Class: Safe::SafeHash

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/safestruct/safe_hash.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SafeHash

Returns a new instance of SafeHash.



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# File 'lib/safestruct/safe_hash.rb', line 75

def initialize
  ## todo/check: if hash works if value is a (nested) hash
  @h = {}
end

Class Method Details

.build_class(klass_key, klass_value) ⇒ Object

note: need to create new class!! for every safe hash

make klass_key class and
     klass_value class  into class instance variables
that can get used by zero
  self.new returns a Hash.new/SafeHash.new like object



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# File 'lib/safestruct/safe_hash.rb', line 20

def self.build_class( klass_key, klass_value )
  ## note: care for now only about value type / class

  ## note: keep a class cache
  cache = @@cache ||= {}
  klass = cache[ klass_value ]
  if debug?
    puts "[debug] SafeHash - build_class klass_value:"
    pp klass_value
    pp klass_value.to_s    ## note: for "anonymous" class something like #<Class:>
  end

  if klass.nil?
    if debug?
      puts "[debug] SafeHash - build_class new class (no cache hit)"
    end

    klass = Class.new( SafeHash )

    klass.define_singleton_method( :klass_key ) do
      @klass_key ||= klass_key
    end
    klass.define_singleton_method( :klass_value ) do
      @klass_value ||= klass_value
    end

    ### was:  - NOT working for "anonymous" classes e.g. klass_value.to_s starting with #<Class:>
    # klass.class_eval( <<RUBY )
    #  def self.klass_key
    #    @klass_key   ||= #{klass_key}
    #  end
    #  def self.klass_value
    #    @klass_value ||= #{klass_value}
    #  end
# RUBY

    ## add to cache for later (re)use
    cache[ klass_value ] = klass
  else
    if debug?
      puts "[debug] SafeHash - build_class bingo!! (re)use cached class:"
      pp klass
    end
  end

  klass
end

.debug=(value) ⇒ Object 



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# File 'lib/safestruct/safe_hash.rb', line 8

def self.debug=(value) @debug = value; end

.debug? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/safestruct/safe_hash.rb', line 7

def self.debug?()      @debug ||= false; end

.new_zero ⇒ Object 



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# File 'lib/safestruct/safe_hash.rb', line 69

def self.new_zero()  new;  end

.zero ⇒ Object 



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# File 'lib/safestruct/safe_hash.rb', line 70

def self.zero()      @zero ||= new_zero.freeze;  end

Instance Method Details

#==(other) ⇒ Object Also known as: eql? 



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# File 'lib/safestruct/safe_hash.rb', line 86

def ==( other )
  if other.is_a?( self.class )                    ## note: must be same hash class
    @h == other.instance_variable_get( '@h' )    ## compare "wrapped" hash
  else
    false
  end
end

#[](key) ⇒ Object 



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# File 'lib/safestruct/safe_hash.rb', line 102

def [](key)
  item = @h[ key ]
  if item.nil?
    ## pp self.class.klass_value
    ## pp self.class.klass_value.zero

    #####
    # todo/check:
    #    add zero to hash on lookup (increases size/length)
    #    why? why not?

    if self.class.klass_value.respond_to?( :new_zero )
      ## note: use a dup(licated) unfrozen copy of the zero object
      ##    changes to the object MUST be possible (new "empty" modifable object expected)
      item = @h[ key ] = self.class.klass_value.new_zero
    else  # assume value semantics e.g. Integer, Bool, etc. zero values gets replaced
      ## puts "use value semantics"
      item = @h[ key ] = self.class.klass_value.zero
    end
  end
  item
end

#[]=(key, value) ⇒ Object 



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# File 'lib/safestruct/safe_hash.rb', line 98

def []=(key, value)
  @h[key] = value
end

#freeze ⇒ Object 



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# File 'lib/safestruct/safe_hash.rb', line 80

def freeze
  super
  @h.freeze  ## note: pass on freeze to "wrapped" hash
  self   # return reference to self
end

#zero? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/safestruct/safe_hash.rb', line 72

def zero?() self == self.class.zero; end