UnusedL10nCommand class

Analyzes unused localization keys across all packages in the project.

The UnusedL10nCommand scans all ARB (Application Resource Bundle) files to extract localization keys, then searches through all Dart files in parallel to identify which keys are not being used in the codebase. It respects concurrency settings from morpheme.yaml for optimal performance.

Usage

Basic unused localization analysis (with presentation folder filtering):

morpheme unused-l10n

Search all Dart files without filtering:

morpheme unused-l10n --no-filter-presentation

Automatically remove unused keys from ARB files:

morpheme unused-l10n --auto-remove

Auto-remove with backup files:

morpheme unused-l10n --auto-remove --backup

Auto-remove without confirmation prompt:

morpheme unused-l10n --auto-remove --confirm

With custom configuration:

morpheme unused-l10n --morpheme-yaml custom/path/morpheme.yaml

Configuration

The command reads concurrency settings from morpheme.yaml:

concurrent: 4  # Number of parallel file processing tasks

Auto-Remove Feature

When --auto-remove is enabled, the command will:

• Show a confirmation prompt (unless --confirm is used)
• Optionally create backup files with .backup extension (if --backup is used)
• Remove unused keys from all ARB files
• Preserve all metadata entries (@-prefixed keys)
• Report the number of files modified and keys removed

Safety Considerations

• By default, no backup files are created to avoid cluttering the workspace
• Use --backup flag when you want to preserve original ARB files
• Backup files use .arb.backup extension and can be restored if needed

Backup files can be restored using:

find . -name "*.arb.backup" -exec sh -c 'mv "$1" "${1%.backup}"' _ {} \;

Filtering Behavior

By default, the command filters feature packages to only search in presentation folders (lib/presentation/**), while searching all files in non-feature packages. This optimization focuses on UI-related code where localization is typically used.

Feature packages are identified by having lib/presentation, lib/data, or lib/domain directories. Use --no-filter-presentation to disable this behavior.

Output

• Displays progress of file analysis
• Reports unused localization keys with counts
• Shows detailed analysis results
• If --auto-remove is used, shows removal progress and results

Performance

• Uses parallel processing for scanning Dart files
• Searches all .dart files in the project (not just lib/**)
• Optimized regex patterns for localization usage detection
• True isolate-based parallelism for handling 15k+ files

Dependencies

• Uses ModularHelper for package discovery
• Requires valid ARB files for localization keys
• Supports both modular and traditional project structures

Exceptions

Throws FileSystemException if ARB files cannot be read or modified. Throws FormatException if ARB files contain invalid JSON. Throws ProcessException if file processing fails.