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# File 'lib/deterministic/enum.rb', line 112
def enum(&block)
mod = Class.new do class << self; private :new; end
def self.match(obj, &block)
caller_ctx = block.binding.eval 'self'
matcher = self::Matcher.new(obj)
matcher.instance_eval(&block)
variants_in_match = matcher.matches.collect {|e| e[1].name.split('::')[-1].to_sym}.uniq.sort
variants_not_covered = variants - variants_in_match
raise Enum::MatchError, "Match is non-exhaustive, #{variants_not_covered} not covered" unless variants_not_covered.empty?
type_matches = matcher.matches.select { |r| r[0].is_a?(r[1]) }
type_matches.each { |match|
obj, type, block, args, guard = match
if args.count == 0
return caller_ctx.instance_eval(&block)
else
if args.count != obj.args.count
raise Enum::MatchError, "Pattern (#{args.join(', ')}) must match (#{obj.args.join(', ')})"
end
guard_ctx = guard_context(obj, args)
if guard
if guard_ctx.instance_exec(obj, &guard)
return caller_ctx.instance_exec(* obj.wrapped_values, &block)
end
else
return caller_ctx.instance_exec(* obj.wrapped_values, &block)
end
end
}
raise Enum::MatchError, "No match could be made"
end
def self.variants; constants - [:Matcher, :MatchError]; end
private
def self.guard_context(obj, args)
if obj.is_a?(Deterministic::EnumBuilder::DataType::Binary)
Struct.new(*(args)).new(*(obj.value.values))
else
Struct.new(*(args)).new(obj.value)
end
end
end
enum = EnumBuilder.new(mod)
enum.instance_eval(&block)
type_variants = mod.constants
matcher = Class.new {
def initialize(obj)
@obj = obj
@matches = []
@vars = []
end
attr_reader :matches, :vars
def where(&guard)
guard
end
type_variants.each { |m|
define_method(m) { |guard = nil, &block|
raise ArgumentError, "No block given to `#{m}`" if block.nil?
params_spec = block.parameters
if params_spec.any? {|spec| spec.size < 2 }
raise ArgumentError, "Unnamed param found in block parameters: #{params_spec.inspect}"
end
if params_spec.any? {|spec| spec[0] != :req && spec[0] != :opt }
raise ArgumentError, "Only :req & :opt params allowed; parameters=#{params_spec.inspect}"
end
args = params_spec.map {|spec| spec[1] }
type = Kernel.eval("#{mod.name}::#{m}")
if guard && !guard.is_a?(Proc)
guard = nil
end
@matches << [@obj, type, block, args, guard]
}
}
}
mod.const_set(:Matcher, matcher)
type_variants.each { |variant|
mod.singleton_class.class_exec {
define_method(variant) { |*args|
const_get(variant).new(*args)
}
}
}
mod
end
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