1 files changed, 38 insertions, 12 deletions

diff --git a/platform/default/sqlite3.hpp b/platform/default/sqlite3.hpp
index 4080d33950..20d09b550c 100644
--- a/platform/default/sqlite3.hpp
+++ b/platform/default/sqlite3.hpp
@@ -67,6 +67,7 @@ public:
 class DatabaseImpl;
 class Statement;
 class StatementImpl;
+class Query;
 
 class Database {
 private:
@@ -81,7 +82,6 @@ public:
 
     void setBusyTimeout(std::chrono::milliseconds);
     void exec(const std::string &sql);
-    Statement prepare(const char *query);
 
 private:
     std::unique_ptr<DatabaseImpl> impl;
@@ -89,28 +89,54 @@ private:
     friend class Statement;
 };
 
+// A Statement object represents a prepared statement that can be run repeatedly run with a Query object.
 class Statement {
+public:
+    Statement(Database& db, const char* sql);
+    Statement(const Statement&) = delete;
+    Statement(Statement&&) = delete;
+    Statement& operator=(const Statement&) = delete;
+    Statement& operator=(Statement&&) = delete;
+    ~Statement();
+
+    friend class Query;
+
 private:
-    Statement(const Statement &) = delete;
-    Statement &operator=(const Statement &) = delete;
+    std::unique_ptr<StatementImpl> impl;
 
+#ifndef NDEBUG
+    // This flag stores whether there exists a Query object that uses this prepared statement.
+    // There may only be one Query object at a time. Statement objects must outlive Query objects.
+    // While a Query object exists, a Statement object may not be moved or deleted.
+    bool used = false;
+#endif
+};
+
+// A Query object is used to run a database query with a prepared statement (stored in a Statement
+// object). There may only exist one Query object per Statement object. Query objects are designed
+// to be constructed and destroyed frequently.
+class Query {
 public:
-    Statement(Database *db, const char *sql);
-    Statement(Statement &&);
-    ~Statement();
-    Statement &operator=(Statement &&);
+    Query(Statement&);
+    Query(const Query&) = delete;
+    Query(Query&&) = delete;
+    Query& operator=(const Query&) = delete;
+    Query& operator=(Query&&) = delete;
+    ~Query();
 
-    template <typename T> void bind(int offset, T value);
+    template <typename T>
+    void bind(int offset, T value);
 
     // Text
-    void bind(int offset, const char *, std::size_t length, bool retain = true);
+    void bind(int offset, const char*, std::size_t length, bool retain = true);
     void bind(int offset, const std::string&, bool retain = true);
 
     // Blob
-    void bindBlob(int offset, const void *, std::size_t length, bool retain = true);
+    void bindBlob(int offset, const void*, std::size_t length, bool retain = true);
     void bindBlob(int offset, const std::vector<uint8_t>&, bool retain = true);
 
-    template <typename T> T get(int offset);
+    template <typename T>
+    T get(int offset);
 
     bool run();
     void reset();
@@ -120,7 +146,7 @@ public:
     uint64_t changes() const;
 
 private:
-    std::unique_ptr<StatementImpl> impl;
+    Statement& stmt;
 };
 
 class Transaction {