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Diffstat (limited to 'lib/declarative_policy/dsl.rb')
-rw-r--r-- | lib/declarative_policy/dsl.rb | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/lib/declarative_policy/dsl.rb b/lib/declarative_policy/dsl.rb new file mode 100644 index 00000000000..b26807a7622 --- /dev/null +++ b/lib/declarative_policy/dsl.rb @@ -0,0 +1,103 @@ +module DeclarativePolicy + # The DSL evaluation context inside rule { ... } blocks. + # Responsible for creating and combining Rule objects. + # + # See Base.rule + class RuleDsl + def initialize(context_class) + @context_class = context_class + end + + def can?(ability) + Rule::Ability.new(ability) + end + + def all?(*rules) + Rule::And.make(rules) + end + + def any?(*rules) + Rule::Or.make(rules) + end + + def none?(*rules) + ~Rule::Or.new(rules) + end + + def cond(condition) + Rule::Condition.new(condition) + end + + def delegate(delegate_name, condition) + Rule::DelegatedCondition.new(delegate_name, condition) + end + + def method_missing(m, *a, &b) + return super unless a.size == 0 && !block_given? + + if @context_class.delegations.key?(m) + DelegateDsl.new(self, m) + else + cond(m.to_sym) + end + end + end + + # Used when the name of a delegate is mentioned in + # the rule DSL. + class DelegateDsl + def initialize(rule_dsl, delegate_name) + @rule_dsl = rule_dsl + @delegate_name = delegate_name + end + + def method_missing(m, *a, &b) + return super unless a.size == 0 && !block_given? + + @rule_dsl.delegate(@delegate_name, m) + end + end + + # The return value of a rule { ... } declaration. + # Can call back to register rules with the containing + # Policy class (context_class here). See Base.rule + # + # Note that the #policy method just performs an #instance_eval, + # which is useful for multiple #enable or #prevent callse. + # + # Also provides a #method_missing proxy to the context + # class's class methods, so that helper methods can be + # defined and used in a #policy { ... } block. + class PolicyDsl + def initialize(context_class, rule) + @context_class = context_class + @rule = rule + end + + def policy(&b) + instance_eval(&b) + end + + def enable(*abilities) + @context_class.enable_when(abilities, @rule) + end + + def prevent(*abilities) + @context_class.prevent_when(abilities, @rule) + end + + def prevent_all + @context_class.prevent_all_when(@rule) + end + + def method_missing(m, *a, &b) + return super unless @context_class.respond_to?(m) + + @context_class.__send__(m, *a, &b) + end + + def respond_to_missing?(m) + @context_class.respond_to?(m) || super + end + end +end |