Class: CfnCamelizer

Inherits:
Object
  • Object
show all
Extended by:
Memoist
Defined in:
lib/cfn_camelizer.rb,
lib/cfn_camelizer/version.rb

Overview

Custom Camelizer with CloudFormation specific handling. Based on: stackoverflow.com/questions/8706930/converting-nested-hash-keys-from-camelcase-to-snake-case-in-ruby

Constant Summary collapse

VERSION = 
"0.4.8"

Class Method Summary collapse

Class Method Details

.camelize(value, resource_type = nil) ⇒ Object 



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# File 'lib/cfn_camelizer.rb', line 58

def camelize(value, resource_type=nil)
  return value if value.is_a?(Integer)

  value = value.to_s.camelize
  v = special_map[value] || value # after the special_keys map
  resource_map(resource_type)[v] || v
end

.camelize_key(k, parent_keys = [], resource_type = nil) ⇒ Object 



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# File 'lib/cfn_camelizer.rb', line 34

def camelize_key(k, parent_keys=[], resource_type=nil)
  k = k.to_s

  if passthrough?(k, parent_keys)
    k # pass through untouch
  elsif parent_keys.last == "EventPattern" # top-level
    k.dasherize
  elsif parent_keys.include?("EventPattern")
    # Any keys at 2nd level under EventPattern will be pascalized
    pascalize(k)
  else
    camelize(k, resource_type)
  end
end

.camelizer_yaml ⇒ Object 



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# File 'lib/cfn_camelizer.rb', line 82

def camelizer_yaml
  # default
  path = File.expand_path("camelizer.yml", File.dirname(__FILE__))
  default = YAML.load_file(path)
  # project specific
  path = "#{Dir.pwd}/configs/camelizer.yml"
  if File.exist?(path)
    project = YAML.load_file(path)
    default.deep_merge(project)
  else
    default
  end
end

.pascalize(value) ⇒ Object 



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# File 'lib/cfn_camelizer.rb', line 66

def pascalize(value)
  new_value = value.camelize
  first_char = new_value[0..0].downcase
  new_value[0] = first_char
  new_value
end

.passthrough?(k, parent_keys) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/cfn_camelizer.rb', line 49

def passthrough?(k, parent_keys)
  # Do not transform keys under certain parent keys or keys that contain - or /
  passthrough = camelizer_yaml["passthrough_parent_keys"]
  intersection = parent_keys & passthrough
  top_level_parameters = parent_keys.first == "Parameters"
  return false if top_level_parameters
  !intersection.empty? || k.include?('-') || k.include?('/') || k.include?('.')
end

.resource_map(resource_type) ⇒ Object 



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# File 'lib/cfn_camelizer.rb', line 78

def resource_map(resource_type)
  camelizer_yaml["resource_keys"][resource_type] || {}
end

.special_map ⇒ Object

Some keys have special mappings



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# File 'lib/cfn_camelizer.rb', line 74

def special_map
  camelizer_yaml["special_keys"]
end

.transform(value, parent_keys = [], resource_type = nil) ⇒ Object 



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# File 'lib/cfn_camelizer.rb', line 14

def transform(value, parent_keys=[], resource_type=nil)
  case value
  when Array
    value.map { |v| transform(v, parent_keys, resource_type) }
  when Hash
    camelized_copy = value.dup.deep_transform_keys { |k| k.to_s.camelize }
    if camelized_copy.keys.include?("Type")
      resource_type ||= camelized_copy["Type"]
    end

    initializer = value.map do |k, v|
      new_key = camelize_key(k, parent_keys, resource_type)
      [new_key, transform(v, parent_keys+[new_key], resource_type)]
    end
    Hash[initializer]
  else
    value # do not transform values
  end
end