branch, for-each-ref, tag: add option to omit empty lines

If the given format string expands to the empty string, a newline is
still printed. This makes using the output linewise more tedious. For
example, git update-ref --stdin does not accept empty lines.

Add options to "git branch", "git for-each-ref", and "git tag" to
not print these empty lines.  The default behavior remains the same.

Signed-off-by: Øystein Walle <oystwa@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 15 insertions, 4 deletions

diff --git a/builtin/branch.c b/builtin/branch.c
index f63fd45edb..b47fef51fb 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -41,6 +41,7 @@ static const char *head;
 static struct object_id head_oid;
 static int recurse_submodules = 0;
 static int submodule_propagate_branches = 0;
+static int omit_empty = 0;
 
 static int branch_use_color = -1;
 static char branch_colors[][COLOR_MAXLEN] = {
@@ -461,7 +462,8 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
 			string_list_append(output, out.buf);
 		} else {
 			fwrite(out.buf, 1, out.len, stdout);
-			putchar('\n');
+			if (out.len || !omit_empty)
+				putchar('\n');
 		}
 	}
 
@@ -670,6 +672,8 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		OPT_BIT('D', NULL, &delete, N_("delete branch (even if not merged)"), 2),
 		OPT_BIT('m', "move", &rename, N_("move/rename a branch and its reflog"), 1),
 		OPT_BIT('M', NULL, &rename, N_("move/rename a branch, even if target exists"), 2),
+		OPT_BOOL(0, "omit-empty",  &omit_empty,
+			N_("do not output a newline after empty formatted refs")),
 		OPT_BIT('c', "copy", &copy, N_("copy a branch and its reflog"), 1),
 		OPT_BIT('C', NULL, &copy, N_("copy a branch, even if target exists"), 2),
 		OPT_BOOL('l', "list", &list, N_("list branch names")),
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 6f62f40d12..1fc5130481 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -19,7 +19,7 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 	int i;
 	struct ref_sorting *sorting;
 	struct string_list sorting_options = STRING_LIST_INIT_DUP;
-	int maxcount = 0, icase = 0;
+	int maxcount = 0, icase = 0, omit_empty = 0;
 	struct ref_array array;
 	struct ref_filter filter;
 	struct ref_format format = REF_FORMAT_INIT;
@@ -35,6 +35,8 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 			N_("quote placeholders suitably for python"), QUOTE_PYTHON),
 		OPT_BIT(0 , "tcl",  &format.quote_style,
 			N_("quote placeholders suitably for Tcl"), QUOTE_TCL),
+		OPT_BOOL(0, "omit-empty",  &omit_empty,
+			N_("do not output a newline after empty formatted refs")),
 
 		OPT_GROUP(""),
 		OPT_INTEGER( 0 , "count", &maxcount, N_("show only <n> matched refs")),
@@ -88,7 +90,8 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 		if (format_ref_array_item(array.items[i], &format, &output, &err))
 			die("%s", err.buf);
 		fwrite(output.buf, 1, output.len, stdout);
-		putchar('\n');
+		if (output.len || !omit_empty)
+			putchar('\n');
 	}
 
 	strbuf_release(&err);
diff --git a/builtin/tag.c b/builtin/tag.c
index d428c45dc8..61bc732c92 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -37,6 +37,7 @@ static const char * const git_tag_usage[] = {
 static unsigned int colopts;
 static int force_sign_annotate;
 static int config_sign_tag = -1; /* unspecified */
+static int omit_empty = 0;
 
 static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting,
 		     struct ref_format *format)
@@ -74,7 +75,8 @@ static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting,
 		if (format_ref_array_item(array.items[i], format, &output, &err))
 			die("%s", err.buf);
 		fwrite(output.buf, 1, output.len, stdout);
-		putchar('\n');
+		if (output.len || !omit_empty)
+			putchar('\n');
 	}
 
 	strbuf_release(&err);
@@ -473,6 +475,8 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		OPT_WITHOUT(&filter.no_commit, N_("print only tags that don't contain the commit")),
 		OPT_MERGED(&filter, N_("print only tags that are merged")),
 		OPT_NO_MERGED(&filter, N_("print only tags that are not merged")),
+		OPT_BOOL(0, "omit-empty",  &omit_empty,
+			N_("do not output a newline after empty formatted refs")),
 		OPT_REF_SORT(&sorting_options),
 		{
 			OPTION_CALLBACK, 0, "points-at", &filter.points_at, N_("object"),