Make column type constants constexpr

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Update googletest to v1.18.0 (#583)
 - Improve tests for `Savepoint::rollbackTo()` and scope-exit rollback semantics (#584)
 - Fix link errors in supplied assertion handlers and add handler-enabled CI coverage (#587)
+- Make column type constants usable in constant expressions (ABI change) (#609)
 
 ### Removed
 

include/SQLiteCpp/Column.h

@@ -24,11 +24,12 @@ struct sqlite3_stmt;
 namespace SQLite
 {
 
-SQLITECPP_API extern const int INTEGER;   ///< SQLITE_INTEGER
-SQLITECPP_API extern const int FLOAT;     ///< SQLITE_FLOAT
-SQLITECPP_API extern const int TEXT;      ///< SQLITE_TEXT
-SQLITECPP_API extern const int BLOB;      ///< SQLITE_BLOB
-SQLITECPP_API extern const int Null;      ///< SQLITE_NULL
+/// SQLite result type codes, usable in constant expressions without including sqlite3.h.
+inline constexpr int INTEGER = 1;   ///< SQLITE_INTEGER
+inline constexpr int FLOAT   = 2;   ///< SQLITE_FLOAT
+inline constexpr int TEXT    = 3;   ///< SQLITE_TEXT
+inline constexpr int BLOB    = 4;   ///< SQLITE_BLOB
+inline constexpr int Null    = 5;   ///< SQLITE_NULL
 
 /**
  * @brief Encapsulation of a Column in a row of the result pointed by the prepared Statement.

src/Column.cpp

@@ -17,11 +17,11 @@
 namespace SQLite
 {
 
-const int INTEGER   = SQLITE_INTEGER;
-const int FLOAT     = SQLITE_FLOAT;
-const int TEXT      = SQLITE_TEXT;
-const int BLOB      = SQLITE_BLOB;
-const int Null      = SQLITE_NULL;
+static_assert(INTEGER == SQLITE_INTEGER, "SQLite::INTEGER must match SQLITE_INTEGER");
+static_assert(FLOAT == SQLITE_FLOAT, "SQLite::FLOAT must match SQLITE_FLOAT");
+static_assert(TEXT == SQLITE_TEXT, "SQLite::TEXT must match SQLITE_TEXT");
+static_assert(BLOB == SQLITE_BLOB, "SQLite::BLOB must match SQLITE_BLOB");
+static_assert(Null == SQLITE_NULL, "SQLite::Null must match SQLITE_NULL");
 
 
 // Encapsulation of a Column in a row of the result pointed by the prepared Statement.

tests/Column_test.cpp

@@ -19,6 +19,41 @@
 #include <stdint.h>
 
 
+TEST(Column, typeConstantsAsCaseLabels)
+{
+    SQLite::Database db(":memory:", SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE);
+    SQLite::Statement query(db, "SELECT 42, 1.5, 'text', X'1234', NULL");
+
+    ASSERT_TRUE(query.executeStep());
+    ASSERT_EQ(5, query.getColumnCount());
+
+    // Each label must be a constant expression, and each code must match SQLite's runtime type.
+    for (int i = 0; i < query.getColumnCount(); ++i)
+    {
+        switch (query.getColumn(i).getType())
+        {
+            case SQLite::INTEGER:
+                EXPECT_EQ(0, i);
+                break;
+            case SQLite::FLOAT:
+                EXPECT_EQ(1, i);
+                break;
+            case SQLite::TEXT:
+                EXPECT_EQ(2, i);
+                break;
+            case SQLite::BLOB:
+                EXPECT_EQ(3, i);
+                break;
+            case SQLite::Null:
+                EXPECT_EQ(4, i);
+                break;
+            default:
+                FAIL() << "Unexpected type for column " << i;
+        }
+    }
+}
+
+
 static void test_column_basis(bool utf16)
 {
     // Create a new database