117 lines
3.4 KiB
Ruby
117 lines
3.4 KiB
Ruby
module Gitlab
|
|
module Diff
|
|
class InlineDiff
|
|
# Regex to find a run of deleted lines followed by the same number of added lines
|
|
LINE_PAIRS_PATTERN = %r{
|
|
# Runs start at the beginning of the string (the first line) or after a space (for an unchanged line)
|
|
(?:\A|\s)
|
|
|
|
# This matches a number of `-`s followed by the same number of `+`s through recursion
|
|
(?<del_ins>
|
|
-
|
|
\g<del_ins>?
|
|
\+
|
|
)
|
|
|
|
# Runs end at the end of the string (the last line) or before a space (for an unchanged line)
|
|
(?=\s|\z)
|
|
}x.freeze
|
|
|
|
attr_accessor :old_line, :new_line, :offset
|
|
|
|
def initialize(old_line, new_line, offset: 0)
|
|
@old_line = old_line[offset..-1]
|
|
@new_line = new_line[offset..-1]
|
|
@offset = offset
|
|
end
|
|
|
|
def inline_diffs
|
|
# Skip inline diff if empty line was replaced with content
|
|
return if old_line == ""
|
|
|
|
lcp = longest_common_prefix(old_line, new_line)
|
|
lcs = longest_common_suffix(old_line[lcp..-1], new_line[lcp..-1])
|
|
|
|
lcp += offset
|
|
old_length = old_line.length + offset
|
|
new_length = new_line.length + offset
|
|
|
|
old_diff_range = lcp..(old_length - lcs - 1)
|
|
new_diff_range = lcp..(new_length - lcs - 1)
|
|
|
|
old_diffs = [old_diff_range] if old_diff_range.begin <= old_diff_range.end
|
|
new_diffs = [new_diff_range] if new_diff_range.begin <= new_diff_range.end
|
|
|
|
[old_diffs, new_diffs]
|
|
end
|
|
|
|
class << self
|
|
def for_lines(lines)
|
|
changed_line_pairs = find_changed_line_pairs(lines)
|
|
|
|
inline_diffs = []
|
|
|
|
changed_line_pairs.each do |old_index, new_index|
|
|
old_line = lines[old_index]
|
|
new_line = lines[new_index]
|
|
|
|
old_diffs, new_diffs = new(old_line, new_line, offset: 1).inline_diffs
|
|
|
|
inline_diffs[old_index] = old_diffs
|
|
inline_diffs[new_index] = new_diffs
|
|
end
|
|
|
|
inline_diffs
|
|
end
|
|
|
|
private
|
|
|
|
# Finds pairs of old/new line pairs that represent the same line that changed
|
|
def find_changed_line_pairs(lines)
|
|
# Prefixes of all diff lines, indicating their types
|
|
# For example: `" - + -+ ---+++ --+ -++"`
|
|
line_prefixes = lines.each_with_object("") { |line, s| s << (line[0] || ' ') }.gsub(/[^ +-]/, ' ')
|
|
|
|
changed_line_pairs = []
|
|
line_prefixes.scan(LINE_PAIRS_PATTERN) do
|
|
# For `"---+++"`, `begin_index == 0`, `end_index == 6`
|
|
begin_index, end_index = Regexp.last_match.offset(:del_ins)
|
|
|
|
# For `"---+++"`, `changed_line_count == 3`
|
|
changed_line_count = (end_index - begin_index) / 2
|
|
|
|
halfway_index = begin_index + changed_line_count
|
|
(begin_index...halfway_index).each do |i|
|
|
# For `"---+++"`, index 1 maps to 1 + 3 = 4
|
|
changed_line_pairs << [i, i + changed_line_count]
|
|
end
|
|
end
|
|
|
|
changed_line_pairs
|
|
end
|
|
end
|
|
|
|
private
|
|
|
|
def longest_common_prefix(a, b)
|
|
max_length = [a.length, b.length].max
|
|
|
|
length = 0
|
|
(0..max_length - 1).each do |pos|
|
|
old_char = a[pos]
|
|
new_char = b[pos]
|
|
|
|
break if old_char != new_char
|
|
|
|
length += 1
|
|
end
|
|
|
|
length
|
|
end
|
|
|
|
def longest_common_suffix(a, b)
|
|
longest_common_prefix(a.reverse, b.reverse)
|
|
end
|
|
end
|
|
end
|
|
end
|