65 lines
2.2 KiB
Ruby
65 lines
2.2 KiB
Ruby
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# When provided a diff for a specific file, maps old line numbers to new line
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# numbers and back, to find out where a specific line in a file was moved by the
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# changes.
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module Gitlab
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module Diff
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class LineMapper
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attr_accessor :diff_file
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def initialize(diff_file)
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@diff_file = diff_file
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end
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# Find new line number for old line number.
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def old_to_new(old_line)
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map_line_number(old_line, from: :old_line, to: :new_line)
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end
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# Find old line number for new line number.
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def new_to_old(new_line)
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map_line_number(new_line, from: :new_line, to: :old_line)
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end
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private
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def diff_lines
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@diff_lines ||= @diff_file.diff_lines
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end
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# Find old/new line number based on its old/new counterpart line number.
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def map_line_number(from_line, from:, to:)
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# If no diff file could be found, the file wasn't changed, and the
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# mapped line number is the same as the specified line number.
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return from_line unless diff_file
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# To find the mapped line number for the specified line number,
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# we need to find:
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# - The diff line with that exact line number, if it is in the diff context
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# - The first diff line with a higher line number, if it falls between diff contexts
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# - The last known diff line, if it falls after the last diff context
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diff_line = diff_lines.find do |diff_line|
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diff_from_line = diff_line.send(from)
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diff_from_line && diff_from_line >= from_line
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end
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diff_line ||= diff_lines.last
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# If no diff line could be found, the file wasn't changed, and the
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# mapped line number is the same as the specified line number.
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return from_line unless diff_line
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diff_from_line = diff_line.send(from)
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diff_to_line = diff_line.send(to)
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# If the line was removed, there is no mapped line number.
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return unless diff_to_line
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# Because we may not have the diff line with the exact line number
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# we were looking for, we need to adjust the mapped line number.
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distance = diff_from_line - from_line
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diff_to_line - distance
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end
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end
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end
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end
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