Replace ostruct with custom version

Avoid future deprecations, behavior changes, and performance warnings.

Closes #1545
See #1525

Author: lsegal

benchmarks/struct_vs_ostruct.rb

@@ -0,0 +1,23 @@
+require 'benchmark'
+require 'ostruct'
+require_relative '../lib/yard'
+
+n = 100000
+class MyStruct < Struct.new(:a, :b, :c); end
+ostruct = OpenStruct.new
+yostruct = YARD::OpenStruct.new
+mystruct = MyStruct.new
+
+Benchmark.bmbm do |x|
+  x.report("Struct.new(args)") { n.times { MyStruct.new 1, 2, 3 } }
+  x.report("Struct (assign)") { n.times { mystruct.a = 1 } }
+  x.report("Struct (read)") { n.times { mystruct.a } }
+  x.report("OpenStruct.new(args)") { n.times { OpenStruct.new a: 1, b: 2, c: 3 } }
+  x.report("OpenStruct.new (blank)") { n.times { OpenStruct.new } }
+  x.report("OpenStruct (assign)") { n.times { ostruct.a = 1 } }
+  x.report("OpenStruct (read)") { n.times { ostruct.a } }
+  x.report("YARD::OpenStruct.new(args)") { n.times { YARD::OpenStruct.new a: 1, b: 2, c: 3 } }
+  x.report("YARD::OpenStruct.new (blank)") { n.times { YARD::OpenStruct.new } }
+  x.report("YARD::OpenStruct (assign)") { n.times { yostruct.a = 1 } }
+  x.report("YARD::OpenStruct (read)") { n.times { yostruct.a } }
+end

lib/yard/autoload.rb

@@ -298,6 +298,7 @@ module Markup # Namespace for markup providers
   autoload :DocstringParser,  __p('docstring_parser')
   autoload :GemIndex,         __p('gem_index')
   autoload :Logger,           __p('logging')
+  autoload :OpenStruct,       __p('open_struct')
   autoload :Options,          __p('options')
   autoload :Registry,         __p('registry')
   autoload :RegistryResolver, __p('registry_resolver')

lib/yard/code_objects/macro_object.rb

@@ -1,5 +1,4 @@
 # frozen_string_literal: true
-require 'ostruct'
 
 module YARD
   module CodeObjects

lib/yard/docstring_parser.rb

@@ -1,5 +1,4 @@
 # frozen_string_literal: true
-require 'ostruct'
 
 module YARD
   # Parses text and creates a {Docstring} object to represent documentation

lib/yard/handlers/processor.rb

@@ -1,5 +1,4 @@
 # frozen_string_literal: true
-require 'ostruct'
 
 module YARD
   module Handlers

lib/yard/open_struct.rb

@@ -0,0 +1,66 @@
+module YARD
+  # An OpenStruct compatible struct class that allows for basic access of attributes
+  # via +struct.attr_name+ and +struct.attr_name = value+.
+  class OpenStruct
+    def initialize(hash = {})
+      @table = hash.each_pair { |k, v| [k.to_sym, v] }
+    end
+
+    # @private
+    def method_missing(name, *args)
+      if name.to_s.end_with?('=')
+        varname = name.to_s[0..-2].to_sym
+        __cache_lookup__(varname)
+        self[varname] = args.first
+      else
+        __cache_lookup__(name)
+        self[name]
+      end
+    end
+
+    def to_h
+      @table.dup
+    end
+
+    def ==(other)
+      other.is_a?(self.class) && to_h == other.to_h
+    end
+
+    def hash
+      @table.hash
+    end
+
+    def dig(*keys)
+      @table.dig(*keys)
+    end
+
+    def []=(key, value)
+      @table[key.to_sym] = value
+    end
+
+    def [](key)
+      @table[key.to_sym]
+    end
+
+    def each_pair(&block)
+      @table.each_pair(&block)
+    end
+
+    def marshal_dump
+      @table
+    end
+
+    def marshal_load(data)
+      @table = data
+    end
+
+    private
+
+    def __cache_lookup__(name)
+      instance_eval <<-RUBY, __FILE__, __LINE__ + 1
+        def #{name}; @table[:#{name}]; end
+        def #{name}=(v); @table[:#{name}] = v; end
+      RUBY
+    end
+  end
+end

lib/yard/parser/source_parser.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 require 'stringio'
-require 'ostruct'
 
 module YARD
   module Parser

lib/yard/tags/directives.rb

@@ -1,5 +1,4 @@
 # frozen_string_literal: true
-require 'ostruct'
 
 module YARD
   module Tags

lib/yard/templates/engine.rb

@@ -1,5 +1,4 @@
 # frozen_string_literal: true
-require 'ostruct'
 
 module YARD
   module Templates

lib/yard/templates/template_options.rb

@@ -1,5 +1,4 @@
 # frozen_string_literal: true
-require 'ostruct'
 
 module YARD
   module Templates