migrate to crystal std db. keeping old code side by side

src/sqlite3.cr

@@ -1 +1,2 @@
+require "db"
 require "./sqlite3/**"

src/sqlite3/driver.cr

@@ -0,0 +1,22 @@
+class SQLite3::Driver < DB::Driver
+  def initialize(options)
+    super
+    filename = options["database"]
+    check LibSQLite3.open_v2(filename, out @db, (LibSQLite3::Flag::READWRITE | LibSQLite3::Flag::CREATE), nil)
+    # @closed = false
+  end
+
+  def prepare(query)
+    Statement2.new(self, query)
+  end
+
+  def to_unsafe
+    @db
+  end
+
+  private def check(code)
+    raise Exception.new(@db) unless code == 0
+  end
+end
+
+DB.register_driver "sqlite3", SQLite3::Driver

src/sqlite3/result_set2.cr

@@ -0,0 +1,68 @@
+class SQLite3::ResultSet2 < DB::ResultSet
+  @column_index = 0
+
+  # Advances to the next row. Returns `true` if there's a next row,
+  # `false` otherwise. Must be called at least once to advance to the first
+  # row.
+  def move_next
+    @column_index = 0
+
+    case step
+    when LibSQLite3::Code::ROW
+      true
+    when LibSQLite3::Code::DONE
+      false
+    else
+      raise Exception.new(@statement.driver)
+    end
+  end
+
+  {% for t in DB::TYPES %}
+    def read?(t : {{t}}.class) : {{t}}?
+      if read_nil?
+        moving_column { nil }
+      else
+        read(t)
+      end
+    end
+  {% end %}
+
+  def read(t : String.class) : String
+    moving_column { |col| String.new(LibSQLite3.column_text(self, col)) }
+  end
+
+  def read(t : Int32.class) : Int32
+    read(Int64).to_i32
+  end
+
+  def read(t : Int64.class) : Int64
+    moving_column { |col| LibSQLite3.column_int64(self, col) }
+  end
+
+  def read(t : Float32.class) : Float32
+    read(Float64).to_f32
+  end
+
+  def read(t : Float64.class) : Float64
+    moving_column { LibSQLite3.column_double(self, @column_index) }
+  end
+
+  def to_unsafe
+    @statement.to_unsafe
+  end
+
+  private def read_nil?
+    LibSQLite3.column_type(self, @column_index) == Type::NULL
+  end
+
+  # :nodoc:
+  private def step
+    LibSQLite3::Code.new LibSQLite3.step(@statement)
+  end
+
+  private def moving_column
+    res = yield @column_index
+    @column_index += 1
+    res
+  end
+end

src/sqlite3/statement2.cr

@@ -0,0 +1,19 @@
+class SQLite3::Statement2 < DB::Statement
+  def initialize(@driver, sql)
+    check LibSQLite3.prepare_v2(@driver, sql, sql.bytesize + 1, out @stmt, nil)
+    # @closed = false
+  end
+
+  def exec(*args)
+    LibSQLite3.reset(self)
+    ResultSet2.new(self)
+  end
+
+  private def check(code)
+    raise Exception.new(@driver) unless code == 0
+  end
+
+  def to_unsafe
+    @stmt
+  end
+end