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class Hash
# Return a new hash with all keys converted using the block operation.
#
# { :name => 'Rob', :years => '28' }.transform_keys{ |key| key.to_s.upcase }
# # => { "NAME" => "Rob", "YEARS" => "28" }
def transform_keys
result = {}
keys.each do |key|
result[yield(key)] = self[key]
end
result
end
# Destructively convert all keys using the block operations.
# Same as transform_keys but modifies +self+
def transform_keys!
keys.each do |key|
self[yield(key)] = delete(key)
end
self
end
# Return a new hash with all keys converted to strings.
#
# { :name => 'Rob', :years => '28' }.stringify_keys
# #=> { "name" => "Rob", "years" => "28" }
def stringify_keys
transform_keys{ |key| key.to_s }
end
# Destructively convert all keys to strings. Same as
# +stringify_keys+, but modifies +self+.
def stringify_keys!
transform_keys!{ |key| key.to_s }
end
# Return a new hash with all keys converted to symbols, as long as
# they respond to +to_sym+.
#
# { 'name' => 'Rob', 'years' => '28' }.symbolize_keys
# #=> { :name => "Rob", :years => "28" }
def symbolize_keys
transform_keys{ |key| key.to_sym rescue key }
end
alias_method :to_options, :symbolize_keys
# Destructively convert all keys to symbols, as long as they respond
# to +to_sym+. Same as +symbolize_keys+, but modifies +self+.
def symbolize_keys!
transform_keys!{ |key| key.to_sym rescue key }
end
alias_method :to_options!, :symbolize_keys!
# Validate all keys in a hash match *valid keys, raising ArgumentError on a mismatch.
# Note that keys are NOT treated indifferently, meaning if you use strings for keys but assert symbols
# as keys, this will fail.
#
# { :name => 'Rob', :years => '28' }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: years"
# { :name => 'Rob', :age => '28' }.assert_valid_keys('name', 'age') # => raises "ArgumentError: Unknown key: name"
# { :name => 'Rob', :age => '28' }.assert_valid_keys(:name, :age) # => passes, raises nothing
def assert_valid_keys(*valid_keys)
valid_keys.flatten!
each_key do |k|
raise ArgumentError.new("Unknown key: #{k}") unless valid_keys.include?(k)
end
end
end
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