[PATCH v4 1/3] list_objects_filter_options: introduce 'list_object_filter_config_name'

[Taylor Blau <me@ttaylorr.com>]

In a subsequent commit, we will add configuration options that are
specific to each kind of object filter, in which case it is handy to
have a function that translates between 'enum
list_objects_filter_choice' and an appropriate configuration-friendly
string.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 list-objects-filter-options.c | 23 +++++++++++++++++++++++
 list-objects-filter-options.h |  6 ++++++
 2 files changed, 29 insertions(+)

diff --git a/list-objects-filter-options.c b/list-objects-filter-options.c
index 3553ad7b0a..92b408c0c8 100644
--- a/list-objects-filter-options.c
+++ b/list-objects-filter-options.c
@@ -15,6 +15,29 @@ static int parse_combine_filter(
 	const char *arg,
 	struct strbuf *errbuf);
 
+const char *list_object_filter_config_name(enum list_objects_filter_choice c)
+{
+	switch (c) {
+	case LOFC_DISABLED:
+		/* we have no name for "no filter at all" */
+		break;
+	case LOFC_BLOB_NONE:
+		return "blob:none";
+	case LOFC_BLOB_LIMIT:
+		return "blob:limit";
+	case LOFC_TREE_DEPTH:
+		return "tree";
+	case LOFC_SPARSE_OID:
+		return "sparse:oid";
+	case LOFC_COMBINE:
+		return "combine";
+	case LOFC__COUNT:
+		/* not a real filter type; just the count of all filters */
+		break;
+	}
+	BUG("list_object_filter_choice_name: invalid argument '%d'", c);
+}
+
 /*
  * Parse value of the argument to the "filter" keyword.
  * On the command line this looks like:
diff --git a/list-objects-filter-options.h b/list-objects-filter-options.h
index 73fffa4ad7..01767c3c96 100644
--- a/list-objects-filter-options.h
+++ b/list-objects-filter-options.h
@@ -17,6 +17,12 @@ enum list_objects_filter_choice {
 	LOFC__COUNT /* must be last */
 };
 
+/*
+ * Returns a configuration key suitable for describing the given object filter,
+ * e.g.: "blob:none", "combine", etc.
+ */
+const char *list_object_filter_config_name(enum list_objects_filter_choice c);
+
 struct list_objects_filter_options {
 	/*
 	 * 'filter_spec' is the raw argument value given on the command line
-- 
2.28.0.rc1.13.ge78abce653