vim-patch:9.1.1557: not possible to anchor specific lines in difff mode #34967
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Problem: not possible to anchor specific lines in difff mode
Solution: Add support for the anchoring lines in diff mode using the
'diffanchor' option (Yee Cheng Chin).
Adds support for anchoring specific lines to each other while viewing a
diff. While lines are anchored, they are guaranteed to be aligned to
each other in a diff view, allowing the user to control and inform the
diff algorithm what the desired alignment is. Internally, this is done
by splitting up the buffer at each anchor and run the diff algorithm on
each split section separately, and then merge the results back for a
logically consistent diff result.
To do this, add a new "diffanchors" option that takes a list of
`{address}`, and a new "diffopt" option value "anchor". Each address
specified will be an anchor, and the user can choose to use any type of
address, including marks, line numbers, or pattern search. Anchors are
sorted by line number in each file, and it's possible to have multiple
anchors on the same line (this is useful when doing multi-buffer diff).
Update documentation to provide examples.
This is similar to Git diff's `--anchored` flag. Other diff tools like
Meld/Araxis Merge also have similar features (called "synchronization
points" or "synchronization links"). We are not using Git/Xdiff's
`--anchored` implementation here because it has a very limited API
(it requires usage of the Patience algorithm, and can only anchor
unique lines that are the same across both files).
Because the user could anchor anywhere, diff anchors could result in
adjacent diff blocks (one block is directly touching another without a
gap), if there is a change right above the anchor point. We don't want
to merge these diff blocks because we want to line up the change at the
anchor. Adjacent diff blocks were first allowed when linematch was
added, but the existing code had a lot of branched paths where
line-matched diff blocks were handled differently. As a part of this
change, refactor them to have a more unified code path that is
generalized enough to handle adjacent diff blocks correctly and without
needing to carve in exceptions all over the place.
closes: vim/vim#17615
vim/vim@0d9160e
Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>
justinmk
approved these changes
Jul 17, 2025
AungMyoKyaw
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to AungMyoKyaw/neovim
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Jul 20, 2025
neovim#34967) Problem: not possible to anchor specific lines in diff mode Solution: Add support for the anchoring lines in diff mode using the 'diffanchor' option (Yee Cheng Chin). Adds support for anchoring specific lines to each other while viewing a diff. While lines are anchored, they are guaranteed to be aligned to each other in a diff view, allowing the user to control and inform the diff algorithm what the desired alignment is. Internally, this is done by splitting up the buffer at each anchor and run the diff algorithm on each split section separately, and then merge the results back for a logically consistent diff result. To do this, add a new "diffanchors" option that takes a list of `{address}`, and a new "diffopt" option value "anchor". Each address specified will be an anchor, and the user can choose to use any type of address, including marks, line numbers, or pattern search. Anchors are sorted by line number in each file, and it's possible to have multiple anchors on the same line (this is useful when doing multi-buffer diff). Update documentation to provide examples. This is similar to Git diff's `--anchored` flag. Other diff tools like Meld/Araxis Merge also have similar features (called "synchronization points" or "synchronization links"). We are not using Git/Xdiff's `--anchored` implementation here because it has a very limited API (it requires usage of the Patience algorithm, and can only anchor unique lines that are the same across both files). Because the user could anchor anywhere, diff anchors could result in adjacent diff blocks (one block is directly touching another without a gap), if there is a change right above the anchor point. We don't want to merge these diff blocks because we want to line up the change at the anchor. Adjacent diff blocks were first allowed when linematch was added, but the existing code had a lot of branched paths where line-matched diff blocks were handled differently. As a part of this change, refactor them to have a more unified code path that is generalized enough to handle adjacent diff blocks correctly and without needing to carve in exceptions all over the place. closes: vim/vim#17615 vim/vim@0d9160e Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>
dundargoc
pushed a commit
to dundargoc/neovim
that referenced
this pull request
Sep 27, 2025
neovim#34967) Problem: not possible to anchor specific lines in diff mode Solution: Add support for the anchoring lines in diff mode using the 'diffanchor' option (Yee Cheng Chin). Adds support for anchoring specific lines to each other while viewing a diff. While lines are anchored, they are guaranteed to be aligned to each other in a diff view, allowing the user to control and inform the diff algorithm what the desired alignment is. Internally, this is done by splitting up the buffer at each anchor and run the diff algorithm on each split section separately, and then merge the results back for a logically consistent diff result. To do this, add a new "diffanchors" option that takes a list of `{address}`, and a new "diffopt" option value "anchor". Each address specified will be an anchor, and the user can choose to use any type of address, including marks, line numbers, or pattern search. Anchors are sorted by line number in each file, and it's possible to have multiple anchors on the same line (this is useful when doing multi-buffer diff). Update documentation to provide examples. This is similar to Git diff's `--anchored` flag. Other diff tools like Meld/Araxis Merge also have similar features (called "synchronization points" or "synchronization links"). We are not using Git/Xdiff's `--anchored` implementation here because it has a very limited API (it requires usage of the Patience algorithm, and can only anchor unique lines that are the same across both files). Because the user could anchor anywhere, diff anchors could result in adjacent diff blocks (one block is directly touching another without a gap), if there is a change right above the anchor point. We don't want to merge these diff blocks because we want to line up the change at the anchor. Adjacent diff blocks were first allowed when linematch was added, but the existing code had a lot of branched paths where line-matched diff blocks were handled differently. As a part of this change, refactor them to have a more unified code path that is generalized enough to handle adjacent diff blocks correctly and without needing to carve in exceptions all over the place. closes: vim/vim#17615 vim/vim@0d9160e Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>
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vim-patch:9.1.1557: not possible to anchor specific lines in difff mode
Problem: not possible to anchor specific lines in difff mode
Solution: Add support for the anchoring lines in diff mode using the
'diffanchor' option (Yee Cheng Chin).
Adds support for anchoring specific lines to each other while viewing a
diff. While lines are anchored, they are guaranteed to be aligned to
each other in a diff view, allowing the user to control and inform the
diff algorithm what the desired alignment is. Internally, this is done
by splitting up the buffer at each anchor and run the diff algorithm on
each split section separately, and then merge the results back for a
logically consistent diff result.
To do this, add a new "diffanchors" option that takes a list of
{address}, and a new "diffopt" option value "anchor". Each addressspecified will be an anchor, and the user can choose to use any type of
address, including marks, line numbers, or pattern search. Anchors are
sorted by line number in each file, and it's possible to have multiple
anchors on the same line (this is useful when doing multi-buffer diff).
Update documentation to provide examples.
This is similar to Git diff's
--anchoredflag. Other diff tools likeMeld/Araxis Merge also have similar features (called "synchronization
points" or "synchronization links"). We are not using Git/Xdiff's
--anchoredimplementation here because it has a very limited API(it requires usage of the Patience algorithm, and can only anchor
unique lines that are the same across both files).
Because the user could anchor anywhere, diff anchors could result in
adjacent diff blocks (one block is directly touching another without a
gap), if there is a change right above the anchor point. We don't want
to merge these diff blocks because we want to line up the change at the
anchor. Adjacent diff blocks were first allowed when linematch was
added, but the existing code had a lot of branched paths where
line-matched diff blocks were handled differently. As a part of this
change, refactor them to have a more unified code path that is
generalized enough to handle adjacent diff blocks correctly and without
needing to carve in exceptions all over the place.
closes: vim/vim#17615
vim/vim@0d9160e
Co-authored-by: Yee Cheng Chin ychin.git@gmail.com