From 8c483aa805eb3da25be685ee875555662cab1038 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?louiz=E2=80=99?= <louiz@louiz.org>
Date: Sat, 17 Mar 2018 17:33:29 +0100
Subject: Re-apply "Use if constexpr to make things a lot more readable"

This reverts commit d0e3c71b91f1a1c1780158789fd42b8ac7209495.
---
 src/database/insert_query.hpp | 91 +++++++++++++++++++------------------------
 1 file changed, 40 insertions(+), 51 deletions(-)

(limited to 'src/database/insert_query.hpp')

diff --git a/src/database/insert_query.hpp b/src/database/insert_query.hpp
index 04c098c..ed1944f 100644
--- a/src/database/insert_query.hpp
+++ b/src/database/insert_query.hpp
@@ -11,20 +11,17 @@
 #include <tuple>
 
 template <std::size_t N=0, typename... T>
-typename std::enable_if<N < sizeof...(T), void>::type
-update_autoincrement_id(std::tuple<T...>& columns, Statement& statement)
+void update_autoincrement_id(std::tuple<T...>& columns, Statement& statement)
 {
-  using ColumnType = typename std::decay<decltype(std::get<N>(columns))>::type;
-  if (std::is_same<ColumnType, Id>::value)
-    auto&& column = std::get<Id>(columns);
-  update_autoincrement_id<N+1>(columns, statement);
+  if constexpr(N < sizeof...(T))
+    {
+      using ColumnType = typename std::decay<decltype(std::get<N>(columns))>::type;
+      if (std::is_same<ColumnType, Id>::value)
+        auto&& column = std::get<Id>(columns);
+      update_autoincrement_id<N + 1>(columns, statement);
+    }
 }
 
-template <std::size_t N=0, typename... T>
-typename std::enable_if<N == sizeof...(T), void>::type
-update_autoincrement_id(std::tuple<T...>&, Statement&)
-{}
-
 struct InsertQuery: public Query
 {
   template <typename... T>
@@ -53,23 +50,20 @@ struct InsertQuery: public Query
   }
 
   template <int N=0, typename... T>
-  typename std::enable_if<N < sizeof...(T), void>::type
-  bind_param(const std::tuple<T...>& columns, Statement& statement, int index=1)
+  void bind_param(const std::tuple<T...>& columns, Statement& statement, int index=1)
   {
-    auto&& column = std::get<N>(columns);
-    using ColumnType = std::decay_t<decltype(column)>;
+    if constexpr(N < sizeof...(T))
+      {
+        auto&& column = std::get<N>(columns);
+        using ColumnType = std::decay_t<decltype(column)>;
 
-    if (!std::is_same<ColumnType, Id>::value)
-      actual_bind(statement, column.value, index++);
+        if constexpr(!std::is_same<ColumnType, Id>::value)
+          actual_bind(statement, column.value, index++);
 
-    this->bind_param<N+1>(columns, statement, index);
+        this->bind_param<N + 1>(columns, statement, index);
+      }
   }
 
-  template <int N=0, typename... T>
-  typename std::enable_if<N == sizeof...(T), void>::type
-  bind_param(const std::tuple<T...>&, Statement&, int)
-  {}
-
   template <typename... T>
   void insert_values(const std::tuple<T...>& columns)
   {
@@ -79,23 +73,21 @@ struct InsertQuery: public Query
   }
 
   template <int N=0, typename... T>
-  typename std::enable_if<N < sizeof...(T), void>::type
-  insert_value(const std::tuple<T...>& columns, int index=1)
+  void insert_value(const std::tuple<T...>& columns, int index=1)
   {
-    using ColumnType = std::decay_t<decltype(std::get<N>(columns))>;
-
-    if (!std::is_same<ColumnType, Id>::value)
+    if constexpr(N < sizeof...(T))
       {
-        this->body += "$" + std::to_string(index++);
-        if (N != sizeof...(T) - 1)
-          this->body += ", ";
+        using ColumnType = std::decay_t<decltype(std::get<N>(columns))>;
+
+        if (!std::is_same<ColumnType, Id>::value)
+          {
+            this->body += "$" + std::to_string(index++);
+            if (N != sizeof...(T) - 1)
+              this->body += ", ";
+          }
+        this->insert_value<N + 1>(columns, index);
       }
-    this->insert_value<N+1>(columns, index);
   }
-  template <int N=0, typename... T>
-  typename std::enable_if<N == sizeof...(T), void>::type
-  insert_value(const std::tuple<T...>&, const int)
-  { }
 
   template <typename... T>
   void insert_col_names(const std::tuple<T...>& columns)
@@ -106,24 +98,21 @@ struct InsertQuery: public Query
   }
 
   template <int N=0, typename... T>
-  typename std::enable_if<N < sizeof...(T), void>::type
-  insert_col_name(const std::tuple<T...>& columns)
+  void insert_col_name(const std::tuple<T...>& columns)
   {
-    using ColumnType = std::decay_t<decltype(std::get<N>(columns))>;
-
-    if (!std::is_same<ColumnType, Id>::value)
+    if constexpr(N < sizeof...(T))
       {
-        this->body += ColumnType::name;
+        using ColumnType = std::decay_t<decltype(std::get<N>(columns))>;
 
-        if (N < (sizeof...(T) - 1))
-          this->body += ", ";
-      }
+        if (!std::is_same<ColumnType, Id>::value)
+          {
+            this->body += ColumnType::name;
 
-    this->insert_col_name<N+1>(columns);
-  }
+            if (N < (sizeof...(T) - 1))
+              this->body += ", ";
+          }
 
-  template <int N=0, typename... T>
-  typename std::enable_if<N == sizeof...(T), void>::type
-  insert_col_name(const std::tuple<T...>&)
-  {}
+        this->insert_col_name<N + 1>(columns);
+      }
+  }
 };
-- 
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