(#19201) Add concat function to join two arrays

Without this patch applied there is no easy way to append one array to
another.  This is a problem because it is often desirable to join two
arrays without flattening the contents into a single, one dimensional
array.

This patch addresses the problem by adding a `concat()` function which
takes two arguments.  The arguments will be concatenated together and a
new array returned to the caller.

Reviewed-by: Jeff McCune <jeff@puppetlabs.com>

3 files changed, 59 insertions, 0 deletions

diff --git a/README.markdown b/README.markdown
index 922383c..c58d31f 100644
--- a/README.markdown
+++ b/README.markdown
@@ -98,6 +98,13 @@ Requires a string or array of strings as input.
 
 - *Type*: rvalue
 
+concat
+-----
+Appends the contents of the second array onto the first array.
+
+
+- *Type*: rvalue
+
 defined_with_params
 -------------------
 Takes a resource reference and an optional hash of attributes.
diff --git a/lib/puppet/parser/functions/concat.rb b/lib/puppet/parser/functions/concat.rb
new file mode 100644
index 0000000..c86aa00
--- /dev/null
+++ b/lib/puppet/parser/functions/concat.rb
@@ -0,0 +1,37 @@
+#
+# concat.rb
+#
+
+module Puppet::Parser::Functions
+  newfunction(:concat, :type => :rvalue, :doc => <<-EOS
+Appends the contents of array 2 onto array 1.
+
+*Example:*
+
+    concat(['1','2','3'],['4','5','6'])
+
+Would result in:
+
+  ['1','2','3','4','5','6']
+    EOS
+  ) do |arguments|
+
+    # Check that 2 arguments have been given ...
+    raise(Puppet::ParseError, "concat(): Wrong number of arguments " +
+      "given (#{arguments.size} for 2)") if arguments.size != 2
+
+    a = arguments[0]
+    b = arguments[1]
+
+    # Check that both args are arrays.
+    unless a.is_a?(Array) and b.is_a?(Array)
+      raise(Puppet::ParseError, 'concat(): Requires array to work with')
+    end
+
+    result = a.concat(b)
+
+    return result
+  end
+end
+
+# vim: set ts=2 sw=2 et :
diff --git a/spec/unit/puppet/parser/functions/concat_spec.rb b/spec/unit/puppet/parser/functions/concat_spec.rb
new file mode 100644
index 0000000..123188b
--- /dev/null
+++ b/spec/unit/puppet/parser/functions/concat_spec.rb
@@ -0,0 +1,15 @@
+#! /usr/bin/env ruby -S rspec
+require 'spec_helper'
+
+describe "the concat function" do
+  let(:scope) { PuppetlabsSpec::PuppetInternals.scope }
+
+  it "should raise a ParseError if there is less than 1 arguments" do
+    lambda { scope.function_concat([]) }.should( raise_error(Puppet::ParseError))
+  end
+
+  it "should be able to concat an array" do
+    result = scope.function_concat([['1','2','3'],['4','5','6']])
+    result.should(eq(['1','2','3','4','5','6']))
+  end
+end