Re: [PATCH 4/5] odb/source: introduce function to map source type to name

[Junio C Hamano <gitster@pobox.com>]

Patrick Steinhardt <ps@pks.im> writes:

> Introduce a new function that maps an object source's type to a
> human-readable name. Use the function to provide better human-readable
> error messages for the downcasting functions.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  odb/source-files.h    |  4 +++-
>  odb/source-inmemory.h |  4 +++-
>  odb/source-loose.h    |  4 +++-
>  odb/source-packed.h   |  4 +++-
>  odb/source.c          | 19 +++++++++++++++++++
>  odb/source.h          |  6 ++++++
>  6 files changed, 37 insertions(+), 4 deletions(-)

OK.

> +static const char * const odb_source_names_by_type[] = {
> +	[ODB_SOURCE_UNKNOWN] = "unknown",
> +	[ODB_SOURCE_FILES] = "files",
> +	[ODB_SOURCE_LOOSE] = "loose",
> +	[ODB_SOURCE_PACKED] = "packed",
> +	[ODB_SOURCE_INMEMORY] = "inmemory",
> +};

This is a trivially obvious implementation for mapping in either
direction.

'inmemory' should probably be spelled 'in-memory', though.

Thanks.

> +const char *odb_source_type_to_name(enum odb_source_type type)
> +{
> +	const char *name;
> +	if (type < 0 || type >= ARRAY_SIZE(odb_source_names_by_type))
> +		type = ODB_SOURCE_UNKNOWN;
> +	name = odb_source_names_by_type[type];
> +	if (!name)
> +		BUG("name missing in `odb_source_names_by_type` for '%d'", type);
> +	return name;
> +}
> +
>  struct odb_source *odb_source_new(struct object_database *odb,
>  				  const char *path,
>  				  bool local)
> diff --git a/odb/source.h b/odb/source.h
> index cd63dba91f..ab16d152f4 100644
> --- a/odb/source.h
> +++ b/odb/source.h
> @@ -25,6 +25,12 @@ enum odb_source_type {
>  	ODB_SOURCE_INMEMORY,
>  };
>  
> +/*
> + * Convert between the enum and its name. Returns the equivalent of "unknown"
> + * for unknown types.
> + */
> +const char *odb_source_type_to_name(enum odb_source_type type);
> +
>  struct object_id;
>  struct odb_read_stream;
>  struct strvec;