[RFC PATCH] pathspec: get non matching arguments without reporting.

[Stefan Beller <sbeller@google.com>]

When giving more than just pathspec arguments (e.g. submodule labels),
we need a way to check all non-matching arguments for the pathspec parsing
if these are the submodule labels or typos.

This patch prepares for that use case by splitting up `report_path_error`
into a new checking function `unmatched_pathspec_items` and a
reporting callback.

Signed-off-by: Stefan Beller <sbeller@google.com>
---

  So I imagine the unmatched_pathspec_items to be used later similar as
  in report_path_error, maybe just like this:

void submodule_list_fn(const struct pathspec *pathspec,
			  int pathspec_index,
			  void *data_cb)
{
	if (submodule_label_exist(pathspec->items[pathspec_index].original))
		// ok, record in data_cb
	else
		error(" '%s' is neither recognized as matching pathspec nor did it
			match any submodule label",
			pathspec->items[pathspec_index].original);
}

submodule_list(const char *ps_matched,
		 const struct pathspec *pathspec,
		 const char *prefix)
{
	struct string_list detected_labels;
	unmatched_pathspec_items(ps_matched, pathspec, prefix,
				submodule_list_fn, &detected_labels);
	
	foreach (submodule s) { 
		if matches_pathspec(s, pathspec) or label_match(s, detected_labels)
			// do a thing
		else
			continue
	}
}

What do you think of such a design? Is it worth carrying and polishing or
would there be another way to do it which matches the pathspec mechanism better?

Thanks,
Stefan

 dir.c | 36 ++++++++++++++++++++++++++----------
 dir.h |  8 ++++++++
 2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/dir.c b/dir.c
index a4a9d9f..bc8b199 100644
--- a/dir.c
+++ b/dir.c
@@ -394,14 +394,13 @@ int match_pathspec(const struct pathspec *ps,
 	return negative ? 0 : positive;
 }
 
-int report_path_error(const char *ps_matched,
-		      const struct pathspec *pathspec,
-		      const char *prefix)
+void unmatched_pathspec_items(const char *ps_matched,
+			     const struct pathspec *pathspec,
+			     const char *prefix,
+			     unmatched_pathspec_items_fn fn,
+			     void *data_cb)
 {
-	/*
-	 * Make sure all pathspec matched; otherwise it is an error.
-	 */
-	int num, errors = 0;
+	int num;
 	for (num = 0; num < pathspec->nr; num++) {
 		int other, found_dup;
 
@@ -428,10 +427,27 @@ int report_path_error(const char *ps_matched,
 		if (found_dup)
 			continue;
 
-		error("pathspec '%s' did not match any file(s) known to git.",
-		      pathspec->items[num].original);
-		errors++;
+		fn(pathspec, num, data_cb);
 	}
+}
+
+void report_path_error_fn(const struct pathspec *pathspec,
+			  int pathspec_index,
+			  void *data_cb)
+{
+	int *errors = data_cb;
+	error("pathspec '%s' did not match any file(s) known to git.",
+	      pathspec->items[pathspec_index].original);
+	(*errors)++;
+}
+
+int report_path_error(const char *ps_matched,
+		      const struct pathspec *pathspec,
+		      const char *prefix)
+{
+	int errors = 0;
+	unmatched_pathspec_items(ps_matched, pathspec, prefix,
+				report_path_error_fn, &errors);
 	return errors;
 }
 
diff --git a/dir.h b/dir.h
index cd46f30..ea222eb 100644
--- a/dir.h
+++ b/dir.h
@@ -211,6 +211,14 @@ extern char *common_prefix(const struct pathspec *pathspec);
 extern int match_pathspec(const struct pathspec *pathspec,
 			  const char *name, int namelen,
 			  int prefix, char *seen, int is_dir);
+typedef void (*unmatched_pathspec_items_fn)(const struct pathspec *pathspec,
+					    int pathspec_index,
+					    void *data_cb);
+void unmatched_pathspec_items(const char *ps_matched,
+			     const struct pathspec *pathspec,
+			     const char *prefix,
+			     unmatched_pathspec_items_fn fn,
+			     void *data_cb);
 extern int report_path_error(const char *ps_matched, const struct pathspec *pathspec, const char *prefix);
 extern int within_depth(const char *name, int namelen, int depth, int max_depth);
 
-- 
2.8.0.1.g3af9c03