Add RubyFeatures.ripper_supported?

Changelog.md

@@ -4,6 +4,8 @@ Enhancements:
 
 * Improve formatting of `Delegator` based objects (e.g. `SimpleDelgator`) in
   failure messages and diffs. (Andrew Horner, #215)
+* Add `ComparableVersion`. (Yuji Nakayama, #245)
+* Add `Ripper` support detection. (Yuji Nakayama, #245)
 
 Bug Fixes:
 

benchmarks/ripper.rb

@@ -0,0 +1,44 @@
+require 'benchmark/ips'
+require 'ripper'
+
+ruby_version = defined?(JRUBY_VERSION) ? JRUBY_VERSION : RUBY_VERSION
+puts "#{RUBY_ENGINE} #{ruby_version}"
+
+source = File.read(__FILE__)
+
+Benchmark.ips do |x|
+  x.report("Ripper") do
+    Ripper.sexp(source)
+    Ripper.lex(source)
+  end
+end
+
+__END__
+
+ruby 1.9.3
+Calculating -------------------------------------
+              Ripper   284.000  i/100ms
+
+ruby 2.2.3
+Calculating -------------------------------------
+              Ripper   320.000  i/100ms
+
+jruby 1.7.5
+Calculating -------------------------------------
+              Ripper    24.000  i/100ms
+
+jruby 1.7.13
+Calculating -------------------------------------
+              Ripper    25.000  i/100ms
+
+jruby 1.7.14
+Calculating -------------------------------------
+              Ripper   239.000  i/100ms
+
+jruby 1.7.22
+Calculating -------------------------------------
+              Ripper   231.000  i/100ms
+
+jruby 9.0.1.0
+Calculating -------------------------------------
+              Ripper   218.000  i/100ms

lib/rspec/support/comparable_version.rb

@@ -0,0 +1,46 @@
+module RSpec
+  module Support
+    # @private
+    class ComparableVersion
+      include Comparable
+
+      attr_reader :string
+
+      def initialize(string)
+        @string = string
+      end
+
+      def <=>(other)
+        other = self.class.new(other) unless other.is_a?(self.class)
+
+        return 0 if string == other.string
+
+        longer_segment_count = [self, other].map { |version| version.segments.count }.max
+
+        longer_segment_count.times do |index|
+          self_segment = segments[index] || 0
+          other_segment = other.segments[index] || 0
+
+          if self_segment.class == other_segment.class
+            result = self_segment <=> other_segment
+            return result unless result == 0
+          else
+            return self_segment.is_a?(String) ? -1 : 1
+          end
+        end
+
+        0
+      end
+
+      def segments
+        @segments ||= string.scan(/[a-z]+|\d+/i).map do |segment|
+          if segment =~ /\A\d+\z/
+            segment.to_i
+          else
+            segment
+          end
+        end
+      end
+    end
+  end
+end

lib/rspec/support/ruby_features.rb

@@ -1,4 +1,5 @@
 require 'rbconfig'
+RSpec::Support.require_rspec_support "comparable_version"
 
 module RSpec
   module Support
@@ -65,6 +66,24 @@ def supports_exception_cause?
         end
       end
 
+      ripper_requirements = [ComparableVersion.new(RUBY_VERSION) >= '1.9.2']
+
+      if Ruby.jruby?
+        ripper_requirements.push(ComparableVersion.new(JRUBY_VERSION) >= '1.7.5')
+        # Ripper on JRuby 9.0.0.0.rc1 or later reports wrong line number.
+        ripper_requirements.push(ComparableVersion.new(JRUBY_VERSION) < '9.0.0.0.rc1')
+      end
+
+      if ripper_requirements.all?
+        def ripper_supported?
+          true
+        end
+      else
+        def ripper_supported?
+          false
+        end
+      end
+
       if Ruby.mri?
         def kw_args_supported?
           RUBY_VERSION >= '2.0.0'

spec/rspec/support/comparable_version_spec.rb

@@ -0,0 +1,39 @@
+require 'rspec/support/comparable_version'
+
+module RSpec::Support
+  describe ComparableVersion do
+    describe '#<=>' do
+      [
+        ['1.2.3',        '1.2.3',        0],
+        ['1.2.4',        '1.2.3',        1],
+        ['1.3.0',        '1.2.3',        1],
+        ['1.2.3',        '1.2.4',       -1],
+        ['1.2.3',        '1.3.0',       -1],
+        ['1.2.10',       '1.2.3',        1],
+        ['1.2.3',        '1.2.10',      -1],
+        ['1.2.3.0',      '1.2.3',        0],
+        ['1.2.3',        '1.2.3.0',      0],
+        ['1.2.3.1',      '1.2.3',        1],
+        ['1.2.3.1',      '1.2.3.0',      1],
+        ['1.2.3',        '1.2.3.1',     -1],
+        ['1.2.3.0',      '1.2.3.1',     -1],
+        ['1.2.3.rc1',    '1.2.3',       -1],
+        ['1.2.3.rc1',    '1.2.3.rc2',   -1],
+        ['1.2.3.rc2',    '1.2.3.rc10',  -1],
+        ['1.2.3.alpha2', '1.2.3.beta1', -1],
+        ['1.2.3',        '1.2.3.rc1',    1],
+        ['1.2.3.rc2',    '1.2.3.rc1',    1],
+        ['1.2.3.rc10',   '1.2.3.rc2',    1],
+        ['1.2.3.beta1',  '1.2.3.alpha2', 1]
+      ].each do |subject_string, other_string, expected|
+        context "with #{subject_string.inspect} and #{other_string.inspect}" do
+          subject do
+            ComparableVersion.new(subject_string) <=> ComparableVersion.new(other_string)
+          end
+
+          it { should eq(expected) }
+        end
+      end
+    end
+  end
+end

spec/rspec/support/ruby_features_spec.rb

@@ -81,6 +81,65 @@ module Support
           expect(RubyFeatures.caller_locations_supported?).to eq(RUBY_VERSION >= '2.0.0')
         end
       end
+
+      describe "#ripper_supported?" do
+        it 'does not load Ripper' do
+          expect { RubyFeatures.ripper_supported? }.not_to change { defined?(::Ripper) }
+        end
+
+        describe 'Ripper' do
+          let(:line_number) do
+            token = tokens.first
+            location = token.first
+            location.first
+          end
+
+          let(:tokens) do
+            require 'ripper'
+            ::Ripper.lex('foo')
+          end
+
+          if Ruby.mri?
+            context 'on MRI' do
+              context '1.8.x', :if => RUBY_VERSION.start_with?('1.8.') do
+                it 'is not supported' do
+                  expect { tokens }.to raise_error(LoadError)
+                end
+              end
+
+              context '1.9.x or later', :if => RUBY_VERSION >= '1.9' do
+                it 'is supported' do
+                  expect(line_number).to eq(1)
+                end
+              end
+            end
+          end
+
+          if Ruby.jruby?
+            context 'on JRuby' do
+              context '1.7.x', :if => JRUBY_VERSION.start_with?('1.7.') do
+                context 'in 1.8 mode', :if => RUBY_VERSION.start_with?('1.8.') do
+                  it 'is not supported' do
+                    expect { tokens }.to raise_error(NameError)
+                  end
+                end
+
+                context 'in non 1.8 mode', :unless => RUBY_VERSION.start_with?('1.8.') do
+                  it 'is supported' do
+                    expect(line_number).to eq(1)
+                  end
+                end
+              end
+
+              context '9.x.x.x', :if => JRUBY_VERSION.start_with?('9.') do
+                it 'reports wrong line number' do
+                  expect(line_number).to eq(2)
+                end
+              end
+            end
+          end
+        end
+      end
     end
   end
 end