Ideas.Common.Strategy.Prefix

Basic machinery for fully executing a strategy expression, or only partially. Partial execution results in a prefix that keeps the current locations in the strategy (a list of Paths) for continuing the execution later on. A path can be used to reconstruct the sequence of steps already performed (a so-called trace). Prefixes can be merged with the Monoid operation.

Prefix

data Prefix a

Instances

Show (Prefix a)

Methods

showsPrec :: Int -> Prefix a -> ShowS

show :: Prefix a -> String

showList :: [Prefix a] -> ShowS

Monoid (Prefix a)

Methods

mempty :: Prefix a

mappend :: Prefix a -> Prefix a -> Prefix a

mconcat :: [Prefix a] -> Prefix a

Firsts (Prefix a)

Associated Types

type Elem (Prefix a) :: *

Methods

ready :: Prefix a -> Bool

firsts :: Prefix a -> [(Elem (Prefix a), Prefix a)]

type Elem (Prefix a)

type Elem (Prefix a) = (Rule a, a, Environment)

noPrefix :: Prefix a

The error prefix (i.e., without a location in the strategy).

makePrefix :: Process (Leaf a) -> a -> Prefix a

Make a prefix from a core strategy and a start term.

firstsOrdered :: (Rule a -> Rule a -> Ordering) -> Prefix a -> [((Rule a, a, Environment), Prefix a)]

replayProcess :: Path -> Process (Leaf a) -> ([Rule a], a -> Prefix a)

Construct a prefix by replaying a path in a core strategy: the third argument is the current term.

isEmptyPrefix :: Prefix a -> Bool

majorPrefix :: Prefix a -> Prefix a

Transforms the prefix such that only major steps are kept in the remaining strategy.

searchModePrefix :: Prefix a -> Prefix a

The searchModePrefix transformation changes the process in such a way that all intermediate states can only be reached by one path. A prerequisite is that symbols are unique (or only used once).

prefixPaths :: Prefix a -> [Path]

Returns the current Path.

Path

data Path

A path encodes a location in a strategy. Paths are represented as a list of integers and terms (the latter act as input for the dynamic strategies).

Instances

Eq Path

Methods

(==) :: Path -> Path -> Bool

(/=) :: Path -> Path -> Bool

Show Path

Methods

showsPrec :: Int -> Path -> ShowS

show :: Path -> String

showList :: [Path] -> ShowS

emptyPath :: Path

The empty path.

readPath :: Monad m => String -> m Path

readPaths :: Monad m => String -> m [Path]