Class: Invoca::Utils::Diff

Inherits:
Object
  • Object
show all
Defined in:
lib/invoca/utils/diff.rb

Constant Summary collapse

LCS = 
::Diff::LCS
VERSION = 
0.3

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(a, b) ⇒ Diff

Returns a new instance of Diff.



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# File 'lib/invoca/utils/diff.rb', line 226

def initialize(a, b)
  @difftype = a.class
  @diffs    = []
  @curdiffs = []
  makediff(a, b)
end

Instance Attribute Details

#diffs ⇒ Object (readonly)

Returns the value of attribute diffs.



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# File 'lib/invoca/utils/diff.rb', line 224

def diffs
  @diffs
end

#difftype ⇒ Object (readonly)

Returns the value of attribute difftype.



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# File 'lib/invoca/utils/diff.rb', line 224

def difftype
  @difftype
end

Class Method Details

.compare(arg1, arg2, options = {}) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 81

def self.compare arg1, arg2, options = {}
  result = ''
  if arg1 != arg2
    if arg1.class == arg2.class || (arg1.is_a?(Hash) && arg2.is_a?(Hash)) || (arg1.is_a?(Array) && arg2.is_a?(Array)) # Hash and Array are equivalent when specialized
      case arg1
      when Array
        diff_obj  = Diff.new(arg1, arg2)
        summary   = diff_obj.summary
        curr_diff = nil
        (arg1 + [nil]).each_with_index do |arg, index|
          if curr_diff.nil? || index > curr_diff[1].last
            curr_diff = summary.shift
          end
          unless curr_diff && (curr_diff[1].first..curr_diff[1].last) === index
            result += "  #{format arg}\n" unless arg.nil? || options[:short_description]
          end
          if curr_diff && curr_diff[1].first == index
            verb, _a_range, _b_range, del, add = curr_diff
            result +=
              case verb
              when 'd'
                del.map { |t| "- #{format t}\n" }.join
              when 'a'
                add.map { |t| "+ #{format t}\n" }.join +
                  (arg.nil? ? '' : "  #{format arg}\n")
              when 'c'
                del.map_with_index { |t, del_index| "- #{format t}\n#{nested_compare(del, add, del_index)}" }.join +
                  add.map { |t| "+ #{format t}\n" }.join
              end
          end
        end
        summary.empty? or raise "Summary left: #{summary.inspect}"
      when Hash
        arg1.each do |key, value|
          if arg2.has_key? key
            result += "[#{key.inspect}] #{compare value, arg2[key]};\n" if value != arg2[key]
          else
            result += "[#{key.inspect}] expected #{value.inspect}, was missing;\n"
          end
        end
        (arg2.keys - arg1.keys).each do |key|
          result += "[#{key.inspect}] not expected, was #{arg2[key].inspect};\n"
        end
      else
        result = "expected #{arg1.inspect}, was #{arg2.inspect} "
      end
    elsif arg1.class.in?([Float, BigDecimal]) && arg2.class.in?([Float, BigDecimal])
      result = "expected #{arg1.class}: #{arg1.to_s}, was #{arg2.class}: #{arg2.to_s} "
    else
      result = "expected #{arg1.class}:#{arg1.inspect}, was #{arg2.class}:#{arg2.inspect} "
    end
  end
  result
end

.format(value) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 77

def self.format(value)
  value.is_a?(Numeric) || value.is_a?(String) ? value : value.inspect
end

.lcs(a, b) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 15

def self.lcs(a, b)
  astart  = 0
  bstart  = 0
  afinish = a.length - 1
  bfinish = b.length - 1
  lcs     = []

  # First we prune off any common elements at the beginning
  while (astart <= afinish && bstart <= afinish && a[astart] == b[bstart])
    lcs[astart] = bstart
    astart      += 1
    bstart      += 1
  end

  # now the end
  while (astart <= afinish && bstart <= bfinish && a[afinish] == b[bfinish])
    lcs[afinish] = bfinish
    afinish      -= 1
    bfinish      -= 1
  end

  bmatches = reverse_hash(b, bstart..bfinish)
  thresh   = []
  links    = []

  (astart..afinish).each { |aindex|
    aelem = a[aindex]
    next unless bmatches.has_key? aelem
    k = nil
    bmatches[aelem].reverse.each { |bindex|
      if k && (thresh[k] > bindex) && (thresh[k - 1] < bindex)
        thresh[k] = bindex
      else
        k = replacenextlarger(thresh, bindex, k)
      end
      links[k] = [(k == 0) ? nil : links[k - 1], aindex, bindex] if k
    }
  }

  if !thresh.empty?
    link = links[thresh.length - 1]
    while link
      lcs[link[1]] = link[2]
      link         = link[0]
    end
  end

  return lcs
end

.nested_compare(subtractions, additions, index) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 65

def self.nested_compare(subtractions, additions, index)
  subtraction = subtractions[index]
  addition    = additions[index]
  if subtraction.is_a?(Array) && addition.is_a?(Array)
    return "Nested array diff:\n#{ compare(subtraction, addition) }\n"
  elsif subtraction.is_a?(Hash) && addition.is_a?(Hash)
    return "Nested hash diff:\n#{ compare(subtraction, addition) }\n"
  else
    ""
  end
end

.patch(lhs, diff) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 294

def self.patch(lhs, diff)
  newary = nil
  if diff.difftype == String
    newary = diff.difftype.new('')
  else
    newary = diff.difftype.new
  end
  ai = 0
  bi = 0
  diff.diffs.each { |d|
    d.each { |mod|
      case mod[0]
      when '-'
        while ai < mod[1]
          newary << lhs[ai]
          ai += 1
          bi += 1
        end
        ai += 1
      when '+'
        while bi < mod[1]
          newary << lhs[ai]
          ai += 1
          bi += 1
        end
        newary << mod[2]
        bi += 1
      else
        raise "Unknown diff action"
      end
    }
  }
  while ai < lhs.length
    newary << lhs[ai]
    ai += 1
    bi += 1
  end
  return newary
end

.replacenextlarger(lhs, value, high = nil) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 267

def self.replacenextlarger(lhs, value, high = nil)
  high ||= lhs.length
  if lhs.empty? || value > lhs[-1]
    lhs.push value
    return high
  end
  # binary search for replacement point
  low = 0
  while low < high
    index = (high + low) / 2
    found = lhs[index]
    return nil if value == found
    if value > found
      low = index + 1
    else
      high = index
    end
  end

  lhs[low] = value
  # $stderr << "replace #{value} : 0/#{low}/#{init_high} (#{steps} steps) (#{init_high-low} off )\n"
  # $stderr.puts lhs.inspect
  #gets
  #p length - low
  return low
end

.reverse_hash(lhs, range = nil) ⇒ Object

Create a hash that maps elements of the array to arrays of indices where the elements are found.



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# File 'lib/invoca/utils/diff.rb', line 253

def self.reverse_hash(lhs, range = nil)
  range  ||= (0...lhs.length)
  revmap = {}
  range.each { |i|
    elem = lhs[i]
    if revmap.has_key? elem
      revmap[elem].push i
    else
      revmap[elem] = [i]
    end
  }
  return revmap
end

Instance Method Details

#compact ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 189

def compact
  result = self.dup
  result.compact!
  result
end

#compact! ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 164

def compact!
  diffs = []
  @diffs.each do |diff|
    puts "compacting #{diff.inspect}"
    i       = 0
    curdiff = []
    while i < diff.length
      action = diff[i][0]
      s      = @difftype.is_a?(String) ? diff[i][2, 1] : [diff[i][2]]
      offset = diff[i][1]
      last   = offset
      i      += 1
      while diff[i] && diff[i][0] == action && diff[i][1] == last + 1
        s << diff[i][2]
        last = diff[i][1]
        i    += 1
      end
      curdiff.push [action, offset, s]
    end
    diffs.push curdiff
  end
  @diffs = diffs
  self
end

#discarda(i, elem) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 238

def discarda(i, elem)
  @curdiffs.push ['-', i, elem]
end

#discardb(i, elem) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 242

def discardb(i, elem)
  @curdiffs.push ['+', i, elem]
end

#inspect ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 246

def inspect
  @diffs.inspect
end

#makediff(a, b) ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 137

def makediff(a, b)
  lcs = self.class.lcs(a, b)
  ai  = bi = 0
  while ai < lcs.length
    if lcs[ai]
      while bi < lcs[ai]
        discardb(bi, b[bi])
        bi += 1
      end
      match
      bi += 1
    else
      discarda(ai, a[ai])
    end
    ai += 1
  end
  while ai < a.length
    discarda(ai, a[ai])
    ai += 1
  end
  while bi < b.length
    discardb(bi, b[bi])
    bi += 1
  end
  match
end

#match ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 233

def match
  @diffs << @curdiffs unless @curdiffs.empty?
  @curdiffs = []
end

#summary ⇒ Object 



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# File 'lib/invoca/utils/diff.rb', line 195

def summary
  result   = []
  b_offset = 0
  @diffs.each do |block|
    del = []
    add = []
    block.each do |diff|
      case diff[0]
      when "-"
        del << diff[2]
      when "+"
        add << diff[2]
      end
    end
    first                  = block[0][1]
    verb, a_range, b_range =
      if del.empty?
        ['a', [first - b_offset, first - b_offset], [first, first + add.size - 1]]
      elsif add.empty?
        ['d', [first, first + del.size - 1], [first + b_offset, first + b_offset]]
      else
        ['c', [first, first + del.size - 1], [first + b_offset, first + b_offset + add.size - 1]]
      end
    b_offset               = b_offset + add.size - del.size
    result << [verb, a_range, b_range, del, add]
  end
  result
end