Add clamp function

Clamp keeps value within the range.
Employ of soft() makes the whole thing is independant of order.

Author: mpolenchuk

lib/puppet/parser/functions/clamp.rb

@@ -0,0 +1,31 @@
+#
+# clamp.rb
+#
+
+module Puppet::Parser::Functions
+  newfunction(:clamp, :type => :rvalue, :doc => <<-EOS
+    Clamps value to a range.
+    EOS
+  ) do |args|
+
+    raise(Puppet::ParseError, "clamp(): Wrong number of arguments " +
+          "need at least one") if args.size < 1
+
+    result = []
+
+    args.each do |x|
+      if x.is_a?(Array)
+        result += x
+      else
+        result << x
+      end
+    end
+
+    raise(Puppet::ParseError, "clamp(): Wrong number/type of arguments " +
+          "need three to clamp") if result.size != 3
+
+    result.map{ |n| n.to_i }.sort[1]
+  end
+end
+
+# vim: set ts=2 sw=2 et :

spec/acceptance/clamp_spec.rb

@@ -0,0 +1,40 @@
+#! /usr/bin/env ruby -S rspec
+require 'spec_helper_acceptance'
+
+describe 'clamp function', :unless => UNSUPPORTED_PLATFORMS.include?(fact('operatingsystem')) do
+  describe 'success' do
+    it 'clamps list of values' do
+      pp = <<-EOS
+      $x = 17
+      $y = 225
+      $z = 155
+      $o = clamp($x, $y, $z)
+      if $o == $z {
+        notify { 'output correct': }
+      }
+      EOS
+
+      apply_manifest(pp, :catch_failures => true) do |r|
+        expect(r.stdout).to match(/Notice: output correct/)
+      end
+    end
+    it 'clamps array of values' do
+      pp = <<-EOS
+      $a = [7, 19, 66]
+      $b = 19
+      $o = clamp($a)
+      if $o == $b {
+        notify { 'output correct': }
+      }
+      EOS
+
+      apply_manifest(pp, :catch_failures => true) do |r|
+        expect(r.stdout).to match(/Notice: output correct/)
+      end
+    end
+  end
+  describe 'failure' do
+    it 'handles improper argument counts'
+    it 'handles no arguments'
+  end
+end

spec/functions/clamp_spec.rb

@@ -0,0 +1,13 @@
+require 'spec_helper'
+
+describe 'clamp' do
+  it { is_expected.not_to eq(nil) }
+  it { is_expected.to run.with_params().and_raise_error(Puppet::ParseError) }
+  it { is_expected.to run.with_params("string1").and_raise_error(Puppet::ParseError) }
+  it { is_expected.to run.with_params([]).and_raise_error(Puppet::ParseError) }
+  it { is_expected.to run.with_params([4,3,99]).and_return(4) }
+  it { is_expected.to run.with_params(444,3,99).and_return(99) }
+  it { is_expected.to run.with_params([4,873],73).and_return(73) }
+  it { is_expected.to run.with_params([4],8,99).and_return(8) }
+  it { is_expected.to run.with_params([4],[31], 9911).and_return(31) }
+end