(#8709) Add hash merging function

In Puppet, it is not possible to reassign hash
values.

This function allows a reasonable way to perform
hash munging in Puppet.

Reviewed-by: Jeff McCune

2 files changed, 82 insertions, 0 deletions

diff --git a/lib/puppet/parser/functions/merge.rb b/lib/puppet/parser/functions/merge.rb
new file mode 100644
index 0000000..6693884
--- /dev/null
+++ b/lib/puppet/parser/functions/merge.rb
@@ -0,0 +1,28 @@
+module Puppet::Parser::Functions
+
+  newfunction(:merge, :type => :rvalue, :doc => <<-'ENDHEREDOC') do |args|
+    Merges two or more hashes together and returns the resulting hash.
+
+    For example:
+
+      $hash1 = {'one' => 1, 'two', => 2}
+      $hash1 = {'two' => 2, 'three', => 2}
+      $merged_hash = merge($hash1, $hash2)
+      # merged_hash =  {'one' => 1, 'two' => 2, 'three' => 2}
+
+    ENDHEREDOC
+
+    if args.length < 2
+      raise Puppet::ParseError, ("merge(): wrong number of arguments (#{args.length}; must be at least 2)")
+    end
+    args.each do |arg|
+      unless arg.is_a?(Hash)
+        raise Puppet::ParseError, "merge: unexpected argument type #{arg.class}, only expects hash arguments"
+      end
+    end
+
+    args.inject({}, :merge)
+
+  end
+
+end
diff --git a/spec/unit/puppet/parser/functions/merge_spec.rb b/spec/unit/puppet/parser/functions/merge_spec.rb
new file mode 100644
index 0000000..71e1869
--- /dev/null
+++ b/spec/unit/puppet/parser/functions/merge_spec.rb
@@ -0,0 +1,54 @@
+require 'puppet'
+require 'mocha'
+describe Puppet::Parser::Functions.function(:merge) do
+
+  # Pulled from Dan's create_resources function
+  # TODO - these let statements should be moved somewhere
+  # where they can be resued
+  let(:compiler) {
+    topscope = Puppet::Parser::Scope.new
+    # This is necessary so we don't try to use the compiler to discover our parent.
+    topscope.parent = nil
+    my_scope = Puppet::Parser::Scope.new
+    my_scope.compiler = Puppet::Parser::Compiler.new(Puppet::Node.new("floppy", :environment => 'production'))
+    my_scope.parent = topscope
+    compiler = my_scope.compiler
+  }
+  let(:scope) {
+    scope = Puppet::Parser::Scope.new
+    scope.stubs(:environment).returns(Puppet::Node::Environment.new('production'))
+    scope
+  }
+
+  describe 'when calling merge from puppet' do
+    it "should not compile when no arguments are passed" do
+      Puppet[:code] = 'merge()'
+      expect { compiler.compile }.should raise_error(Puppet::ParseError, /wrong number of arguments/)
+    end
+    it "should not compile when 1 argument is passed" do
+      Puppet[:code] = "$my_hash={'one' => 1}\nmerge($my_hash)"
+      expect { compiler.compile }.should raise_error(Puppet::ParseError, /wrong number of arguments/)
+    end
+  end
+  describe 'when calling merge on the scope instance' do
+    it 'should require all parameters are hashes' do
+      expect { new_hash = scope.function_merge([{}, '2'])}.should raise_error(Puppet::ParseError, /unexpected argument type String/)
+
+    end
+    it 'should be able to merge two hashes' do
+      new_hash = scope.function_merge([{'one' => '1', 'two' => '1'}, {'two' => '2', 'three' => '2'}])
+      new_hash['one'].should   == '1'
+      new_hash['two'].should   == '2'
+      new_hash['three'].should == '2'
+    end
+    it 'should merge multiple hashes' do
+      hash = scope.function_merge([{'one' => 1}, {'one' => '2'}, {'one' => '3'}])
+      hash['one'].should == '3'
+    end
+    it 'should accept empty hashes' do
+      scope.function_merge([{},{},{}]).should == {}
+    end
+
+  end
+
+end