refs: generalize `refs_for_each_namespaced_ref()`

The function `refs_for_each_namespaced_ref()` iterates through all
references that are part of the current ref namespace. This namespace
can be configured by setting the `GIT_NAMESPACE` environment variable
and is then retrieved by calling `get_git_namespace()`.

If a namespace is configured, then we:

  - Obviously only yield refs that exist in this namespace.

  - Rewrite exclude patterns so that they work for the given namespace,
    if any namespace is currently configured.

Port this logic to `refs_for_each_ref_ext()` by adding a new `namespace`
field to the options structure. This gives callers more flexibility as
they can decide by themselves whether they want to use the globally
configured or an arbitrary other namespace.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/refs.h b/refs.h
index a66dbf3865..5a5fb4e1e4 100644
--- a/refs.h
+++ b/refs.h
@@ -469,6 +469,13 @@ struct refs_for_each_ref_options {
 	const char *pattern;
 
 	/*
+	 * If set, only yield refs part of the configured namespace. Exclude
+	 * patterns will be rewritten to apply to the namespace, and the prefix
+	 * will be considered relative to the namespace.
+	 */
+	const char *namespace;
+
+	/*
 	 * Exclude any references that match any of these patterns on a
 	 * best-effort basis. The caller needs to be prepared for the exclude
 	 * patterns to be ignored.