Generate equivalent source for ASTs from parser.
The following constraints apply:
- No support for macruby extensions
- Only support for the modern AST format
- Only support for Ruby >= 2.5
- mutant - Code review engine via mutation testing.
- ruby-next - Ruby Syntax Backports.
- May other reverse-dependencies.
(if you want your tool to be mentioned here please PR the addition with a TLDR of your use case).
While unparser is in the
0.x versions its public API can change any moment.
I recommend to use
~> 0.x.y style version constraints that should give the best mileage.
require 'parser/current' require 'unparser' ast = Unparser.parse('your(ruby(code))') Unparser.unparse(ast) # => 'your(ruby(code))'
To preserve the comments from the source:
require 'parser/current' require 'unparser' ast, comments = Unparser.parse_with_comments('your(ruby(code)) # with comments') Unparser.unparse(ast, comments) # => 'your(ruby(code)) # with comments'
Passing in manually constructed AST:
require 'parser/current' require 'unparser' module YourHelper def s(type, *children) Parser::AST::Node.new(type, children) end end include YourHelper node = s(:def, :foo, s(:args, s(:arg, :x) ), s(:send, s(:lvar, :x), :+, s(:int, 3) ) ) Unparser.unparse(node) # => "def foo(x)\n x + 3\nend"
Note: DO NOT attempt to pass in nodes generated via
AST::Sexp#s, these ones return
AST::Node instances, unparser needs
Equivalent vs identical:
require 'unparser' node = Unparser.parse(<<~'RUBY') %w[foo bar] RUBY generated = Unparser.unparse(node) # ["foo", "bar"], NOT %w[foo bar] ! code == generated # false, not identical code Unparser.parse(generated) == node # true, but identical AST
Summary: unparser does not reproduce your source! It produces equivalent source.
Unparsers primay reason for existance is mutant and its supported Ruby-Versions.
Basically: All non EOL MRI releases.
If you need to generate Ruby Syntax outside of this band feel free to contact me (email in gemspec).
Unparser currently successfully round trips almost all ruby code around. Using MRI-2.5.x. If there is a non round trippable example that is NOT subjected to known Limitations. please report a bug.
On CI unparser is currently tested against rubyspec with minor excludes.
Source parsed with magic encoding headers other than UTF-8 and that have literal strings. where parts can be represented in UTF-8 will fail to get reproduced.
A fix is possible as with latest updates the parser gem carries the information.
# -*- encoding: binary -*- "\x98\x76\xAB\xCD\x45\x32\xEF\x01\x01\x23\x45\x67\x89\xAB\xCD\xEF"
@@ -1,2 +1,2 @@ -(str "\x98v\xAB\xCDE2\xEF\x01\x01#Eg\x89\xAB\xCD\xEF") +(str "\x98v\xAB\xCDE2\xEF\u0001\u0001#Eg\x89\xAB\xCD\xEF")
Install the gem
unparser via your prefered method.
Various people contributed to this repository. See Contributors.
- Fork the project.
- Make your feature addition or bug fix.
- Add tests for it. This is important so I don't break it in a future version unintentionally.
- Commit, do not mess with Rakefile or version (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
- Send me a pull request. Bonus points for topic branches.
See LICENSE file.