regex-tdfa-1.1.7: Replaces/Enhances Text.Regex

Text.Regex.TDFA.Pattern

Contents

Description

This Text.Regex.TDFA.Pattern module provides the Pattern data type and its subtypes. This Pattern type is used to represent the parsed form of a Regular Expression.

Synopsis

Documentation

data Pattern

Pattern is the type returned by the regular expression parser. This is consumed by the CorePattern module and the tender leaves are nibbled by the TNFA module.

Instances

Eq Pattern 
Show Pattern 

data PatternSet

Constructors

PatternSet (Maybe (Set Char)) (Maybe (Set PatternSetCharacterClass)) (Maybe (Set PatternSetCollatingElement)) (Maybe (Set PatternSetEquivalenceClass)) 

Instances

type GroupIndex = Int

GroupIndex is for indexing submatches from capturing parenthesized groups (PGroup/Group)

newtype DoPa

Used to track elements of the pattern that accept characters or are anchors

Constructors

DoPa 

Fields

dopaIndex :: Int
 

Instances

Enum DoPa 
Eq DoPa 
Ord DoPa 
Show DoPa 

showPattern :: Pattern -> String

I have not been checking, but this should have the property that parsing the resulting string should result in an identical Pattern. This is not true if starTrans has created PNonCapture and PNonEmpty values or a (PStar False). The contents of a [ ] grouping are always shown in a sorted canonical order.

Internal use

starTrans :: Pattern -> Pattern

Do the transformation and simplification in a single traversal. This removes the PPlus, PQuest, and PBound values, changing to POr and PEmpty and PStar True/False. For some PBound values it adds PNonEmpty and PNonCapture semantic marker. It also simplifies to flatten out nested POr and PConcat instances and eliminate some unneeded PEmpty values.

Internal use, Operations to support debugging under ghci

simplify' :: Pattern -> Pattern

Function to transform a pattern into an equivalent, but less redundant form. Nested POr and PConcat are flattened. PEmpty is propagated.

dfsPattern

Arguments

:: (Pattern -> Pattern)

The transformation function

-> Pattern

The Pattern to transform

-> Pattern

The transformed Pattern

Apply a Pattern transfomation function depth first