103 lines
2.3 KiB
Ruby
103 lines
2.3 KiB
Ruby
module DeclarativePolicy
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# The DSL evaluation context inside rule { ... } blocks.
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# Responsible for creating and combining Rule objects.
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#
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# See Base.rule
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class RuleDsl
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def initialize(context_class)
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@context_class = context_class
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end
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def can?(ability)
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Rule::Ability.new(ability)
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end
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def all?(*rules)
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Rule::And.make(rules)
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end
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def any?(*rules)
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Rule::Or.make(rules)
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end
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def none?(*rules)
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~Rule::Or.new(rules)
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end
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def cond(condition)
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Rule::Condition.new(condition)
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end
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def delegate(delegate_name, condition)
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Rule::DelegatedCondition.new(delegate_name, condition)
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end
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def method_missing(m, *a, &b)
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return super unless a.size == 0 && !block_given?
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if @context_class.delegations.key?(m)
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DelegateDsl.new(self, m)
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else
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cond(m.to_sym)
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end
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end
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end
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# Used when the name of a delegate is mentioned in
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# the rule DSL.
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class DelegateDsl
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def initialize(rule_dsl, delegate_name)
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@rule_dsl = rule_dsl
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@delegate_name = delegate_name
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end
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def method_missing(m, *a, &b)
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return super unless a.size == 0 && !block_given?
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@rule_dsl.delegate(@delegate_name, m)
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end
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end
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# The return value of a rule { ... } declaration.
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# Can call back to register rules with the containing
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# Policy class (context_class here). See Base.rule
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#
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# Note that the #policy method just performs an #instance_eval,
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# which is useful for multiple #enable or #prevent callse.
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#
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# Also provides a #method_missing proxy to the context
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# class's class methods, so that helper methods can be
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# defined and used in a #policy { ... } block.
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class PolicyDsl
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def initialize(context_class, rule)
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@context_class = context_class
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@rule = rule
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end
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def policy(&b)
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instance_eval(&b)
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end
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def enable(*abilities)
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@context_class.enable_when(abilities, @rule)
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end
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def prevent(*abilities)
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@context_class.prevent_when(abilities, @rule)
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end
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def prevent_all
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@context_class.prevent_all_when(@rule)
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end
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def method_missing(m, *a, &b)
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return super unless @context_class.respond_to?(m)
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@context_class.__send__(m, *a, &b)
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end
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def respond_to_missing?(m)
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@context_class.respond_to?(m) || super
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end
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end
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end
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