Package net.sf.saxon.regex

Class Operation

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      protected static class  Operation.ForceProgressIterator
      The ForceProgressIterator is used to protect against non-termination; specifically, iterators that return an infinite number of zero-length matches.

    • Constructor Summary

      Constructors 
      Constructor Description
      Operation()  

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      boolean containsCapturingExpressions()
      Ask whether the expression contains any capturing sub-expressions
      abstract java.lang.String display()
      Display the operation as a regular expression, possibly in abbreviated form
      CharacterClass getInitialCharacterClass​(boolean caseBlind)
      Get a CharacterClass identifying the set of characters that can appear as the first character of a non-empty string that matches this term.
      int getMatchLength()
      Get the length of the matches returned by this operation if they are fixed-length
      int getMinimumMatchLength()
      Get the minimum length of the matches returned by this operation
      abstract IntIterator iterateMatches​(REMatcher matcher, int position)
      Get an iterator returning all the matches for this operation
      abstract 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 java.lang.Object

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

    • Constructor Detail

      • Operation

        public Operation()

    • Method Detail

      • iterateMatches

        public abstract IntIterator iterateMatches​(REMatcher matcher,
                                           int position)
        Get an iterator returning all the matches for this operation
        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

      • getMatchLength

        public int getMatchLength()
        Get the length of the matches returned by this operation if they are fixed-length
        Returns:
        the length of the matches, or -1 if the length is variable

      • getMinimumMatchLength

        public int getMinimumMatchLength()
        Get the minimum length of the matches returned by this operation
        Returns:
        the length of the shortest string that will match the operation

      • matchesEmptyString

        public abstract int matchesEmptyString()
        Ask whether the regular expression is known, after static analysis, to match a zero-length string
        Returns:
        a value indicating whether the regex is statically known to match a zero-length string. Specifically:
        • returns MATCHES_ZLS_AT_START if the expression is statically known to match a zero-length string at the start of the supplied input;
        • returns MATCHES_ZLS_AT_END if it is statically known to return a zero-length string at the end of the supplied input;
        • returns MATCHES_ZLS_ANYWHERE if it is statically known to match a zero-length string anywhere in the input.
        • returns 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.

      • containsCapturingExpressions

        public boolean containsCapturingExpressions()
        Ask whether the expression contains any capturing sub-expressions
        Returns:
        true if the expression contains any capturing sub-expressions (but not if it is a capturing expression itself, unless it contains nested capturing expressions)

      • getInitialCharacterClass

        public CharacterClass getInitialCharacterClass​(boolean caseBlind)
        Get a CharacterClass identifying the set of characters that can appear as the first character of a non-empty string that matches this term. This is allowed to be an over-estimate (that is, the returned Character class must match every character that can legitimately appear at the start of the matched string, but it can also match other characters).
        Parameters:
        caseBlind - true if case-blind matching is in force ("i" flag)

      • optimize

        public Operation optimize​(REProgram program,
                          REFlags flags)
        Optimize the operation
        Parameters:
        program - the program being optimized
        flags - the regular expression flags
        Returns:
        the optimized operation

      • display

        public abstract java.lang.String display()
        Display the operation as a regular expression, possibly in abbreviated form
        Returns:
        the operation in a form that is recognizable as a regular expression or abbreviated regular expression