net.sf.saxon.regex

Class OpUnambiguousRepeat

java.lang.Object

net.sf.saxon.regex.Operation

net.sf.saxon.regex.OpRepeat

net.sf.saxon.regex.OpUnambiguousRepeat

public class OpUnambiguousRepeat
extends OpRepeat

Handle a repetition where there is no ambiguity; if the repeated term is matched in the string, then it cannot match anything other than the repeated term. It is also used when the number of occurrences is fixed. In this situation there will never be any need for backtracking, so there is no need to keep any information to support backtracking, and in addition, there is no distinction between greedy and reluctant matching. This operation is used only for a repeated atom or CharClass, which also means that if the repeated term matches then it can only match in one way; a typical example is the term "A*" in the regex "A*B".

Nested Class Summary

Nested classes/interfaces inherited from class net.sf.saxon.regex.Operation

Operation.ForceProgressIterator

Field Summary

Fields inherited from class net.sf.saxon.regex.OpRepeat

max, min, op

Fields inherited from class net.sf.saxon.regex.Operation

MATCHES_ZLS_ANYWHERE, MATCHES_ZLS_AT_END, MATCHES_ZLS_AT_START, MATCHES_ZLS_NEVER

Method Summary

Modifier and Type	Method and Description
int	getMatchLength() Get the length of the matches returned by this operation if they are fixed-length
IntIterator	iterateMatches(REMatcher matcher, int position) Get an iterator returning all the matches for this operation
int	matchesEmptyString() Ask whether the regular expression is known, after static analysis, to match a zero-length string
Operation	optimize(REProgram program, REFlags flags) Optimize the operation

Methods inherited from class net.sf.saxon.regex.OpRepeat

containsCapturingExpressions, display, getInitialCharacterClass, getMinimumMatchLength

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

matchesEmptyString

public int matchesEmptyString()

Description copied from class: Operation

Ask whether the regular expression is known, after static analysis, to match a zero-length string

Overrides:

matchesEmptyString in class OpRepeat

Returns:

a value indicating whether the regex is statically known to match a zero-length string. Specifically:

• returns Operation.MATCHES_ZLS_AT_START if the expression is statically known to match a zero-length string at the start of the supplied input;
• returns Operation.MATCHES_ZLS_AT_END if it is statically known to return a zero-length string at the end of the supplied input;
• returns Operation.MATCHES_ZLS_ANYWHERE if it is statically known to match a zero-length string anywhere in the input.
• returns Operation.MATCHES_ZLS_NEVER if it is statically known that the regex will never match a zero length string.

Returning 0 means that it is not known statically whether or not the regex will match a zero-length string; this case typically arises when back-references are involved.

getMatchLength

public int getMatchLength()

Description copied from class: Operation

Get the length of the matches returned by this operation if they are fixed-length

Overrides:

getMatchLength in class OpRepeat

Returns:

the length of the matches, or -1 if the length is variable

optimize

public Operation optimize(REProgram program,
                          REFlags flags)

Description copied from class: Operation

Optimize the operation

Overrides:

optimize in class OpRepeat

Parameters:

program - the program being optimized

flags - the regular expression flags

Returns:

the optimized operation

iterateMatches

public IntIterator iterateMatches(REMatcher matcher,
                                  int position)

Description copied from class: Operation

Get an iterator returning all the matches for this operation

Overrides:

iterateMatches in class OpRepeat

Parameters:

matcher - supplies the context for the matching; may be updated with information about captured groups

position - the start position to seek a match

Returns:

an iterator returning the endpoints of all matches starting at the supplied position