moving constants around, starting the to_ruby visitor

11 files changed, 77 insertions, 31 deletions

diff --git a/lib/psych.rb b/lib/psych.rb
index df5486a..bdc2458 100644
--- a/lib/psych.rb
+++ b/lib/psych.rb
@@ -1,3 +1,5 @@
+require 'psych/visitable'
+
 require 'psych/nodes/node'
 require 'psych/nodes/stream'
 require 'psych/nodes/document'
@@ -6,6 +8,8 @@ require 'psych/nodes/scalar'
 require 'psych/nodes/mapping'
 require 'psych/nodes/alias'
 
+require 'psych/visitors'
+
 require 'psych/handler'
 require 'psych/tree_builder'
 require 'psych/parser'
@@ -15,30 +19,6 @@ module Psych
   VERSION         = '1.0.0'
   LIBYAML_VERSION = Psych.libyaml_version.join '.'
 
-  # Encodings supported by Psych (and libyaml)
-  ANY_ENCODING      = 1
-  UTF8_ENCODING     = 2
-  UTF16LE_ENCODING  = 3
-  UTF16BE_ENCODING  = 4
-
-  # Scalar Styles
-  ANY_SCALAR_STYLE            = 0
-  PLAIN_SCALAR_STYLE          = 1
-  SINGLE_QUOTED_SCALAR_STYLE  = 2
-  DOUBLE_QUOTED_SCALAR_STYLE  = 3
-  LITERAL_SCALAR_STYLE        = 4
-  FOLDED_SCALAR_STYLE         = 5
-
-  # Sequence Styles
-  ANY_SEQUENCE_STYLE    = 0
-  BLOCK_SEQUENCE_STYLE  = 1
-  FLOW_SEQUENCE_STYLE   = 2
-
-  # Mapping Styles
-  ANY_MAPPING_STYLE   = 0
-  BLOCK_MAPPING_STYLE = 1
-  FLOW_MAPPING_STYLE  = 2
-
   def self.parse thing
     Psych::Parser.new.parse thing
   end
diff --git a/lib/psych/handler.rb b/lib/psych/handler.rb
index 5324174..84ce4c2 100644
--- a/lib/psych/handler.rb
+++ b/lib/psych/handler.rb
@@ -26,12 +26,12 @@ module Psych
     ###
     # Called when a scalar +value+ is found.  The scalar may have an
     # +anchor+, a +tag+, be implicitly +plain+ or implicitly +quoted+
-    def scalar value, anchor = nil, tag = nil, plain = true, quoted = true, style = ANY_SCALAR_STYLE
+    def scalar value, anchor, tag, plain, quoted, style
     end
 
     ###
     # Called when a sequence is started.
-    def start_sequence anchor = nil, tag = nil, implicit = true, style = BLOCK_SEQUENCE_STYLE
+    def start_sequence anchor, tag, implicit, style
     end
 
     ###
@@ -41,7 +41,7 @@ module Psych
 
     ###
     # Called when a map starts
-    def start_mapping anchor = nil, tag = nil, implicit = true, style = BLOCK_MAPPING_STYLE
+    def start_mapping anchor, tag, implicit, style
     end
 
     ###
diff --git a/lib/psych/nodes/mapping.rb b/lib/psych/nodes/mapping.rb
index 0f47e89..2c56ec1 100644
--- a/lib/psych/nodes/mapping.rb
+++ b/lib/psych/nodes/mapping.rb
@@ -3,6 +3,11 @@ module Psych
     ###
     # This class represents a {YAML Mapping}[http://yaml.org/spec/1.1/#mapping].
     class Mapping < Psych::Nodes::Node
+      # Mapping Styles
+      ANY   = 0
+      BLOCK = 1
+      FLOW  = 2
+
       # The optional anchor for this mapping
       attr_accessor :anchor
 
@@ -15,7 +20,7 @@ module Psych
       # The style of this mapping
       attr_accessor :style
 
-      def initialize anchor, tag, implicit, style
+      def initialize anchor = nil, tag = nil, implicit = true, style = BLOCK
         super()
         @anchor   = anchor
         @tag      = tag
diff --git a/lib/psych/nodes/node.rb b/lib/psych/nodes/node.rb
index cb8f632..ce1bfe8 100644
--- a/lib/psych/nodes/node.rb
+++ b/lib/psych/nodes/node.rb
@@ -4,6 +4,8 @@ module Psych
     # The base class for any Node in a YAML parse tree.  This class should
     # never be instantiated.
     class Node
+      include Psych::Visitable
+
       attr_reader :children
 
       def initialize
diff --git a/lib/psych/nodes/scalar.rb b/lib/psych/nodes/scalar.rb
index bfa494f..b84e0ed 100644
--- a/lib/psych/nodes/scalar.rb
+++ b/lib/psych/nodes/scalar.rb
@@ -3,6 +3,14 @@ module Psych
     ###
     # This class represents a {YAML Scalar}[http://yaml.org/spec/1.1/#id858081].
     class Scalar < Psych::Nodes::Node
+      # Scalar Styles
+      ANY           = 0
+      PLAIN         = 1
+      SINGLE_QUOTED = 2
+      DOUBLE_QUOTED = 3
+      LITERAL       = 4
+      FOLDED        = 5
+
       # The scalar value
       attr_accessor :value
 
@@ -21,7 +29,7 @@ module Psych
       # The style of this scalar
       attr_accessor :style
 
-      def initialize value, anchor, tag, plain, quoted, style
+      def initialize value, anchor = nil, tag = nil, plain = true, quoted = true, style = ANY
         super()
         @value  = value
         @anchor = anchor
diff --git a/lib/psych/nodes/sequence.rb b/lib/psych/nodes/sequence.rb
index aea97dc..a0fdb54 100644
--- a/lib/psych/nodes/sequence.rb
+++ b/lib/psych/nodes/sequence.rb
@@ -30,6 +30,11 @@ module Psych
     #   ]
     #
     class Sequence < Psych::Nodes::Node
+      # Sequence Styles
+      ANY   = 0
+      BLOCK = 1
+      FLOW  = 2
+
       # The anchor for this sequence (if any)
       attr_accessor :anchor
 
@@ -42,7 +47,7 @@ module Psych
       # The sequece style used
       attr_accessor :style
 
-      def initialize anchor, tag, implicit, style
+      def initialize anchor = nil, tag = nil, implicit = true, style = BLOCK
         super()
         @anchor   = anchor
         @tag      = tag
diff --git a/lib/psych/nodes/stream.rb b/lib/psych/nodes/stream.rb
index 911bea8..59493a6 100644
--- a/lib/psych/nodes/stream.rb
+++ b/lib/psych/nodes/stream.rb
@@ -4,8 +4,17 @@ module Psych
     # Represents a YAML stream.  This is the root node for any YAML parse
     # tree.
     class Stream < Psych::Nodes::Node
+
+      # Encodings supported by Psych (and libyaml)
+      ANY     = 0
+      UTF8    = 1
+      UTF16LE = 2
+      UTF16BE = 3
+
+      # The encoding used for this stream
       attr_reader :encoding
-      def initialize encoding
+
+      def initialize encoding = UTF8
         super()
         @encoding = encoding
       end
diff --git a/lib/psych/visitable.rb b/lib/psych/visitable.rb
new file mode 100644
index 0000000..72b3073
--- /dev/null
+++ b/lib/psych/visitable.rb
@@ -0,0 +1,7 @@
+module Psych
+  module Visitable
+    def accept target
+      target.accept self
+    end
+  end
+end
diff --git a/lib/psych/visitors.rb b/lib/psych/visitors.rb
new file mode 100644
index 0000000..45b4b58
--- /dev/null
+++ b/lib/psych/visitors.rb
@@ -0,0 +1,2 @@
+require 'psych/visitors/visitor'
+require 'psych/visitors/to_ruby'
diff --git a/lib/psych/visitors/to_ruby.rb b/lib/psych/visitors/to_ruby.rb
new file mode 100644
index 0000000..bd04dda
--- /dev/null
+++ b/lib/psych/visitors/to_ruby.rb
@@ -0,0 +1,11 @@
+module Psych
+  module Visitors
+    ###
+    # This class walks a YAML AST, converting each node to ruby
+    class ToRuby < Psych::Visitors::Visitor
+      visitor_for(Nodes::Scalar) do |o|
+        o.value
+      end
+    end
+  end
+end
diff --git a/lib/psych/visitors/visitor.rb b/lib/psych/visitors/visitor.rb
new file mode 100644
index 0000000..8bc1965
--- /dev/null
+++ b/lib/psych/visitors/visitor.rb
@@ -0,0 +1,17 @@
+module Psych
+  module Visitors
+    class Visitor
+      def self.visitor_for *klasses, &block
+        klasses.each do |klass|
+          method_name = klass.name.split('::').join('_')
+          define_method(:"visit_#{method_name}", block)
+        end
+      end
+
+      def accept target
+        method_name = target.class.name.split('::').join('_')
+        send(:"visit_#{method_name}", target)
+      end
+    end
+  end
+end