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-rw-r--r--lib/puppet/parser/functions/deep_merge.rb44
1 files changed, 44 insertions, 0 deletions
diff --git a/lib/puppet/parser/functions/deep_merge.rb b/lib/puppet/parser/functions/deep_merge.rb
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+++ b/lib/puppet/parser/functions/deep_merge.rb
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+module Puppet::Parser::Functions
+ newfunction(:deep_merge, :type => :rvalue, :doc => <<-'ENDHEREDOC') do |args|
+ Recursively merges two or more hashes together and returns the resulting hash.
+
+ For example:
+
+ $hash1 = {'one' => 1, 'two' => 2, 'three' => { 'four' => 4 } }
+ $hash2 = {'two' => 'dos', 'three' => { 'five' => 5 } }
+ $merged_hash = deep_merge($hash1, $hash2)
+ # The resulting hash is equivalent to:
+ # $merged_hash = { 'one' => 1, 'two' => 'dos', 'three' => { 'four' => 4, 'five' => 5 } }
+
+ When there is a duplicate key that is a hash, they are recursively merged.
+ When there is a duplicate key that is not a hash, the key in the rightmost hash will "win."
+
+ ENDHEREDOC
+
+ if args.length < 2
+ raise Puppet::ParseError, ("deep_merge(): wrong number of arguments (#{args.length}; must be at least 2)")
+ end
+
+ deep_merge = Proc.new do |hash1,hash2|
+ hash1.merge(hash2) do |key,old_value,new_value|
+ if old_value.is_a?(Hash) && new_value.is_a?(Hash)
+ deep_merge.call(old_value, new_value)
+ else
+ new_value
+ end
+ end
+ end
+
+ result = Hash.new
+ args.each do |arg|
+ next if arg.is_a? String and arg.empty? # empty string is synonym for puppet's undef
+ # If the argument was not a hash, skip it.
+ unless arg.is_a?(Hash)
+ raise Puppet::ParseError, "deep_merge: unexpected argument type #{arg.class}, only expects hash arguments"
+ end
+
+ result = deep_merge.call(result, arg)
+ end
+ return( result )
+ end
+end