Đây là thuật toán để so sánh sâu hai hàm băm, cũng sẽ so sánh các Mảng lồng nhau:
HashDiff.new(
{val: 1, nested: [{a:1}, {b: [1, 2]}] },
{val: 2, nested: [{a:1}, {b: [1]}] }
).report
# Output:
val:
- 1
+ 2
nested > 1 > b > 1:
- 2
Thực hiện:
class HashDiff
attr_reader :left, :right
def initialize(left, right, config = {}, path = nil)
@left = left
@right = right
@config = config
@path = path
@conformity = 0
end
def conformity
find_differences
@conformity
end
def report
@config[:report] = true
find_differences
end
def find_differences
if hash?(left) && hash?(right)
compare_hashes_keys
elsif left.is_a?(Array) && right.is_a?(Array)
compare_arrays
else
report_diff
end
end
def compare_hashes_keys
combined_keys.each do |key|
l = value_with_default(left, key)
r = value_with_default(right, key)
if l == r
@conformity += 100
else
compare_sub_items l, r, key
end
end
end
private
def compare_sub_items(l, r, key)
diff = self.class.new(l, r, @config, path(key))
@conformity += diff.conformity
end
def report_diff
return unless @config[:report]
puts "#{@path}:"
puts "- #{left}" unless left == NO_VALUE
puts "+ #{right}" unless right == NO_VALUE
end
def combined_keys
(left.keys + right.keys).uniq
end
def hash?(value)
value.is_a?(Hash)
end
def compare_arrays
l, r = left.clone, right.clone
l.each_with_index do |l_item, l_index|
max_item_index = nil
max_conformity = 0
r.each_with_index do |r_item, i|
if l_item == r_item
@conformity += 1
r[i] = TAKEN
break
end
diff = self.class.new(l_item, r_item, {})
c = diff.conformity
if c > max_conformity
max_conformity = c
max_item_index = i
end
end or next
if max_item_index
key = l_index == max_item_index ? l_index : "#{l_index}/#{max_item_index}"
compare_sub_items l_item, r[max_item_index], key
r[max_item_index] = TAKEN
else
compare_sub_items l_item, NO_VALUE, l_index
end
end
r.each_with_index do |item, index|
compare_sub_items NO_VALUE, item, index unless item == TAKEN
end
end
def path(key)
p = "#{@path} > " if @path
"#{p}#{key}"
end
def value_with_default(obj, key)
obj.fetch(key, NO_VALUE)
end
module NO_VALUE; end
module TAKEN; end
end