88 lines
2.7 KiB
Ruby
88 lines
2.7 KiB
Ruby
require_dependency 'declarative_policy/cache'
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require_dependency 'declarative_policy/condition'
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require_dependency 'declarative_policy/dsl'
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require_dependency 'declarative_policy/preferred_scope'
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require_dependency 'declarative_policy/rule'
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require_dependency 'declarative_policy/runner'
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require_dependency 'declarative_policy/step'
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require_dependency 'declarative_policy/base'
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require 'thread'
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module DeclarativePolicy
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CLASS_CACHE_MUTEX = Mutex.new
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CLASS_CACHE_IVAR = :@__DeclarativePolicy_CLASS_CACHE
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class << self
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def policy_for(user, subject, opts = {})
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cache = opts[:cache] || {}
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key = Cache.policy_key(user, subject)
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cache[key] ||= class_for(subject).new(user, subject, opts)
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end
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def class_for(subject)
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return GlobalPolicy if subject == :global
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return NilPolicy if subject.nil?
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subject = find_delegate(subject)
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class_for_class(subject.class)
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end
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private
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# This method is heavily cached because there are a lot of anonymous
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# modules in play in a typical rails app, and #name performs quite
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# slowly for anonymous classes and modules.
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#
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# See https://bugs.ruby-lang.org/issues/11119
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#
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# if the above bug is resolved, this caching could likely be removed.
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def class_for_class(subject_class)
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unless subject_class.instance_variable_defined?(CLASS_CACHE_IVAR)
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CLASS_CACHE_MUTEX.synchronize do
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# re-check in case of a race
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break if subject_class.instance_variable_defined?(CLASS_CACHE_IVAR)
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policy_class = compute_class_for_class(subject_class)
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subject_class.instance_variable_set(CLASS_CACHE_IVAR, policy_class)
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end
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end
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policy_class = subject_class.instance_variable_get(CLASS_CACHE_IVAR)
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raise "no policy for #{subject.class.name}" if policy_class.nil?
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policy_class
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end
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def compute_class_for_class(subject_class)
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subject_class.ancestors.each do |klass|
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next unless klass.name
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begin
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policy_class = "#{klass.name}Policy".constantize
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# NOTE: the < operator here tests whether policy_class
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# inherits from Base. We can't use #is_a? because that
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# tests for *instances*, not *subclasses*.
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return policy_class if policy_class < Base
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rescue NameError
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nil
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end
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end
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end
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def find_delegate(subject)
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seen = Set.new
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while subject.respond_to?(:declarative_policy_delegate)
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raise ArgumentError, "circular delegations" if seen.include?(subject.object_id)
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seen << subject.object_id
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subject = subject.declarative_policy_delegate
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end
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subject
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end
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end
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end
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