regexdot-0.12.2.2: A polymorphic, POSIX, extended regex-engine.

RegExDot.Anchor

Description

AUTHOR
Dr. Alistair Ward
DESCRIPTION
• A type of zero-width assertion: the Bow-predicate is True if no input-data has yet been consumed; the Stern-predicate is True if no input-data remains to be consumed.
• Whilst at the top-level of the regex, the absence of an anchor is equivalent to a non-capturing .*?, tempting one to implement them using this property, it doesn't apply to those anchors encountered at either end of a sub-expression. So in all cases, an anchor constrains the permissible consumption of input-data, but at the top level it also prevents the regex drifting away from either end of the input-data.
Synopsis

# Types

## Data-types

data Anchor Source #

Defines the types on anchor by which a regex can be moored to a part of the input-data.

Constructors

 Bow Matches only if no input data has yet been consumed. Can only exist at the start of the entire regex, or (in theory) the start of any alternative. Stern Matches only if no input data remains to be consumed. Can only exist at the end of the entire regex, or (in theory) the end of any alternative.
Instances
 Source # Instance detailsDefined in RegExDot.Anchor Methods(==) :: Anchor -> Anchor -> Bool #(/=) :: Anchor -> Anchor -> Bool # Source # Instance detailsDefined in RegExDot.Anchor Methods Source # Instance detailsDefined in RegExDot.Anchor MethodsshowsPrec :: Int -> Anchor -> ShowS #showList :: [Anchor] -> ShowS # Source # Instance detailsDefined in RegExDot.Anchor Methodsrnf :: Anchor -> () #

## Type-synonyms

A specification for the anchors required around the expression

# Constants

The conventional token used to denote a Bow-anchor, when in String-form.

The conventional token used to denote a Stern-anchor, when in String-form.

The set of Char to which a specific meaning is attributed, when reading from String.

The specification for an unanchored expression.