blob: 540628957c1ea6d65550b2c3f9f157697fcbb7c7 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
module Rake
# InvocationChain tracks the chain of task invocations to detect
# circular dependencies.
class InvocationChain < LinkedList
# Is the invocation already in the chain?
def member?(invocation)
head == invocation || tail.member?(invocation)
end
# Append an invocation to the chain of invocations. It is an error
# if the invocation already listed.
def append(invocation)
if member?(invocation)
fail RuntimeError, "Circular dependency detected: #{to_s} => #{invocation}"
end
conj(invocation)
end
# Convert to string, ie: TOP => invocation => invocation
def to_s
"#{prefix}#{head}"
end
# Class level append.
def self.append(invocation, chain)
chain.append(invocation)
end
private
def prefix
"#{tail} => "
end
# Null object for an empty chain.
class EmptyInvocationChain < LinkedList::EmptyLinkedList
@parent = InvocationChain
def member?(obj)
false
end
def append(invocation)
conj(invocation)
end
def to_s
"TOP"
end
end
EMPTY = EmptyInvocationChain.new
end
end
|
