libstore: hide raw sqlite C api

this is, once again, what wrappers are for in the first place.

Change-Id: Ied8cb7384f561a345e457ccc977ba98e50dba207

lix/libstore/local-store.cc

@@ -524,8 +524,7 @@ void LocalStore::openDB(DBState & state, bool create)
     {
         SQLiteStmt stmt = db.create("pragma main.journal_mode;");
         auto use = stmt.use();
-        if (use.step() != SQLITE_ROW)
-            SQLiteError::throw_(db, "querying journal mode");
+        assert(use.next());
         prevMode = use.getStr(0);
     }
     if (prevMode != mode)

lix/libstore/sqlite.cc

@@ -206,22 +206,15 @@ SQLiteStmt::Use & SQLiteStmt::Use::bind()
     return *this;
 }
 
-int SQLiteStmt::Use::step()
-{
-    return sqlite3_step(stmt.stmt.get());
-}
-
 void SQLiteStmt::Use::exec()
 {
-    int r = step();
-    assert(r != SQLITE_ROW);
-    if (r != SQLITE_DONE)
-        SQLiteError::throw_(stmt.db, fmt("executing SQLite statement '%s'", sqlite3_expanded_sql(stmt.stmt.get())));
+    bool r = next();
+    assert(!r);
 }
 
 bool SQLiteStmt::Use::next()
 {
-    int r = step();
+    int r = sqlite3_step(stmt.stmt.get());
     if (r != SQLITE_DONE && r != SQLITE_ROW)
         SQLiteError::throw_(stmt.db, fmt("executing SQLite query '%s'", sqlite3_expanded_sql(stmt.stmt.get())));
     return r == SQLITE_ROW;

lix/libstore/sqlite.hh

@@ -74,6 +74,8 @@ public:
  */
 class SQLiteStmt
 {
+    friend SQLite;
+
     struct Finalize {
         SQLiteStmt * parent;
         void operator()(sqlite3_stmt * stmt);
@@ -83,9 +85,10 @@ class SQLiteStmt
     std::unique_ptr<sqlite3_stmt, Finalize> stmt;
     std::string sql;
 
+    SQLiteStmt(sqlite3 * db, const std::string & sql);
+
 public:
     SQLiteStmt() = default;
-    SQLiteStmt(sqlite3 * db, const std::string & sql);
 
     /**
      * Helper for binding / executing statements.
@@ -110,8 +113,6 @@ public:
         Use & operator () (int64_t value, bool notNull = true);
         Use & bind(); // null
 
-        int step();
-
         /**
          * Execute a statement that does not return rows.
          */
@@ -141,34 +142,30 @@ public:
  */
 class SQLiteTxn
 {
+    friend SQLite;
+
     struct Rollback {
         void operator()(sqlite3 * db);
     };
     std::unique_ptr<sqlite3, Rollback> db;
 
-public:
     explicit SQLiteTxn(sqlite3 * db);
 
+public:
     void commit();
 };
 
 
 struct SQLiteError : Error
 {
+    friend SQLite;
+    friend SQLiteStmt;
+    friend SQLiteTxn;
+
     std::string path;
     std::string errMsg;
     int errNo, extendedErrNo, offset;
 
-    template<typename... Args>
-    [[noreturn]] static void throw_(SQLite & db, const std::string & fs, const Args & ... args) {
-        throw_(db.db.get(), HintFmt(fs, args...));
-    }
-
-    template<typename... Args>
-    [[noreturn]] static void throw_(sqlite3 * db, const std::string & fs, const Args & ... args) {
-        throw_(db, HintFmt(fs, args...));
-    }
-
     SQLiteError(const char *path, const char *errMsg, int errNo, int extendedErrNo, int offset, HintFmt && hf);
 
 protected:
@@ -178,6 +175,11 @@ protected:
       : SQLiteError(path, errMsg, errNo, extendedErrNo, offset, HintFmt(fs, args...))
     { }
 
+    template<typename... Args>
+    [[noreturn]] static void throw_(sqlite3 * db, const std::string & fs, const Args & ... args) {
+        throw_(db, HintFmt(fs, args...));
+    }
+
     [[noreturn]] static void throw_(sqlite3 * db, HintFmt && hf);
 
 };