instiki/lib/diff.rb

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# heavily based off difflib.py - see that file for documentation
# ported from Python by Bill Atkins
# This does not support all features offered by difflib; it
# implements only the subset of features necessary
# to support a Ruby version of HTML Differ. You're welcome to finish this off.
# By default, String#each iterates by line. This isn't really appropriate
# for diff, so often a string will be split by // to get an array of one-
# character strings.
# Some methods in Diff are untested and are not guaranteed to work. The
# methods in HTMLDiff and any methods it calls should work quite well.
# changes by DenisMertz
# * main change:
# ** get the tag soup away
# the tag soup problem was first reported with <p> tags, but it appeared also with
# <li>, <ul> etc... tags
# this version should mostly fix these problems
# ** added a Builder class to manage the creation of the final htmldiff
# * minor changes:
# ** use symbols instead of string to represent opcodes
# ** small fix to html2list
#
module Enumerable
def reduce(init)
result = init
each { |item| result = yield(result, item) }
result
end
end
module Diff
class SequenceMatcher
def initialize(a=[''], b=[''], isjunk=nil, byline=false)
a = (!byline and a.kind_of? String) ? a.split(//) : a
b = (!byline and b.kind_of? String) ? b.split(//) : b
@isjunk = isjunk || proc {}
set_seqs a, b
end
def set_seqs(a, b)
set_seq_a a
set_seq_b b
end
def set_seq_a(a)
@a = a
@matching_blocks = @opcodes = nil
end
def set_seq_b(b)
@b = b
@matching_blocks = @opcodes = nil
chain_b
end
def chain_b
@fullbcount = nil
@b2j = {}
pophash = {}
junkdict = {}
@b.each_with_index do |elt, i|
if @b2j.has_key? elt
indices = @b2j[elt]
if @b.length >= 200 and indices.length * 100 > @b.length
pophash[elt] = 1
indices.clear
else
indices.push i
end
else
@b2j[elt] = [i]
end
end
pophash.each_key { |elt| @b2j.delete elt }
junkdict = {}
unless @isjunk.nil?
[pophash, @b2j].each do |d|
d.each_key do |elt|
if @isjunk.call(elt)
junkdict[elt] = 1
d.delete elt
end
end
end
end
@isbjunk = junkdict.method(:has_key?)
@isbpopular = junkdict.method(:has_key?)
end
def find_longest_match(alo, ahi, blo, bhi)
besti, bestj, bestsize = alo, blo, 0
j2len = {}
(alo..ahi).step do |i|
newj2len = {}
(@b2j[@a[i]] || []).each do |j|
if j < blo
next
end
if j >= bhi
break
end
k = newj2len[j] = (j2len[j - 1] || 0) + 1
if k > bestsize
besti, bestj, bestsize = i - k + 1, j - k + 1, k
end
end
j2len = newj2len
end
while besti > alo and bestj > blo and
not @isbjunk.call(@b[bestj-1]) and
@a[besti-1] == @b[bestj-1]
besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
end
while besti+bestsize < ahi and bestj+bestsize < bhi and
not @isbjunk.call(@b[bestj+bestsize]) and
@a[besti+bestsize] == @b[bestj+bestsize]
bestsize += 1
end
while besti > alo and bestj > blo and
@isbjunk.call(@b[bestj-1]) and
@a[besti-1] == @b[bestj-1]
besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
end
while besti+bestsize < ahi and bestj+bestsize < bhi and
@isbjunk.call(@b[bestj+bestsize]) and
@a[besti+bestsize] == @b[bestj+bestsize]
bestsize += 1
end
[besti, bestj, bestsize]
end
def get_matching_blocks
return @matching_blocks unless @matching_blocks.nil? or
@matching_blocks.empty?
@matching_blocks = []
la, lb = @a.length, @b.length
match_block_helper(0, la, 0, lb, @matching_blocks)
@matching_blocks.push [la, lb, 0]
end
def match_block_helper(alo, ahi, blo, bhi, answer)
i, j, k = x = find_longest_match(alo, ahi, blo, bhi)
if not k.zero?
if alo < i and blo < j
match_block_helper(alo, i, blo, j, answer)
end
answer.push x
if i + k < ahi and j + k < bhi
match_block_helper(i + k, ahi, j + k, bhi, answer)
end
end
end
def get_opcodes
unless @opcodes.nil? or @opcodes.empty?
return @opcodes
end
i = j = 0
@opcodes = answer = []
get_matching_blocks.each do |ai, bj, size|
tag = if i < ai and j < bj
:replace
elsif i < ai
:delete
elsif j < bj
:insert
end
answer.push [tag, i, ai, j, bj] if tag
i, j = ai + size, bj + size
answer.push [:equal, ai, i, bj, j] unless size.zero?
end
return answer
end
# XXX: untested
def get_grouped_opcodes(n=3)
codes = get_opcodes
if codes[0][0] == :equal
tag, i1, i2, j1, j2 = codes[0]
codes[0] = tag, [i1, i2 - n].max, i2, [j1, j2-n].max, j2
end
if codes[-1][0] == :equal
tag, i1, i2, j1, j2 = codes[-1]
codes[-1] = tag, i1, min(i2, i1+n), j1, min(j2, j1+n)
end
nn = n + n
group = []
codes.each do |tag, i1, i2, j1, j2|
if tag == :equal and i2-i1 > nn
group.push [tag, i1, [i2, i1 + n].min, j1, [j2, j1 + n].min]
yield group
group = []
i1, j1 = [i1, i2-n].max, [j1, j2-n].max
group.push [tag, i1, i2, j1 ,j2]
end
end
if group and group.length != 1 and group[0][0] == :equal
yield group
end
end
def ratio
matches = get_matching_blocks.reduce(0) do |sum, triple|
sum + triple[-1]
end
Diff.calculate_ratio(matches, @a.length + @b.length)
end
def quick_ratio
if @fullbcount.nil? or @fullbcount.empty?
@fullbcount = {}
@b.each do |elt|
@fullbcount[elt] = (@fullbcount[elt] || 0) + 1
end
end
avail = {}
matches = 0
@a.each do |elt|
if avail.has_key? elt
numb = avail[elt]
else
numb = @fullbcount[elt] || 0
end
avail[elt] = numb - 1
if numb > 0
matches += 1
end
end
Diff.calculate_ratio matches, @a.length + @b.length
end
def real_quick_ratio
la, lb = @a.length, @b.length
Diff.calculate_ratio([la, lb].min, la + lb)
end
protected :chain_b, :match_block_helper
end # end class SequenceMatcher
def self.calculate_ratio(matches, length)
return 1.0 if length.zero?
2.0 * matches / length
end
# XXX: untested
def self.get_close_matches(word, possibilities, n=3, cutoff=0.6)
unless n > 0
raise "n must be > 0: #{n}"
end
unless 0.0 <= cutoff and cutoff <= 1.0
raise "cutoff must be in (0.0..1.0): #{cutoff}"
end
result = []
s = SequenceMatcher.new
s.set_seq_b word
possibilities.each do |x|
s.set_seq_a x
if s.real_quick_ratio >= cutoff and
s.quick_ratio >= cutoff and
s.ratio >= cutoff
result.push [s.ratio, x]
end
end
unless result.nil? or result.empty?
result.sort
result.reverse!
result = result[-n..-1]
end
result.collect { |score, x| x }
end
def self.count_leading(line, ch)
i, n = 0, line.length
while i < n and line[i].chr == ch
i += 1
end
i
end
end
module HTMLDiff
include Diff
class Builder
VALID_METHODS = [:replace, :insert, :delete, :equal]
def initialize(a, b)
@a = a
@b = b
@content = []
end
def do_op(opcode)
@opcode = opcode
op = @opcode[0]
VALID_METHODS.include?(op) or raise(NameError, "Invalid opcode #{op}")
self.method(op).call
end
def result
@content.join('')
end
#this methods have to be called via do_op(opcode) so that @opcode is set properly
private
def replace
delete("diffmod")
insert("diffmod")
end
def insert(tagclass="diffins")
op_helper("ins", tagclass, @b[@opcode[3]...@opcode[4]])
end
def delete(tagclass="diffdel")
op_helper("del", tagclass, @a[@opcode[1]...@opcode[2]])
end
def equal
@content += @b[@opcode[3]...@opcode[4]]
end
# using this as op_helper would be equivalent to the first version of diff.rb by Bill Atkins
def op_helper_simple(tagname, tagclass, to_add)
@content << "<#{tagname} class=\"#{tagclass}\">"
@content += to_add
@content << "</#{tagname}>"
end
# this tries to put <p> tags or newline chars before the opening diff tags (<ins> or <del>)
# or after the ending diff tags
# as a result the diff tags should be the "more inside" possible.
# this seems to work nice with html containing only paragraphs
# but not sure it works if there are other tags (div, span ... ? ) around
def op_helper(tagname, tagclass, to_add)
@content << to_add.shift while ( HTMLDiff.is_newline(to_add.first) or
HTMLDiff.is_p_close_tag(to_add.first) or
HTMLDiff.is_p_open_tag(to_add.first) )
@content << "<#{tagname} class=\"#{tagclass}\">"
@content += to_add
last_tags = []
last_tags.unshift(@content.pop) while ( HTMLDiff.is_newline(@content.last) or
HTMLDiff.is_p_close_tag(@content.last) or
HTMLDiff.is_p_open_tag(@content.last) )
last_tags.unshift "</#{tagname}>"
@content += last_tags
remove_empty_diff(tagname, tagclass)
end
def remove_empty_diff(tagname, tagclass)
if @content[-2] == "<#{tagname} class=\"#{tagclass}\">" and @content[-1] == "</#{tagname}>" then
@content.pop
@content.pop
end
end
end
def self.is_newline(x)
(x == "\n") or (x == "\r") or (x == "\t")
end
def self.is_p_open_tag(x)
x =~ /\A<(p|li|ul|ol|dir|dt|dl)/
end
def self.is_p_close_tag(x)
x =~ %r!\A</(p|li|ul|ol|dir|dt|dl)!
end
def self.diff(a, b)
a = html2list(a)
b = html2list(b)
out = Builder.new(a, b)
s = SequenceMatcher.new(a, b)
s.get_opcodes.each do |opcode|
out.do_op(opcode)
end
out.result
end
def self.html2list(x)
mode = :char
cur = ''
out = []
x.split('').each do |c|
if mode == :tag
cur += c
if c == '>'
out.push(cur)
cur = ''
mode = :char
end
elsif mode == :char
if c == '<'
out.push cur
cur = c
mode = :tag
elsif c =~ /\s/
out.push cur + c
cur = ''
else
cur += c
end
end
end
out.push cur
out.find_all { |x| x != '' }
end
end