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# SecureRandom.choose generates a string that randomly draws from a source array of

# characters.

#

# The argument _source_ specifies the array of characters from which to generate the

# string. The argument _n_ specifies the length, in characters, of the string to be

# generated.

#

# If _n_ is not specified or is nil, 16 is assumed.

# It may be larger in the future.

#

# The result may contain whatever characters are in the source array.

#

# p SecureRandom.choose([*'l'..'r']) #=> "lmrqpoonmmlqlron"

# p SecureRandom.choose([*'0'..'9'], 5) #=> "27309"

#

# If a secure random number generator is not available,

# +NotImplementedError+ is raised.

def self.choose(source, n=nil)

n = 16 if n.nil?

size = source.size

n.times.map {source[random_number(size)]}.join('')

end

GRAPH = [*'!'..'~'] unless defined? GRAPH

# SecureRandom.graph generates a random graph string that contains all the printable

# ASCII characters except for space.

#

# The argument _n_ specifies the length, in characters, of the string to be

# generated.

#

# If _n_ is not specified or is nil, 16 is assumed.

# It may be larger in the future.

#

# The result may contain all the printable ASCII characters except for space.

#

# p SecureRandom.graph #=> "$|yjZXTSXL\Tg+ip"

# p SecureRandom.graph(10) #=> "<8Qz@py?LG"

#

# If a secure random number generator is not available,

# +NotImplementedError+ is raised.

def self.graph(n=nil)

choose(GRAPH, n)

end

ALPHANUMERIC = [*'A'..'Z', *'a'..'z', *'0'..'9'] unless defined? ALPHANUMERIC

# SecureRandom.alphanumeric generates a random alphanumeric string.

#

# The argument _n_ specifies the length, in characters, of the alphanumeric

# string to be generated.

#

# If _n_ is not specified or is nil, 16 is assumed.

# It may be larger in the future.

#

# The result may contain A-Z, a-z and 0-9.

#

# p SecureRandom.alphanumeric #=> "2BuBuLf3WfSKyQbR"

# p SecureRandom.alphanumeric(10) #=> "i6K93NdqiH"

#

# If a secure random number generator is not available,

# +NotImplementedError+ is raised.

def self.alphanumeric(n=nil)

choose(ALPHANUMERIC, n)

end