1 files changed, 98 insertions, 0 deletions
diff --git a/lib/puppet/parser/functions/values_at.rb b/lib/puppet/parser/functions/values_at.rb
new file mode 100644
index 0000000..d3e69d9
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+++ b/lib/puppet/parser/functions/values_at.rb
@@ -0,0 +1,98 @@
+#
+# 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|
+      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 :