ident.c: add split_ident_line() to parse formatted ident line

The commit formatting logic format_person_part() in pretty.c
implements the logic to split an author/committer ident line into
its parts, intermixed with logic to compute its output using these
piece it computes.

Separate the former out to a helper function split_ident_line() so
that other codepath can use the same logic, and rewrite the function
using the helper function.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/ident.c b/ident.c
index f619619b82..87c697c2b0 100644
--- a/ident.c
+++ b/ident.c
@@ -220,6 +220,74 @@ static int copy(char *buf, size_t size, int offset, const char *src)
 	return offset;
 }
 
+/*
+ * Reverse of fmt_ident(); given an ident line, split the fields
+ * to allow the caller to parse it.
+ * Signal a success by returning 0, but date/tz fields of the result
+ * can still be NULL if the input line only has the name/email part
+ * (e.g. reading from a reflog entry).
+ */
+int split_ident_line(struct ident_split *split, const char *line, int len)
+{
+	const char *cp;
+	size_t span;
+	int status = -1;
+
+	memset(split, 0, sizeof(*split));
+
+	split->name_begin = line;
+	for (cp = line; *cp && cp < line + len; cp++)
+		if (*cp == '<') {
+			split->mail_begin = cp + 1;
+			break;
+		}
+	if (!split->mail_begin)
+		return status;
+
+	for (cp = split->mail_begin - 2; line < cp; cp--)
+		if (!isspace(*cp)) {
+			split->name_end = cp + 1;
+			break;
+		}
+	if (!split->name_end)
+		return status;
+
+	for (cp = split->mail_begin; cp < line + len; cp++)
+		if (*cp == '>') {
+			split->mail_end = cp;
+			break;
+		}
+	if (!split->mail_end)
+		return status;
+
+	for (cp = split->mail_end + 1; cp < line + len && isspace(*cp); cp++)
+		;
+	if (line + len <= cp)
+		goto person_only;
+	split->date_begin = cp;
+	span = strspn(cp, "0123456789");
+	if (!span)
+		goto person_only;
+	split->date_end = split->date_begin + span;
+	for (cp = split->date_end; cp < line + len && isspace(*cp); cp++)
+		;
+	if (line + len <= cp || (*cp != '+' && *cp != '-'))
+		goto person_only;
+	split->tz_begin = cp;
+	span = strspn(cp + 1, "0123456789");
+	if (!span)
+		goto person_only;
+	split->tz_end = split->tz_begin + 1 + span;
+	return 0;
+
+person_only:
+	split->date_begin = NULL;
+	split->date_end = NULL;
+	split->tz_begin = NULL;
+	split->tz_end = NULL;
+	return 0;
+}
+
 static const char *env_hint =
 "\n"
 "*** Please tell me who you are.\n"