Class: HappyMapper::Differ

Inherits:
Object
  • Object
show all
Defined in:
lib/happymapper/differ.rb

Overview

Differ compares the differences betwee two HappyMapper objects.

Two step process First step is map all nodes into a DiffedItem Step two is present all the changes via DiffedItem.changes

Constant Summary collapse

VERSION = 
"0.2"

Instance Method Summary collapse

Constructor Details

#initialize(left, right) ⇒ Differ

Returns a new instance of Differ.



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# File 'lib/happymapper/differ.rb', line 12

def initialize(left, right)
  @left = left
  @right = right
end

Instance Method Details

#diff ⇒ Object

Diff is a method to find what elements and attributes have changed and how.It extends each element and attribute with the DiffedItem module



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# File 'lib/happymapper/differ.rb', line 19

def diff
  @left = DiffedItem.create(@left, @right)

  # setup for each element (has_one and has_many) and attribute
  all_items.each do |item|
    lvalue = get_value(@left, item.name) 
    rvalue = get_value(@right, item.name)

    # skip if both sides are nil
    next if rvalue.nil? && lvalue.nil?

    if ! item.options[:single]
      setup_element(lvalue, rvalue)
      # Find the side with the most items. If the right has more, the left
      # will be padded with UnExtendable instances
      count = [lvalue.size, (rvalue || []).size].max

      count.times do |i|
        lvalue[i] = setup_element(lvalue[i], (rvalue || [])[i])
      end
    else
      lvalue = setup_element(lvalue, rvalue)
    end

    @left.send("#{item.name}=", lvalue)
  end

  @left
end