puppetlabs-stdlib/lib/puppet/parser/functions/is_numeric.rb

#
# is_numeric.rb
#

module Puppet::Parser::Functions
  newfunction(:is_numeric, :type => :rvalue, :doc => <<-EOS
Returns true if the given argument is a Numeric (Integer or Float),
or a String containing either a valid integer in decimal base 10 form, or
a valid floating point string representation.

The function recognizes only decimal (base 10) integers and float but not
integers in hex (base 16) or octal (base 8) form.

The string representation may start with a '-' (minus). If a decimal '.' is used,
it must be followed by at least one digit.

Valid examples:

  77435
  10e-12
  -8475
  0.2343
  -23.561e3
    EOS
  ) do |arguments|

    if (arguments.size != 1) then
      raise(Puppet::ParseError, "is_numeric(): Wrong number of arguments "+
        "given #{arguments.size} for 1")
    end

    value = arguments[0]

    # Regex is taken from the lexer of puppet
    # puppet/pops/parser/lexer.rb but modified to match also
    # negative values and disallow invalid octal numbers or
    # numbers prefixed with multiple 0's (except in hex numbers)
    #
    # TODO these parameters should be constants but I'm not sure
    # if there is no risk to declare them inside of the module
    # Puppet::Parser::Functions

    # TODO decide if this should be used
    # HEX numbers like
    # 0xaa230F
    # 0X1234009C
    # 0x0012
    # -12FcD
    #numeric_hex = %r{^-?0[xX][0-9A-Fa-f]+$}

    # TODO decide if this should be used
    # OCTAL numbers like
    # 01234567
    # -045372
    #numeric_oct = %r{^-?0[1-7][0-7]*$}

    # Integer/Float numbers like
    # -0.1234568981273
    # 47291
    # 42.12345e-12
    numeric = %r{^-?(?:(?:[1-9]\d*)|0)(?:\.\d+)?(?:[eE]-?\d+)?$}

    if value.is_a? Numeric or (value.is_a? String and (
      value.match(numeric) #or
    #  value.match(numeric_hex) or
    #  value.match(numeric_oct)
    ))
      return true
    else
      return false
    end
  end
end

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