diff.c: add a blocks mode for moved code detection

The new "blocks" mode provides a middle ground between plain and zebra.
It is as intuitive (few colors) as plain, but still has the requirement
for a minimum of lines/characters to count a block as moved.

Suggested-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
(https://public-inbox.org/git/87o9j0uljo.fsf@evledraar.gmail.com/)
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index e3a44f03cdcee92098287bfccc9801fde042ef2b..ba56169de311fffd28134f43cffddaf66e731222 100644 (file)
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -276,10 +276,14 @@ plain::
        that are added somewhere else in the diff. This mode picks up any
        moved line, but it is not very useful in a review to determine
        if a block of code was moved without permutation.
-zebra::
+blocks::
        Blocks of moved text of at least 20 alphanumeric characters
        are detected greedily. The detected blocks are
-       painted using either the 'color.diff.{old,new}Moved' color or
+       painted using either the 'color.diff.{old,new}Moved' color.
+       Adjacent blocks cannot be told apart.
+zebra::
+       Blocks of moved text are detected as in 'blocks' mode. The blocks
+       are painted using either the 'color.diff.{old,new}Moved' color or
        'color.diff.{old,new}MovedAlternative'. The change between
        the two colors indicates that a new block was detected.
 dimmed_zebra::

diff --git a/diff.c b/diff.c
index d1bae900cdccf3a2dd09ce8e09e317da8e587688..95c51c0b7df0fe68743dd571143196d5760d4abe 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -271,6 +271,8 @@ static int parse_color_moved(const char *arg)
                return COLOR_MOVED_NO;
        else if (!strcmp(arg, "plain"))
                return COLOR_MOVED_PLAIN;
+       else if (!strcmp(arg, "blocks"))
+               return COLOR_MOVED_BLOCKS;
        else if (!strcmp(arg, "zebra"))
                return COLOR_MOVED_ZEBRA;
        else if (!strcmp(arg, "default"))
@@ -278,7 +280,7 @@ static int parse_color_moved(const char *arg)
        else if (!strcmp(arg, "dimmed_zebra"))
                return COLOR_MOVED_ZEBRA_DIM;
        else
-               return error(_("color moved setting must be one of 'no', 'default', 'zebra', 'dimmed_zebra', 'plain'"));
+               return error(_("color moved setting must be one of 'no', 'default', 'blocks', 'zebra', 'dimmed_zebra', 'plain'"));
 }
 
 int git_diff_ui_config(const char *var, const char *value, void *cb)
@@ -903,7 +905,7 @@ static void mark_color_as_moved(struct diff_options *o,
 
                block_length++;
 
-               if (flipped_block)
+               if (flipped_block && o->color_moved != COLOR_MOVED_BLOCKS)
                        l->flags |= DIFF_SYMBOL_MOVED_LINE_ALT;
        }
        adjust_last_block(o, n, block_length);

diff --git a/diff.h b/diff.h
index d29560f822ca0ee4738f769e2feb3939851d7ff1..7bd4f182c334f635e75760e96983bfd7e9ea795a 100644 (file)
--- a/diff.h
+++ b/diff.h
@@ -208,8 +208,9 @@ struct diff_options {
        enum {
                COLOR_MOVED_NO = 0,
                COLOR_MOVED_PLAIN = 1,
-               COLOR_MOVED_ZEBRA = 2,
-               COLOR_MOVED_ZEBRA_DIM = 3,
+               COLOR_MOVED_BLOCKS = 2,
+               COLOR_MOVED_ZEBRA = 3,
+               COLOR_MOVED_ZEBRA_DIM = 4,
        } color_moved;
        #define COLOR_MOVED_DEFAULT COLOR_MOVED_ZEBRA
        #define COLOR_MOVED_MIN_ALNUM_COUNT 20

diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index ddbc39013856ad0e85a7c65c14e8c00dc64116af..e54529f026dc4b64adefe8991025d8110c19acc2 100755 (executable)
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1223,7 +1223,7 @@ test_expect_success 'plain moved code, inside file' '
        test_cmp expected actual
 '
 
-test_expect_success 'detect permutations inside moved code -- dimmed_zebra' '
+test_expect_success 'detect blocks of moved code' '
        git reset --hard &&
        cat <<-\EOF >lines.txt &&
                long line 1
@@ -1271,6 +1271,50 @@ test_expect_success 'detect permutations inside moved code -- dimmed_zebra' '
        test_config color.diff.newMovedDimmed "normal cyan" &&
        test_config color.diff.oldMovedAlternativeDimmed "normal blue" &&
        test_config color.diff.newMovedAlternativeDimmed "normal yellow" &&
+       git diff HEAD --no-renames --color-moved=blocks --color >actual.raw &&
+       grep -v "index" actual.raw | test_decode_color >actual &&
+       cat <<-\EOF >expected &&
+       <BOLD>diff --git a/lines.txt b/lines.txt<RESET>
+       <BOLD>--- a/lines.txt<RESET>
+       <BOLD>+++ b/lines.txt<RESET>
+       <CYAN>@@ -1,16 +1,16 @@<RESET>
+       <MAGENTA>-long line 1<RESET>
+       <MAGENTA>-long line 2<RESET>
+       <MAGENTA>-long line 3<RESET>
+        line 4<RESET>
+        line 5<RESET>
+        line 6<RESET>
+        line 7<RESET>
+        line 8<RESET>
+        line 9<RESET>
+       <CYAN>+<RESET><CYAN>long line 1<RESET>
+       <CYAN>+<RESET><CYAN>long line 2<RESET>
+       <CYAN>+<RESET><CYAN>long line 3<RESET>
+       <CYAN>+<RESET><CYAN>long line 14<RESET>
+       <CYAN>+<RESET><CYAN>long line 15<RESET>
+       <CYAN>+<RESET><CYAN>long line 16<RESET>
+        line 10<RESET>
+        line 11<RESET>
+        line 12<RESET>
+        line 13<RESET>
+       <MAGENTA>-long line 14<RESET>
+       <MAGENTA>-long line 15<RESET>
+       <MAGENTA>-long line 16<RESET>
+       EOF
+       test_cmp expected actual
+
+'
+
+test_expect_success 'detect permutations inside moved code -- dimmed_zebra' '
+       # reuse setup from test before!
+       test_config color.diff.oldMoved "magenta" &&
+       test_config color.diff.newMoved "cyan" &&
+       test_config color.diff.oldMovedAlternative "blue" &&
+       test_config color.diff.newMovedAlternative "yellow" &&
+       test_config color.diff.oldMovedDimmed "normal magenta" &&
+       test_config color.diff.newMovedDimmed "normal cyan" &&
+       test_config color.diff.oldMovedAlternativeDimmed "normal blue" &&
+       test_config color.diff.newMovedAlternativeDimmed "normal yellow" &&
        git diff HEAD --no-renames --color-moved=dimmed_zebra --color >actual.raw &&
        grep -v "index" actual.raw | test_decode_color >actual &&
        cat <<-\EOF >expected &&
@@ -1669,7 +1713,8 @@ test_expect_success '--color-moved treats adjacent blocks as separate for MIN_AL
        7charsA
        EOF
 
-       git diff HEAD --color-moved=zebra --color --no-renames | grep -v "index" | test_decode_color >actual &&
+       git diff HEAD --color-moved=zebra --color --no-renames >actual.raw &&
+       grep -v "index" actual.raw | test_decode_color >actual &&
        cat >expected <<-\EOF &&
        <BOLD>diff --git a/bar b/bar<RESET>
        <BOLD>--- a/bar<RESET>