46 lines
1.2 KiB
Ruby
46 lines
1.2 KiB
Ruby
# frozen_string_literal: true
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module Arel # :nodoc: all
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module Visitors
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class Visitor
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def initialize
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@dispatch = get_dispatch_cache
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end
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def accept(object, collector = nil)
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visit object, collector
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end
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private
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attr_reader :dispatch
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def self.dispatch_cache
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@dispatch_cache ||= Hash.new do |hash, klass|
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hash[klass] = "visit_#{(klass.name || '').gsub('::', '_')}"
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end
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end
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def get_dispatch_cache
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self.class.dispatch_cache
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end
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def visit(object, collector = nil)
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dispatch_method = dispatch[object.class]
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if collector
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send dispatch_method, object, collector
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else
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send dispatch_method, object
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end
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rescue NoMethodError => e
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raise e if respond_to?(dispatch_method, true)
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superklass = object.class.ancestors.find { |klass|
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respond_to?(dispatch[klass], true)
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}
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raise(TypeError, "Cannot visit #{object.class}") unless superklass
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dispatch[object.class] = dispatch[superklass]
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retry
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end
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end
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end
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end
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