@spec build_alias_index() :: map()

Builds the alias index from all transform XML files and stores it in a persistent_term. Called at application startup to avoid lazy initialization on the first transform call.

Returns

The alias index map.

@spec find_transform(String.t()) :: {Path.t(), :forward | :backward} | nil

Finds the XML file path and direction for a given transform ID.

Resolves transform names by checking:

1. Exact filename match (e.g., "Latin-ASCII" → "priv/transforms/Latin-ASCII.xml").

2. Forward alias match from XML metadata.

3. Backward alias match from XML metadata.

4. Reverse direction lookup (e.g., "ConjoiningJamo-Latin" found via "Latin-ConjoiningJamo.xml" with direction="both").

5. BCP47 (ISO 15924) script code resolution (e.g., "Grek-Latn" → "Greek-Latin").

Arguments

• transform_id — the transform name to resolve.

Returns

• {file_path, :forward} — use the file's rules in forward direction.

• {file_path, :backward} — use the file's rules in backward/reverse direction.

• nil — no matching transform found.

@spec list_transforms() :: [Path.t()]

Lists all available transform XML files.

Returns

A list of file paths to transform XML files.

@spec load_file(Path.t()) :: map()

Loads a transform definition from an XML file.

Arguments

• file_path — path to the XML file.

Returns

A map with the following keys:

• :source — source script/locale.

• :target — target script/locale.

• :direction — "forward", "backward", or "both".

• :alias — transform alias string.

• :backward_alias — backward transform alias string.

• :rules — the raw rule text string.

@spec transform_id(String.t(), String.t()) :: String.t()

Derives a transform ID from source and target.

Arguments

• source — the source script name.

• target — the target script name.

Returns

A string like "Latin-ASCII" or "Greek-Latin".

@spec transform_id_from_file(Path.t()) :: String.t()

Derives a transform ID from a filename.

Arguments

• file_path — the path to the XML file.

Returns

A string transform ID derived from the filename.

@spec transforms_dir() :: Path.t()

Returns the default transforms directory path.

Returns

The path to the transforms directory.