Pegasus::Language::RuleAlternative

Computes the variants created by optionals. For example, a? b? has four variants, a b, a, b, <empty>.

Same as compute_optional_variants, but what's optional is now decided by the block.

Determines if this rule alternative can be empty, or derive lambda.

Determines if the rule alternative can be empty, using the block to check whether each element can be empty or not.

The elements of the rule.

Checks if this specific alternative is the lambda alternative.