Add dig() function

Deprecates #try_get_value()

2 files changed, 64 insertions, 34 deletions

diff --git a/lib/puppet/parser/functions/dig.rb b/lib/puppet/parser/functions/dig.rb
new file mode 100644
index 0000000..a9aa770
--- /dev/null
+++ b/lib/puppet/parser/functions/dig.rb
@@ -0,0 +1,54 @@
+#
+# dig.rb
+#
+
+module Puppet::Parser::Functions
+  newfunction(:dig, :type => :rvalue, :doc => <<-EOS
+Looks up into a complex structure of arrays and hashes and returns nil
+or the default value if nothing was found.
+
+Path is an array of keys to be looked up in data argument. The function
+will go down the structure and try to extract the required value.
+
+$data = {
+  'a' => {
+    'b' => [
+      'b1',
+      'b2',
+      'b3' ]}}
+
+$value = dig($data, ['a', 'b', '2'], 'not_found')
+=> $value = 'b3'
+
+a -> first hash key
+b -> second hash key
+2 -> array index starting with 0
+
+not_found -> (optional) will be returned if there is no value or the path
+did not match. Defaults to nil.
+
+In addition to the required "path" argument, "dig" accepts default
+argument. It will be returned if no value was found or a path component is
+missing. And the fourth argument can set a variable path separator.
+    EOS
+             ) do |arguments|
+    # Two arguments are required
+    raise(Puppet::ParseError, "dig(): Wrong number of arguments " +
+                              "given (#{arguments.size} for at least 2)") if arguments.size < 2
+
+    data, path, default = *arguments
+
+    if !(data.is_a?(Hash) || data.is_a?(Array))
+      raise(Puppet::ParseError, "dig(): first argument must be a hash or an array, " <<
+                                "given #{data.class.name}")
+    end
+
+    unless path.is_a? Array
+      raise(Puppet::ParseError, "dig(): second argument must be an array, " <<
+                                "given #{path.class.name}")
+    end
+
+    value = path.reduce(data) { |h, k| (h.is_a?(Hash) || h.is_a?(Array)) ? h[k] : break }
+    value.nil? ? default : value
+  end
+end
diff --git a/lib/puppet/parser/functions/try_get_value.rb b/lib/puppet/parser/functions/try_get_value.rb
index 0c19fd9..fc19a23 100644
--- a/lib/puppet/parser/functions/try_get_value.rb
+++ b/lib/puppet/parser/functions/try_get_value.rb
@@ -4,6 +4,8 @@ module Puppet::Parser::Functions
       :type => :rvalue,
       :arity => -2,
       :doc => <<-eos
+DEPRECATED: this function is deprecated, please use dig() instead.
+
 Looks up into a complex structure of arrays and hashes and returns a value
 or the default value if nothing was found.
 
@@ -35,43 +37,17 @@ argument. It will be returned if no value was found or a path component is
 missing. And the fourth argument can set a variable path separator.
   eos
   ) do |args|
-    path_lookup = lambda do |data, path, default|
-      debug "Try_get_value: #{path.inspect} from: #{data.inspect}"
-      if data.nil?
-        debug "Try_get_value: no data, return default: #{default.inspect}"
-        break default
-      end
-      unless path.is_a? Array
-        debug "Try_get_value: wrong path, return default: #{default.inspect}"
-        break default
-      end
-      unless path.any?
-        debug "Try_get_value: value found, return data: #{data.inspect}"
-        break data
-      end
-      unless data.is_a? Hash or data.is_a? Array
-        debug "Try_get_value: incorrect data, return default: #{default.inspect}"
-        break default
-      end
-
-      key = path.shift
-      if data.is_a? Array
-        begin
-          key = Integer key
-        rescue ArgumentError
-          debug "Try_get_value: non-numeric path for an array, return default: #{default.inspect}"
-          break default
-        end
-      end
-      path_lookup.call data[key], path, default
-    end
-
+    warning("try_get_value() DEPRECATED: this function is deprecated, please use dig() instead.")
     data = args[0]
     path = args[1] || ''
     default = args[2]
-    separator = args[3] || '/'
 
-    path = path.split separator
-    path_lookup.call data, path, default
+    if !(data.is_a?(Hash) || data.is_a?(Array)) || path == ''
+      return default || data
+    end
+
+    separator = args[3] || '/'
+    path = path.split(separator).map{ |key| key =~ /^\d+$/ ? key.to_i : key }
+    function_dig([data, path, default])
   end
 end