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Contents
require 'caruby/util/validation'
# An AttributePath encapsulates an array of attributes that can be evaluated on a source object.
class AttributePath < Array
# Creates an AttributePath from the path Array, String or Symbol. A path string is a period-delimited sequence
# of attributes, e.g. +person.name+.
def initialize(path)
raise ArgumentError.new("Path empty") if path.nil_or_empty?
# standardize the argument as a symbol array
attributes = case path
when Symbol then
[path]
when String then
path.split('.').map { |name| name.to_sym }
when Array then
path.map { |name| name.to_sym }
else
raise ArgumentError.new("Argument type unsupported - expected Symbol, String or Array; found #{path.class}")
end
# make the array
super(attributes)
end
# Returns the result of evaluating this evaluator's attribute path on the source object.
# If the evaluation results in a migratable object, then that object is migrated.
def evaluate(source)
# call the attribute path as far as possible
inject(source) do |current, attr|
return if current.nil?
evaluate_attribute(attr, current)
end
end
# Returns the result of evaluating attribute on the source object.
# If attr is +self+, then the source object is returned.
def evaluate_attribute(attr, source)
# call the attribute path as far as possible
attr == :self ? source : source.send(attr)
end
def to_s
join('.')
end
end
Version data entries
6 entries across 6 versions & 1 rubygems