--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/modules/php/lib/puppet/parser/functions/ensure_prefix.rb	Mon Jan 03 17:09:39 2022 +0000
@@ -0,0 +1,57 @@
+
+module Puppet::Parser::Functions
+  newfunction(:ensure_prefix, type: :rvalue, doc: <<-EOS
+    This function ensures a prefix for all elements in an array or the keys in a hash.
+
+    *Examples:*
+
+      ensure_prefix({'a' => 1, 'b' => 2, 'p.c' => 3}, 'p.')
+
+    Will return:
+      {
+        'p.a' => 1,
+        'p.b' => 2,
+        'p.c' => 3,
+      }
+
+      ensure_prefix(['a', 'p.b', 'c'], 'p.')
+
+    Will return:
+      ['p.a', 'p.b', 'p.c']
+EOS
+             ) do |arguments|
+    if arguments.size < 2
+      raise(Puppet::ParseError, 'ensure_prefix(): Wrong number of arguments ' \
+        "given (#{arguments.size} for 2)")
+    end
+
+    enumerable = arguments[0]
+
+    unless enumerable.is_a?(Array) || enumerable.is_a?(Hash)
+      raise Puppet::ParseError, "ensure_prefix(): expected first argument to be an Array or a Hash, got #{enumerable.inspect}"
+    end
+
+    prefix = arguments[1] if arguments[1]
+
+    if prefix
+      unless prefix.is_a?(String)
+        raise Puppet::ParseError, "ensure_prefix(): expected second argument to be a String, got #{prefix.inspect}"
+      end
+    end
+
+    result = if enumerable.is_a?(Array)
+               # Turn everything into string same as join would do ...
+               enumerable.map do |i|
+                 i = i.to_s
+                 prefix && !i.start_with?(prefix) ? prefix + i : i
+               end
+             else
+               Hash[enumerable.map do |k, v|
+                 k = k.to_s
+                 [prefix && !k.start_with?(prefix) ? prefix + k : k, v]
+               end]
+             end
+
+    return result
+  end
+end