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require "active_support/core_ext/regexp"
class Object
# An object is blank if it's false, empty, or a whitespace string.
# For example, +false+, '', ' ', +nil+, [], and {} are all blank.
#
# This simplifies
#
# !address || address.empty?
#
# to
#
# address.blank?
#
# @return [true, false]
def blank?
respond_to?(:empty?) ? !!empty? : !self
end
# An object is present if it's not blank.
#
# @return [true, false]
def present?
!blank?
end
# Returns the receiver if it's present otherwise returns +nil+.
# <tt>object.presence</tt> is equivalent to
#
# object.present? ? object : nil
#
# For example, something like
#
# 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'
#
# @return [Object]
def presence
self if present?
end
end
class NilClass
# +nil+ is blank:
#
# nil.blank? # => true
#
# @return [true]
def blank?
true
end
end
class FalseClass
# +false+ is blank:
#
# false.blank? # => true
#
# @return [true]
def blank?
true
end
end
class TrueClass
# +true+ is not blank:
#
# true.blank? # => false
#
# @return [false]
def blank?
false
end
end
class Array
# An array is blank if it's empty:
#
# [].blank? # => true
# [1,2,3].blank? # => false
#
# @return [true, false]
alias_method :blank?, :empty?
end
class Hash
# A hash is blank if it's empty:
#
# {}.blank? # => true
# { key: 'value' }.blank? # => false
#
# @return [true, false]
alias_method :blank?, :empty?
end
class String
BLANK_RE = /\A[[:space:]]*\z/
# A string is blank if it's empty or contains whitespaces only:
#
# ''.blank? # => true
# ' '.blank? # => true
# "\t\n\r".blank? # => true
# ' blah '.blank? # => false
#
# Unicode whitespace is supported:
#
# "\u00a0".blank? # => true
#
# @return [true, false]
def blank?
# The regexp that matches blank strings is expensive. For the case of empty
# strings we can speed up this method (~3.5x) with an empty? call. The
# penalty for the rest of strings is marginal.
empty? || BLANK_RE.match?(self)
end
end
class Numeric #:nodoc:
# No number is blank:
#
# 1.blank? # => false
# 0.blank? # => false
#
# @return [false]
def blank?
false
end
end
class Time #:nodoc:
# No Time is blank:
#
# Time.now.blank? # => false
#
# @return [false]
def blank?
false
end
end