RuboCop: Modularity and AST Insights

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Plugin System, Ruby LSP Add-on, and Prism

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Support OSS community

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HVSBCMF # .rubocop.yml Style/StringLiterals: EnforcedStyle: single_quotes SupportedStyles: - single_quotes - double_quotes

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50%0Ϋϥεਤʁ MJCSVCPDPQFYBNQMFSC require 'rubocop' require_relative 'rubocop/example' require_relative 'rubocop/example/version' require_relative 'rubocop/example/inject'
RuboCop::Example::Inject.defaults! require_relative 'rubocop/cop/example_cops' #.rubocop.yml require: - rubocop-example Extension gem require 'rubocop-example' *UJTF ff FDUJWFMZFRVJWBMFOUUP require 'rubocop-example' User's configuration *OKFDUIBDL

*OKFDUIBDLT1SPCMFNT w 50%0Ϋϥεਤʁ class RuboCop::Example::Inject def self.default! path = CONFIG_DEFAULT.to_s
h = ConfigLoader.load_yaml_configuration(path) conf = Config.new(h, path).tap(&:make_excludes_absolute) puts "configuration from..." if ConfigLoader.debug? new_conf = ConfigLoader.merge_with_default(conf, path) ConfigLoader.instance_variable_set( :@default_configuration, new_conf ) end -BUFSBEEFECVH fi Y #SPLFOFODBQTVMBUJPO 3FEVOEBOUEFCVHMPHHJOH

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MJOU@SPMMFS A plugin specification for linters "Depend on Abstractions" Agile
Software Development: Principles, Patterns, and Practices Robert C. Martin

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*OIFSJU-JOU3PMMFS1MVHJO require 'lint_roller' module RuboCop module Example class Plugin
< LintRoller::Plugin def about def supported?(context) def rules(_context) end end end *OIFSJUGSPN-JOU3PMMFS1MVHJO Define a plugin class RuboCop::Example::Plugin

$SFBUF-JOU3PMMFS"CPVU class Plugin < LintRoller::Plugin def about LintRoller::About.new( name:
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$SFBUF-JOU3PMMFS3VMFT class Plugin < LintRoller::Plugin def about def supported?(context)
def rules(_context) LintRoller::Rules.new( type: :path, config_format: :rubocop, value: "#{__dir__}/../../../config/default.yml" ) end end NOTE: There are no dependencies on RuboCop's API like those seen in the "Inject" hack %F fi OFSVMFTNFUIPEUIBUSFUVSOTB -JOU3PMMFS3VMFTXJUIUIFJOGP3VCP$PQ OFFETUPMPDBUFUIFQMVHJODPO fi H 3BJTFTBOFYDFQUJPOJGOPUEF fi OFE

HFNTQFD ,FZUP"CTUSBDUJPO Gem::Specification.new do |spec| # snip spec.metadata = {
'default_lint_roller_plugin' => 'RuboCop::Example::Plugin' } spec.add_dependency('lint_roller', '~> 1.1') end 💡Setting default_lint_roller_plugin key allows RuboCop engine and user's .rubocop.yml to avoid needing to know the plugin's custom name. 4FUUIFQMVHJOOBNFJOUIFHFNTQFD TP3VCP$PQDBOEJTDPWFSJU

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3VCP$PQ1MVHJO module RuboCop module Plugin class << self def integrate_plugins(rubocop_config,
plugins) plugins = Plugin::Loader.load(plugins) ConfigurationIntegrator. integrate_plugins_into_rubocop_config( rubocop_config, plugins ) plugins end end end *OUFSOBM"1*XIFSF3VCP$PQMPBETQMVHJOT BOENFSHFTDPO fi HT

module RuboCop::Plugin class Loader def self.load(plugins) plugin_configs = normalize(plugins) plugin_configs.filter_map
do |name, config| next unless plugin_config['enabled'] plugin_class = constantize_plugin_from(name, config) plugin_class.new(plugin_config) end end name = Gem.loaded_specs[plugin_name].metadata[ 'default_lint_roller_plugin' ] Kernel.const_get(name) Implementation Details 3VCP$PQ1MVHJO-PBEFS (FUTUIFQMVHJODPOTUGSPN QMVHJOTHFNTQFDNFUBEBUB

3VCP$PQ1MVHJO$PO fi HVSBUJPO*OUFHSBUPS module RuboCop::Plugin class ConfigurationIntegrator def self.integrate_plugins_into_rubocop_config( rubocop_config,
plugins ) default_config = ConfigLoader.default_configuration runner_context = create_context(rubocop_config) validate_plugins!(plugins, runner_context) # snip (Merging of configurations) end end &OHJOFDPMMBCPSBUFTXJUI QMVHJOGPSQSPDFTTJOH

$SFBUF-JOU3PMMFS$POUFYU module RuboCop::Plugin class ConfigurationIntegrator def self.create_context(rubocop_config) LintRoller::Context.new( runner: :rubocop,
runner_version: Version.version, engine: :rubocop, engine_version: Version.version, target_ruby_version: rubocop_config.target_ruby_version ) end end 3FUVSOTB-JOU3PMMFS$POUFYUXJUISVOUJNFJOGP MJLFUIFMJOUFSFOHJOFBOEBOBMZTJT3VCZWFSTJPO QBTTFEUPQMVHJOT

7BMJEBUJPO module RuboCop::Plugin class ConfigurationIntegrator def self.validate_plugins!(plugins, runner_context) unsupported_plugins =
plugins.reject { |plugin| plugin.supported?(runner_context) } return if unsupported_plugins.none? raise NotSupportedError, unsupported_plugins end end class Plugin < LintRoller::Plugin def supported?(context) context.engine == :rubocop end Plugin's Implementation

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3VCZ-413VCP$PQ"EEPO w 50%0Ϋϥεਤʁ module RubyLSP::RuboCop class Addon < RubyLSP::Addon def
activate(global_state, message_queue) @runtime_adapter = RuntimeAdapter.new global_state.register_formatter( 'rubocop', @runtime_adapter ) # snip end def deactivate @runtime_adapter = nil end *OIFSJUGSPN3VCZ-41"EEPO *OUIFBDUJWBUFDBMMCBDLNFUIPEGSPN 3VCZ-41 SFHJTUFSBOBEBQUFSUP UIF3VCP$PQCVJMUJO-41SVOUJNF

3VCZ-413VCP$PQ3VOUJNF"EBQUFS w 50%0Ϋϥεਤʁ module RubyLSP::RuboCop class RuntimeAdapter def initialize @runtime
= RuboCop::LSP::Runtime.new(config) end def run_diagnostic(uri, document) @runtime.offenses(uri_to_path(uri), document.source, document.encoding) end def run_formatting(uri, document) @runtime.format(uri_to_path(uri), document.source, command: '...') end $SFBUFTUIF3VOUJNFDMBTTUPIBOEMFDBMMCBDLTGSPN3VCZ-41 %F fi OFTEFMFHBUJPOGSPNUIFSVO@EJBHOPTUJDDBMMCBDL %F fi OFTEFMFHBUJPOGSPNUIFSVO@GPSNBUUJOHDBMMCBDL

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ParserEngine: parser_prism # Ruby 3.3+ Syntax

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class Prism::Translation::Parser < ::Parser::Base def initialize(builder = Parser::Builder.new, parser: Prism)
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SVCPDPQSVCPDPQBTU w 50%0Ϋϥεਤʁ module RuboCop::AST class PrismParsed # Internal API
def initialized(prism_result) @prism_result = prism_result end def parse_lex(_source, **_prism_options) @prism_result end end end 💡An internal class for duck typing with parse_lex. 4UPSFUIFQBSTFESFTVMUGSPN1SJTN 3FUVSOUIFQBSTFESFTVMUGSPN1SJTNXJUIPVUQBSTJOH

SVCPDPQSVCPDPQBTU w 50%0Ϋϥεਤʁ class RuboCop::AST::ProcessedSource def create_parser( ruby_version, parser_engine, prism_result
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In the near future ***"45*OTJHIUT

.PUJWBUJPO#BDLHSPVOE Two years earlier than expected :-)

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%FTJHOPGUIF1BSTFSHFN generate QBSTFZ 3VCZ1BSTFS QBSTFD QBSTFTP GPS3VCZ 3VCZ1BSTFS QBSTFD
QBSTFTP GPS3VCZ $ lrama QBSTFZ read read generate ruby/ruby <<generate>> SVCZZ 3VCZ1BSTFS SVCZSC 3VCZ1BSTFS SVCZSC $ racc SVCZZ read read <<generate>> whitequark/parser *OIFSJUTGSPNParser::Base

%FTJHOPGUIF1BSTFSHFN generate QBSTFZ 3VCZ1BSTFS QBSTFD QBSTFTP GPS3VCZ 3VCZ1BSTFS QBSTFD
QBSTFTP GPS3VCZ $ lrama QBSTFZ read read generate ruby/ruby <<generate>> SVCZZ 3VCZ1BSTFS SVCZSC 3VCZ1BSTFS SVCZSC $ racc SVCZZ read read <<generate>> whitequark/parser porting and more tracking *OIFSJUTGSPNParser::Base )VNBOQPXFS

%FTJHOPG1SJTN5SBOTMBUJPO1BSTFS 1BSTFS#BTF 1SJTN 1SJTN5SBOTMBUJPO 1BSTFS 1SJTN5SBOTMBUJPO 1BSTFS 1SJTN5SBOTMBUJPO 1BSTFS <<use>>
1BSTFS#VJMEFST %FGBVMU 1SJTN5SBOTMBUJPO 1BSTFS#VJMEFS <<use>> <<use>> 5IFEFGBVMUQBSTFSTJODF3VCZ "WBJMBCMFGSPN3VCZ SC QSPHSBN "DMBTTUIBU TFSWFTBTBO "EBQUFS CFUXFFOUIF 1BSTFSHFN BOE1SJTN 4ZOUBY FYUFOTJPOTJO 3VCZ FH itCMPDL

%FTJHOPG1SJTN5SBOTMBUJPO1BSTFS 1BSTFS#BTF 1SJTN 1SJTN5SBOTMBUJPO 1BSTFS 1SJTN5SBOTMBUJPO 1BSTFS 1SJTN5SBOTMBUJPO 1BSTFS <<use>>
1BSTFS#VJMEFST %FGBVMU 1SJTN5SBOTMBUJPO 1BSTFS#VJMEFS <<use>> <<use>> 5IFEFGBVMUQBSTFSTJODF3VCZ "WBJMBCMFGSPN3VCZ SC QSPHSBN "DMBTTUIBU TFSWFTBTBO "EBQUFS CFUXFFOUIF 1BSTFSHFN BOE1SJTN 4ZOUBY FYUFOTJPOTJO 3VCZ FH itCMPDL %JSFDUEFQFOEFODZ

QBSTFS@QSJTNCZ%FGBVMUGPS3VCZ "OBMZTJTDPEFXJUI3VCP$PQ 3VOOJOH3VCP$PQXJUI3VCZ AllCops: # Use parser_prism parser
by default TargetRubyVersion: 3.4 $ bundle exec rubocop Use the same parser in Ruby and RuboCop!

*TUIFOFYUTUFQGPS 3VCP$PQUPTVQQPSU OBUJWF1SJTN"45🤔

w $45LFFQTBMMTPVSDFJOGPSNBUJPO w "CTUSBDUJPODBVTFTMPTTPGJOGPSNBUJPO 5IF-SBNB$SFBUPS5BMLT"CPVU4ZOUBY5SFF ࠷ߴͷߏจ໦ͷઃܭ೥൛ @yui_knk Concrete Syntax Tree

8IBU-FWFMPG"CTUSBDUJPO%P:PV/FFE 5IFMFWFMPGBCTUSBDUJPOJO"45WBSJFTCBTFEPOVTFSOFFET VOMJLF$45 $45 $PODSFUF4ZOUBY5SFF 3VCZ4PVSDF$PEF /BUJWF1SJTN"45 "CTUSBDU4ZOUBY5SFF 5IF1BSTFSHFN"45 "CTUSBDU4ZOUBY5SFF
RuboCop Ruby LSP, ReplTypeCompletor /PNJTTJOHJOGPSNBUJPO Abstraction Prism.parse Prism::Translation::Parser "OZUSBOTMBUPS Syntax Tree :FUBOPUIFSUIFCFTU45 Client 5IFCFTU 🤔

6OJWFSTBM1BSTFS JTOPU 6OJWFSTBM"45🤔 8IFUIFSUPBEPQU1SJTNTOBUJWF"45OFFETGVSUIFSEJTDVTTJPO

4JHOJ fi DBOU*NQBDUPO6TFSTJT&YQFDUFE w $IBOHJOHUIF"45JO3VCP$PQNFBOT SFXSJUJOHBMMOPEFQBUUFSOTBOEDPQT w 8JUITPNBOZDVTUPNQMVHJODPQTPVUUIFSF JUTVODMFBSJGUIFDPTUJTXPSUIJU
w .JHSBUJPOXPVMECFUPVHI TPBEWBODFNFOUJO "*BTTJTUBOUTVTJOH--.UFDIOPMPHJFTMJLF -BOH$IBJO 3"( BOE.$1JTFYQFDUFE

w 1FSGPSNBODF*OUFSNTPGTQFFE PQUJNJ[JOHUIFUSBOTMBUJPOMBZFSNJHIUCF XPSUIDPOTJEFSJOH'PDVTPOPWFSBMM OPU MPDBM QFSGPSNBODF w &SSPSUPMFSBODF*OXIBUTJUVBUJPOTXPVME
JUCFVTFGVMJO-JOUFSBOE'PSNBUUFS 5IJOL"CPVUUIF6TFS#FOF fi UT

IUUQTXXXZPVUVCFDPNXBUDI W),@-G8E/3: On considering the potential of Lrama

w 6TF1SJTNXJUIUIF1BSTFSHFNJOUFSGBDF w 1SJTNUSBOTMBUJPODBOCFSFVTFEBTMPOHBTJU QSPWJEFTNFUIPETMJLFparseBOEparser_lex w *G-SBNBTQBSTFSSFUVSOT PSBEBQUT B 1SJTNDPNQBUJCMFTZOUBYUSFF
JUT fi OFGPS 3VCP$PQ 1SJTN5SBOTMBUJPO1BSTFSJT3FVTBCMF

class Prism::Translation::Parser < ::Parser::Base def initialize(builder = Parser::Builder.new, parser: Prism)
@parser = parser super(builder) end def tokenize(source_buffer, recover = false) # snip result = unwrap( @parser.parse_lex(source, **prism_options), offset_cache) # snip end SVCZQSJTN "HBJO 5IFEFGBVMUQBSTFSDMBTTJT1SJTN JUDBOCFTXJUDIFE "OZSFDFJWFSUIBUSFTQPOETUPQBSTFS@MFYXPSLT

%FQFOEPO"CTUSBDUJPOT w 3VCP$PQSFMJFTPOMZPOUIF1BSTFSHFN"1* w 1BSTFSHFNT"45JOUFSGBDFJTTUJMMGPMMPXFE FWFOJG1BSTFSHFNEFWFMPQNFOUIBTTMPXFE w 1SPHSBNUPBOJOUFSGBDF
OPUBOJNQMFNFOUBUJPOCZ(P' w *O3VCZ FWFSZUIJOHJTBOJOUFSGBDF @kakutani

3VCP$PQT1BSTFS&OHJOFT 1BSTJOH5BSHFU 1BSTFSHFN 1SJTNT1BSTFS5SBOTMBUJPO-BZFS 3VCZUP %FGBVMU 5IF4PMF#BDLFOE1BSTFS N/A 3VCZ %FGBVMU
ParserEngine: parser_whitequark "MUFSOBUJWF ParserEngine: parser_prism 3VCZ %FGBVMUVOUJM3VCP$PQ 4ZOUBY*ODPNQBUJCJMJUZ %FGBVMUTJODF3VCP$PQ 4ZOUBY$PNQBUJCJMJUZ 3VCZ FYQFSJNFOUBM N/A %FGBVMU 5IF4PMF#BDLFOE1BSTFS Status in April 2025

w 5IF1BSTFSHFNJTHFUUJOHIBSEFSUPNBJOUBJO w 3VCP$PQOPXEFGBVMUTUP1SJTNTUSBOTMBUJPO MBZFSGPS3VCZ UPFOTVSFTZOUBY DPNQBUJCJMJUZBOESFEVDFNBJOUFOBODFDPTUT w 3VCZTitCMPDLQBSBNFUFSJTTVQQPSUFE JO3VCP$PQ
1BSU***,FZ1PJOUT

#P[IJEBS#BUTPW +VTUJO4FBSMT ,FWJO/FXUPO 7JOJDJVT4UPDL :VJDIJSP,BOFLP )BWF'VO (JU)VC!LPJD 4QFDJBM5IBOLT

RuboCop: Modularity and AST Insights

RuboCop: Modularity and AST Insights

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