diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt index c19e64ea0eff61..f212079a1311c2 100644 --- a/Documentation/gitattributes.txt +++ b/Documentation/gitattributes.txt @@ -758,6 +758,43 @@ with the above configuration, i.e. `j-c-diff`, with 7 parameters, just like `GIT_EXTERNAL_DIFF` program is called. See linkgit:git[1] for details. +Setting the internal diff algorithm +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The diff algorithm can be set through the `diff.algorithm` config key, but +sometimes it may be helpful to set the diff algorithm by path. For example, one +might wish to set a diff algorithm automatically for all `.json` files such that +the user would not need to pass in a separate command line `--diff-algorithm` +flag each time. + +First, in `.gitattributes`, assign the `diff` attribute for paths. + +------------------------ +*.json diff= +------------------------ + +Then, define a "diff..algorithm" configuration to specify the diff +algorithm, choosing from `meyers`, `patience`, `minimal`, or `histogram`. + +---------------------------------------------------------------- +[diff ""] + algorithm = histogram +---------------------------------------------------------------- + +This diff algorithm applies to user facing diff output like git-diff(1), +git-show(1) and is used for the `--stat` output as well. The merge machinery +will not use the diff algorithm set through this method. + +NOTE: If the `command` key also exists, then Git will treat this as an external +diff and attempt to use the value set for `command` as an external program. For +instance, the following config, combined with the above `.gitattributes` file, +will result in `command` favored over `algorithm`. + +---------------------------------------------------------------- +[diff ""] + command = j-c-diff + algorithm = histogram +---------------------------------------------------------------- Defining a custom hunk-header ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/diff.c b/diff.c index 5efc22ca06b7bb..04469da6d34526 100644 --- a/diff.c +++ b/diff.c @@ -4456,15 +4456,13 @@ static void run_diff_cmd(const char *pgm, const char *xfrm_msg = NULL; int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score; int must_show_header = 0; + struct userdiff_driver *drv = NULL; - - if (o->flags.allow_external) { - struct userdiff_driver *drv; - + if (o->flags.allow_external || !o->ignore_driver_algorithm) drv = userdiff_find_by_path(o->repo->index, attr_path); - if (drv && drv->external) - pgm = drv->external; - } + + if (o->flags.allow_external && drv && drv->external) + pgm = drv->external; if (msg) { /* @@ -4481,12 +4479,16 @@ static void run_diff_cmd(const char *pgm, run_external_diff(pgm, name, other, one, two, xfrm_msg, o); return; } - if (one && two) + if (one && two) { + if (drv && !o->ignore_driver_algorithm && drv->algorithm) + set_diff_algorithm(o, drv->algorithm); + builtin_diff(name, other ? other : name, one, two, xfrm_msg, must_show_header, o, complete_rewrite); - else + } else { fprintf(o->file, "* Unmerged path %s\n", name); + } } static void diff_fill_oid_info(struct diff_filespec *one, struct index_state *istate) @@ -4583,6 +4585,14 @@ static void run_diffstat(struct diff_filepair *p, struct diff_options *o, const char *name; const char *other; + if (!o->ignore_driver_algorithm) { + struct userdiff_driver *drv = userdiff_find_by_path(o->repo->index, p->one->path); + + if (drv && drv->algorithm) { + set_diff_algorithm(o, drv->algorithm); + } + } + if (DIFF_PAIR_UNMERGED(p)) { /* unmerged */ builtin_diffstat(p->one->path, NULL, NULL, NULL, @@ -5130,6 +5140,8 @@ static int diff_opt_diff_algorithm(const struct option *opt, return error(_("option diff-algorithm accepts \"myers\", " "\"minimal\", \"patience\" and \"histogram\"")); + options->ignore_driver_algorithm = 1; + return 0; } @@ -5145,6 +5157,8 @@ static int diff_opt_diff_algorithm_no_arg(const struct option *opt, BUG("available diff algorithms include \"myers\", " "\"minimal\", \"patience\" and \"histogram\""); + options->ignore_driver_algorithm = 1; + return 0; } @@ -5285,6 +5299,7 @@ static int diff_opt_patience(const struct option *opt, for (i = 0; i < options->anchors_nr; i++) free(options->anchors[i]); options->anchors_nr = 0; + options->ignore_driver_algorithm = 1; return set_diff_algorithm(options, "patience"); } diff --git a/diff.h b/diff.h index 41eb2c3d428801..8d770b1d579c8e 100644 --- a/diff.h +++ b/diff.h @@ -333,6 +333,7 @@ struct diff_options { int prefix_length; const char *stat_sep; int xdl_opts; + int ignore_driver_algorithm; /* see Documentation/diff-options.txt */ char **anchors; diff --git a/t/lib-diff-alternative.sh b/t/lib-diff-alternative.sh index 8d1e408bb58f5e..2dc02bca873bc0 100644 --- a/t/lib-diff-alternative.sh +++ b/t/lib-diff-alternative.sh @@ -105,10 +105,46 @@ index $file1..$file2 100644 } EOF + cat >expect_diffstat < file2 | 21 ++++++++++----------- + 1 file changed, 10 insertions(+), 11 deletions(-) +EOF + STRATEGY=$1 + test_expect_success "$STRATEGY diff from attributes" ' + echo "file* diff=driver" >.gitattributes && + git config diff.driver.algorithm "$STRATEGY" && + test_must_fail git diff --no-index file1 file2 > output && + cat expect && + cat output && + test_cmp expect output + ' + + test_expect_success "$STRATEGY diff from attributes has valid diffstat" ' + echo "file* diff=driver" >.gitattributes && + git config diff.driver.algorithm "$STRATEGY" && + test_must_fail git diff --stat --no-index file1 file2 > output && + test_cmp expect_diffstat output + ' + test_expect_success "$STRATEGY diff" ' - test_must_fail git diff --no-index "--$STRATEGY" file1 file2 > output && + test_must_fail git diff --no-index "--diff-algorithm=$STRATEGY" file1 file2 > output && + test_cmp expect output + ' + + test_expect_success "$STRATEGY diff command line precedence before attributes" ' + echo "file* diff=driver" >.gitattributes && + git config diff.driver.algorithm meyers && + test_must_fail git diff --no-index "--diff-algorithm=$STRATEGY" file1 file2 > output && + test_cmp expect output + ' + + test_expect_success "$STRATEGY diff attributes precedence before config" ' + git config diff.algorithm default && + echo "file* diff=driver" >.gitattributes && + git config diff.driver.algorithm "$STRATEGY" && + test_must_fail git diff --no-index file1 file2 > output && test_cmp expect output ' diff --git a/userdiff.c b/userdiff.c index d71b82feb74704..ff25cfc4b4cc9c 100644 --- a/userdiff.c +++ b/userdiff.c @@ -293,7 +293,7 @@ PATTERNS("scheme", "|([^][)(}{[ \t])+"), PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$", "\\\\[a-zA-Z@]+|\\\\.|[a-zA-Z0-9\x80-\xff]+"), -{ "default", NULL, -1, { NULL, 0 } }, +{ "default", NULL, NULL, -1, { NULL, 0 } }, }; #undef PATTERNS #undef IPATTERN @@ -394,6 +394,8 @@ int userdiff_config(const char *k, const char *v) return parse_bool(&drv->textconv_want_cache, k, v); if (!strcmp(type, "wordregex")) return git_config_string(&drv->word_regex, k, v); + if (!strcmp(type, "algorithm")) + return git_config_string(&drv->algorithm, k, v); return 0; } diff --git a/userdiff.h b/userdiff.h index aee91bc77e6d59..24419db6973f5c 100644 --- a/userdiff.h +++ b/userdiff.h @@ -14,6 +14,7 @@ struct userdiff_funcname { struct userdiff_driver { const char *name; const char *external; + const char *algorithm; int binary; struct userdiff_funcname funcname; const char *word_regex;