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#
# values_at.rb
#
module Puppet::Parser::Functions
newfunction(:values_at, :type => :rvalue, :doc => <<-EOS
Finds value inside an array based on location.
The first argument is the array you want to analyze, and the second element can
be a combination of:
* A single numeric index
* A range in the form of 'start-stop' (eg. 4-9)
* An array combining the above
*Examples*:
values_at(['a','b','c'], 2)
Would return ['c'].
values_at(['a','b','c'], ["0-1"])
Would return ['a','b'].
values_at(['a','b','c','d','e'], [0, "2-3"])
Would return ['a','c','d'].
EOS
) do |arguments|
raise(Puppet::ParseError, "values_at(): Wrong number of arguments given (#{arguments.size} for 2)") if arguments.size < 2
array = arguments.shift
unless array.is_a?(Array)
raise(Puppet::ParseError, 'values_at(): Requires array to work with')
end
indices = [arguments.shift].flatten() # Get them all ... Pokemon ...
if not indices or indices.empty?
raise(Puppet::ParseError, 'values_at(): You must provide at least one positive index to collect')
end
result = []
indices_list = []
indices.each do |i|
i = i.to_s
if m = i.match(/^(\d+)(\.\.\.?|\-)(\d+)$/)
start = m[1].to_i
stop = m[3].to_i
type = m[2]
if start > stop
raise(Puppet::ParseError, 'values_at(): Stop index in given indices range is smaller than the start index')
elsif stop > array.size - 1 # First element is at index 0 is it not?
raise(Puppet::ParseError, 'values_at(): Stop index in given indices range exceeds array size')
end
range = case type
when /^(\.\.|\-)$/ then (start .. stop)
when /^(\.\.\.)$/ then (start ... stop) # Exclusive of last element ...
end
range.each { |i| indices_list << i.to_i }
else
# Only positive numbers allowed in this case ...
if not i.match(/^\d+$/)
raise(Puppet::ParseError, 'values_at(): Unknown format of given index')
end
# In Puppet numbers are often string-encoded ...
i = i.to_i
if i > array.size - 1 # Same story. First element is at index 0 ...
raise(Puppet::ParseError, 'values_at(): Given index exceeds array size')
end
indices_list << i
end
end
# We remove nil values as they make no sense in Puppet DSL ...
result = indices_list.collect { |i| array[i] }.compact
return result
end
end
# vim: set ts=2 sw=2 et :
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