From af6b8f78f2560cbea6baae4d0f5dd29611042b6c Mon Sep 17 00:00:00 2001
From: kwatch <kwatch@gmail.com>
Date: Sat, 19 Nov 2016 08:12:00 +0900
Subject: [PATCH 1/9] feat(psych): allow to generate custom Hash object

This is necessary to create custom object as mapping instead of Hash.
For example, if you prefer `hashobj.key` instead of `hashobj['key']`:

    ## allows `h.foo` instead of `h['foo']`
    class MagicHash < Hash
      def method_missing(method, *args)
        return super unless args.empty?
        return self[method.to_s]
      end
    end

    ## override to generate MagicHash instead of Hash
    class MagicVisitor < Psych::Visitors::ToRuby
      def empty_mapping(o)
        MagicHash.new
      end
    end

    ## example to access `ydoc.foo` instead of `ydoc['foo']`
    input = <<'END'
    tables:
      - name: admin_users
        columns:
          - name:  id
            type:  int
            pkey:  true
    END
    tree = Psych.parse(input)
    visitor = MagicVisitor.create
    ydoc = visitor.accept(tree)
    p ydoc.tables[0].columns[0].name   #=> "name"
    p ydoc.tables[0].columns[0].type   #=> "int"
---
 ext/psych/lib/psych/visitors/to_ruby.rb | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/ext/psych/lib/psych/visitors/to_ruby.rb b/ext/psych/lib/psych/visitors/to_ruby.rb
index fd1c8e6..fdd1c83 100644
--- a/ext/psych/lib/psych/visitors/to_ruby.rb
+++ b/ext/psych/lib/psych/visitors/to_ruby.rb
@@ -159,7 +159,7 @@ def visit_Psych_Nodes_Mapping o
         if Psych.load_tags[o.tag]
           return revive(resolve_class(Psych.load_tags[o.tag]), o)
         end
-        return revive_hash(register(o, {}), o) unless o.tag
+        return revive_hash(register(o, empty_mapping(o)), o) unless o.tag
 
         case o.tag
         when /^!ruby\/struct:?(.*)?$/
@@ -320,6 +320,11 @@ def visit_Psych_Nodes_Alias o
       end
 
       private
+
+      def empty_mapping o
+        return {}
+      end
+
       def register node, object
         @st[node.anchor] = object if node.anchor
         object
-- 
2.9.3 (Apple Git-75)