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# encoding: utf-8
class Object
# An object is blank if it's false, empty, or a whitespace string.
# For example, '', ' ', +nil+, [], and {} are all blank.
#
# This simplifies:
#
# if address.nil? || address.empty?
#
# ...to:
#
# if address.blank?
def blank?
respond_to?(:empty?) ? empty? : !self
end
# An object is present if it's not <tt>blank?</tt>.
def present?
!blank?
end
# Returns object if it's <tt>present?</tt> otherwise returns +nil+.
# <tt>object.presence</tt> is equivalent to <tt>object.present? ? object : nil</tt>.
#
# This is handy for any representation of objects where blank is the same
# as not present at all. For example, this simplifies a common check for
# HTTP POST/query parameters:
#
# state = params[:state] if params[:state].present?
# country = params[:country] if params[:country].present?
# region = state || country || 'US'
#
# ...becomes:
#
# region = params[:state].presence || params[:country].presence || 'US'
def presence
self if present?
end
end
class NilClass
# +nil+ is blank:
#
# nil.blank? # => true
def blank?
true
end
end
class FalseClass
# +false+ is blank:
#
# false.blank? # => true
def blank?
true
end
end
class TrueClass
# +true+ is not blank:
#
# true.blank? # => false
def blank?
false
end
end
class Array
# An array is blank if it's empty:
#
# [].blank? # => true
# [1,2,3].blank? # => false
alias_method :blank?, :empty?
end
class Hash
# A hash is blank if it's empty:
#
# {}.blank? # => true
# { key: 'value' }.blank? # => false
alias_method :blank?, :empty?
end
class String
# A string is blank if it's empty or contains whitespaces only:
#
# ''.blank? # => true
# ' '.blank? # => true
# ' '.blank? # => true
# ' something here '.blank? # => false
def blank?
self !~ /[^[:space:]]/
end
end
class Numeric #:nodoc:
# No number is blank:
#
# 1.blank? # => false
# 0.blank? # => false
def blank?
false
end
end
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