Module: InsertAfter

Defined in:
lib/insert_after.rb,
lib/insert_after/version.rb

Constant Summary collapse

VERSION = 
'0.3.0'.freeze

Class Method Summary collapse

Class Method Details

.cmd(argv = ARGV) ⇒ Object 



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# File 'lib/insert_after.rb', line 73

def self.cmd(argv = ARGV)
  InsertAfter.help if argv.empty?
  if argv.include? '-a'
    all = true
    argv.delete '-a'
  end
  InsertAfter.help 'The new line to insert was not provided' if argv.length == 1
  InsertAfter.help 'No file name was provided' if argv.length == 2
  InsertAfter.help 'Too many arguments' if argv.length > 3
  regex    = argv[0].downcase
  new_line = argv[1].gsub('\n', "\n").gsub('\r', "\r").gsub('\t', "\t")
  filename = argv[2]
  InsertAfter.insert_after(regex, new_line, filename, all: all)
end

.help(msg = nil) ⇒ Object 



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# File 'lib/insert_after.rb', line 6

def self.help(msg = nil)
  puts "Error: #{msg}\n\n" if msg
  puts <<~END_MSG
    Inserts a line into a file after a line matching a regular expression.
    String comparisons are case-insensitive.
    Works on very large files because it reads the file line by line instead of reading the entire file into memory.

    Can be used on the command line or in a Ruby program.

    Command line usage:
      # Inserts 'Inserted 1' after the first line containing 'line' into demo/my_file.txt:
      $ insert_after line 'Inserted 1' demo/my_file.txt

      # Inserts 'Inserted 1' after every line containing 'line' into demo/my_file.txt:
      $ insert_after -a line 'Inserted 1' demo/my_file.txt

      # Inserts an empty line after the first line containing 'line 1' into demo/my_file.txt:
      $ insert_after 'line 1' '' demo/my_file.txt

      # Inserts an empty line after every line containing 'line 1' into demo/my_file.txt:
      $ insert_after -a 'line 1' '' demo/my_file.txt

      # Inserts 'Inserted 2' after the first line starting with 'line 2' into demo/my_file.txt:
      $ insert_after '^line 2' 'Inserted 2' demo/my_file.txt

      # Inserts 'Inserted 2' after every line starting with 'line 2' into demo/my_file.txt:
      $ insert_after -a '^line 2' 'Inserted 2' demo/my_file.txt

      # Inserts 'Inserted 3' after the first line containing an 'e' followed by a '2' into demo/my_file.txt:
      $ insert_after 'e.*2' 'Inserted 3' demo/my_file.txt

      # Inserts 'Inserted 3' after every line containing an 'e' followed by a '2' into demo/my_file.txt:
      $ insert_after -a 'e.*2' 'Inserted 3' demo/my_file.txt

    Ruby usage:
      require 'insert_after'
      InsertAfter.insert_after 'line 2', 'New line', 'demo/my_file.txt'

      InsertAfter.insert_after 'line 2', 'New line', 'demo/my_file.txt', all: true
  END_MSG
  exit 1
end

.insert_after(regex, new_line, filename, all: false) ⇒ Object 



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# File 'lib/insert_after.rb', line 49

def self.insert_after(regex, new_line, filename, all: false)
  InsertAfter.help "#{filename} does not exist" unless File.exist? filename

  original_file  = File.new(filename)
  temporary_file = Tempfile.new(filename)
  inserted = false
  begin
    original_file.each do |line|
      temporary_file << line
      if line.downcase.match?(/#{regex}/)
        temporary_file << "#{new_line}\n" unless inserted
        inserted = true unless all
      end
    end
    original_file.close
    temporary_file.close
    FileUtils.mv(temporary_file.path, filename)
  ensure
    original_file.close unless original_file.closed?
    temporary_file.close unless temporary_file.closed?
    temporary_file.unlink if File.exist? temporary_file.path
  end
end