Class: Blockchain

Inherits:
Object
  • Object
show all
Defined in:
lib/blockchain-lite/blockchain.rb

Instance Method Summary collapse

Constructor Details

#initialize(chain = nil, block_class: nil) ⇒ Blockchain

Returns a new instance of Blockchain.



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# File 'lib/blockchain-lite/blockchain.rb', line 10

def initialize( chain=nil, block_class: nil )
  if chain.nil?
    @block_class = if block_class
      block_class
    else
      ## check if Block is defined

      ##    if yes, use it othwerwise fallback for ProofOfWork::Block

      defined?( Block ) ? Block : BlockchainLite::ProofOfWork::Block
    end

    b0 = @block_class.first( 'Genesis' )
    @chain = [b0]
  else
    @chain = chain    # "wrap" passed in blockchain (in array)

    @block_class = if block_class
        block_class
      else
        ### no block class configured; use class of first block

        if @chain.first
          @chain.first.class
        else
          ##  todo/fix: throw except if chain is empty (no class configured) - why? why not??

          ##   throw exception on add block if not a block - why? why not??

        end
      end
  end
end

Instance Method Details

#<<(arg) ⇒ Object

make method-<< abstract/virtual - why? why not?

must be added by to make sure proper block_class is always used - why? why not??



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# File 'lib/blockchain-lite/blockchain.rb', line 47

def <<( arg )
  if arg.is_a? Array   ## assume its (just) data

    data = arg
    bl   = @chain.last
    b    = @block_class.next( bl, data )
  elsif arg.class.respond_to?( :first ) &&       ## check if respond_to? Block.first? and Block.next? - assume it's a block

        arg.class.respond_to?( :next )           ##  check/todo: use is_a? @block_class why? why not?

    b = arg
  else  ## fallback; assume single transaction record; wrap in array - allow fallback - why? why not??

    data = [arg]
    bl   = @chain.last
    b    = @block_class.next( bl, data )
  end
  @chain << b   ## add/append (new) block to chain

end

#broken? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/blockchain-lite/blockchain.rb', line 65

def broken?
  ## check for validation conventions

  ##   - start with first block?

  ##   - or start with last block (reversve)? -why? why not??


  @chain.size.times do |i|
    ###puts "checking block #{i+1}/#{@chain.size}..."


    current = @chain[i]

    if i==0   ### special case for first (genesis) block; has no previous/parent block

      if current.index != 0
        ## raise error -- invalid index!!!

        return true
      end
      if current.previous_hash != '0'
        ## raise error -- invalid previous hash (hash checksums MUST match)

        return true
      end
    else
      previous = @chain[i-1]

      if current.index != previous.index+1
        ## raise error -- invalid index!!!

        puts "!!! blockchain corrupt - block ##{current.index}: index must be a sequence (with +1 steps)"
        return true
      end

      if current.previous_hash != previous.hash
        ## raise error -- invalid previous hash (hash checksums MUST match)

        puts "!!! blockchain corrupt - block ##{current.index}: previous_hash and hash in previous block must match"
        return true
      end
    end

    if current.hash != current.calc_hash    ## (re)calc / double-check hash

      ## raise error -- invalid hash (hash checksums MUST match)

      puts "!!! blockchain corrupt - block ##{current.index}: calc_hash and hash must match; block corrupt - cannot recalculate hash"
      return true
    end
  end # loop times


  false   ## chain OK -- chain is NOT broken if we get here

end

#last ⇒ Object

return last block in chain



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# File 'lib/blockchain-lite/blockchain.rb', line 40

def last() @chain.last; end

#valid? ⇒ Boolean

method broken?

Returns:

  • (Boolean) 


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# File 'lib/blockchain-lite/blockchain.rb', line 110

def valid?() !broken?; end