# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 130
def initialize(connection, logger, config)
  super(connection, logger)

  @active     = nil
  @statements = StatementPool.new(@connection,
                                  self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
  @config = config

  if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
    @prepared_statements = true
    @visitor = Arel::Visitors::SQLite.new self
  else
    @visitor = unprepared_visitor
  end
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 185
def active?
  @active != false
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 209
def allowed_index_name_length
  index_name_length - 2
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 477
def change_column_null(table_name, column_name, null, default = nil)
  unless null || default.nil?
    exec_query("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
  end
  alter_table(table_name) do |definition|
    definition[column_name].null = null
  end
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 198
def clear_cache!
  @statements.clear
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 191
def disconnect!
  super
  @active = false
  @connection.close rescue nil
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 218
def encoding
  @connection.encoding.to_s
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 323
def exec_delete(sql, name = 'SQL', binds = [])
  exec_query(sql, name, binds)
  @connection.changes
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 293
def exec_query(sql, name = nil, binds = [])
  type_casted_binds = binds.map { |col, val|
    [col, type_cast(val, col)]
  }

  log(sql, name, type_casted_binds) do
    # Don't cache statements if they are not prepared
    if without_prepared_statement?(binds)
      stmt    = @connection.prepare(sql)
      begin
        cols    = stmt.columns
        records = stmt.to_a
      ensure
        stmt.close
      end
      stmt = records
    else
      cache = @statements[sql] ||= {
        :stmt => @connection.prepare(sql)
      }
      stmt = cache[:stmt]
      cols = cache[:cols] ||= stmt.columns
      stmt.reset!
      stmt.bind_params type_casted_binds.map { |_, val| val }
    end

    ActiveRecord::Result.new(cols, stmt.to_a)
  end
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 274
def explain(arel, binds = [])
  sql = "EXPLAIN QUERY PLAN #{to_sql(arel, binds)}"
  ExplainPrettyPrinter.new.pp(exec_query(sql, 'EXPLAIN', binds))
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 329
def last_inserted_id(result)
  @connection.last_insert_row_id
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 228
def quote(value, column = nil)
  if value.kind_of?(String) && column && column.type == :binary
    s = value.unpack("H*")[0]
    "x'#{s}'"
  else
    super
  end
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 241
def quote_table_name_for_assignment(table, attr)
  quote_column_name(attr)
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 444
def rename_table(table_name, new_name)
  exec_query "ALTER TABLE #{quote_table_name(table_name)} RENAME TO #{quote_table_name(new_name)}"
  rename_table_indexes(table_name, new_name)
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 177
def requires_reloading?
  true
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 353
def select_rows(sql, name = nil, binds = [])
  exec_query(sql, name, binds).rows
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 181
def supports_add_column?
  true
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 150
def supports_ddl_transactions?
  true
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 222
def supports_explain?
  true
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 202
def supports_index_sort_order?
  true
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 158
def supports_partial_index?
  sqlite_version >= '3.8.0'
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 154
def supports_savepoints?
  true
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 164
def supports_statement_cache?
  true
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 384
def table_exists?(table_name)
  table_name && tables(nil, table_name).any?
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 451
def valid_alter_table_options( type, options)
  type.to_sym != :primary_key
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 608
def sqlite_version
  @sqlite_version ||= SQLite3Adapter::Version.new(select_value('select sqlite_version(*)'))
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 513
def table_structure(table_name)
  structure = exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", 'SCHEMA').to_hash
  raise(ActiveRecord::StatementInvalid, "Could not find table '#{table_name}'") if structure.empty?
  structure
end

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 612
def translate_exception(exception, message)
  case exception.message
  # SQLite 3.8.2 returns a newly formatted error message:
  #   UNIQUE constraint failed: *table_name*.*column_name*
  # Older versions of SQLite return:
  #   column *column_name* is not unique
  when /column(s)? .* (is|are) not unique/, /UNIQUE constraint failed: .*/
    RecordNotUnique.new(message, exception)
  else
    super
  end
end