From 9394ed9af8b4cc0a05c15bb24267d34ee2f3468d Mon Sep 17 00:00:00 2001
From: "sangwan.kwon" <sangwan.kwon@samsung.com>
Date: Mon, 22 Jan 2018 17:04:40 +0900
Subject: [PATCH] Add type-check-logic on query expression

Change-Id: I5b51c4e69f1b28a8940d59d187ffdc19f7403376
Signed-off-by: sangwan.kwon <sangwan.kwon@samsung.com>
---
 include/klay/db/query-builder/column.hxx     |  1 +
 include/klay/db/query-builder/expression.hxx | 28 ++++++++++++---
 include/klay/db/query-builder/table-impl.hxx |  8 ++---
 include/klay/db/query-builder/table.hxx      |  2 +-
 include/klay/db/query-builder/type.hxx       | 37 ++++++++++++++++++++
 test/query-builder.cpp                       | 15 ++++++++
 6 files changed, 81 insertions(+), 10 deletions(-)
 create mode 100644 include/klay/db/query-builder/type.hxx

diff --git a/include/klay/db/query-builder/column.hxx b/include/klay/db/query-builder/column.hxx
index 4c43eeb..6fb99a9 100644
--- a/include/klay/db/query-builder/column.hxx
+++ b/include/klay/db/query-builder/column.hxx
@@ -24,6 +24,7 @@ namespace qxx {
 template<typename Object, typename Field>
 struct Column {
 	typedef Field Object::*Type;
+	using FieldType = Field;
 
 	std::string name;
 	Type type;
diff --git a/include/klay/db/query-builder/expression.hxx b/include/klay/db/query-builder/expression.hxx
index a7e7db8..37e76bc 100644
--- a/include/klay/db/query-builder/expression.hxx
+++ b/include/klay/db/query-builder/expression.hxx
@@ -16,6 +16,9 @@
 
 #pragma once
 
+#include "column.hxx"
+#include "type.hxx"
+
 #include <type_traits>
 
 namespace qxx {
@@ -52,7 +55,23 @@ struct Binary : public Base {
 	L l;
 	R r;
 
-	Binary(L l, R r) : l(l), r(r) {}
+	Binary(L l, R r) : l(l), r(r)
+	{
+		using FieldType = typename L::FieldType;
+		type::assert_compare(FieldType(), r);
+	}
+};
+
+template<typename L>
+struct Binary<L, const char*> : public Base {
+	L l;
+	std::string r;
+
+	Binary(L l, const char* r) : l(l), r(r)
+	{
+		using FieldType = typename L::FieldType;
+		type::assert_compare(FieldType(), std::string());
+	}
 };
 
 } // namespace condition
@@ -62,10 +81,11 @@ struct Expression {
 	Type value;
 };
 
-template<typename Type>
-Expression<Type> expr(Type value)
+template<typename O, typename F>
+Expression<Column<O, F>> expr(F O::*field)
 {
-	return {value};
+	Column<O, F> anonymous = {"anonymous", field};
+	return {anonymous};
 }
 
 template<typename L, typename R>
diff --git a/include/klay/db/query-builder/table-impl.hxx b/include/klay/db/query-builder/table-impl.hxx
index 9a29774..2fa813a 100644
--- a/include/klay/db/query-builder/table-impl.hxx
+++ b/include/klay/db/query-builder/table-impl.hxx
@@ -16,6 +16,8 @@
 
 #pragma once
 
+#include "type.hxx"
+
 #include <string>
 #include <vector>
 
@@ -50,11 +52,7 @@ public:
 
 	template<typename ColumnType>
 	std::string getColumnName(ColumnType type) const noexcept {
-		// [TO-DO] Do Not Cast.
-		// [ALTER] std::is_same<F, typename T::field_type>{}
-		// [PROBLEM] Cannot multi-table select..
-		// [CRITICAL] (&Data::int == &Data2::int) is same
-		if (reinterpret_cast<ColumnType>(column.type) == type)
+		if (type::compare(column.type, type))
 			return column.name;
 
 		return Base::template getColumnName<ColumnType>(type);
diff --git a/include/klay/db/query-builder/table.hxx b/include/klay/db/query-builder/table.hxx
index fc26e34..d6a33fe 100644
--- a/include/klay/db/query-builder/table.hxx
+++ b/include/klay/db/query-builder/table.hxx
@@ -332,7 +332,7 @@ template<typename... Columns>
 template<typename Expr>
 std::string Table<Columns...>::processWhere(Expr expr) {
 	std::stringstream ss;
-	ss << this->impl.getColumnName(expr.l);
+	ss << this->impl.getColumnName(expr.l.type);
 	ss << " " << std::string(expr) << " ?";
 
 	return ss.str();
diff --git a/include/klay/db/query-builder/type.hxx b/include/klay/db/query-builder/type.hxx
new file mode 100644
index 0000000..d1a3e3f
--- /dev/null
+++ b/include/klay/db/query-builder/type.hxx
@@ -0,0 +1,37 @@
+/*
+ *  Copyright (c) 2017 Samsung Electronics Co., Ltd All Rights Reserved
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License
+ */
+
+#pragma once
+
+#include <type_traits>
+
+namespace qxx {
+namespace type {
+
+template<typename L, typename R>
+inline bool compare(L l, R r)
+{
+	return (l == reinterpret_cast<L>(r));
+}
+
+template<typename L, typename R>
+inline void assert_compare(L l, R r)
+{
+	static_assert(std::is_same<L, R>::value, "Type is unsafe.");
+}
+
+} // namespace type
+} // namespace qxx
diff --git a/test/query-builder.cpp b/test/query-builder.cpp
index 75639be..faa13d4 100644
--- a/test/query-builder.cpp
+++ b/test/query-builder.cpp
@@ -109,3 +109,18 @@ TESTCASE(INSERT)
 	TEST_EXPECT(true, insert1 == "INSERT INTO admin (id, pkg, uid, key) VALUES (?, ?, ?, ?)");
 	TEST_EXPECT(true, insert2 == "INSERT INTO admin (id, pkg, key) VALUES (?, ?, ?)");
 }
+
+TESTCASE(TYPE_SAFE)
+{
+/*
+ * Below cause complie error since expression types are dismatch.
+
+	std::string type_unsafe1 = admin.selectAll().where(expr(&Admin::uid) > "dpm");
+	std::string type_unsafe2 = admin.selectAll().where(expr(&Admin::uid) == "dpm");
+	std::string type_unsafe3 = admin.selectAll().where(expr(&Admin::pkg) == 3);
+	int pkg = 3;
+	std::string type_unsafe4 = admin.selectAll().where(expr(&Admin::pkg) < pkg);
+	std::string type_unsafe5 = admin.remove().where(expr(&Admin::pkg) == "dpm" &&
+													expr(&Admin::uid) == "dpm");
+*/
+}
-- 
2.34.1