strbuf_split*(): document functions

Document strbuf_split_buf(), strbuf_split_str(), strbuf_split_max(),
strbuf_split(), and strbuf_list_free() in the header file and in
api-strbuf.txt.  (These functions were previously completely
undocumented.)

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jeff King <peff@peff.net>

Documentation/technical/api-strbuf.txt

@@ -279,6 +279,22 @@ same behaviour as well.
 	Strip whitespace from a buffer. The second parameter controls if
 	comments are considered contents to be removed or not.
 
+`strbuf_split_buf`::
+`strbuf_split_str`::
+`strbuf_split_max`::
+`strbuf_split`::
+
+	Split a string or strbuf into a list of strbufs at a specified
+	terminator character.  The returned substrings include the
+	terminator characters.  Some of these functions take a `max`
+	parameter, which, if positive, limits the output to that
+	number of substrings.
+
+`strbuf_list_free`::
+
+	Free a list of strbufs (for example, the return values of the
+	`strbuf_split()` functions).
+
 `launch_editor`::
 
 	Launch the user preferred editor to edit a file and fill the buffer

strbuf.h

@@ -44,23 +44,56 @@ extern void strbuf_rtrim(struct strbuf *);
 extern void strbuf_ltrim(struct strbuf *);
 extern int strbuf_cmp(const struct strbuf *, const struct strbuf *);
 
+/*
+ * Split str (of length slen) at the specified terminator character.
+ * Return a null-terminated array of pointers to strbuf objects
+ * holding the substrings.  The substrings include the terminator,
+ * except for the last substring, which might be unterminated if the
+ * original string did not end with a terminator.  If max is positive,
+ * then split the string into at most max substrings (with the last
+ * substring containing everything following the (max-1)th terminator
+ * character).
+ *
+ * For lighter-weight alternatives, see string_list_split() and
+ * string_list_split_in_place().
+ */
 extern struct strbuf **strbuf_split_buf(const char *, size_t,
 					int terminator, int max);
+
+/*
+ * Split a NUL-terminated string at the specified terminator
+ * character.  See strbuf_split_buf() for more information.
+ */
 static inline struct strbuf **strbuf_split_str(const char *str,
 					       int terminator, int max)
 {
 	return strbuf_split_buf(str, strlen(str), terminator, max);
 }
+
+/*
+ * Split a strbuf at the specified terminator character.  See
+ * strbuf_split_buf() for more information.
+ */
 static inline struct strbuf **strbuf_split_max(const struct strbuf *sb,
 						int terminator, int max)
 {
 	return strbuf_split_buf(sb->buf, sb->len, terminator, max);
 }
+
+/*
+ * Split a strbuf at the specified terminator character.  See
+ * strbuf_split_buf() for more information.
+ */
 static inline struct strbuf **strbuf_split(const struct strbuf *sb,
 					   int terminator)
 {
 	return strbuf_split_max(sb, terminator, 0);
 }
+
+/*
+ * Free a NULL-terminated list of strbufs (for example, the return
+ * values of the strbuf_split*() functions).
+ */
 extern void strbuf_list_free(struct strbuf **);
 
 /*----- add data in your buffer -----*/