class RuboCop::Formatter::JSONFormatter

This formatter formats the report data in JSON format.

def file_finished(file, offenses) 

def file_finished(file, offenses)
  output_hash[:files] << hash_for_file(file, offenses)
  output_hash[:summary][:offense_count] += offenses.count
end

def finished(inspected_files) 

def finished(inspected_files)
  output_hash[:summary][:inspected_file_count] = inspected_files.count
  output.write output_hash.to_json
end

def hash_for_file(file, offenses) 

def hash_for_file(file, offenses)
  {
    path:     smart_path(file),
    offenses: offenses.map { |o| hash_for_offense(o) }
  }
end

def hash_for_location(offense)

And non-zero value of `last_column` should be used as is.
So, the minimum value of `last_column` should be 1.
The minimum value of `start_column: real_column` is 1.
TODO: Consider better solution for Offense#real_column. 
def hash_for_location(offense)
  {
    start_line:   offense.line,
    start_column: offense.real_column,
    last_line:    offense.last_line,
    last_column:  offense.last_column.zero? ? 1 : offense.last_column,
    length:       offense.location.length,
    # `line` and `column` exist for compatibility.
    # Use `start_line` and `start_column` instead.
    line:         offense.line,
    column:       offense.real_column
  }
end

def hash_for_offense(offense) 

def hash_for_offense(offense)
  {
    severity:    offense.severity.name,
    message:     offense.message,
    cop_name:    offense.cop_name,
    corrected:   offense.corrected?,
    correctable: offense.correctable?,
    location:    hash_for_location(offense)
  }
end

def initialize(output, options = {}) 

def initialize(output, options = {})
  super
  @output_hash = { metadata: metadata_hash, files: [], summary: { offense_count: 0 } }
end

def metadata_hash 

def metadata_hash
  {
    rubocop_version: RuboCop::Version::STRING,
    ruby_engine:     RUBY_ENGINE,
    ruby_version:    RUBY_VERSION,
    ruby_patchlevel: RUBY_PATCHLEVEL.to_s,
    ruby_platform:   RUBY_PLATFORM
  }
end

def started(target_files) 

def started(target_files)
  output_hash[:summary][:target_file_count] = target_files.count
end