module Rake
####################################################################
# InvocationChain tracks the chain of task invocations to detect
# circular dependencies.
class InvocationChain
def initialize(value, tail)
@value = value
@tail = tail
end
def member?(obj)
@value == obj || @tail.member?(obj)
end
def append(value)
if member?(value)
fail RuntimeError, "Circular dependency detected: #{to_s} => #{value}"
end
self.class.new(value, self)
end
def to_s
"#{prefix}#{@value}"
end
def self.append(value, chain)
chain.append(value)
end
private
def prefix
"#{@tail.to_s} => "
end
class EmptyInvocationChain
def member?(obj)
false
end
def append(value)
InvocationChain.new(value, self)
end
def to_s
"TOP"
end
end
EMPTY = EmptyInvocationChain.new
end
end
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