Class RegExp

Regular Expression extension to Automaton.

Regular expressions are built from the following abstract syntax:

regexp	::=	unionexp
	\|
unionexp	::=	interexp `\|` unionexp	(union)
	\|	interexp
interexp	::=	concatexp `&` interexp	(intersection)	[OPTIONAL]
	\|	concatexp
concatexp	::=	repeatexp concatexp	(concatenation)
	\|	repeatexp
repeatexp	::=	repeatexp `?`	(zero or one occurrence)
	\|	repeatexp `*`	(zero or more occurrences)
	\|	repeatexp `+`	(one or more occurrences)
	\|	repeatexp `{n}`	(`n` occurrences)
	\|	repeatexp `{n,}`	(`n` or more occurrences)
	\|	repeatexp `{n,m}`	(`n` to `m` occurrences, including both)
	\|	complexp
complexp	::=	`~` complexp	(complement)	[OPTIONAL]
	\|	charclassexp
charclassexp	::=	`[` charclasses `]`	(character class)
	\|	`[^` charclasses `]`	(negated character class)
	\|	simpleexp
charclasses	::=	charclass charclasses
	\|	charclass
charclass	::=	charexp `-` charexp	(character range, including end-points)
	\|	charexp
simpleexp	::=	charexp
	\|	`.`	(any single character)
	\|	`#`	(the empty language)	[OPTIONAL]
	\|	`@`	(any string)	[OPTIONAL]
	\|	`"` <Unicode string without double-quotes> `"`	(a string)
	\|	`(` `)`	(the empty string)
	\|	`(` unionexp `)`	(precedence override)
	\|	`<` <identifier> `>`	(named automaton)	[OPTIONAL]
	\|	`<n-m>`	(numerical interval)	[OPTIONAL]
charexp	::=	<Unicode character>	(a single non-reserved character)
	\|	`\` <Unicode character>	(a single character)

The productions marked [OPTIONAL] are only allowed if specified by the syntax flags passed to the RegExp constructor. The reserved characters used in the (enabled) syntax must be escaped with backslash (\) or double-quotes ("..."). (In contrast to other regexp syntaxes, this is required also in character classes.) Be aware that dash (-) has a special meaning in charclass expressions. An identifier is a string not containing right angle bracket (>) or dash (-). Numerical intervals are specified by non-negative decimal integers and include both end points, and if n and m have the same number of digits, then the conforming strings must have that length (i.e. prefixed by 0's).

Note

This API is experimental and might change in incompatible ways in the next release.

Inheritance

object

RegExp

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: Lucene.Net.Util.Automaton

Assembly: Lucene.Net.dll

Syntax

public class RegExp

Constructors

RegExp(string)

Constructs new RegExp from a string. Same as RegExp(s, RegExpSyntax.ALL).

Declaration

public RegExp(string s)

Parameters

Type	Name	Description
string	s	Regexp string.

Exceptions

Type	Condition
ArgumentException	If an error occured while parsing the regular expression.

RegExp(string, RegExpSyntax)

Constructs new RegExp from a string.

Declaration

public RegExp(string s, RegExpSyntax syntax_flags)

Parameters

Type	Name	Description
string	s	Regexp string.
RegExpSyntax	syntax_flags	Boolean 'or' of optional RegExpSyntax constructs to be enabled.

Exceptions

Type	Condition
ArgumentException	If an error occured while parsing the regular expression

Methods

GetIdentifiers()

Returns set of automaton identifiers that occur in this regular expression.

Declaration

public virtual ISet<string> GetIdentifiers()

Returns

Type	Description
ISet<string>

SetAllowMutate(bool)

Sets or resets allow mutate flag. If this flag is set, then automata construction uses mutable automata, which is slightly faster but not thread safe. By default, the flag is not set.

Declaration

public virtual bool SetAllowMutate(bool flag)

Parameters

Type	Name	Description
bool	flag	If `true`, the flag is set

Returns

Type	Description
bool	Previous value of the flag.

ToAutomaton()

Constructs new Automaton from this RegExp. Same as ToAutomaton(null) (empty automaton map).

Declaration

public virtual Automaton ToAutomaton()

Returns

Type	Description
Automaton

ToAutomaton(IAutomatonProvider)

Constructs new Automaton from this RegExp. The constructed automaton is minimal and deterministic and has no transitions to dead states.

Declaration

public virtual Automaton ToAutomaton(IAutomatonProvider automaton_provider)

Parameters

Type	Name	Description
IAutomatonProvider	automaton_provider	Provider of automata for named identifiers.

Returns

Type	Description
Automaton

Exceptions

Type	Condition
ArgumentException	If this regular expression uses a named identifier that is not available from the automaton provider.

ToAutomaton(IDictionary<string, Automaton>)

Constructs new Automaton from this RegExp. The constructed automaton is minimal and deterministic and has no transitions to dead states.

Declaration

public virtual Automaton ToAutomaton(IDictionary<string, Automaton> automata)

Parameters

Type	Name	Description
IDictionary<string, Automaton>	automata	A map from automaton identifiers to automata (of type Automaton).

Returns

Type	Description
Automaton

Exceptions

Type	Condition
ArgumentException	If this regular expression uses a named identifier that does not occur in the automaton map.

ToString()

Constructs string from parsed regular expression.

Declaration

public override string ToString()

Returns

Type	Description
string

Overrides

object.ToString()