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require 'set'
module Moneta
# Adds weak key enumeration support to the underlying store
#
# @note This class wraps methods that store and retrieve entries in order to
# track which keys are in the store, and uses this list when doing key
# traversal. This means that {#each_key each_key} will only yield keys
# which have been accessed previously via the present store object. This
# wrapper is therefore best suited to adapters which are not persistent, and
# which cannot be shared.
#
# @api public
class WeakEachKey < Wrapper
supports :each_key
# @param [Moneta store] adapter The underlying store
# @param [Hash] options
def initialize(adapter, options = {})
raise 'Store already supports feature :each_key' if adapter.supports?(:each_key)
@all_keys = Set.new
super
end
# (see Proxy#each_key)
def each_key
return enum_for(:each_key) { all_keys.size } unless block_given?
all_keys.each { |key| yield key }
self
end
protected
attr_reader :all_keys
def wrap(name, *args)
case name
when :create, :store, :increment, :create
each_key_save(args[0])
yield
when :key?
if found = yield
each_key_save(args[0])
else
all_keys.delete(args[0])
end
found
when :load
key?(*args)
yield
when :delete
all_keys.delete(args[0])
yield
when :clear, :close
all_keys.clear
yield
when :values_at, :fetch_values, :slice
args[0].each { |key| key?(key) }
yield
when :merge!
args[0].each { |key, _| each_key_save(key) }
yield
else
yield
end
end
def each_key_save(key)
@all_keys = Set.new(@all_keys).add(key)
end
end
end
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