Add prism parser support

Resolves #385

Related Prism bug: ruby/prism#3540 (merged)

`test/corpus/literal/before/34.rb` contains expressions rejected by Prism (and regexp-related bug, see #385 (comment)):
```bash
$ ASDF_RUBY_VERSION=3.4.2 ruby --parser prism test/corpus/literal/before/34.rb
test/corpus/literal/before/34.rb:1: syntax errors found (SyntaxError)
>  1 | retry
     | ^~~~~ Invalid retry without rescue
>  2 | in {"#{"a"}": 1} then
     | ^~ unexpected 'in', ignoring it
     |                  ^~~~ unexpected 'then', ignoring it
     |                  ^~~~ unexpected 'then', expecting end-of-input
   3 |   true
   4 | /\c*a/
   5 | /\c*a\c*/
   6 | /\c*\c*\c*/
>  7 | (break foo) || a
     |  ^~~~~~~~~ Invalid break
     |  ^~~~~~~~~ unexpected void value expression
>  8 | (return foo) || a
     |  ^~~~~~~~~~ unexpected void value expression
>  9 | a = b || break
     |          ^~~~~ Invalid break
> 10 | a = b || next
     |          ^~~~ Invalid next
> 11 | a || (break foo)
     |       ^~~~~~~~~ Invalid break
> 12 | b or break
     |      ^~~~~ Invalid break
> 13 | b or next
     |      ^~~~ Invalid next
> 14 | break or b
     | ^~~~~ Invalid break
     | ^~~~~ unexpected void value expression
> 15 | next or b
     | ^~~~ Invalid next
     | ^~~~ unexpected void value expression
> 16 | return or a
     | ^~~~~~ unexpected void value expression
```

The `prism` gem is temporary pointed to the main since `Prism::Translation::ParserCurrent` is not yet released. Let me know if we want to support prism 1.4.

Author: viralpraxis

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ruby-3.2, ruby-3.3]
+        ruby: [ruby-3.2, ruby-3.3, ruby-3.4]
         os: [ubuntu-latest]
     steps:
     - uses: actions/checkout@v4
@@ -35,7 +35,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ruby-3.2, ruby-3.3]
+        ruby: [ruby-3.2, ruby-3.3, ruby-3.4]
         os: [ubuntu-latest]
     steps:
     - uses: actions/checkout@v4
@@ -53,7 +53,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ruby-3.2, ruby-3.3]
+        ruby: [ruby-3.2, ruby-3.3, ruby-3.4]
         os: [ubuntu-latest]
     steps:
     - uses: actions/checkout@v4
@@ -69,7 +69,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ruby-3.2, ruby-3.3]
+        ruby: [ruby-3.2, ruby-3.3, ruby-3.4]
         os: [ubuntu-latest]
     steps:
     - uses: actions/checkout@v4
@@ -85,7 +85,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ruby-3.2, ruby-3.3]
+        ruby: [ruby-3.2, ruby-3.3, ruby-3.4]
         os: [ubuntu-latest]
     steps:
     - uses: actions/checkout@v4

Changelog.md

@@ -1,3 +1,9 @@
+# Unreleased
+
+[#387](https://github.com/mbj/unparser/pull/387)
+
+* Add `prism` parser support for Ruby 3.4. ([viralpraxis](https://github.com/viralpraxis))
+
 # v0.7.0 2025-03-16
 
 [#366](https://github.com/mbj/unparser/pull/366)

Gemfile.lock

@@ -1,9 +1,10 @@
 PATH
   remote: .
   specs:
-    unparser (0.7.0)
+    unparser (0.8.0)
       diff-lcs (~> 1.6)
       parser (>= 3.3.0)
+      prism (>= 1.4)
 
 GEM
   remote: https://rubygems.org/
@@ -26,6 +27,7 @@ GEM
     parser (3.3.7.2)
       ast (~> 2.4.1)
       racc
+    prism (1.4.0)
     racc (1.8.1)
     rainbow (3.1.1)
     regexp_parser (2.9.3)

lib/unparser.rb

@@ -3,7 +3,6 @@
 require 'diff/lcs'
 require 'diff/lcs/hunk'
 require 'optparse'
-require 'parser/current'
 require 'set'
 
 require 'unparser/equalizer'
@@ -20,13 +19,27 @@
 # Library namespace
 module Unparser
   # Unparser specific AST builder defaulting to modern AST format
-  class Builder < Parser::Builders::Default
-    modernize
+  if Gem::Version.new(RUBY_VERSION) <= '3.4'
+    require 'parser/current'
+    class Builder < Parser::Builders::Default
+      modernize
 
-    def initialize
-      super
+      def initialize
+        super
 
-      self.emit_file_line_as_literals = false
+        self.emit_file_line_as_literals = false
+      end
+    end
+  else
+    require 'prism'
+    class Builder < Prism::Translation::Parser::Builder
+      modernize
+
+      def initialize
+        super
+
+        self.emit_file_line_as_literals = false
+      end
     end
   end
 
@@ -203,7 +216,14 @@ def self.parse_ast(source, static_local_variables: Set.new)
   #
   # @api private
   def self.parser
-    Parser::CurrentRuby.new(Builder.new).tap do |parser|
+    parser_class =
+      if Gem::Version.new(RUBY_VERSION) <= '3.4'
+        Parser::CurrentRuby
+      else
+        Prism::Translation::ParserCurrent
+      end
+
+    parser_class.new(Builder.new).tap do |parser|
       parser.diagnostics.tap do |diagnostics|
         diagnostics.all_errors_are_fatal = true
       end

lib/unparser/cli.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'pathname'
+
 module Unparser
   # Unparser CLI implementation
   class CLI

spec/unit/unparser_spec.rb

@@ -459,6 +459,14 @@ def foo(bar)
     let(:version_excludes) do
       excludes = []
 
+      if RUBY_VERSION >= '3.4.'
+        excludes.concat(
+          %w[
+            test/corpus/literal/before/34.rb
+          ]
+        )
+      end
+
       if RUBY_VERSION < '3.2.'
         excludes.concat(
           %w[

test/corpus/literal/before/34.rb

@@ -0,0 +1,16 @@
+retry
+in {"#{"a"}": 1} then
+  true
+/\c*a/
+/\c*a\c*/
+/\c*\c*\c*/
+(break foo) || a
+(return foo) || a
+a = b || break
+a = b || next
+a || (break foo)
+b or break
+b or next
+break or b
+next or b
+return or a

test/corpus/literal/binary.rb

@@ -1,20 +1,10 @@
 (a || b).foo
-(break foo) || a
-(return foo) || a
 a && b && c
-a = b || break
-a = b || next
 a = b || return
 a and return foo
 a or return
 a or return foo
 a || (b || c)
-a || (break foo)
 a || (return foo)
-b or break
-b or next
-break or b
-next or b
-return or a
 a = b or c
 a = b and c

test/corpus/literal/control.rb

@@ -1,7 +1,6 @@
 next
 return
 break
-retry
 redo
 return 1
 return 1, 2

test/corpus/literal/pattern.rb

@@ -17,8 +17,6 @@
   true
 in {**nil} then
   true
-in {"#{"a"}": 1} then
-  true
 in 1 | 2 then
   true
 in 1 => a then