Make sure prettier print works with ractors

Author: kddnewton

lib/prettier_print.rb

@@ -122,10 +122,10 @@ def pretty_print(q)
 
   # Below here are the most common combination of options that are created when
   # creating new breakables. They are here to cut down on some allocations.
-  BREAKABLE_SPACE = Breakable.new(" ", 1, indent: true, force: false)
-  BREAKABLE_EMPTY = Breakable.new("", 0, indent: true, force: false)
-  BREAKABLE_FORCE = Breakable.new(" ", 1, indent: true, force: true)
-  BREAKABLE_RETURN = Breakable.new(" ", 1, indent: false, force: true)
+  BREAKABLE_SPACE = Breakable.new(" ", 1, indent: true, force: false).freeze
+  BREAKABLE_EMPTY = Breakable.new("", 0, indent: true, force: false).freeze
+  BREAKABLE_FORCE = Breakable.new(" ", 1, indent: true, force: true).freeze
+  BREAKABLE_RETURN = Breakable.new(" ", 1, indent: false, force: true).freeze
 
   # A node in the print tree that forces the surrounding group to print out in
   # the "break" mode as opposed to the "flat" mode. Useful for when you need to
@@ -138,7 +138,7 @@ def pretty_print(q)
 
   # Since there's really no difference in these instances, just using the same
   # one saves on some allocations.
-  BREAK_PARENT = BreakParent.new
+  BREAK_PARENT = BreakParent.new.freeze
 
   # A node in the print tree that represents a group of items which the printer
   # should try to fit onto one line. This is the basic command to tell the
@@ -267,7 +267,7 @@ def pretty_print(q)
 
   # Since all of the instances here are the same, we can reuse the same one to
   # cut down on allocations.
-  TRIM = Trim.new
+  TRIM = Trim.new.freeze
 
   # When building up the contents in the output buffer, it's convenient to be
   # able to trim trailing whitespace before newlines. If the output object is a
@@ -348,6 +348,7 @@ def self.for(output)
   # behavior (for instance to use tabs) by passing a different genspace
   # procedure.
   DEFAULT_GENSPACE = ->(n) { " " * n }
+  Ractor.make_shareable(DEFAULT_GENSPACE) if defined?(Ractor)
 
   # There are two modes in printing, break and flat. When we're in break mode,
   # any lines will use their newline, any if-breaks will use their break

test/prettier_print_test.rb

@@ -216,46 +216,48 @@ class PrettierPrintTest < Test::Unit::TestCase
 
     test "large integration" do
       result =
-        PrettierPrint.format([]) do |q|
-          q.group do
-            q.text("# This is the main class for the PrettierPrint gem.")
-            q.breakable_force
-
-            q.text("class ")
-            q.group { q.text("PrettierPrint") }
-
-            q.indent do
+        Ractor.new do
+          PrettierPrint.format([]) do |q|
+            q.group do
+              q.text("# This is the main class for the PrettierPrint gem.")
               q.breakable_force
 
-              q.trim
-              q.text("=begin")
-              q.breakable_return
-              q.text("This is embedded documentation.")
-              q.breakable_return
-              q.text("=end")
-              q.breakable_force
+              q.text("class ")
+              q.group { q.text("PrettierPrint") }
 
-              q.group do
-                q.text("def ")
-                q.text("format(")
+              q.indent do
+                q.breakable_force
+
+                q.trim
+                q.text("=begin")
+                q.breakable_return
+                q.text("This is embedded documentation.")
+                q.breakable_return
+                q.text("=end")
+                q.breakable_force
 
                 q.group do
-                  q.seplist(%w[foo bar baz]) do |item|
-                    q.text(item)
+                  q.text("def ")
+                  q.text("format(")
+
+                  q.group do
+                    q.seplist(%w[foo bar baz]) do |item|
+                      q.text(item)
+                    end
                   end
-                end
 
-                q.text(")")
-                q.breakable_force
-                q.text("end")
+                  q.text(")")
+                  q.breakable_force
+                  q.text("end")
+                end
               end
+
+              q.breakable_force
+              q.text("end")
             end
 
             q.breakable_force
-            q.text("end")
           end
-
-          q.breakable_force
         end
 
       expected = <<~RUBY
@@ -269,7 +271,7 @@ def format(foo, bar, baz)
         end
       RUBY
 
-      assert_equal expected, result.join
+      assert_equal expected, result.take.join
     end
   end
 end