Turn Ruby AST into semantically equivalent Ruby source
MIT License
Generate equivalent source for ASTs from parser.
The following constraints apply:
Notable Users:
(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
API incompatible AST::Node
instances, unparser needs Parser::AST::Node
instances.
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 Ruby >= 2.6. 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.
Example:
Original-Source:
# -*- encoding: binary -*-
"\x98\x76\xAB\xCD\x45\x32\xEF\x01\x01\x23\x45\x67\x89\xAB\xCD\xEF"
Original-AST:
(str "\x98v\xAB\xCDE2\xEF\x01\x01#Eg\x89\xAB\xCD\xEF")
Generated-Source:
"\x98v\xAB\xCDE2\xEF\x01\x01#Eg\x89\xAB\xCD\xEF"
Generated-AST:
(str "\x98v\xAB\xCDE2\xEF\u0001\u0001#Eg\x89\xAB\xCD\xEF")
Diff:
@@ -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.
For dependency reduction reasons unparser ships vendored (and reduced) versions of:
See LICENSE file.