properties.rb

# frozen_string_literal: true

# Cloud Foundry Java Buildpack
# Copyright 2013-2020 the original author or authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

require 'java_buildpack/util'

module JavaBuildpack
  module Util

    # A class representing a collection of Java properties
    class Properties < Hash

      # Create a new instance, populating it with values from a properties file
      #
      # @param [Pathname, nil] file_name the file to use for initialization. If no file is passed in, the instance is
      #                                  empty.
      def initialize(file_name)
        return if file_name.nil?

        contents = file_name.open(&:read)
        contents.gsub!(/[\r\n\f]+ /, '')

        contents.each_line do |line|
          next if blank_line?(line) || comment_line?(line)

          match_data          = /^\s*([^:=\s]+)\s*[=:]?\s*(.*?)\s*$/.match(line)
          self[match_data[1]] = match_data[2] if match_data
        end
      end

      private

      def blank_line?(line)
        line =~ /^\s*$/
      end

      def comment_line?(line)
        line =~ /^\s*[#!].*$/
      end

    end

  end
end