diff: add option to show context between close hunks

Merge two hunks if there is only the specified number of otherwise unshown
context between them.  For --inter-hunk-context=1, the resulting patch has
the same number of lines but shows uninterrupted context instead of a
context header line in between.

Patches generated with this option are easier to read but are also more
likely to conflict if the file to be patched contains other changes.

This patch keeps the default for this option at 0.  It is intended to just
make the feature available in order to see its advantages and downsides.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index c62b45cdbade990878b8e8e9371d41d4e3c43bfe..c7fcc8007af18163d7d1583e116b625b54d428ca 100644 (file)
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -215,6 +215,10 @@ endif::git-format-patch[]
 -w::
        Shorthand for "--ignore-all-space".
 
+--inter-hunk-context=<lines>::
+       Show the context between diff hunks, up to the specified number
+       of lines, thereby fusing hunks that are close to each other.
+
 --exit-code::
        Make the program exit with codes similar to diff(1).
        That is, it exits with 1 if there were differences and

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index e00454983ee16624910e40fec9ddb12849110b1b..a046441974ec1240281058562ce17249fa10d604 100755 (executable)
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -776,6 +776,7 @@ _git_diff ()
                        --no-ext-diff
                        --no-prefix --src-prefix= --dst-prefix=
                        --base --ours --theirs
+                       --inter-hunk-context=
                        "
                return
                ;;
@@ -967,6 +968,7 @@ _git_log ()
                        --color-words --walk-reflogs
                        --parents --children --full-history
                        --merge
+                       --inter-hunk-context=
                        "
                return
                ;;

diff --git a/diff.c b/diff.c
index 0484601f42a8aeac408d560091d341f571f231dd..56b80f9609a4cafaf82b711f5f2865eecbba0c74 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -1469,6 +1469,7 @@ static void builtin_diff(const char *name_a,
                ecbdata.file = o->file;
                xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
                xecfg.ctxlen = o->context;
+               xecfg.interhunkctxlen = o->interhunkcontext;
                xecfg.flags = XDL_EMIT_FUNCNAMES;
                if (pe)
                        xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
@@ -2538,6 +2539,9 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                options->b_prefix = arg + 13;
        else if (!strcmp(arg, "--no-prefix"))
                options->a_prefix = options->b_prefix = "";
+       else if (opt_arg(arg, '\0', "inter-hunk-context",
+                        &options->interhunkcontext))
+               ;
        else if (!prefixcmp(arg, "--output=")) {
                options->file = fopen(arg + strlen("--output="), "w");
                options->close_file = 1;

diff --git a/diff.h b/diff.h
index 42582edee68a4a4717ae5debebf37e6b9610fc8f..4d5a32781da81295d5aa1b4dd33dd2765be3ff89 100644 (file)
--- a/diff.h
+++ b/diff.h
@@ -78,6 +78,7 @@ struct diff_options {
        const char *a_prefix, *b_prefix;
        unsigned flags;
        int context;
+       int interhunkcontext;
        int break_opt;
        int detect_rename;
        int skip_stat_unmatch;

diff --git a/t/t4032-diff-inter-hunk-context.sh b/t/t4032-diff-inter-hunk-context.sh
new file mode 100755 (executable)
index 0000000..e4e3e28
--- /dev/null
+++ b/t/t4032-diff-inter-hunk-context.sh
@@ -0,0 +1,92 @@
+#!/bin/sh
+
+test_description='diff hunk fusing'
+
+. ./test-lib.sh
+
+f() {
+       echo $1
+       i=1
+       while test $i -le $2
+       do
+               echo $i
+               i=$(expr $i + 1)
+       done
+       echo $3
+}
+
+t() {
+       case $# in
+       4) hunks=$4; cmd="diff -U$3";;
+       5) hunks=$5; cmd="diff -U$3 --inter-hunk-context=$4";;
+       esac
+       label="$cmd, $1 common $2"
+       file=f$1
+       expected=expected.$file.$3.$hunks
+
+       if ! test -f $file
+       then
+               f A $1 B >$file
+               git add $file
+               git commit -q -m. $file
+               f X $1 Y >$file
+       fi
+
+       test_expect_success "$label: count hunks ($hunks)" "
+               test $(git $cmd $file | grep '^@@ ' | wc -l) = $hunks
+       "
+
+       test -f $expected &&
+       test_expect_success "$label: check output" "
+               git $cmd $file | grep -v '^index ' >actual &&
+               test_cmp $expected actual
+       "
+}
+
+cat <<EOF >expected.f1.0.1 || exit 1
+diff --git a/f1 b/f1
+--- a/f1
++++ b/f1
+@@ -1,3 +1,3 @@
+-A
++X
+ 1
+-B
++Y
+EOF
+
+cat <<EOF >expected.f1.0.2 || exit 1
+diff --git a/f1 b/f1
+--- a/f1
++++ b/f1
+@@ -1 +1 @@
+-A
++X
+@@ -3 +3 @@ A
+-B
++Y
+EOF
+
+# common lines ctx     intrctx hunks
+t 1 line       0               2
+t 1 line       0       0       2
+t 1 line       0       1       1
+t 1 line       0       2       1
+t 1 line       1               1
+
+t 2 lines      0               2
+t 2 lines      0       0       2
+t 2 lines      0       1       2
+t 2 lines      0       2       1
+t 2 lines      1               1
+
+t 3 lines      1               2
+t 3 lines      1       0       2
+t 3 lines      1       1       1
+t 3 lines      1       2       1
+
+t 9 lines      3               2
+t 9 lines      3       2       2
+t 9 lines      3       3       1
+
+test_done

diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index 84fff583e2a6e3411da4260b9af98043fade1e49..361f80231905c66b642dcc764eeea32e7814ba07 100644 (file)
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -84,6 +84,7 @@ typedef long (*find_func_t)(const char *line, long line_len, char *buffer, long
 
 typedef struct s_xdemitconf {
        long ctxlen;
+       long interhunkctxlen;
        unsigned long flags;
        find_func_t find_func;
        void *find_func_priv;

diff --git a/xdiff/xemit.c b/xdiff/xemit.c
index 4625c1b4215231dc343478b2f4f7b4bfccf2c766..05bfa41f102801a5182e7fc642976f91e9ba7db6 100644 (file)
--- a/xdiff/xemit.c
+++ b/xdiff/xemit.c
@@ -59,9 +59,10 @@ static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *
  */
 xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg) {
        xdchange_t *xch, *xchp;
+       long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen;
 
        for (xchp = xscr, xch = xscr->next; xch; xchp = xch, xch = xch->next)
-               if (xch->i1 - (xchp->i1 + xchp->chg1) > 2 * xecfg->ctxlen)
+               if (xch->i1 - (xchp->i1 + xchp->chg1) > max_common)
                        break;
 
        return xchp;