git.c: provide setup_auto_pager()

The previous patch introduced a way for builtins to declare that they
will take responsibility for handling the `pager.foo`-config item. (See
the commit message of that patch for why that could be useful.)

Provide setup_auto_pager(), which builtins can call in order to handle
`pager.<cmd>`, including possibly starting the pager. Make this function
don't do anything if a pager has already been started, as indicated by
use_pager or pager_in_use().

Whenever this function is called from a builtin, git.c will already have
called commit_pager_choice(). Since commit_pager_choice() treats the
special value -1 as "punt" or "not yet decided", it is not a problem
that we might end up calling commit_pager_choice() once in git.c and
once (or more) in the builtin. Make the new function use -1 in the same
way and document it as "punt".

Don't add any users of setup_auto_pager just yet, one will follow in
a later patch.

Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin.h b/builtin.h
index 0f3a7b7704775cca9da052c58be942ca81a9d161..42378f3aa471eb79594d96736ad2410b54d6c4dd 100644 (file)
--- a/builtin.h
+++ b/builtin.h
@@ -113,6 +113,18 @@ struct fmt_merge_msg_opts {
 extern int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
                         struct fmt_merge_msg_opts *);
 
+/**
+ * If a built-in has DELAY_PAGER_CONFIG set, the built-in should call this early
+ * when it wishes to respect the `pager.foo`-config. The `cmd` is the name of
+ * the built-in, e.g., "foo". If a paging-choice has already been setup, this
+ * does nothing. The default in `def` should be 0 for "pager off", 1 for "pager
+ * on" or -1 for "punt".
+ *
+ * You should most likely use a default of 0 or 1. "Punt" (-1) could be useful
+ * to be able to fall back to some historical compatibility name.
+ */
+extern void setup_auto_pager(const char *cmd, int def);
+
 extern int is_builtin(const char *s);
 
 extern int cmd_add(int argc, const char **argv, const char *prefix);

diff --git a/git.c b/git.c
index 79195ebbdfc1a1964d155f28951ee9ffbe279887..66832f2324f6f9ad4d6b697f95d0d36eaecb62c1 100644 (file)
--- a/git.c
+++ b/git.c
@@ -33,6 +33,16 @@ static void commit_pager_choice(void) {
        }
 }
 
+void setup_auto_pager(const char *cmd, int def)
+{
+       if (use_pager != -1 || pager_in_use())
+               return;
+       use_pager = check_pager_config(cmd);
+       if (use_pager == -1)
+               use_pager = def;
+       commit_pager_choice();
+}
+
 static int handle_options(const char ***argv, int *argc, int *envchanged)
 {
        const char **orig_argv = *argv;