[PATCH v2 02/19] parse-options-cb: implement parse_opt_pass_argv_array()

[Paul Tan <pyokagan@gmail.com>]

Certain git commands, such as git-pull, are simply wrappers around other
git commands like git-fetch, git-merge and git-rebase. As such, these
wrapper commands will typically need to "pass through" command-line
options of the commands they wrap.

Implement the parse_opt_pass_argv_array() parse-options callback, which
will reconstruct all the provided command-line options into an
argv_array, such that it can be passed to another git command. This is
useful for passing command-line options that can be specified multiple
times.

Signed-off-by: Paul Tan <pyokagan@gmail.com>
---

Notes:
    v2
    
    * This function is a requirement for the rewrite of git-am to handle
      passing git-apply's options to git-apply. Since it would be
      implemented anyway I thought it would be good if git-pull could take
      advantage of it as well to handle --strategy and --strategy-option.

 parse-options-cb.c | 32 ++++++++++++++++++++++++++++++++
 parse-options.h    |  1 +
 2 files changed, 33 insertions(+)

diff --git a/parse-options-cb.c b/parse-options-cb.c
index 5b1dbcf..7330506 100644
--- a/parse-options-cb.c
+++ b/parse-options-cb.c
@@ -4,6 +4,7 @@
 #include "commit.h"
 #include "color.h"
 #include "string-list.h"
+#include "argv-array.h"
 
 /*----- some often used options -----*/
 
@@ -163,3 +164,34 @@ int parse_opt_pass_strbuf(const struct option *opt, const char *arg, int unset)
 
 	return 0;
 }
+
+/**
+ * For an option opt, recreate the command-line option, appending it to
+ * opt->value which must be a argv_array. This is useful when we need to pass
+ * the command-line option, which can be specified multiple times, to another
+ * command.
+ */
+int parse_opt_pass_argv_array(const struct option *opt, const char *arg, int unset)
+{
+	struct strbuf sb = STRBUF_INIT;
+	struct argv_array *opt_value = opt->value;
+
+	if (opt->long_name) {
+		strbuf_addstr(&sb, unset ? "--no-" : "--");
+		strbuf_addstr(&sb, opt->long_name);
+		if (arg) {
+			strbuf_addch(&sb, '=');
+			strbuf_addstr(&sb, arg);
+		}
+	} else if (opt->short_name && !unset) {
+		strbuf_addch(&sb, '-');
+		strbuf_addch(&sb, opt->short_name);
+		if (arg)
+			strbuf_addstr(&sb, arg);
+	} else
+		return -1;
+
+	argv_array_push(opt_value, sb.buf);
+	strbuf_release(&sb);
+	return 0;
+}
diff --git a/parse-options.h b/parse-options.h
index 1d21398..b663f87 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -225,6 +225,7 @@ extern int parse_opt_tertiary(const struct option *, const char *, int);
 extern int parse_opt_string_list(const struct option *, const char *, int);
 extern int parse_opt_noop_cb(const struct option *, const char *, int);
 extern int parse_opt_pass_strbuf(const struct option *, const char *, int);
+extern int parse_opt_pass_argv_array(const struct option *, const char *, int);
 
 #define OPT__VERBOSE(var, h)  OPT_COUNTUP('v', "verbose", (var), (h))
 #define OPT__QUIET(var, h)    OPT_COUNTUP('q', "quiet",   (var), (h))
-- 
2.1.4