1 files changed, 113 insertions, 7 deletions
diff --git a/Library/Homebrew/cmd/style.rb b/Library/Homebrew/cmd/style.rb
index 20575c065..0f089b8ae 100644
--- a/Library/Homebrew/cmd/style.rb
+++ b/Library/Homebrew/cmd/style.rb
@@ -1,3 +1,25 @@
+#:  * `style` [`--fix`] [`--display-cop-names`] [<formulae>|<files>]:
+#:    Check formulae or files for conformance to Homebrew style guidelines.
+#:
+#:    <formulae> is a list of formula names.
+#:
+#:    <files> is a list of file names.
+#:
+#:    <formulae> and <files> may not be combined. If both are omitted, style will run
+#:    style checks on the whole Homebrew `Library`, including core code and all
+#:    formulae.
+#:
+#:    If `--fix` is passed and `HOMEBREW_DEVELOPER` is set, style violations
+#:    will be automatically fixed using RuboCop's `--auto-correct` feature.
+#:
+#:    If `--display-cop-names` is passed, the RuboCop cop name for each violation
+#:    is included in the output.
+#:
+#:    Exits with a non-zero status if any style violations are found.
+
+require "utils"
+require "utils/json"
+
 module Homebrew
   def style
     target = if ARGV.named.empty?
@@ -8,18 +30,102 @@ module Homebrew
       ARGV.formulae.map(&:path)
     end
 
+    Homebrew.failed = check_style_and_print(target, :fix => ARGV.flag?("--fix"))
+  end
+
+  # Checks style for a list of files, printing simple RuboCop output.
+  # Returns true if violations were found, false otherwise.
+  def check_style_and_print(files, options = {})
+    check_style_impl(files, :print, options)
+  end
+
+  # Checks style for a list of files, returning results as a RubocopResults
+  # object parsed from its JSON output.
+  def check_style_json(files, options = {})
+    check_style_impl(files, :json, options)
+  end
+
+  def check_style_impl(files, output_type, options = {})
+    fix = options[:fix]
     Homebrew.install_gem_setup_path! "rubocop", "0.39"
 
-    args = [
-      "--format", "simple", "--force-exclusion", "--config",
-      "#{HOMEBREW_LIBRARY}/.rubocop.yml",
+    args = %W[
+      --force-exclusion
+      --config #{HOMEBREW_LIBRARY}/.rubocop.yml
     ]
+    args << "--auto-correct" if ARGV.homebrew_developer? && fix
+    args += files
 
-    args << "--auto-correct" if ARGV.homebrew_developer? && ARGV.flag?("--fix")
+    case output_type
+    when :print
+      args << "--display-cop-names" if ARGV.include? "--display-cop-names"
+      system "rubocop", "--format", "simple", *args
+      !$?.success?
+    when :json
+      json = Utils.popen_read_text("rubocop", "--format", "json", *args)
+      # exit status of 1 just means violations were found; others are errors
+      raise "Error while running rubocop" if $?.exitstatus > 1
+      RubocopResults.new(Utils::JSON.load(json))
+    else
+      raise "Invalid output_type for check_style_impl: #{output_type}"
+    end
+  end
 
-    args += target
+  class RubocopResults
+    def initialize(json)
+      @metadata = json["metadata"]
+      @file_offenses = {}
+      json["files"].each do |f|
+        next if f["offenses"].empty?
+        file = File.realpath(f["path"])
+        @file_offenses[file] = f["offenses"].map { |x| RubocopOffense.new(x) }
+      end
+    end
+
+    def file_offenses(path)
+      @file_offenses[path.to_s]
+    end
+  end
 
-    system "rubocop", *args
-    Homebrew.failed = !$?.success?
+  class RubocopOffense
+    attr_reader :severity, :message, :corrected, :location, :cop_name
+
+    def initialize(json)
+      @severity = json["severity"]
+      @message = json["message"]
+      @cop_name = json["cop_name"]
+      @corrected = json["corrected"]
+      @location = RubocopLineLocation.new(json["location"])
+    end
+
+    def severity_code
+      @severity[0].upcase
+    end
+
+    def to_s(options = {})
+      if options[:display_cop_name]
+        "#{severity_code}: #{location.to_short_s}: #{cop_name}: #{message}"
+      else
+        "#{severity_code}: #{location.to_short_s}: #{message}"
+      end
+    end
+  end
+
+  class RubocopLineLocation
+    attr_reader :line, :column, :length
+
+    def initialize(json)
+      @line = json["line"]
+      @column = json["column"]
+      @length = json["length"]
+    end
+
+    def to_s
+      "#{line}: col #{column} (#{length} chars)"
+    end
+
+    def to_short_s
+      "#{line}: col #{column}"
+    end
   end
 end