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Find and Replace
Code based on AST
Richard Huang
@flyerhzm
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What is AST?
Abstract Syntax Tree
class RubyKaigi
def year
2023
end
def location
'Matsumoto'
end
end
s(:class,
s(:const, nil, :RubyKaigi), nil,
s(:begin,
s(:def, :year,
s(:args),
s(:int, 2023)),
s(:def, :location,
s(:args),
s(:str, "Matsumoto"))))
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Why based on AST?
Precise
# match puts
puts "hello world"
puts"hello world"
puts("hello world")
puts(
"hello world"
)
puts\
"hello world"
# not match puts
'puts "hello world"'
<<~HEREDOC
puts "hello world"
HEREDOC
custom_puts "hello world"
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Why based on AST?
Precise
Powerful
Find hash pair where key and value are identical
and delete the value
Find old hash rocket syntax and replace with new
hash syntax
Find minitest setup methods that do not call
super and prepend the super
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What tools based on AST?
Reek
Rubocop
Rufo
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Synvert
Write snippet code to rewrite your source code
https://synvert.net/
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Original Idea
Simplify the process of upgrading a Rails project
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RubyKaigi 2014
Write ruby code to change ruby code
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New Idea
Give everyone the ability to
find and replace code based on AST
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Node Query
NQL - css like node query language
Node Rules - hash object
https://github.com/xinminlabs/node-query-ruby
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Find debug code
puts "hello world"
p current_user
# NQL
'.send[receiver=nil][message IN (puts p)]'
# Node Rules
{ node_type: 'send', receiver: nil, message: { in: %w[puts p] } }
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Find two string arguments
'slug from title'.gsub(' ', '_')
# NQL
'.send[message=gsub]
[arguments.size=2]
[arguments.first=.str]
[arguments.last=.str]'
# Node Rules
{ node_type: 'send',
message: 'gsub',
arguments: {
size: 2,
first: { node_type: 'str' },
last: { node_type: 'str' } } }
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Find hash rocket key
{ :foo => 'bar' }
# NQL
%q{.pair[key=.sym][key=~/\A:([^'"]+)\z/]}
# Node Rules
{ node_type: 'pair', key: /\A:([^'"]+)\z/ }
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Find hash pairs where the key and value
are identical
a: a,
c: c,
some_method(
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2
b: b + 2,
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4
d: d + 4
5
)
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# NQL
'.pair[key="{{value}}"]'
# Node Rules
{ node_type: 'pair', key: "{{value}}" }
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Find minitest setup methods that do not
call super
def setup
do_something
end
class TestMeme < Minitest::Test
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2
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end
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# NQL
'.class[parent_class=Minitest::Test]
.def[name=setup]:not_has(> .super)'
# Node Rules
{ node_type: 'class', parent_class: 'Minitest::Test' } # first step
{ node_type: 'def', name: 'setup' } # second step
children.none? { |node| node.type == 'super' } # third step
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Find hash value
render nothing: true, status: :created
render nothing: true
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# NQL
'.hash[status_value!=nil]'
# Node Rules
{ node_type: 'hash', status_value: { not: nil } }
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NQL
rex
racc
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Node Mutation
Provides a set of APIs to rewrite node source code
https://github.com/xinminlabs/node-mutation-ruby
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replace_with
errors[:base] = "author not present"
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errors.add(:base, "author not present")
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replace_with node,
'{{receiver}}.add({{arguments.0}}, {{arguments.1}})'
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replace_with
errors[:base] = "author not present"
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errors.add(:base, "author not present")
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errors[:base] = "author not present"
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replace_with node,
'{{receiver}}.add({{arguments.0}}, {{arguments.1}})'
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replace
class Post < ActiveRecord::Base
end
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class Post < ApplicationRecord
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end
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replace node, :parent_class, with: 'ApplicationRecord'
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replace
class Post < ActiveRecord::Base
end
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class Post < ApplicationRecord
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end
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class Post < ApplicationRecord
end
class Post < ActiveRecord::Base
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end
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replace node, :parent_class, with: 'ApplicationRecord'
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insert
open('http://test.com')
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URI.open('http://test.com')
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insert node, 'URI.', at: 'beginning'
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insert
open('http://test.com')
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URI.open('http://test.com')
3 URI.open('http://test.com')
open('http://test.com')
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3
insert node, 'URI.', at: 'beginning'
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prepend
def setup
do_something
end
class TestMeme < Minitest::Test
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end
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class TestMeme < Minitest::Test
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def setup
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super
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do_something
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end
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end
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prepend node, 'super'
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prepend
def setup
do_something
end
class TestMeme < Minitest::Test
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end
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class TestMeme < Minitest::Test
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def setup
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super
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do_something
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end
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end
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def setup
super
do_something
end
class TestMeme < Minitest::Test
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def setup
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do_something
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end
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end
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class TestMeme < Minitest::Test
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end
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prepend node, 'super'
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append
class TestMeme < Minitest::Test
def teardown
clean_something
end
end
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class TestMeme < Minitest::Test
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def teardown
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clean_something
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super
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end
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end
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append node, 'super'
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append
class TestMeme < Minitest::Test
def teardown
clean_something
end
end
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class TestMeme < Minitest::Test
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def teardown
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clean_something
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super
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end
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end
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class TestMeme < Minitest::Test
def teardown
clean_something
super
end
end
class TestMeme < Minitest::Test
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def teardown
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clean_something
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end
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end
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append node, 'super'
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delete
FactoryBot.create(:user)
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create(:user)
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delete node, :receiver, :dot
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delete
FactoryBot.create(:user)
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create(:user)
3 create(:user)
FactoryBot.create(:user)
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delete node, :receiver, :dot
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remove
puts(
"hello"\
"world"
)
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# nothing
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remove node
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remove
puts(
"hello"\
"world"
)
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# nothing
6 # nothing
puts(
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"hello"\
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"world"
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)
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remove node
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Hash node
after_commit :add_to_index_later, on: :create
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after_create_commit :add_to_index_later
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replace node, :message, with:
'after_{{arguments.-1.on_value.to_value}}_commit'
delete node, 'arguments.-1.on_pair', and_comma: true
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Hash node
after_commit :add_to_index_later, on: :create
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after_create_commit :add_to_index_later
3 after_create_commit :add_to_index_later
after_commit :add_to_index_later, on: :create
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replace node, :message, with:
'after_{{arguments.-1.on_value.to_value}}_commit'
delete node, 'arguments.-1.on_pair', and_comma: true
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node_query + node_mutation
require 'parser/current'
require 'parser_node_ext'
require 'node_query'
require 'node_mutation'
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source = "foo\nputs foo\n"
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node = Parser::CurrentRuby.parse(source)
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query = NodeQuery.new('.send[receiver=nil][message IN (p puts)]')
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mutation = NodeMutation.new(source)
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query.query_nodes(node).each do |matching_node|
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mutation.remove(matching_node)
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end
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result = mutation.process
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result.new_source # foo\n
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node_query + node_mutation
require 'parser/current'
require 'parser_node_ext'
require 'node_query'
require 'node_mutation'
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source = "foo\nputs foo\n"
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node = Parser::CurrentRuby.parse(source)
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query = NodeQuery.new('.send[receiver=nil][message IN (p puts)]')
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mutation = NodeMutation.new(source)
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query.query_nodes(node).each do |matching_node|
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mutation.remove(matching_node)
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end
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result = mutation.process
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result.new_source # foo\n
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source = "foo\nputs foo\n"
node = Parser::CurrentRuby.parse(source)
query = NodeQuery.new('.send[receiver=nil][message IN (p puts)]')
query.query_nodes(node).each do |matching_node|
end
require 'parser/current'
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require 'parser_node_ext'
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require 'node_query'
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require 'node_mutation'
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mutation = NodeMutation.new(source)
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mutation.remove(matching_node)
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result = mutation.process
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result.new_source # foo\n
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node_query + node_mutation
require 'parser/current'
require 'parser_node_ext'
require 'node_query'
require 'node_mutation'
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source = "foo\nputs foo\n"
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node = Parser::CurrentRuby.parse(source)
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query = NodeQuery.new('.send[receiver=nil][message IN (p puts)]')
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mutation = NodeMutation.new(source)
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query.query_nodes(node).each do |matching_node|
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mutation.remove(matching_node)
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end
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result = mutation.process
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result.new_source # foo\n
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source = "foo\nputs foo\n"
node = Parser::CurrentRuby.parse(source)
query = NodeQuery.new('.send[receiver=nil][message IN (p puts)]')
query.query_nodes(node).each do |matching_node|
end
require 'parser/current'
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require 'parser_node_ext'
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require 'node_query'
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require 'node_mutation'
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mutation = NodeMutation.new(source)
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mutation.remove(matching_node)
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result = mutation.process
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result.new_source # foo\n
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source = "foo\nputs foo\n"
mutation = NodeMutation.new(source)
mutation.remove(matching_node)
result = mutation.process
result.new_source # foo\n
require 'parser/current'
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require 'parser_node_ext'
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require 'node_query'
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require 'node_mutation'
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node = Parser::CurrentRuby.parse(source)
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query = NodeQuery.new('.send[receiver=nil][message IN (p puts)]')
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query.query_nodes(node).each do |matching_node|
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end
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Adapter
parser
syntax_tree (under development)
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Synvert
Synvert::Rewriter.new 'ruby', 'remove_debug_code' do
within_files Synvert::ALL_RUBY_FILES do
find_node '.send[receiver=nil][message IN (puts p)]' do
remove
end
end
end
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Check dependencies
if_ruby '3.0.0'
if_gem 'rails', '~> 6.0.0'
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Manipulate files
add_file 'app/models/application_record.rb', <<~EOS
class ApplicationRecord < ActiveRecord::Base
self.abstract_class = true
end
EOS
remove_file 'config/initializers/secret_token.rb'
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Add other snippets
add_snippet 'minitest', 'assert_empty'
add_snippet 'minitest/assert_instance_of'
add_snippet '/Users/flyerhzm/.synvert-ruby/lib/minitest/assert_match.
add_snippet 'https://github.com/xinminlabs/synvert-snippets-ruby/blob
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Support View Files (Erb, Haml, Slim)
# <%= h user.login %>
# =>
# <%= user.login %>
within_files Synvert::RAILS_VIEW_FILES do
with_node type: 'send', receiver: nil, message: 'h' do
replace_with '{{arguments}}'
end
end
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Synvert CLI
synvert-ruby --run rspec/use_new_syntax
synvert-ruby --run ~/.synvert-ruby/lib/rspec/use_new_syntax.rb
synvert-ruby --run https://raw.githubusercontent.com/xinminlabs/synve
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Synvert GUI
https://synvert.net/
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Run Snippet
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Automatically generate snippet
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List Snippets
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Use Synvert without writing any code
Demo
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Compare with Rubocop
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Synvert::Rewriter.new 'ruby', 'perfer_not_nil' do
within_files Synvert::ALL_RUBY_FILES do
find_node '.send[message=!=][arguments.size=1][arguments.0=nil]' do
replace_with '!{{receiver}}.nil?'
end
end
end
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Synvert VSCode Extension
https://synvert.net/
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Synvert Web (Playground)
https://playground.synvert.net/
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Synvert Javascript
new Synvert.Rewriter("typescript", "array-type", () => {
configure({ parser: Synvert.Parser.TYPESCRIPT });
// const z: Array = ['a', 'b'];
// =>
// const z: (string|number)[] = ['a', 'b'];
withinFiles(Synvert.ALL_TS_FILES, function () {
findNode(
`.TypeReference
[typeName.escapedText=Array]
[typeArguments.0=.UnionType]`,
() => {
replaceWith("({{typeArguments}})[]");
}
);
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Video Tutorials
https://synvert.substack.com/
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Contact Us
https://synvert.net/contact_us
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Thank You!
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