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# frozen_string_literal: true
class String
# If you pass a single integer, returns a substring of one character at that
# position. The first character of the string is at position 0, the next at
# position 1, and so on. If a range is supplied, a substring containing
# characters at offsets given by the range is returned. In both cases, if an
# offset is negative, it is counted from the end of the string. Returns +nil+
# if the initial offset falls outside the string. Returns an empty string if
# the beginning of the range is greater than the end of the string.
#
# str = "hello"
# str.at(0) # => "h"
# str.at(1..3) # => "ell"
# str.at(-2) # => "l"
# str.at(-2..-1) # => "lo"
# str.at(5) # => nil
# str.at(5..-1) # => ""
#
# If a Regexp is given, the matching portion of the string is returned.
# If a String is given, that given string is returned if it occurs in
# the string. In both cases, +nil+ is returned if there is no match.
#
# str = "hello"
# str.at(/lo/) # => "lo"
# str.at(/ol/) # => nil
# str.at("lo") # => "lo"
# str.at("ol") # => nil
def at(position)
self[position]
end
# Returns a substring from the given position to the end of the string.
# If the position is negative, it is counted from the end of the string.
#
# str = "hello"
# str.from(0) # => "hello"
# str.from(3) # => "lo"
# str.from(-2) # => "lo"
#
# You can mix it with +to+ method and do fun things like:
#
# str = "hello"
# str.from(0).to(-1) # => "hello"
# str.from(1).to(-2) # => "ell"
def from(position)
self[position..-1]
end
# Returns a substring from the beginning of the string to the given position.
# If the position is negative, it is counted from the end of the string.
#
# str = "hello"
# str.to(0) # => "h"
# str.to(3) # => "hell"
# str.to(-2) # => "hell"
#
# You can mix it with +from+ method and do fun things like:
#
# str = "hello"
# str.from(0).to(-1) # => "hello"
# str.from(1).to(-2) # => "ell"
def to(position)
self[0..position]
end
# Returns the first character. If a limit is supplied, returns a substring
# from the beginning of the string until it reaches the limit value. If the
# given limit is greater than or equal to the string length, returns a copy of self.
#
# str = "hello"
# str.first # => "h"
# str.first(1) # => "h"
# str.first(2) # => "he"
# str.first(0) # => ""
# str.first(6) # => "hello"
def first(limit = 1)
ActiveSupport::Deprecation.warn(
"Calling String#first with a negative integer limit " \
"will raise an ArgumentError in Rails 6.1."
) if limit < 0
if limit == 0
""
elsif limit >= size
dup
else
to(limit - 1)
end
end
# Returns the last character of the string. If a limit is supplied, returns a substring
# from the end of the string until it reaches the limit value (counting backwards). If
# the given limit is greater than or equal to the string length, returns a copy of self.
#
# str = "hello"
# str.last # => "o"
# str.last(1) # => "o"
# str.last(2) # => "lo"
# str.last(0) # => ""
# str.last(6) # => "hello"
def last(limit = 1)
ActiveSupport::Deprecation.warn(
"Calling String#last with a negative integer limit " \
"will raise an ArgumentError in Rails 6.1."
) if limit < 0
if limit == 0
""
elsif limit >= size
dup
else
from(-limit)
end
end
end
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