Automatically compute the max label width to always properly align the output

.github/workflows/ci.yml

@@ -5,7 +5,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.3, 2.4, 2.5, 2.6, 2.7, '3.0', 3.1, 3.2, head, jruby, truffleruby]
+        ruby: [2.3, 2.4, 2.5, 2.6, 2.7, '3.0', 3.1, 3.2, 3.3, 3.4, head, jruby, truffleruby]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4

lib/benchmark/compare.rb

@@ -56,6 +56,8 @@ module Compare
     def compare(*entries, order: :fastest)
       return if entries.size < 2
 
+      max_width = entries.map { |e| e.label.to_s.size }.max
+
       case order
       when :baseline
         baseline = entries.shift
@@ -69,12 +71,12 @@ def compare(*entries, order: :fastest)
 
       $stdout.puts "\nComparison:"
 
-      $stdout.printf "%20s: %10.1f i/s\n", baseline.label.to_s, baseline.stats.central_tendency
+      $stdout.printf "%#{max_width}s: %10.1f i/s\n", baseline.label.to_s, baseline.stats.central_tendency
 
       sorted.each do |report|
         name = report.label.to_s
 
-        $stdout.printf "%20s: %10.1f i/s - ", name, report.stats.central_tendency
+        $stdout.printf "%#{max_width}s: %10.1f i/s - ", name, report.stats.central_tendency
 
         if report.stats.overlaps?(baseline.stats)
           $stdout.print "same-ish: difference falls within error"

lib/benchmark/ips/job.rb

@@ -51,6 +51,10 @@ class Job
       # @return [Integer]
       attr_accessor :confidence
 
+      # The maximum label width
+      # @return [Integer]
+      attr_reader :max_width
+
       # Silence output
       # @return [Boolean]
       def quiet
@@ -72,6 +76,7 @@ def initialize opts={}
         @compare_order = :fastest
         @held_path = nil
         @held_results = nil
+        @max_width = 20 # automatically computed as entries are added
 
         @timing = Hash.new 1 # default to 1 in case warmup isn't run
         @full_report = Report.new
@@ -85,7 +90,7 @@ def initialize opts={}
         @stats = :sd
         @confidence = 95
 
-        @out = MultiReport.new(StreamReport.new)
+        @out = MultiReport.new(StreamReport.new(self))
       end
 
       # Job configuration options, set +@warmup+ and +@time+.
@@ -106,7 +111,7 @@ def quiet=(val)
         if val # remove instances of StreamReport
           @out.quiet!
         else # ensure there is an instance of StreamReport
-          @out << StreamReport.new if @out.quiet?
+          @out << StreamReport.new(self) if @out.quiet?
         end
       end
 
@@ -180,6 +185,8 @@ def item(label="", str=nil, &blk) # :yield:
         action = str || blk
         raise ArgumentError, "no block or string" unless action
 
+        @max_width = label.size if label.size > @max_width
+
         @list.push Entry.new(label, action)
         self
       end

lib/benchmark/ips/job/stream_report.rb

@@ -2,9 +2,10 @@ module Benchmark
   module IPS
     class Job
       class StreamReport
-        def initialize(stream = $stdout)
+        def initialize(job, stream = $stdout)
           @last_item = nil
           @out = stream
+          @job = job
         end
 
         def start_warming
@@ -17,8 +18,9 @@ def start_running
         end
 
         def warming(label, _warmup)
-          @out.print rjust(label)
+          @out.print label.to_s.rjust(@job.max_width)
         end
+        alias_method :running, :warming
 
         def warmup_stats(_warmup_time_us, timing)
           case format
@@ -29,8 +31,6 @@ def warmup_stats(_warmup_time_us, timing)
           end
         end
 
-        alias_method :running, :warming
-
         def add_report(item, caller)
           @out.puts " #{item.body}"
           @last_item = item
@@ -48,18 +48,6 @@ def footer
         def format
           Benchmark::IPS.options[:format]
         end
-
-        # Add padding to label's right if label's length < 20,
-        # Otherwise add a new line and 20 whitespaces.
-        # @return [String] Right justified label.
-        def rjust(label)
-          label = label.to_s
-          if label.size > 20
-            "#{label}\n#{' ' * 20}"
-          else
-            label.rjust(20)
-          end
-        end
       end
     end
   end