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|
module Hashie
class CoercionError < StandardError; end
module Extensions
module Coercion
CORE_TYPES = {
Integer => :to_i,
Float => :to_f,
Complex => :to_c,
Rational => :to_r,
String => :to_s,
Symbol => :to_sym
}
ABSTRACT_CORE_TYPES = {
Integer => [Fixnum, Bignum],
Numeric => [Fixnum, Bignum, Float, Complex, Rational]
}
def self.included(base)
base.send :include, InstanceMethods
base.extend ClassMethods # NOTE: we wanna make sure we first define set_value_with_coercion before extending
base.send :alias_method, :set_value_without_coercion, :[]= unless base.method_defined?(:set_value_without_coercion)
base.send :alias_method, :[]=, :set_value_with_coercion
end
module InstanceMethods
def set_value_with_coercion(key, value)
into = self.class.key_coercion(key) || self.class.value_coercion(value)
return set_value_without_coercion(key, value) if value.nil? || into.nil?
begin
return set_value_without_coercion(key, coerce_or_init(into).call(value)) unless into.is_a?(Enumerable)
if into.class <= ::Hash
key_coerce = coerce_or_init(into.flatten[0])
value_coerce = coerce_or_init(into.flatten[-1])
value = into.class[value.map { |k, v| [key_coerce.call(k), value_coerce.call(v)] }]
else # Enumerable but not Hash: Array, Set
value_coerce = coerce_or_init(into.first)
value = into.class.new(value.map { |v| value_coerce.call(v) })
end
rescue NoMethodError, TypeError => e
raise CoercionError, "Cannot coerce property #{key.inspect} from #{value.class} to #{into}: #{e.message}"
end
set_value_without_coercion(key, value)
end
def coerce_or_init(type)
return type if type.is_a? Proc
if CORE_TYPES.key?(type)
lambda do |v|
return v if v.is_a? type
return v.send(CORE_TYPES[type])
end
elsif type.respond_to?(:coerce)
lambda do |v|
return v if v.is_a? type
type.coerce(v)
end
elsif type.respond_to?(:new)
lambda do |v|
return v if v.is_a? type
type.new(v)
end
else
fail TypeError, "#{type} is not a coercable type"
end
end
private :coerce_or_init
def custom_writer(key, value, _convert = true)
self[key] = value
end
def replace(other_hash)
(keys - other_hash.keys).each { |key| delete(key) }
other_hash.each { |key, value| self[key] = value }
self
end
end
module ClassMethods
attr_writer :key_coercions
protected :key_coercions=
# Set up a coercion rule such that any time the specified
# key is set it will be coerced into the specified class.
# Coercion will occur by first attempting to call Class.coerce
# and then by calling Class.new with the value as an argument
# in either case.
#
# @param [Object] key the key or array of keys you would like to be coerced.
# @param [Class] into the class into which you want the key(s) coerced.
#
# @example Coerce a "user" subhash into a User object
# class Tweet < Hash
# include Hashie::Extensions::Coercion
# coerce_key :user, User
# end
def coerce_key(*attrs)
into = attrs.pop
attrs.each { |key| key_coercions[key] = into }
end
alias_method :coerce_keys, :coerce_key
# Returns a hash of any existing key coercions.
def key_coercions
@key_coercions ||= {}
end
# Returns the specific key coercion for the specified key,
# if one exists.
def key_coercion(key)
key_coercions[key.to_sym]
end
# Set up a coercion rule such that any time a value of the
# specified type is set it will be coerced into the specified
# class.
#
# @param [Class] from the type you would like coerced.
# @param [Class] into the class into which you would like the value coerced.
# @option options [Boolean] :strict (true) whether use exact source class only or include ancestors
#
# @example Coerce all hashes into this special type of hash
# class SpecialHash < Hash
# include Hashie::Extensions::Coercion
# coerce_value Hash, SpecialHash
#
# def initialize(hash = {})
# super
# hash.each_pair do |k,v|
# self[k] = v
# end
# end
# end
def coerce_value(from, into, options = {})
options = { strict: true }.merge(options)
if ABSTRACT_CORE_TYPES.key? from
ABSTRACT_CORE_TYPES[from].each do | type |
coerce_value type, into, options
end
end
if options[:strict]
strict_value_coercions[from] = into
else
while from.superclass && from.superclass != Object
lenient_value_coercions[from] = into
from = from.superclass
end
end
end
# Return all value coercions that have the :strict rule as true.
def strict_value_coercions
@strict_value_coercions ||= {}
end
# Return all value coercions that have the :strict rule as false.
def lenient_value_coercions
@lenient_value_coercions ||= {}
end
# Fetch the value coercion, if any, for the specified object.
def value_coercion(value)
from = value.class
strict_value_coercions[from] || lenient_value_coercions[from]
end
def inherited(klass)
super
klass.key_coercions = key_coercions.dup
end
end
end
end
end
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