adding yaml streaming api

1 files changed, 53 insertions, 0 deletions

diff --git a/lib/psych/stream.rb b/lib/psych/stream.rb
new file mode 100644
index 0000000..ac231aa
--- /dev/null
+++ b/lib/psych/stream.rb
@@ -0,0 +1,53 @@
+module Psych
+  ###
+  # Psych::Stream is a streaming YAML emitter.  It will not buffer your YAML,
+  # but send it straight to an IO.
+  #
+  # Here is an example use:
+  #
+  #   stream = Psych::Stream.new($stdout)
+  #   stream.start
+  #   stream.push({:foo => 'bar'})
+  #   stream.finish
+  #
+  # YAML will be immediately emitted to $stdout with no buffering.
+  #
+  # Psych::Stream#start will take a block and ensure that Psych::Stream#finish
+  # is called, so you can do this form:
+  #
+  #   stream = Psych::Stream.new($stdout)
+  #   stream.start do |em|
+  #     em.push(:foo => 'bar')
+  #   end
+  #
+  class Stream < Psych::Visitors::YAMLTree
+    class Emitter < Psych::Emitter # :nodoc:
+      def end_document implicit_end = !streaming?
+        super
+      end
+
+      def streaming?
+        true
+      end
+    end
+
+    ###
+    # Create a new streaming emitter.  Emitter will print to +io+.  See
+    # Psych::Stream for an example.
+    def initialize io
+      super({}, Emitter.new(io))
+    end
+
+    ###
+    # Start streaming using +encoding+
+    def start encoding = Nodes::Stream::UTF8
+      super.tap { yield self if block_given?  }
+    ensure
+      finish if block_given?
+    end
+
+    private
+    def register target, obj
+    end
+  end
+end