Module: Puppet::Util::FileParsing

Includes:
Puppet::Util
Included in:
Provider::ParsedFile
Defined in:
lib/puppet/util/fileparsing.rb

Overview

A mini-language for parsing files. This is only used file the ParsedFile provider, but it makes more sense to split it out so it’s easy to maintain in one place.

You can use this module to create simple parser/generator classes. For instance, the following parser should go most of the way to parsing /etc/passwd:

class Parser
    include Puppet::Util::FileParsing
    record_line :user, :fields => %w{name password uid gid gecos home shell},
        :separator => ":"
end

You would use it like this:

parser = Parser.new
lines = parser.parse(File.read("/etc/passwd"))

lines.each do |type, hash| # type will always be :user, since we only have one
    p hash
end

Each line in this case would be a hash, with each field set appropriately. You could then call ‘parser.to_line(hash)’ on any of those hashes to generate the text line again.

Defined Under Namespace

Classes: FileRecord

Constant Summary

Constants included from Puppet::Util

AbsolutePathPosix, AbsolutePathWindows, DEFAULT_POSIX_MODE, DEFAULT_WINDOWS_MODE, RFC_3986_URI_REGEX

Constants included from POSIX

POSIX::LOCALE_ENV_VARS, POSIX::USER_ENV_VARS

Constants included from SymbolicFileMode

SymbolicFileMode::SetGIDBit, SymbolicFileMode::SetUIDBit, SymbolicFileMode::StickyBit, SymbolicFileMode::SymbolicMode, SymbolicFileMode::SymbolicSpecialToBit

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Puppet::Util

absolute_path?, benchmark, chuser, clear_environment, default_env, deterministic_rand, deterministic_rand_int, exit_on_fail, get_env, get_environment, logmethods, merge_environment, path_to_uri, pretty_backtrace, replace_file, safe_posix_fork, set_env, symbolizehash, thinmark, uri_encode, uri_query_encode, uri_to_path, which, withenv, withumask

Methods included from POSIX

#get_posix_field, #gid, groups_of, #idfield, #methodbyid, #methodbyname, #search_posix_field, #uid

Methods included from SymbolicFileMode

#normalize_symbolic_mode, #symbolic_mode_to_int, #valid_symbolic_mode?

Instance Attribute Details

#line_separator ⇒ Object 



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# File 'lib/puppet/util/fileparsing.rb', line 230

def line_separator
  @line_separator ||= "\n"

  @line_separator
end

#trailing_separator ⇒ Object

Whether to add a trailing separator to the file. Defaults to true



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# File 'lib/puppet/util/fileparsing.rb', line 356

def trailing_separator
  if defined?(@trailing_separator)
    return @trailing_separator
  else
    return true
  end
end

Instance Method Details

#clear_records ⇒ Object

Clear all existing record definitions. Only used for testing.



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# File 'lib/puppet/util/fileparsing.rb', line 147

def clear_records
  @record_types.clear
  @record_order.clear
end

#fields(type) ⇒ Object 



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# File 'lib/puppet/util/fileparsing.rb', line 152

def fields(type)
  if record = record_type(type)
    record.fields.dup
  else
    nil
  end
end

#handle_record_line(line, record) ⇒ Hash<Symbol, Object>

Try to match a record.

Parameters:

Returns:

  • (Hash<Symbol, Object>) —

    The parsed elements of the line



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# File 'lib/puppet/util/fileparsing.rb', line 171

def handle_record_line(line, record)
  ret = nil
  if record.respond_to?(:process)
    if ret = record.send(:process, line.dup)
      unless ret.is_a?(Hash)
        raise Puppet::DevError, _("Process record type %{record_name} returned non-hash") % { record_name: record.name }
      end
    else
      return nil
    end
  elsif regex = record.match
    # In this case, we try to match the whole line and then use the
    # match captures to get our fields.
    if match = regex.match(line)
      ret = {}
      record.fields.zip(match.captures).each do |field, value|
        if value == record.absent
          ret[field] = :absent
        else
          ret[field] = value
        end
      end
    else
      nil
    end
  else
    ret = {}
    sep = record.separator

    # String "helpfully" replaces ' ' with /\s+/ in splitting, so we
    # have to work around it.
    if sep == " "
      sep = / /
    end
    line_fields = line.split(sep)
    record.fields.each do |param|
      value = line_fields.shift
      if value and value != record.absent
        ret[param] = value
      else
        ret[param] = :absent
      end
    end

    if record.rollup and ! line_fields.empty?
      last_field = record.fields[-1]
      val = ([ret[last_field]] + line_fields).join(record.joiner)
      ret[last_field] = val
    end
  end

  if ret
    ret[:record_type] = record.name
    return ret
  else
    return nil
  end
end

#handle_text_line(line, record) ⇒ Object

Try to match a specific text line.



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# File 'lib/puppet/util/fileparsing.rb', line 161

def handle_text_line(line, record)
  line =~ record.match ? {:record_type => record.name, :line => line} : nil
end

#lines(text) ⇒ Object

Split text into separate lines using the record separator.



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# File 'lib/puppet/util/fileparsing.rb', line 237

def lines(text)
  # NOTE: We do not have to remove trailing separators because split will ignore
  # them by default (unless you pass -1 as a second parameter)
  text.split(self.line_separator)
end

#parse(text) ⇒ Object

Split a bunch of text into lines and then parse them individually.



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# File 'lib/puppet/util/fileparsing.rb', line 244

def parse(text)
  count = 1
  lines(text).collect do |line|
    count += 1
    if val = parse_line(line)
      val
    else
      error = Puppet::ResourceError.new(_("Could not parse line %{line}") % { line: line.inspect })
      error.line = count
      raise error
    end
  end
end

#parse_line(line) ⇒ Object

Handle parsing a single line.

Raises:



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# File 'lib/puppet/util/fileparsing.rb', line 259

def parse_line(line)
  raise Puppet::DevError, _("No record types defined; cannot parse lines") unless records?

  @record_order.each do |record|
    # These are basically either text or record lines.
    method = "handle_#{record.type}_line"
    if respond_to?(method)
      if result = send(method, line, record)
        record.send(:post_parse, result) if record.respond_to?(:post_parse)
        return result
      end
    else
      raise Puppet::DevError, _("Somehow got invalid line type %{record_type}") % { record_type: record.type }
    end
  end

  nil
end

#record_line(name, options, &block) ⇒ Object

Define a new type of record. These lines get split into hashes. Valid options are:

  • :absent: What to use as value within a line, when a field is absent. Note that in the record object, the literal :absent symbol is used, and not this value. Defaults to “”.

  • :fields: The list of fields, as an array. By default, all fields are considered required.

  • :joiner: How to join fields together. Defaults to ‘t’.

  • :optional: Which fields are optional. If these are missing, you’ll just get the ‘absent’ value instead of an ArgumentError.

  • :rts: Whether to remove trailing whitespace. Defaults to false. If true, whitespace will be removed; if a regex, then whatever matches the regex will be removed.

  • :separator: The record separator. Defaults to /s+/.

Raises:

  • (ArgumentError) 


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# File 'lib/puppet/util/fileparsing.rb', line 292

def record_line(name, options, &block)
  raise ArgumentError, _("Must include a list of fields") unless options.include?(:fields)

  record = FileRecord.new(:record, options, &block)
  record.name = name.intern

  new_line_type(record)
end

#records? ⇒ Boolean

Are there any record types defined?

Returns:

  • (Boolean) 


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# File 'lib/puppet/util/fileparsing.rb', line 302

def records?
  defined?(@record_types) and ! @record_types.empty?
end

#text_line(name, options, &block) ⇒ Object

Define a new type of text record.

Raises:

  • (ArgumentError) 


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# File 'lib/puppet/util/fileparsing.rb', line 307

def text_line(name, options, &block)
  raise ArgumentError, _("You must provide a :match regex for text lines") unless options.include?(:match)

  record = FileRecord.new(:text, options, &block)
  record.name = name.intern

  new_line_type(record)
end

#to_file(records) ⇒ Object

Generate a file from a bunch of hash records.



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# File 'lib/puppet/util/fileparsing.rb', line 317

def to_file(records)
  text = records.collect { |record| to_line(record) }.join(line_separator)

  text += line_separator if trailing_separator

  text
end

#to_line(details) ⇒ Object

Convert our parsed record into a text record.



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# File 'lib/puppet/util/fileparsing.rb', line 326

def to_line(details)
  unless record = record_type(details[:record_type])
    raise ArgumentError, _("Invalid record type %{record_type}") % { record_type: details[:record_type].inspect }
  end

  if record.respond_to?(:pre_gen)
    details = details.dup
    record.send(:pre_gen, details)
  end

  case record.type
  when :text; return details[:line]
  else
    return record.to_line(details) if record.respond_to?(:to_line)

    line = record.join(details)

    if regex = record.rts
      # If they say true, then use whitespace; else, use their regex.
      if regex == true
        regex = /\s+$/
      end
      return line.sub(regex,'')
    else
      return line
    end
  end
end

#valid_attr?(type, attr) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/puppet/util/fileparsing.rb', line 364

def valid_attr?(type, attr)
  type = type.intern
  if record = record_type(type) and record.fields.include?(attr.intern)
    return true
  else
    if attr.intern == :ensure
      return true
    else
      false
    end
  end
end