1 | #
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2 | # values_at.rb
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3 | #
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4 |
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5 | module Puppet::Parser::Functions
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6 | newfunction(:values_at, :type => :rvalue, :doc => <<-EOS
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7 | Finds value inside an array based on location.
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8 |
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9 | The first argument is the array you want to analyze, and the second element can
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10 | be a combination of:
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11 |
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12 | * A single numeric index
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13 | * A range in the form of 'start-stop' (eg. 4-9)
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14 | * An array combining the above
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15 |
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16 | *Examples*:
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17 |
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18 | values_at(['a','b','c'], 2)
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19 |
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20 | Would return ['c'].
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21 |
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22 | values_at(['a','b','c'], ["0-1"])
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23 |
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24 | Would return ['a','b'].
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25 |
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26 | values_at(['a','b','c','d','e'], [0, "2-3"])
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27 |
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28 | Would return ['a','c','d'].
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29 | EOS
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30 | ) do |arguments|
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31 |
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32 | raise(Puppet::ParseError, "values_at(): Wrong number of " +
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33 | "arguments given (#{arguments.size} for 2)") if arguments.size < 2
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34 |
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35 | array = arguments.shift
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36 |
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37 | unless array.is_a?(Array)
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38 | raise(Puppet::ParseError, 'values_at(): Requires array to work with')
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39 | end
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40 |
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41 | indices = [arguments.shift].flatten() # Get them all ... Pokemon ...
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42 |
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43 | if not indices or indices.empty?
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44 | raise(Puppet::ParseError, 'values_at(): You must provide ' +
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45 | 'at least one positive index to collect')
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46 | end
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47 |
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48 | result = []
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49 | indices_list = []
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50 |
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51 | indices.each do |i|
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52 | i = i.to_s
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53 | if m = i.match(/^(\d+)(\.\.\.?|\-)(\d+)$/)
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54 | start = m[1].to_i
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55 | stop = m[3].to_i
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56 |
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57 | type = m[2]
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58 |
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59 | if start > stop
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60 | raise(Puppet::ParseError, 'values_at(): Stop index in ' +
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61 | 'given indices range is smaller than the start index')
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62 | elsif stop > array.size - 1 # First element is at index 0 is it not?
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63 | raise(Puppet::ParseError, 'values_at(): Stop index in ' +
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64 | 'given indices range exceeds array size')
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65 | end
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66 |
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67 | range = case type
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68 | when /^(\.\.|\-)$/ then (start .. stop)
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69 | when /^(\.\.\.)$/ then (start ... stop) # Exclusive of last element ...
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70 | end
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71 |
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72 | range.each { |i| indices_list << i.to_i }
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73 | else
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74 | # Only positive numbers allowed in this case ...
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75 | if not i.match(/^\d+$/)
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76 | raise(Puppet::ParseError, 'values_at(): Unknown format ' +
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77 | 'of given index')
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78 | end
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79 |
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80 | # In Puppet numbers are often string-encoded ...
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81 | i = i.to_i
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82 |
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83 | if i > array.size - 1 # Same story. First element is at index 0 ...
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84 | raise(Puppet::ParseError, 'values_at(): Given index ' +
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85 | 'exceeds array size')
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86 | end
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87 |
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88 | indices_list << i
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89 | end
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90 | end
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91 |
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92 | # We remove nil values as they make no sense in Puppet DSL ...
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93 | result = indices_list.collect { |i| array[i] }.compact
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94 |
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95 | return result
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96 | end
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97 | end
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98 |
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99 | # vim: set ts=2 sw=2 et :
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