Upgrade dependency "parser" and fix code

Gemfile.lock

@@ -12,9 +12,9 @@ PATH
       ice_nine (~> 0.11.1)
       memoizable (~> 0.4.2)
       morpher (~> 0.2.6)
-      parser (~> 2.5.1)
+      parser (~> 2.7.2)
       procto (~> 0.0.2)
-      regexp_parser (~> 1.7, >= 1.7.1)
+      regexp_parser (~> 1.8.2)
       unparser (~> 0.4.2)
     mutant-rspec (0.8.24)
       mutant (~> 0.8.24)
@@ -97,8 +97,8 @@ GEM
       ice_nine (~> 0.11.0)
       procto (~> 0.0.2)
     parallel (1.12.1)
-    parser (2.5.3.0)
-      ast (~> 2.4.0)
+    parser (2.7.2.0)
+      ast (~> 2.4.1)
     path_expander (1.1.0)
     powerpack (0.1.3)
     procto (0.0.3)
@@ -147,13 +147,13 @@ GEM
     simplecov-html (0.10.2)
     thread_safe (0.3.6)
     unicode-display_width (1.4.1)
-    unparser (0.4.2)
+    unparser (0.4.7)
       abstract_type (~> 0.0.7)
       adamantium (~> 0.2.0)
       concord (~> 0.1.5)
       diff-lcs (~> 1.3)
       equalizer (~> 0.0.9)
-      parser (>= 2.3.1.2, < 2.6)
+      parser (>= 2.6.5)
       procto (~> 0.0.2)
     virtus (1.0.5)
       axiom-types (~> 0.1)

lib/mutant/mutator/node/arguments.rb

@@ -26,9 +26,7 @@ module Mutant
           emit_type
 
           Util::Array::Presence.call(children).each do |children|
-            if children.one? && n_mlhs?(Mutant::Util.one(children))
-              emit_procarg(Mutant::Util.one(children))
-            else
+            unless children.one? && n_mlhs?(children.first)
               emit_type(*children)
             end
           end

lib/mutant/mutator/node/procarg_zero.rb

@@ -4,13 +4,6 @@ module Mutant
   class Mutator
     class Node
       class ProcargZero < self
-        MAP = {
-          ::Parser::AST::Node => :emit_argument_node_mutations,
-          Symbol              => :emit_argument_symbol_mutations
-        }.freeze
-
-        private_constant(*constants(false))
-
         handle :procarg0
 
         children :argument
@@ -21,23 +14,9 @@ module Mutant
         #
         # @return [undefined]
         def dispatch
-          __send__(MAP.fetch(argument.class))
-        end
+          name = Mutant::Util.one(argument.children)
 
-        # Emit argument symbol mutations
-        #
-        # @return [undefined]
-        def emit_argument_symbol_mutations
-          emit_type(:"_#{argument}") unless argument.to_s.start_with?('_')
-        end
-
-        # Emit argument node mutations
-        #
-        # @return [undefined]
-        def emit_argument_node_mutations
-          emit_argument_mutations
-          first = Mutant::Util.one(argument.children)
-          emit_type(first)
+          emit_type(s(:arg, :"_#{name}")) unless name.to_s.start_with?('_')
         end
       end # ProcargZero
     end # Node

meta/block.rb

@@ -38,7 +38,6 @@ Mutant::Meta::Example.add :block do
   mutation 'foo { |(a, b), c| raise }'
   mutation 'foo { |(a), c| }'
   mutation 'foo { |(b), c| }'
-  mutation 'foo { |(a, b)| }'
   mutation 'foo { |c, | }'
   mutation 'foo { |(_a, b), c| }'
   mutation 'foo { |(a, _b), c| }'
@@ -85,7 +84,6 @@ Mutant::Meta::Example.add :block do
 
   singleton_mutations
   mutation 'foo { || }'
-  mutation 'foo { |a| }'
   mutation 'foo { |(a)| raise }'
   mutation 'foo { |(_a)| }'
   mutation 'foo'

mutant.gemspec

@@ -31,9 +31,9 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency('ice_nine',      '~> 0.11.1')
   gem.add_runtime_dependency('memoizable',    '~> 0.4.2')
   gem.add_runtime_dependency('morpher',       '~> 0.2.6')
-  gem.add_runtime_dependency('parser',        '~> 2.5.1')
+  gem.add_runtime_dependency('parser',        '~> 2.7.2')
   gem.add_runtime_dependency('procto',        '~> 0.0.2')
-  gem.add_runtime_dependency('regexp_parser', '~> 1.7', '>= 1.7.1')
+  gem.add_runtime_dependency('regexp_parser', '~> 1.8.2')
   gem.add_runtime_dependency('unparser',      '~> 0.4.2')
 
   gem.add_development_dependency('parallel', '~> 1.3')