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Queue/Definition: Difference between revisions
→{{header|Julia}}: A new entry for Julia
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# produces: [1, 2]</lang>
=={{header|Julia}}==
Julia provides a variety of queue-like methods for vectors, making the solution to this task rather straightforward. Define a <tt>Queue</tt> in terms of a one dimensional array, and provide its methods using the appropriate vector operations. To adhere to Julia naming conventions, the queue operations are named "push!", "pop!" and "isempty" rather than "push", "pop" and "empty".
<lang Julia>
type Queue{T}
a::Array{T,1}
end
Queue() = Queue(Any[])
Queue(a::DataType) = Queue(a[])
Queue(a) = Queue(typeof(a)[])
Base.isempty(q::Queue) = isempty(q.a)
function Base.pop!{T}(q::Queue{T})
!isempty(q) || error("queue must be non-empty")
pop!(q.a)
end
function Base.push!{T}(q::Queue{T}, x::T)
unshift!(q.a, x)
return q
end
function Base.push!{T}(q::Queue{Any}, x::T)
unshift!(q.a, x)
return q
end
</lang>
{{out}}
It is easiest to use the REPL to show a <tt>Queue</tt> in action.
<pre>
julia> q = Queue()
Queue{Any}({})
julia> isempty(q)
true
julia> push!(q, 1)
Queue{Any}({1})
julia> isempty(q)
false
julia> push!(q, "two")
Queue{Any}({"two",1})
julia> push!(q, 3.0)
Queue{Any}({3.0,"two",1})
julia> push!(q, false)
Queue{Any}({false,3.0,"two",1})
julia> pop!(q)
1
julia> pop!(q)
"two"
julia> pop!(q)
3.0
julia> pop!(q)
false
julia> pop!(q)
ERROR: queue must be non-empty
in pop! at none:2
</pre>
=={{header|LabVIEW}}==
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