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# frozen_string_literal: true
module Unparser
# Class to create diffs from source code
class Diff
include Adamantium, Concord.new(:old, :new)
ADDITION = '+'
DELETION = '-'
NEWLINE = "\n"
# Unified source diff between old and new
#
# @return [String]
# if there is exactly one diff
#
# @return [nil]
# otherwise
def diff
return if diffs.empty?
minimized_hunk.diff(:unified) + NEWLINE
end
memoize :diff
# Colorized unified source diff between old and new
#
# @return [String]
# if there is a diff
#
# @return [nil]
# otherwise
def colorized_diff
return unless diff
diff.lines.map(&self.class.method(:colorize_line)).join
end
memoize :colorized_diff
# Build new object from source strings
#
# @param [String] old
# @param [String] new
#
# @return [Diff]
def self.build(old, new)
new(lines(old), lines(new))
end
# Break up source into lines
#
# @param [String] source
#
# @return [Array<String>]
def self.lines(source)
source.lines.map(&:chomp)
end
private_class_method :lines
private
def diffs
::Diff::LCS.diff(old, new)
end
def hunks
diffs.map do |diff|
::Diff::LCS::Hunk.new(old.map(&:dup), new, diff, max_length, 0)
end
end
def minimized_hunk
head, *tail = hunks
tail.reduce(head) do |left, right|
right.merge(left)
right
end
end
def max_length
[old, new].map(&:length).max
end
def self.colorize_line(line)
case line[0]
when ADDITION
Color::GREEN
when DELETION
Color::RED
else
Color::NONE
end.format(line)
end
private_class_method :colorize_line
end # Diff
end # Unparser
|
