git/list[1] front-page[2] threads[3] people[4] search[5] about
 

[RFC PATCH v4 2/4] add -p: select modified lines correctly

From
PWPhillip Wood <phillip.wood@talktalk.net>
Date
Jul 26, 2018, 10:22 UTC
Message-ID
<20180726102227.997-3-phillip.wood@talktalk.net>
In-Reply-To
<20180726102227.997-1-phillip.wood@talktalk.net>
From: Phillip Wood <phillip.wood@dunelm.org.uk>

When a set of lines is modified the hunk contains deletions followed by insertions. To correctly stage a subset of the modified lines we need to match up the selected deletions with the selected insertions otherwise we end up with deletions and context lines followed by insertions which is not what we want.

For example given the hunk
      1 -* a longer description of the
      2 -  first item
      3 -* second
      4 -* third
      5 +* first
      6 +  second item
      7 +* the third item
If the user selects 1,2,4–5,7 then we should generate
	-* a longer description of the
	-  first item
	+* first
	 * second
	-* third
	+* the third item
not
	-* a longer description of the
	-  first item
	 * second
	-* third
	+* first
	+* the third item

Currently the code can only cope with selections that contain the same number of groups of insertions and deletions, though each group need not contain the same number of insertions and deletions. If the user wants to stage an unpaired deletion or insertion in a hunk where they also want to stage modified lines they have to do it with two invocations of 'git add -p'.

It would be possible to add some syntax to allow lines to be excluded from groups to allow the user to stage such changes in a single go. It may also be useful to allow users to explicitly group lines. If in the example above the second item is deleted we have

      1 -* a longer description of the
      2 - first item
      3 -* second
      4 -* third
      5 +* first
      6 +* the third item

Selecting 1,2,4–6 will give an error. If lines could be grouped explicitly then it would be possible to type something like 1,2,4,[5],6 to indicate that there are two groups of insertions giving

	-* a longer description of the
	- first item
	+* first
	 * second
	-* third
	+* the third item

We may want to be able to stage an insertion before an unselected deletion to allow the user to stage a new paragraph before the unmodified original in

      1 -original
      2 +a new paragraph before
      3 +original
      4 +
      5 +modified original
by specifying something like ^2-4 to give
	+a new paragraph before
	+original
	+
	 original

I'm not sure how common these cases are in real life and how much effort it's worth putting into handling them at the moment when the user can edit the hunk if need be. Perhaps it would be better to leave it for future extensions when it becomes clearer what would be most useful.

Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
---
 git-add--interactive.perl  | 148 ++++++++++++++++++++++++++++++++++---
 t/t3701-add-interactive.sh | 108 ++++++++++++++++++++++++++-
 2 files changed, 243 insertions(+), 13 deletions(-)
diff --git a/git-add--interactive.perl b/git-add--interactive.perl
index cbc9e5698a..b7e3da0210 100755
--- a/git-add--interactive.perl
+++ b/git-add--interactive.perl
@@ -1015,26 +1015,47 @@ sub color_diff {
 
 use constant {
 	NO_NEWLINE => 1,
+	LAST_ADD_DEL => 2,
+	FIRST_ADD => 4
 };
 
 sub label_hunk_lines {
 	my $hunk = shift;
 	my $text = $hunk->{TEXT};
-	my (@line_flags, @lines);
+	# A block contains the insertions and deletions occurring context
+	# lines.
+	my (@blocks, @line_flags, @lines, @modes);
 	my ($block, $label, $last_mode) = (0, 0, '');
 	for my $line (1..$#{$text}) {
 		$line_flags[$line] = 0;
 		my $mode = substr($text->[$line], 0, 1);
 		if ($mode eq '\\') {
 			$line_flags[$line - 1] |= NO_NEWLINE;
 		}
+		if ($mode ne '-' and $last_mode eq '-' or
+		    $mode ne '+' and $last_mode eq '+') {
+			$line_flags[$line - 1] |= LAST_ADD_DEL;
+		}
+		if ($mode eq '+' and $last_mode ne '+') {
+			$line_flags[$line] |= FIRST_ADD;
+		}
 		if ($mode eq '-' or $mode eq '+') {
-			$lines[++$label] = $line;
+			$blocks[++$label] = $block;
+			$lines[$label] = $line;
+			$modes[$label] = $mode;
+		} elsif ($mode eq ' ' and $last_mode ne ' ') {
+			$block++;
 		}
+		$last_mode = $mode;
+	}
+	if ($last_mode eq '-' or $last_mode eq '+') {
+		$line_flags[-1] |= LAST_ADD_DEL;
 	}
 	if ($label > 1) {
 		$hunk->{LABELS} = {
+			BLOCKS => \@blocks,
 			LINES => \@lines,
+			MODES => \@modes
 		};
 		$hunk->{LINE_FLAGS} = \@line_flags;
 		return 1;
@@ -1061,11 +1082,14 @@ sub select_hunk_lines {
 		}
 	};
 
-	my ($lo, $hi) = splice(@$selected, 0, 2);
+	my ($lo, $hi, $pre_insert, $post_insert) = splice(@$selected, 0, 4);
 	# Lines with this mode will become context lines if they are
 	# not selected
 	my $context_mode = $patch_mode_flavour{IS_REVERSE} ? '+' : '-';
 	for $i (1..$#{$text}) {
+		if ($i == $lo and defined($pre_insert)) {
+			$select_lines->(@$pre_insert);
+		}
 		if ($lo <= $i and $i <= $hi) {
 			$select_lines->($i);
 		} else {
@@ -1080,8 +1104,12 @@ sub select_hunk_lines {
 			}
 		}
 		if ($i == $hi) {
+			if (defined($post_insert)) {
+				$select_lines->(@$post_insert);
+			}
 			if (@$selected) {
-				($lo, $hi) = splice(@$selected, 0, 2);
+				($lo, $hi, $pre_insert, $post_insert) =
+						splice(@$selected, 0, 4);
 			}
 		}
 	}
@@ -1104,6 +1132,109 @@ sub select_hunk_lines {
 	return $newhunk;
 }
 
+sub pair_hunk_selection {
+	my $line_flags = shift;
+	my @ret;
+	my $reverse = $patch_mode_flavour{IS_REVERSE};
+	for my $sel (@_) {
+		my $i = 0;
+		my ($del, $add) = @$sel;
+		my $ndel = @$del / 2;
+		my $nadd = @$add / 2;
+		# If there the same number of insertion and deletion
+		# groups then pair up in insertions and deletions.
+		if ($nadd == $ndel) {
+			while ($i < @{$del}) {
+				my ($ra, $rb) = $reverse ? ($add, $del) :
+							   ($del, $add);
+				my ($starta, $enda) = @{$ra}[$i, $i + 1];
+				my ($startb, $endb) = @{$rb}[$i, $i + 1];
+				if ($line_flags->[$enda] & LAST_ADD_DEL and
+				    $line_flags->[$endb] & NO_NEWLINE) {
+					$endb++;
+				}
+				if ($line_flags->[$enda] & NO_NEWLINE) {
+					$enda++;
+				}
+				push @ret, $reverse ?
+					($starta, $enda,
+					 [ $startb..$endb ], undef) :
+					($starta, $enda,
+					 undef, [ $startb..$endb ]);
+				$i += 2;
+			}
+		}
+		# If there are only deletions or only insertions or
+		# a) we're adding to the index and there is a single group
+		#    of insertions starting at the first inserted line
+		# or
+		# b) we're resetting the index and there is a single group
+		#    of deletions finishing with the last deleted line
+		# then it is okay just to have deletions followed by
+		# insertions.
+		} elsif (!$nadd or !$ndel or
+			 (!$reverse and $ndel == 1 and
+			  $line_flags->[$del->[1]] & LAST_ADD_DEL) or
+			 ($reverse and $nadd == 1 and
+			  $line_flags->[$add->[0]] & FIRST_ADD)) {
+			while ($i < @$del) {
+				my ($start, $end) = @{$del}[$i, $i + 1];
+				if ($line_flags->[$end] & NO_NEWLINE) {
+					$end++;
+				}
+				push @ret, $start, $end, undef, undef;
+				$i += 2;
+			}
+			$i = 0;
+			while ($i < @$add) {
+				my ($start, $end) = @{$add}[$i, $i + 1];
+				if ($line_flags->[$end] & NO_NEWLINE) {
+					$end++;
+				}
+				push @ret, $start, $end, undef, undef;
+				$i += 2;
+			}
+		} else {
+			printf STDERR __("unable to pair up insertions and deletions\n");
+			return undef;
+		}
+	}
+	return \@ret;
+}
+
+sub process_hunk_selection {
+	my ($labels, $line_flags) = @{shift()}{qw(LABELS LINE_FLAGS)};
+	my ($blocks, $lines, $modes) =
+				@{$labels}{qw(BLOCKS LINES MODES)};
+	my @selection = sort { $a <=> $b } @_;
+	unless (@selection) {
+		return [];
+	}
+	my $last_label = shift @selection;
+	my ($last_block, $last_line, $last_mode) =
+	    ($blocks->[$last_label], $lines->[$last_label], $modes->[$last_label]);
+	my ($del, $add) = ([], []);
+	push @{$last_mode eq '-' ? $del : $add}, $last_line;
+	my @sel;
+	for my $label (@selection) {
+		my ($block, $line, $mode) =
+			($blocks->[$label], $lines->[$label], $modes->[$label]);
+		if ($block != $last_block) {
+			push @{$last_mode eq '-' ? $del : $add}, $last_line;
+			push @sel, [ $del, $add ];
+			($del, $add) = ([], []);
+			push @{$mode eq '-' ? $del : $add}, $line;
+		} elsif ($line != $last_line + 1 or $mode ne $last_mode) {
+			push @{$last_mode eq '-' ? $del : $add}, $last_line;
+			push @{$mode eq '-' ? $del : $add}, $line;
+		}
+		($last_block, $last_line, $last_mode) = ($block, $line, $mode);
+	}
+	push @{$last_mode eq '-' ? $del : $add}, $last_line;
+	push @sel, [ $del, $add ];
+	pair_hunk_selection($line_flags, @sel);
+}
+
 sub check_hunk_label {
 	my ($max_label, $label) = @_;
 	if ($label < 1 or $label > $max_label) {
@@ -1138,14 +1269,7 @@ sub parse_hunk_selection {
 			return undef;
 		}
 	}
-	[ map {
-		my $line = $lines->[$_];
-		if ($hunk->{LINE_FLAGS}->[$line] & NO_NEWLINE) {
-			($line, $line + 1);
-		} else {
-			($line, $line);
-		}
-	} sort { $a <=> $b } keys(%selected) ];
+	return process_hunk_selection($hunk, keys(%selected));
 }
 
 sub display_hunk_lines {
diff --git a/t/t3701-add-interactive.sh b/t/t3701-add-interactive.sh
index 5b535a22d5..1d917ad018 100755
--- a/t/t3701-add-interactive.sh
+++ b/t/t3701-add-interactive.sh
@@ -489,7 +489,7 @@ test_expect_success 'setup expected diff' '
 	EOF
 '
 
-test_expect_failure 'can stage modified lines of patch (1)' '
+test_expect_success 'can stage modified lines of patch (1)' '
 	git reset &&
 	printf "%s\n" l "1,3 7-9 12" |
 	EDITOR=: git add -p 2>error &&
@@ -498,6 +498,112 @@ test_expect_failure 'can stage modified lines of patch (1)' '
 	diff_cmp expected actual
 '
 
+test_expect_success 'setup expected diff' '
+	cat >expected <<-\EOF
+	diff --git a/test b/test
+	index 0889435..cc6163b 100644
+	--- a/test
+	+++ b/test
+	@@ -1,6 +1,7 @@
+	 10
+	-20
+	+twenty
+	+thirty
+	 30
+	 40
+	 50
+	-60
+	+sixty
+	\ No newline at end of file
+	EOF
+'
+
+test_expect_success 'can stage modified lines of patch (2)' '
+	git reset &&
+	printf "%s\n" l "2,6,8,9,12" |
+	EDITOR=: git add -p 2>error &&
+	test_must_be_empty error &&
+	git diff --cached HEAD >actual &&
+	diff_cmp expected actual
+'
+
+test_expect_success 'setup HEAD' '
+	git reset &&
+	git apply --cached <<-\EOF &&
+	diff --git a/test b/test
+	--- a/test
+	+++ b/test
+	@@ -3,4 +3,4 @@
+	 30
+	 40
+	 50
+	-60
+	+60
+	\ No newline at end of file
+	EOF
+	git commit
+'
+
+test_expect_success 'setup expected diff' '
+	cat >expected <<-\EOF
+	diff --git a/test b/test
+	index 0889435..cc6163b 100644
+	--- a/test
+	+++ b/test
+	@@ -1,6 +1,8 @@
+	-10
+	+ten
+	+twenty
+	+thirty
+	 20
+	-30
+	+fifty
+	 40
+	 50
+	 60
+	\ No newline at end of file
+	EOF
+'
+
+test_expect_success 'can stage modified lines of patch (3)' '
+	git reset &&
+	printf "%s\n" l "11,1,3 7-9" |
+	EDITOR=: git add -p 2>error &&
+	test_must_be_empty error &&
+	git diff --cached HEAD >actual &&
+	diff_cmp expected actual
+'
+
+test_expect_success 'setup expected diff' '
+	cat >expected <<-\EOF
+	diff --git a/test b/test
+	index 0889435..cc6163b 100644
+	--- a/test
+	+++ b/test
+	@@ -1,6 +1,8 @@
+	-10
+	+ten
+	+twenty
+	+thirty
+	 20
+	 30
+	 40
+	 50
+	-60
+	\ No newline at end of file
+	+fifty
+	EOF
+'
+
+test_expect_success 'can stage modified lines of patch (4)' '
+	git reset &&
+	printf "%s\n" l "9-6 11,1" |
+	EDITOR=: git add -p 2>error &&
+	test_must_be_empty error &&
+	git diff --cached HEAD >actual &&
+	diff_cmp expected actual
+'
+
 test_expect_success 'patch mode ignores unmerged entries' '
 	git reset --hard &&
 	test_commit conflict &&

-- 
2.18.0
Previous: Phillip WoodNext: Phillip Wood
Message 36 of 53 in “add -p: select individual hunk lines”
  1. 0/3 add -p: select individual hunk linesPhillip Wood, Feb 19, 2018
  2. 1/3 add -p: select individual hunk linesPhillip Wood, Feb 19, 2018
  3. 2/3 add -p: allow line selection to be invertedPhillip Wood, Feb 19, 2018
  4. 3/3 add -p: optimize line selection for short hunksPhillip Wood, Feb 19, 2018
  5. Gustavo LeiteFeb 19, 2018
  6. 0/3 add -p: select individual hunk linesPhillip Wood, Mar 6, 2018
  7. 2/3 add -p: allow line selection to be invertedPhillip Wood, Mar 6, 2018
  8. Junio C HamanoMar 6, 2018
  9. Phillip WoodMar 8, 2018
  10. Junio C HamanoMar 8, 2018
  11. Phillip WoodMar 13, 2018
  12. Junio C HamanoMar 13, 2018
  13. Phillip WoodMar 14, 2018
  14. Igor DjordjevicMar 6, 2018
  15. 1/3 add -p: select individual hunk linesPhillip Wood, Mar 6, 2018
  16. Igor DjordjevicMar 6, 2018
  17. Igor DjordjevicMar 6, 2018
  18. 3/3 add -p: optimize line selection for short hunksPhillip Wood, Mar 6, 2018
  19. Igor DjordjevicMar 6, 2018
  20. Igor DjordjevicMar 6, 2018
  21. Junio C HamanoMar 6, 2018
  22. Igor DjordjevicMar 6, 2018
  23. 0/3 add -p: select individual hunk linesPhillip Wood, Mar 16, 2018
  24. 1/3 add -p: select individual hunk linesPhillip Wood, Mar 16, 2018
  25. 2/3 add -p: allow line selection to be invertedPhillip Wood, Mar 16, 2018
  26. 3/3 add -p: optimize line selection for short hunksPhillip Wood, Mar 16, 2018
  27. Junio C HamanoMar 29, 2018
  28. Phillip WoodMar 30, 2018
  29. Ævar Arnfjörð BjarmasonMar 31, 2018
  30. Phillip WoodApr 2, 2018
  31. Ævar Arnfjörð BjarmasonApr 2, 2018
  32. 0/4 add -p: select individual hunk linesPhillip Wood, Jul 26, 2018
  33. 1/4 add -p: select individual hunk linesPhillip Wood, Jul 26, 2018
  34. 4/4 add -p: optimize line selection for short hunksPhillip Wood, Jul 26, 2018
  35. 3/4 add -p: allow line selection to be invertedPhillip Wood, Jul 26, 2018
  36. 2/4 add -p: select modified lines correctlyPhillip Wood, Jul 26, 2018
  37. 0/4 add -p: select individual hunk linesPhillip Wood, Jul 26, 2018
  38. 1/4 add -p: select individual hunk linesPhillip Wood, Jul 26, 2018
  39. Junio C HamanoJul 26, 2018
  40. Phillip WoodJul 27, 2018
  41. Junio C HamanoJul 27, 2018
  42. 2/4 add -p: select modified lines correctlyPhillip Wood, Jul 26, 2018
  43. Junio C HamanoJul 26, 2018
  44. Phillip WoodJul 27, 2018
  45. Junio C HamanoJul 27, 2018
  46. 3/4 add -p: allow line selection to be invertedPhillip Wood, Jul 26, 2018
  47. 4/4 add -p: optimize line selection for short hunksPhillip Wood, Jul 26, 2018
  48. Ævar Arnfjörð BjarmasonJul 27, 2018
  49. Phillip WoodJul 28, 2018
  50. Ævar Arnfjörð BjarmasonJul 28, 2018
  51. Phillip WoodAug 3, 2018
  52. Junio C HamanoAug 3, 2018
  53. Ævar Arnfjörð BjarmasonAug 3, 2018

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.