Class: Goat::DOMDiff

Inherits:
Object show all
Defined in:
lib/goat.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(old, new, id) ⇒ DOMDiff

Returns a new instance of DOMDiff.



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# File 'lib/goat.rb', line 889

def initialize(old, new, id)
  @old = old
  @new = new
  @id = id
  @diffs = []
end

Class Method Details

.diff(old, new, id) ⇒ Object 



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# File 'lib/goat.rb', line 885

def self.diff(old, new, id)
  self.new(old, new, id).diff
end

Instance Method Details

#added(new, par, pos = nil) ⇒ Object 



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# File 'lib/goat.rb', line 934

def added(new, par, pos=nil); [:add, new, par, pos]; end

#array_desc(old, new, par) ⇒ Object 



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# File 'lib/goat.rb', line 966

def array_desc(old, new, par)
  #$stderr.puts "array_desc #{old.inspect} #{new.inspect} #{par.inspect}"

  chgs = Diff::LCS.diff(old, new).map do |diff|
    #$stderr.puts "diff: #{diff.inspect}"
    if is_replacement?(diff[0], diff[1])
      dold, dnew = old_and_new(diff[0], diff[1])
      old = dold.element
      new = dnew.element
      if dom_node?(old) && dom_node?(new) && tag(old) == tag(new) && compare_attrs(old, new)
        localized_change(dold, dnew, par, desc(body(old), body(new), domid(old)))
      elsif old.is_a?(Array) && new.is_a?(Array) #&& old.all?{|x| !dom_node?(x)} && new.all?{|x| !dom_node?(x)}
        array_desc(old, new, par)
      else
        [added(new, par, diff[1].position), removed(old, par, diff[0].position)]
      end
    else
      if diff.size == 1
        diff = diff[0]
        if diff.action == '+'
          [added(diff.element, par, diff.position)]
        elsif diff.action == '-'
          [removed(diff.element, par, diff.position)]
        else
          raise "Don't understand diff in a bad way"
        end
      else
        $stderr.puts "Don't understand diff"
        #$stderr.puts "Diff failed"
        raise JustRerenderError
      end
    end
  end

  chgs.flatten(1)
end

#attrs(node) ⇒ Object 



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# File 'lib/goat.rb', line 941

def attrs(node); node[1] if node[1].is_a?(Hash); end

#body(node) ⇒ Object 



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# File 'lib/goat.rb', line 942

def body(node); node[1].is_a?(Hash) ? node[2..-1] : node[1..-1]; end

#compare_attrs(a, b) ⇒ Object 



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# File 'lib/goat.rb', line 1003

def compare_attrs(a, b)
  if a.is_a?(Hash) && b.is_a?(Hash)
    a_, b_ = a.clone, b.clone
    a.select{|k,v| a_.delete(k) if v =~ /^dom_/}
    b.select{|k,v| b_.delete(k) if v =~ /^dom_/}
    a_ == b_
  else
    false
  end
end

#desc(old, new, par) ⇒ Object 



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# File 'lib/goat.rb', line 1032

def desc(old, new, par)
  #$stderr.puts "desc #{old.inspect} #{new.inspect} #{par.inspect}"
  #$stderr.puts "desc #{self.class.name} #{par.inspect}"

  if old.class != new.class
    [added(new, par), removed(old, par)]
  elsif old.is_a?(Array)
    dom_node?(old) ? node_desc(old, new, domid(old)) : array_desc(old, new, par)
  elsif old.is_a?(String)
    if old != new
      [added(new, par), removed(old, par)]
    end
  else
    raise TypeError.new("Unknown object in the DOM: #{old.class} #{new.class}")
  end
end

#diff ⇒ Object 



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# File 'lib/goat.rb', line 896

def diff
  nested_application(minimized_changes(desc(@old, @new, @id)))
end

#dom_node?(node) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/goat.rb', line 937

def dom_node?(node)
  node.is_a?(Array) && node.first.is_a?(Symbol)
end

#domid(node) ⇒ Object 



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# File 'lib/goat.rb', line 943

def domid(node); attrs(node) ? attrs(node)[:id] : nil; end

#is_replacement?(d1, d2) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/goat.rb', line 956

def is_replacement?(d1, d2)
  d1 && d2 && (
    (d1.action == '+' && d2.action == '-') ||
    (d1.action == '-' && d2.action == '+'))
end

#localized_change(dold, dnew, par, changes) ⇒ Object 



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# File 'lib/goat.rb', line 945

def localized_change(dold, dnew, par, changes)
  old = dold.element
  new = dnew.element
  #$stderr.puts "changes: #{changes.inspect} / #{old.inspect} / #{par.inspect}"
  if changes.all?{|ch| ch[2].nil?} && par
    [added(new, par, dold.position), removed(old, par, dnew.position)]
  else
    changes
  end
end

#minimized_changes(ch) ⇒ Object 



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# File 'lib/goat.rb', line 916

def minimized_changes(ch)
  new = []
  merged = Set.new
  ch.each do |c|
    if c[0] == :rem
      if n = ch.detect{|x| x[0] == :add && x[2] == c[2] && x[3] == c[3]}
        new << [:rep, *n[1..3]]
        merged << n
      else
        new << c
      end
    else
      new << c
    end
  end
  new.reject{|c| merged.include?(c)}
end

#nested_application(ch) ⇒ Object 



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# File 'lib/goat.rb', line 900

def nested_application(ch)
  applied = Set.new

  ch.sort_by{|x| x[3]}.each do |c|
    if (c[0] == :rem || c[0] == :add) && !applied.include?(c)
      if n = ch.detect{|x| x != c && x[2] == c[2] && x[3] >= c[3]}
        n[3] += (c[0] == :rem) ? -1 : 1
      end
    end

    applied << c
  end

  ch
end

#node_desc(old, new, par) ⇒ Object 



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# File 'lib/goat.rb', line 1014

def node_desc(old, new, par)
  #$stderr.puts "node_desc #{old.inspect} #{new.inspect} #{par.inspect}"

  if tag(old) != tag(new) || !compare_attrs(old, new)
    [removed(old, par), added(new, par)]
  else # only body changed (maybe)
    bold = body(old)
    bnew = body(new)
    if bold && bnew
      desc(bold, bnew, domid(old))
    elsif bold && !bnew
      [removed(bold, domid(old))]
    else
      [added(bnew, domid(old))]
    end
  end
end

#old_and_new(d1, d2) ⇒ Object 



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# File 'lib/goat.rb', line 962

def old_and_new(d1, d2)
  d1.action == '+' ? [d2, d1] : [d1, d2]
end

#removed(old, par, pos = nil) ⇒ Object 



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# File 'lib/goat.rb', line 935

def removed(old, par, pos=nil); [:rem, old, par, pos]; end

#tag(node) ⇒ Object 



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# File 'lib/goat.rb', line 940

def tag(node); node[0]; end