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# frozen_string_literal: true
# rubocop:todo all
# Copyright (C) 2020 MongoDB Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
module Mongo
# A Cursor that attempts to load documents from memory first before hitting
# the database if the same query has already been executed.
#
# @api semiprivate
class CachingCursor < Cursor
# @return [ Array <BSON::Document> ] The cursor's cached documents.
# @api private
attr_reader :cached_docs
# We iterate over the cached documents if they exist already in the
# cursor otherwise proceed as normal.
#
# @example Iterate over the documents.
# cursor.each do |doc|
# # ...
# end
def each
if @cached_docs
@cached_docs.each do |doc|
yield doc
end
unless closed?
# StopIteration raised by try_next ends this loop.
loop do
document = try_next
yield document if document
end
end
else
super
end
end
# Get a human-readable string representation of +Cursor+.
#
# @example Inspect the cursor.
# cursor.inspect
#
# @return [ String ] A string representation of a +Cursor+ instance.
def inspect
"#<Mongo::CachingCursor:0x#{object_id} @view=#{@view.inspect}>"
end
# Acquires the next document for cursor iteration and then
# inserts that document in the @cached_docs array.
#
# @api private
def try_next
@cached_docs ||= []
document = super
@cached_docs << document if document
document
end
end
end
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