Language.GroteTrap.Range

Types

type Pos = Int

A Pos is a position in between two elements in a list. For example, position 0 marks the beginning of the list, and position length list marks the end of the list. There are n + 1 valid positions for a list of length n.

type Range = (Pos, Pos)

A range's positions mark the begin and end of a sublist, respectively.

class KnowsPosition a where

Something that knows its range as sublist in a larger list. Minimal complete definition: either range or both begin and end.

Methods

range :: a -> Range

Yields the element's range.

begin :: a -> Pos

Yields the element's begin position.

end :: a -> Pos

Yields the element's end position.

Instances

KnowsPosition ParseTree

Utility functions

distRange :: Range -> Range -> Int

distRange (b1, e1) (b2, e2) is defined as |b1 - b2| + |e1 - e2|.

inRange :: Pos -> Range -> Bool

Whether a position falls within a range, including the range's edges.

includes :: Range -> Range -> Bool

Yields whether the second argument completely falls within the first argument.

unionRange :: Range -> Range -> Range

unionRange x y yields the smallest range z such that x `includes` z and y `includes` z.

size :: Range -> Int

A range's size is the number of elements it contains.

validRange :: Range -> Bool

A range is valid if its positions are nonnegative and begin < end.