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@chsh
Created July 10, 2021 23:46
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Allow to lookup ruby's Hash using xpath like syntax.
# usage:
# hash = { a: 1, b: { x: 'y'}, c: [{m: 10, n: 2}, { m: 20, n: 3} ] }
# hash.path('/a') => 1
# hash.path('b/x') => 'y'
# hash.path('/c[0]/n') => 2
# hash.path('/not/existent/key') => nil
# GenericUtils
module GenericSupport
module Pathable
module ClassMethods
def path(hash, *pathes)
target = hash
pathes.map! do |p|
p.to_s.split(/[\/\.]+/)
end
pathes.flatten.each do |element|
next if (element == nil || element == '')
key, index = parse_element__(element)
target = target[key] || target[key.to_s]
return nil unless target
if index
raise "target=#{target.inspect} is not array. but specified index value." unless target.is_a?(Array)
target = target[index]
return nil unless target
end
end
target
end
private
def parse_element__(elm_string)
if elm_string =~ /^(.+)\[(\d+)\]$/
[$1.to_sym, $2.to_i]
elsif elm_string =~ /^(.+)_(\d+)$/
[$1.to_sym, $2.to_i]
else
[elm_string.to_sym, nil]
end
end
end
module InstanceMethods
def path(*pathes)
self.class.path(self, *pathes)
end
end
end
end
module GenericSupport
module Hash
def self.included(base)
base.send(:extend, GenericSupport::Pathable::ClassMethods)
base.send(:include, GenericSupport::Pathable::InstanceMethods)
end
end
end
Hash.send(:include, GenericSupport::Hash)
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