Feature Rules

• Each feature has a unique name.
• A newly added feature is disabled by default.
• A feature may require a specific subscription, region, or both.
• An empty subscription rule means that every subscription is allowed.
• An empty region rule means that every region is allowed.
• When both rules are present, the user must satisfy both rules.
• A feature is available only when it exists, is enabled, and all its rules match the user.
• Feature names, subscriptions, and regions are case-sensitive.

Class Initialization

FeatureToggleService()

Methods

Add a Feature

boolean addFeature(String featureName, String requiredSubscription, String requiredRegion)

• featureName: The unique name of the feature. It contains characters [a-z] and hyphen -
• requiredSubscription: The required subscription, such as "Premium". Use "" when there is no subscription restriction.
• requiredRegion: The required region, such as "IN". Use "" when there is no region restriction.
• Returns true when the feature is added.
• Returns false when a feature with the same name already exists. The existing feature is not changed.

Enable a Feature

boolean enableFeature(String featureName)

• Returns true when the feature exists, including when it was already enabled.
• Returns false when the feature does not exist.

Disable a Feature

boolean disableFeature(String featureName)

• Returns true when the feature exists, including when it was already disabled.
• Returns false when the feature does not exist.

Remove a Feature

boolean removeFeature(String featureName)

• Returns true when the feature is removed.
• Returns false when the feature does not exist.

Check Feature Availability

boolean isFeatureEnabled(String featureName, String userSubscription, String userRegion)

• userSubscription: The user's subscription. Use "" when the user has no subscription.
• userRegion: The user's region. Use "" when the region is unavailable.
• Returns true only when the feature exists, is enabled, and the user satisfies every configured rule.
• Returns false otherwise.

Constraints

• 1 ≤ featureName.length() ≤ 100
• 0 ≤ requiredSubscription.length() ≤ 50
• 0 ≤ requiredRegion.length() ≤ 20
• 0 ≤ userSubscription.length() ≤ 50
• 0 ≤ userRegion.length() ≤ 20
• At most 100,000 features are stored at the same time.
• All method parameters are non-null strings.

Examples

Example 1: Feature Available to Everyone

Example 2: Subscription and Region Rules

Example 3: Disable and Remove a Feature