Package org.apache.lucene.util.automaton

Class RegExp

  • public class RegExp
extends java.lang.Object
    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).

    • Field Detail

      • INTERSECTION

        public static final int INTERSECTION
        Syntax flag, enables intersection (&).
        See Also:
        Constant Field Values

      • COMPLEMENT

        public static final int COMPLEMENT
        Syntax flag, enables complement (~).
        See Also:
        Constant Field Values

      • EMPTY

        public static final int EMPTY
        Syntax flag, enables empty language (#).
        See Also:
        Constant Field Values

      • ANYSTRING

        public static final int ANYSTRING
        Syntax flag, enables anystring (@).
        See Also:
        Constant Field Values

      • AUTOMATON

        public static final int AUTOMATON
        Syntax flag, enables named automata (<identifier>).
        See Also:
        Constant Field Values

      • INTERVAL

        public static final int INTERVAL
        Syntax flag, enables numerical intervals ( <n-m>).
        See Also:
        Constant Field Values

      • ALL

        public static final int ALL
        Syntax flag, enables all optional regexp syntax.
        See Also:
        Constant Field Values

      • NONE

        public static final int NONE
        Syntax flag, enables no optional regexp syntax.
        See Also:
        Constant Field Values

      • kind

        public final RegExp.Kind kind
        The type of expression

      • exp1

        public final RegExp exp1
        Child expressions held by a container type expression

      • exp2

        public final RegExp exp2
        Child expressions held by a container type expression

      • s

        public final java.lang.String s
        String expression

      • c

        public final int c
        Character expression

      • min

        public final int min
        Limits for repeatable type expressions

      • max

        public final int max
        Limits for repeatable type expressions

      • digits

        public final int digits
        Limits for repeatable type expressions

      • from

        public final int from
        Extents for range type expressions

      • to

        public final int to
        Extents for range type expressions

      • originalString

        private final java.lang.String originalString

      • flags

        int flags

      • pos

        int pos

    • Constructor Detail

      • RegExp

        public RegExp​(java.lang.String s)
       throws java.lang.IllegalArgumentException
        Constructs new RegExp from a string. Same as RegExp(s, ALL).
        Parameters:
        s - regexp string
        Throws:
        java.lang.IllegalArgumentException - if an error occurred while parsing the regular expression

      • RegExp

        public RegExp​(java.lang.String s,
              int syntax_flags)
       throws java.lang.IllegalArgumentException
        Constructs new RegExp from a string.
        Parameters:
        s - regexp string
        syntax_flags - boolean 'or' of optional syntax constructs to be enabled
        Throws:
        java.lang.IllegalArgumentException - if an error occurred while parsing the regular expression

      • RegExp

        RegExp​(RegExp.Kind kind,
       RegExp exp1,
       RegExp exp2,
       java.lang.String s,
       int c,
       int min,
       int max,
       int digits,
       int from,
       int to)

    • Method Detail

      • newLeafNode

        static RegExp newLeafNode​(RegExp.Kind kind,
                          java.lang.String s,
                          int c,
                          int min,
                          int max,
                          int digits,
                          int from,
                          int to)

      • toAutomaton

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

      • toAutomaton

        public Automaton toAutomaton​(int maxDeterminizedStates)
                      throws java.lang.IllegalArgumentException,
                             TooComplexToDeterminizeException
        Constructs new Automaton from this RegExp. The constructed automaton is minimal and deterministic and has no transitions to dead states.
        Parameters:
        maxDeterminizedStates - maximum number of states in the resulting automata. If the automata would need more than this many states TooComplextToDeterminizeException is thrown. Higher number require more space but can process more complex regexes.
        Throws:
        java.lang.IllegalArgumentException - if this regular expression uses a named identifier that is not available from the automaton provider
        TooComplexToDeterminizeException - if determinizing this regexp requires more than maxDeterminizedStates states

      • toAutomaton

        public Automaton toAutomaton​(AutomatonProvider automaton_provider,
                             int maxDeterminizedStates)
                      throws java.lang.IllegalArgumentException,
                             TooComplexToDeterminizeException
        Constructs new Automaton from this RegExp. The constructed automaton is minimal and deterministic and has no transitions to dead states.
        Parameters:
        automaton_provider - provider of automata for named identifiers
        maxDeterminizedStates - maximum number of states in the resulting automata. If the automata would need more than this many states TooComplextToDeterminizeException is thrown. Higher number require more space but can process more complex regexes.
        Throws:
        java.lang.IllegalArgumentException - if this regular expression uses a named identifier that is not available from the automaton provider
        TooComplexToDeterminizeException - if determinizing this regexp requires more than maxDeterminizedStates states

      • toAutomaton

        public Automaton toAutomaton​(java.util.Map<java.lang.String,​Automaton> automata,
                             int maxDeterminizedStates)
                      throws java.lang.IllegalArgumentException,
                             TooComplexToDeterminizeException
        Constructs new Automaton from this RegExp. The constructed automaton is minimal and deterministic and has no transitions to dead states.
        Parameters:
        automata - a map from automaton identifiers to automata (of type Automaton).
        maxDeterminizedStates - maximum number of states in the resulting automata. If the automata would need more than this many states TooComplexToDeterminizeException is thrown. Higher number require more space but can process more complex regexes.
        Throws:
        java.lang.IllegalArgumentException - if this regular expression uses a named identifier that does not occur in the automaton map
        TooComplexToDeterminizeException - if determinizing this regexp requires more than maxDeterminizedStates states

      • toAutomatonInternal

        private Automaton toAutomatonInternal​(java.util.Map<java.lang.String,​Automaton> automata,
                                      AutomatonProvider automaton_provider,
                                      int maxDeterminizedStates)
                               throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • getOriginalString

        public java.lang.String getOriginalString()
        The string that was used to construct the regex. Compare to toString.

      • toString

        public java.lang.String toString()
        Constructs string from parsed regular expression.
        Overrides:
        toString in class java.lang.Object

      • toStringBuilder

        void toStringBuilder​(java.lang.StringBuilder b)

      • toStringTree

        public java.lang.String toStringTree()
        Like to string, but more verbose (shows the higherchy more clearly).

      • toStringTree

        void toStringTree​(java.lang.StringBuilder b,
                  java.lang.String indent)

      • getIdentifiers

        public java.util.Set<java.lang.String> getIdentifiers()
        Returns set of automaton identifiers that occur in this regular expression.

      • getIdentifiers

        void getIdentifiers​(java.util.Set<java.lang.String> set)

      • makeRepeat

        static RegExp makeRepeat​(RegExp exp,
                         int min)

      • makeRepeat

        static RegExp makeRepeat​(RegExp exp,
                         int min,
                         int max)

      • makeComplement

        static RegExp makeComplement​(RegExp exp)

      • makeChar

        static RegExp makeChar​(int c)

      • makeCharRange

        static RegExp makeCharRange​(int from,
                            int to)

      • makeAnyChar

        static RegExp makeAnyChar()

      • makeEmpty

        static RegExp makeEmpty()

      • makeString

        static RegExp makeString​(java.lang.String s)

      • makeAnyString

        static RegExp makeAnyString()

      • makeAutomaton

        static RegExp makeAutomaton​(java.lang.String s)

      • makeInterval

        static RegExp makeInterval​(int min,
                           int max,
                           int digits)

      • peek

        private boolean peek​(java.lang.String s)

      • match

        private boolean match​(int c)

      • more

        private boolean more()

      • next

        private int next()
          throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • check

        private boolean check​(int flag)

      • parseUnionExp

        final RegExp parseUnionExp()
                    throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseInterExp

        final RegExp parseInterExp()
                    throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseConcatExp

        final RegExp parseConcatExp()
                     throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseRepeatExp

        final RegExp parseRepeatExp()
                     throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseComplExp

        final RegExp parseComplExp()
                    throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseCharClassExp

        final RegExp parseCharClassExp()
                        throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseCharClasses

        final RegExp parseCharClasses()
                       throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseCharClass

        final RegExp parseCharClass()
                     throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseSimpleExp

        final RegExp parseSimpleExp()
                     throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException

      • parseCharExp

        final int parseCharExp()
                throws java.lang.IllegalArgumentException
        Throws:
        java.lang.IllegalArgumentException