if (a.type() == TypedValue::Type::Null ||
         b.type() == TypedValue::Type::Null) {
@@ -619,7 +681,7 @@ TypedValue operator||(const TypedValue& a, const TypedValue& b) {
   }
 }
 
-TypedValue operator^(const TypedValue& a, const TypedValue& b) {
+TypedValue operator^(const TypedValue &a, const TypedValue &b) {
   if (IsLogicallyOk(a) && IsLogicallyOk(b)) {
     if (a.type() == TypedValue::Type::Null ||
         b.type() == TypedValue::Type::Null) {
diff --git a/src/query/backend/cpp/typed_value.hpp b/src/query/backend/cpp/typed_value.hpp
index 24ca53f7a..331e1c3f0 100644
--- a/src/query/backend/cpp/typed_value.hpp
+++ b/src/query/backend/cpp/typed_value.hpp
@@ -1,19 +1,19 @@
 #pragma once
 
+#include <cstdint>
 #include <iostream>
+#include <map>
 #include <memory>
 #include <string>
 #include <vector>
-#include <map>
-#include <cstdint>
 
+#include "storage/edge_accessor.hpp"
+#include "storage/property_value.hpp"
+#include "storage/vertex_accessor.hpp"
+#include "traversal/path.hpp"
 #include "utils/exceptions/stacktrace_exception.hpp"
 #include "utils/total_ordering.hpp"
 #include "utils/underlying_cast.hpp"
-#include "storage/property_value.hpp"
-#include "storage/edge_accessor.hpp"
-#include "storage/vertex_accessor.hpp"
-#include "traversal/path.hpp"
 
 typedef traversal_template::Path<VertexAccessor, EdgeAccessor> Path;
 
@@ -26,11 +26,11 @@ typedef traversal_template::Path<VertexAccessor, EdgeAccessor> Path;
  * TypedValue::Type. Each such type corresponds to exactly one C++ type.
  */
 class TypedValue : public TotalOrdering<TypedValue, TypedValue, TypedValue> {
- public:
+public:
   /** Private default constructor, makes Null */
   TypedValue() : type_(Type::Null) {}
 
- public:
+public:
   /** A value type. Each type corresponds to exactly one C++ type */
   enum class Type : unsigned {
     Null,
@@ -58,32 +58,32 @@ class TypedValue : public TotalOrdering<TypedValue, TypedValue, TypedValue> {
   operator PropertyValue() const;
 
   /// constructors for non-primitive types
-  TypedValue(const std::string& value) : type_(Type::String) {
+  TypedValue(const std::string &value) : type_(Type::String) {
     new (&string_v) std::string(value);
   }
-  TypedValue(const char* value) : type_(Type::String) {
+  TypedValue(const char *value) : type_(Type::String) {
     new (&string_v) std::string(value);
   }
-  TypedValue(const std::vector<TypedValue>& value) : type_(Type::List) {
+  TypedValue(const std::vector<TypedValue> &value) : type_(Type::List) {
     new (&list_v) std::vector<TypedValue>(value);
   }
-  TypedValue(const std::map<std::string, TypedValue>& value)
+  TypedValue(const std::map<std::string, TypedValue> &value)
       : type_(Type::Map) {
     new (&map_v) std::map<std::string, TypedValue>(value);
   }
-  TypedValue(const VertexAccessor& vertex) : type_(Type::Vertex) {
+  TypedValue(const VertexAccessor &vertex) : type_(Type::Vertex) {
     new (&vertex_v) VertexAccessor(vertex);
   }
-  TypedValue(const EdgeAccessor& edge) : type_(Type::Edge) {
+  TypedValue(const EdgeAccessor &edge) : type_(Type::Edge) {
     new (&edge_v) EdgeAccessor(edge);
   }
-  TypedValue(const Path& path) : type_(Type::Path) { new (&path_v) Path(path); }
-  TypedValue(const PropertyValue& value);
+  TypedValue(const Path &path) : type_(Type::Path) { new (&path_v) Path(path); }
+  TypedValue(const PropertyValue &value);
 
   // assignment ops
-  TypedValue& operator=(const TypedValue& other);
+  TypedValue &operator=(const TypedValue &other);
 
-  TypedValue(const TypedValue& other);
+  TypedValue(const TypedValue &other);
   ~TypedValue();
 
   Type type() const { return type_; }
@@ -95,12 +95,12 @@ class TypedValue : public TotalOrdering<TypedValue, TypedValue, TypedValue> {
    * @tparam T Type to interpret the value as.
    * @return The value as type T.
    */
-  template <typename T>
-  T Value() const;
+  template <typename T> T &Value();
+  template <typename T> const T &Value() const;
 
-  friend std::ostream& operator<<(std::ostream& stream, const TypedValue&prop);
+  friend std::ostream &operator<<(std::ostream &stream, const TypedValue &prop);
 
- private:
+private:
   // storage for the value of the property
   union {
     bool bool_v;
@@ -133,31 +133,31 @@ class TypedValue : public TotalOrdering<TypedValue, TypedValue, TypedValue> {
  * of incompatible Types.
  */
 class TypedValueException : public StacktraceException {
- public:
+public:
   using ::StacktraceException::StacktraceException;
 };
 
 // comparison operators
 // they return TypedValue because Null can be returned
-TypedValue operator==(const TypedValue& a, const TypedValue& b);
-TypedValue operator<(const TypedValue& a, const TypedValue& b);
-TypedValue operator!(const TypedValue& a);
+TypedValue operator==(const TypedValue &a, const TypedValue &b);
+TypedValue operator<(const TypedValue &a, const TypedValue &b);
+TypedValue operator!(const TypedValue &a);
 
 // arithmetic operators
-TypedValue operator-(const TypedValue& a);
-TypedValue operator+(const TypedValue& a, const TypedValue& b);
-TypedValue operator-(const TypedValue& a, const TypedValue& b);
-TypedValue operator/(const TypedValue& a, const TypedValue& b);
-TypedValue operator*(const TypedValue& a, const TypedValue& b);
-TypedValue operator%(const TypedValue& a, const TypedValue& b);
+TypedValue operator-(const TypedValue &a);
+TypedValue operator+(const TypedValue &a, const TypedValue &b);
+TypedValue operator-(const TypedValue &a, const TypedValue &b);
+TypedValue operator/(const TypedValue &a, const TypedValue &b);
+TypedValue operator*(const TypedValue &a, const TypedValue &b);
+TypedValue operator%(const TypedValue &a, const TypedValue &b);
 
 // binary bool operators
-TypedValue operator&&(const TypedValue& a, const TypedValue& b);
-TypedValue operator||(const TypedValue& a, const TypedValue& b);
+TypedValue operator&&(const TypedValue &a, const TypedValue &b);
+TypedValue operator||(const TypedValue &a, const TypedValue &b);
 // binary bool xor, not power operator
 // Be careful: since ^ is binary operator and || and && are logical operators
 // they have different priority in c++.
-TypedValue operator^(const TypedValue& a, const TypedValue& b);
+TypedValue operator^(const TypedValue &a, const TypedValue &b);
 
 // stream output
-std::ostream& operator<<(std::ostream& os, const TypedValue::Type type);
+std::ostream &operator<<(std::ostream &os, const TypedValue::Type type);