Add Proc, Lambda, Method, proc, lambda, and -> rendering support

lib/phlex/pdf.rb

@@ -46,7 +46,14 @@ def after_template
 
     def yield_content(&block)
       return unless block_given?
-      yield self
+
+      if block.arity.zero?
+        # This handles lambdas and ->
+        yield
+      else
+        # This handles Proc and proc
+        yield self
+      end
     end
 
     def render(renderable, &block)
@@ -57,6 +64,8 @@ def render(renderable, &block)
         @document.text renderable
       when Class
         render(renderable.new, &block) if renderable < Phlex::PDF
+      when Proc, Method
+        yield_content(&renderable)
       when Enumerable
         renderable.each { |r| render(r, &block) }
       else

spec/phlex/pdf_spec.rb

@@ -56,11 +56,22 @@ def view_template
       WarningComponent.new("Danger!"),
       WarningComponent.new("Don't Panic!")
     ]
+
+    render Proc.new { text "Rendered from Proc.new", color: "00FF00" }
+    render proc { text "Rendered from proc", color: "00FFFF" }
+    render lambda { text "Rendered from lambda", color: "FFFF00" }
+    render -> { text "Rendered from ->", color: "99FF00" }
+    render method(:calm)
+
     render BodyComponent do |body|
       body.greet "Brad"
     end
     render FooterComponent.new
   end
+
+  def calm
+    text "Rendered from Method", color: "F0F0F0"
+  end
 end
 
 RSpec.describe Phlex::PDF do