Eliminate ~540MB of allocations from benchmark

- Don't use def_delegators on methods called frequently, it allocates *args
- Build native extension String.strncmp to compare two substrings, which
  results in faster StringPtr#== and StringPtr#start_with?

.gitignore

@@ -1,3 +1,7 @@
 build/generated
 .bundle
 .ruby-version
+lib/strncmp
+ext/strncmp/Makefile
+ext/strncmp/strncmp.h
+ext/strncmp/strncmp.o

.travis.yml

@@ -9,6 +9,8 @@ before_install:
       bundle update --bundler;
     fi
 
+before_script: bundle exec rake compile
+
 rvm:
 # 2.0.0
 - 2.1.0

Gemfile

@@ -4,6 +4,7 @@ gem "cantor", "~> 1.2.1"
 
 group :development do
   gem "rake"
+  gem "rake-compiler"
   gem "term-ansicolor"
 
   gem "rspec", "3.8.0"
@@ -16,12 +17,13 @@ group :development do
   gem "simplecov",              :platforms => [:ruby_24, :ruby_25]
   gem "simplecov-inline-html",  :platforms => [:ruby_24, :ruby_25]
 
-  # gem "stackprof"
+  gem "stackprof"
   # gem "fasterer"
-  # gem "benchmark-ips"
-  # gem "memory_profiler"
+  gem "benchmark-ips"
+  gem "memory_profiler",        :platform => [:ruby_23, :ruby_24, :ruby_25]
   # gem "allocation_stats"
   # gem "heapy"
+  # gem "derailed_benchmarks"
 
   # We're using a patched version installed in yard/ until the
   # maintainer improves the plugin. The patch has been submitted

Gemfile.lock

@@ -1,11 +1,15 @@
 GEM
   remote: http://rubygems.org/
   specs:
+    benchmark-ips (2.7.2)
     cantor (1.2.1)
     diff-lcs (1.3)
     docile (1.3.1)
     json (2.1.0)
+    memory_profiler (0.9.13)
     rake (12.3.2)
+    rake-compiler (1.0.7)
+      rake
     rspec (3.8.0)
       rspec-core (~> 3.8.0)
       rspec-expectations (~> 3.8.0)
@@ -27,6 +31,7 @@ GEM
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
     simplecov-inline-html (0.0.1)
+    stackprof (0.2.12)
     term-ansicolor (1.7.1)
       tins (~> 1.0)
     tins (1.20.2)
@@ -37,14 +42,18 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  benchmark-ips
   cantor (~> 1.2.1)
+  memory_profiler
   rake
+  rake-compiler
   rspec (= 3.8.0)
   rspec-collection_matchers
   simplecov
   simplecov-inline-html
+  stackprof
   term-ansicolor
   yard (~> 0.9.12)
 
 BUNDLED WITH
-   1.17.2
+   1.17.3

Rakefile

@@ -1,6 +1,5 @@
-require "pathname"
-abspath = Pathname.new(File.dirname(__FILE__)).expand_path
-relpath = abspath.relative_path_from(Pathname.pwd)
+require "bundler"
+Bundler::GemHelper.install_tasks
 
 task :default => :spec
 
@@ -18,12 +17,25 @@ end
 
 # Note options are loaded from .yardopts
 require "yard"
+require "pathname"
+abspath = Pathname.new(File.dirname(__FILE__)).expand_path
+relpath = abspath.relative_path_from(Pathname.pwd)
 YARD::Rake::YardocTask.new(:yard => :clobber_yard)
 task :clobber_yard do
+
   rm_rf "#{relpath}/build/generated/doc"
   mkdir_p "#{relpath}/build/generated/doc/images"
 end
 
 task :console do
   exec(*%w(irb -I lib -r stupidedi))
 end
+
+if RUBY_PLATFORM !~ /java/
+  require "rake/extensiontask"
+  gemspec = Gem::Specification.load("stupidedi.gemspec")
+
+  Rake::ExtensionTask.new("strncmp") do |x|
+    x.lib_dir = "lib/strncmp"
+  end
+end

ext/strncmp/extconf.rb

@@ -0,0 +1,6 @@
+require "mkmf"
+extension_name = "strncmp/strncmp"
+
+create_header
+dir_config      extension_name
+create_makefile extension_name

ext/strncmp/strncmp.c

@@ -0,0 +1,34 @@
+#include "ruby.h"
+#include "extconf.h"
+
+VALUE rb_strncmp(VALUE self, VALUE str1, VALUE offset1, VALUE str2, VALUE offset2, VALUE length) {
+  // rb_raise(rb_eArgError, "message %s", "argument");
+
+  if (!FIXNUM_P(length))  rb_raise(rb_eTypeError, "length must be an Integer");
+  if (!FIXNUM_P(offset1)) rb_raise(rb_eTypeError, "offset1 must be an Integer");
+  if (!FIXNUM_P(offset2)) rb_raise(rb_eTypeError, "offset1 must be an Integer");
+
+  long len  = NUM2LONG(length);
+  long beg1 = NUM2LONG(offset1);
+  long beg2 = NUM2LONG(offset2);
+
+  if (len < 0)  rb_raise(rb_eArgError, "length cannot be negative");
+  if (beg1 < 0) rb_raise(rb_eArgError, "offset1 cannot be negative");
+  if (beg2 < 0) rb_raise(rb_eArgError, "offset2 cannot be negative");
+
+  if (beg1 + len > rb_str_strlen(str1)) return Qnil;
+  if (beg2 + len > rb_str_strlen(str2)) return Qnil;
+
+  char *ptr1 = rb_str_subpos(str1, beg1, &len);
+  char *ptr2 = rb_str_subpos(str2, beg2, &len);
+
+  if (ptr1 == 0 || ptr2 == 0) return Qnil;
+
+  return (memcmp(ptr1, ptr2, len) == 0) ? Qtrue : Qfalse;
+}
+
+void Init_strncmp()
+{
+  // VALUE rb_cString = rb_define_class("String", rb_cObject);
+  rb_define_singleton_method(rb_cString, "strncmp", rb_strncmp, 5);
+}

lib/ruby/string.rb

@@ -84,6 +84,17 @@ def position
       def join
         gsub(/\n[ \t]+/, " ")
       end
+
+      unless "".respond_to?(:match?)
+        def match?(pattern, pos=nil)
+          if pos.nil?
+            !!(self =~ pattern)
+          else
+            !!match(pattern, pos)
+          end
+        end
+      end
+
     end
   end
 end

lib/strncmp.rb

@@ -0,0 +1 @@
+require "strncmp/strncmp"

lib/stupidedi.rb

@@ -12,6 +12,10 @@
 
 $:.unshift(File.expand_path("..", __FILE__))
 
+if RUBY_PLATFORM !~ /java/
+  require "strncmp"
+end
+
 require "ruby/regexp"
 require "ruby/array"
 require "ruby/blank"

lib/stupidedi/parser/builder_dsl.rb

@@ -26,10 +26,10 @@ class BuilderDsl
         :empty?, :first?, :last?, :deterministic?
 
       def initialize(machine, strict = true)
-        @position     = Reader::NoPosition
+        @position     = Reader::StacktracePosition
         @machine      = machine
         @strict       = strict
-        @separators   = Reader::Separators.empty
+        @separators   = Reader::Separators.blank
         @segment_dict = Reader::SegmentDict.empty
       end
 

lib/stupidedi/parser/generation.rb

@@ -29,7 +29,7 @@ module Generation
       # @yield  [Reader::IgnoredTok]
       # @return [(StateMachine, Reader::Tokenizer::Result)]
       def read(tokenizer, options = {})
-        limit   = options.fetch(:nondeterminism, 1)
+        #imit   = options.fetch(:nondeterminism, 1)
         machine = self.dup
 
         return machine, tokenizer.each do |token|

lib/stupidedi/parser/states/initial_state.rb

@@ -39,7 +39,7 @@ class << InitialState
       # @return [InitialState]
       def build(zipper)
         new(
-          Reader::Separators.empty,
+          Reader::Separators.blank,
           Reader::SegmentDict.empty,
 
           InstructionTable.build(

lib/stupidedi/reader/input.rb

@@ -12,14 +12,36 @@ class Input
       # @return [Position]
       attr_reader :position
 
-      def_delegators :@pointer, :defined_at?, :empty?, :count, :head, :take,
-        :match?, :slice, :index, :rindex, :reify, :last, :length, :=~, :[]
+      def_delegators :@pointer, :count, :take, :match?, :slice,
+        :index, :rindex, :reify, :last, :length, :=~, :[]
 
       def initialize(pointer, position)
         @pointer, @position =
           pointer, position
       end
 
+      # NOTE: This could be implemented using def_delegators, but unfortunately
+      # that allocates an Array to pass the arguments along. Since this method
+      # is called frequently, we can reduce allocations by defining it this way.
+      def head
+        @pointer.head
+      end
+
+      # NOTE: This could be implemented using def_delegators, but unfortunately
+      # that allocates an Array to pass the arguments along. Since this method
+      # is called frequently, we can reduce allocations by defining it this way.
+      def defined_at?(n)
+        @pointer.defined_at?(n)
+      end
+
+      # NOTE: This could be implemented using def_delegators, but unfortunately
+      # that allocates an Array to pass the arguments along. Since this method
+      # is called frequently, we can reduce allocations by defining it this way.
+      # NOTE: 
+      def empty?
+        @pointer.empty?
+      end
+
       # @NOTE: This allocates 3 objects: Input, Position, and StringPtr
       def tail
         drop(1)
@@ -28,7 +50,11 @@ def tail
       # @NOTE: This allocates 3 objects: Input, Position, and StringPtr, so
       # if you've written x.drop(10).position.. x.position_at(10) is cheaper
       def drop(n)
-        self.class.new(@pointer.drop(n), position_at(n))
+        if n.zero?
+          self
+        else
+          self.class.new(@pointer.drop(n), position_at(n))
+        end
       end
 
       # NOTE: This allocates 2 objects: StringPtr and Position
@@ -41,6 +67,19 @@ def position_at(n)
           @position.advance(@pointer.take(n))
         end
       end
+
+      def start_with?(other)
+        other and @pointer.start_with?(other)
+      end
+
+      def skip_control_characters(offset = 0)
+        while @pointer.defined_at?(offset) \
+          and Reader.is_control_character?(@pointer[offset])
+          offset += 1
+        end
+
+        drop(offset)
+      end
     end
 
     class << Input