Ideas.Common.Strategy.Prefix

A prefix encodes a sequence of steps already performed (a so-called trace), and allows to continue the derivation at that particular point.

Documentation

type Prefix = ParseState LabelInfo

Abstract data type for a (labeled) strategy with a prefix (a sequence of executed rules). A prefix is still aware of the labels that appear in the strategy. A prefix is encoded as a list of integers (and can be reconstructed from such a list: see makePrefix). The list is stored in reversed order.

emptyPrefix :: LabeledStrategy a -> a -> Prefix a

Construct the empty prefix for a labeled strategy

makePrefix :: Monad m => Path -> LabeledStrategy a -> a -> m (Prefix a)

Construct a prefix for a given list of integers and a labeled strategy.

showPrefix :: Prefix a -> String

prefixToSteps :: Prefix a -> [Step LabelInfo a]

prefixTree :: a -> Prefix a -> DerivationTree (Prefix a) a

Create a derivation tree with a prefix as annotation.

stepsToRules :: [Step l a] -> [Rule a]

Retrieves the rules from a list of steps

lastStepInPrefix :: Prefix a -> Maybe (Step LabelInfo a)

Returns the last rule of a prefix (if such a rule exists)

activeLabels :: Prefix a -> [LabelInfo]

Calculate the active labels

searchModePrefix :: (Step LabelInfo a -> Bool) -> (Step LabelInfo a -> Step LabelInfo a -> Bool) -> Prefix a -> Prefix a