Add a simple benchmark script to bin/prism

Author: kddnewton

bin/prism

@@ -8,6 +8,7 @@ module Prism
   class CLI
     def run(argv)
       case argv.shift
+      when "bench"      then bench(argv)
       when "benchmark"  then benchmark(argv)
       when "bundle"     then bundle(argv)
       when "console"    then console
@@ -25,6 +26,7 @@ module Prism
       else
         puts <<~TXT
           Usage:
+            bin/prism bench [file ...]
             bin/prism benchmark [source_file]
             bin/prism bundle [...]
             bin/prism console
@@ -49,6 +51,37 @@ module Prism
     # Commands
     ############################################################################
 
+    # bin/prism bench [file ...]
+    # Measures raw parse throughput using Prism.profile (no Ruby AST creation).
+    def bench(argv)
+      require "benchmark/ips"
+
+      files =
+        if argv.any?
+          argv.map { |path| [path, File.read(path)] }
+        else
+          Dir[File.join(__dir__, "../test/prism/fixtures/**/*.txt")].sort.map { |path| [path, File.read(path)] } +
+            Dir[File.join(__dir__, "../lib/**/*.rb")].sort.map { |path| [path, File.read(path)] }
+        end
+
+      total_bytes = files.sum { |_, source| source.bytesize }
+      puts "Benchmarking #{files.size} files (#{total_bytes} bytes total)"
+      puts
+
+      Benchmark.ips do |x|
+        x.time = 10
+        x.warmup = 3
+
+        x.report("parse (all files)") do
+          files.each { |_, source| Prism.profile(source) }
+        end
+
+        x.report("parse (fixtures only)") do
+          files.each { |path, source| Prism.profile(source) if path.end_with?(".txt") }
+        end
+      end
+    end
+
     # bin/prism benchmark [source_file]
     def benchmark(argv)
       require "benchmark/ips"