58 lines
1.2 KiB
Ruby
58 lines
1.2 KiB
Ruby
# frozen_string_literal: true
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module Rake
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# InvocationChain tracks the chain of task invocations to detect
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# circular dependencies.
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class InvocationChain < LinkedList
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# Is the invocation already in the chain?
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def member?(invocation)
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head == invocation || tail.member?(invocation)
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end
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# Append an invocation to the chain of invocations. It is an error
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# if the invocation already listed.
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def append(invocation)
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if member?(invocation)
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fail RuntimeError, "Circular dependency detected: #{to_s} => #{invocation}"
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end
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conj(invocation)
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end
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# Convert to string, ie: TOP => invocation => invocation
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def to_s
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"#{prefix}#{head}"
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end
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# Class level append.
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def self.append(invocation, chain)
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chain.append(invocation)
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end
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private
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def prefix
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"#{tail} => "
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end
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# Null object for an empty chain.
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class EmptyInvocationChain < LinkedList::EmptyLinkedList
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@parent = InvocationChain
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def member?(obj)
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false
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end
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def append(invocation)
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conj(invocation)
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end
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def to_s
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"TOP"
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end
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end
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EMPTY = EmptyInvocationChain.new
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end
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end
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