Puppet Function: concat_merge

Defined in:
lib/puppet/parser/functions/concat_merge.rb
Function type:
Ruby 3.x API

Overview

concat_merge() ⇒ Any

Merges two or more hashes together concatenating duplicate keys with array values and returns the resulting hash.

For example:

$hash1 = {'a' => [1]}
$hash2 = {'a' => [2]}
concat_merge($hash1, $hash2)
# The resulting hash is equivalent to:
# { 'a' => [1, 2] }

When there is a duplicate key that is not an array, the key in the rightmost hash will “win.”

Returns:

  • (Any) —

    String



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# File 'lib/puppet/parser/functions/concat_merge.rb', line 5

newfunction(
  :concat_merge,
  type: :rvalue,
  doc: <<-ENDHEREDOC) do |args|
  Merges two or more hashes together concatenating duplicate keys
  with array values and returns the resulting hash.

  For example:

      $hash1 = {'a' => [1]}
      $hash2 = {'a' => [2]}
      concat_merge($hash1, $hash2)
      # The resulting hash is equivalent to:
      # { 'a' => [1, 2] }

  When there is a duplicate key that is not an array, the key in
  the rightmost hash will "win."

  @return String
  ENDHEREDOC

  raise Puppet::ParseError, "concat_merge(): wrong number of arguments (#{args.length}; must be at least 2)" if args.length < 2

  concat_merge = proc do |hash1, hash2|
    hash1.merge(hash2) do |_key, old_value, new_value|
      if old_value.is_a?(Array) && new_value.is_a?(Array)
        old_value + new_value
      else
        new_value
      end
    end
  end

  result = {}
  args.each do |arg|
    next if arg.is_a?(String) && arg.empty? # empty string is synonym for puppet's undef
    # If the argument was not a hash, skip it.
    raise Puppet::ParseError, "concat_merge: unexpected argument type #{arg.class}, only expects hash arguments" unless arg.is_a?(Hash)

    result = concat_merge.call(result, arg)
  end
  result
end