From 0168b96b79db2627fdba77a8712956408aa081d1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?louiz=E2=80=99?= <louiz@louiz.org>
Date: Wed, 4 Oct 2017 21:28:18 +0200
Subject: Add postgresql support

---
 src/database/update_query.hpp | 100 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 src/database/update_query.hpp

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

diff --git a/src/database/update_query.hpp b/src/database/update_query.hpp
new file mode 100644
index 0000000..32befc0
--- /dev/null
+++ b/src/database/update_query.hpp
@@ -0,0 +1,100 @@
+#pragma once
+
+#include <database/query.hpp>
+#include <database/engine.hpp>
+
+using namespace std::string_literals;
+
+template <class T, class... Tuple>
+struct Index;
+
+template <class T, class... Types>
+struct Index<T, std::tuple<T, Types...>>
+{
+  static const std::size_t value = 0;
+};
+
+template <class T, class U, class... Types>
+struct Index<T, std::tuple<U, Types...>>
+{
+  static const std::size_t value = Index<T, std::tuple<Types...>>::value + 1;
+};
+
+struct UpdateQuery: public Query
+{
+  template <typename... T>
+  UpdateQuery(const std::string& name, const std::tuple<T...>& columns):
+      Query("UPDATE ")
+  {
+    this->body += name;
+    this->insert_col_names_and_values(columns);
+  }
+
+  template <typename... T>
+  void insert_col_names_and_values(const std::tuple<T...>& columns)
+  {
+    this->body += " SET ";
+    this->insert_col_name_and_value(columns);
+    this->body += " WHERE "s + Id::name + "=$" + std::to_string(this->current_param);
+  }
+
+  template <int N=0, typename... T>
+  typename std::enable_if<N < sizeof...(T), void>::type
+  insert_col_name_and_value(const std::tuple<T...>& columns)
+  {
+    using ColumnType = std::decay_t<decltype(std::get<N>(columns))>;
+
+    if (!std::is_same<ColumnType, Id>::value)
+      {
+        this->body += ColumnType::name + "=$"s + std::to_string(this->current_param);
+        this->current_param++;
+
+        if (N < (sizeof...(T) - 1))
+          this->body += ", ";
+      }
+
+    this->insert_col_name_and_value<N+1>(columns);
+  }
+  template <int N=0, typename... T>
+  typename std::enable_if<N == sizeof...(T), void>::type
+  insert_col_name_and_value(const std::tuple<T...>&)
+  {}
+
+
+  template <typename... T>
+  void execute(DatabaseEngine& db, const std::tuple<T...>& columns)
+  {
+    auto statement = db.prepare(this->body);
+    this->bind_param(columns, *statement);
+    this->bind_id(columns, *statement);
+
+    statement->step();
+  }
+
+  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)
+  {
+    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++);
+
+    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 bind_id(const std::tuple<T...>& columns, Statement& statement)
+  {
+    static constexpr auto index = Index<Id, std::tuple<T...>>::value;
+    auto&& value = std::get<index>(columns);
+
+    actual_bind(statement, value.value, sizeof...(T));
+  }
+};
-- 
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