add strbuf_expand_dict_cb(), a helper for simple cases

The new callback function strbuf_expand_dict_cb() can be used together
with strbuf_expand() if there is only a small number of placeholders
for static replacement texts.  It expects its dictionary as an array of
placeholder+value pairs as context parameter, terminated by an entry
with the placeholder member set to NULL.

The new helper is intended to aid converting the remaining calls of
interpolate().  strbuf_expand() is smaller, more flexible and can be
used to go faster than interpolate(), so it should replace the latter.

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

1 files changed, 7 insertions, 0 deletions

diff --git a/Documentation/technical/api-strbuf.txt b/Documentation/technical/api-strbuf.txt
index a9668e5f2d..a8ee2fe6a1 100644
--- a/Documentation/technical/api-strbuf.txt
+++ b/Documentation/technical/api-strbuf.txt
@@ -205,6 +205,13 @@ In order to facilitate caching and to make it possible to give
 parameters to the callback, `strbuf_expand()` passes a context pointer,
 which can be used by the programmer of the callback as she sees fit.
 
+`strbuf_expand_dict_cb`::
+
+	Used as callback for `strbuf_expand()`, expects an array of
+	struct strbuf_expand_dict_entry as context, i.e. pairs of
+	placeholder and replacement string.  The array needs to be
+	terminated by an entry with placeholder set to NULL.
+
 `strbuf_addf`::
 
 	Add a formatted string to the buffer.