org.apache.xerces.impl.xpath.regex
Class RegularExpression
public
class
RegularExpression
extends Object
implements Serializable
A regular expression matching engine using Non-deterministic Finite Automaton (NFA).
This engine does not conform to the POSIX regular expression.
How to use
- A. Standard way
-
RegularExpression re = new RegularExpression(regex);
if (re.matches(text)) { ... }
- B. Capturing groups
-
RegularExpression re = new RegularExpression(regex);
Match match = new Match();
if (re.matches(text, match)) {
... // You can refer captured texts with methods of the Match
class.
}
Case-insensitive matching
RegularExpression re = new RegularExpression(regex, "i");
if (re.matches(text) >= 0) { ...}
Options
You can specify options to RegularExpression(
regex,
options)
or setPattern(
regex,
options)
.
This options parameter consists of the following characters.
"i"
- This option indicates case-insensitive matching.
"m"
- ^ and $ consider the EOL characters within the text.
"s"
- . matches any one character.
"u"
- Redefines \d \D \w \W \s \S \b \B \< \> as becoming to Unicode.
"w"
- By this option, \b \B \< \> are processed with the method of
'Unicode Regular Expression Guidelines' Revision 4.
When "w" and "u" are specified at the same time,
\b \B \< \> are processed for the "w" option.
","
- The parser treats a comma in a character class as a range separator.
[a,b] matches a or , or b without this option.
[a,b] matches a or b with this option.
"X"
-
By this option, the engine confoms to XML Schema: Regular Expression.
The
match()
method does not do subsring matching
but entire string matching.
Syntax
Differences from the Perl 5 regular expression
- There is 6-digit hexadecimal character representation (\vHHHHHH.)
- Supports subtraction, union, and intersection operations for character classes.
- Not supported: \ooo (Octal character representations),
\G, \C, \lc,
\ uc, \L, \U,
\E, \Q, \N{name},
(?{code}), (??{code})
|
Meta characters are `. * + ? { [ ( ) | \ ^ $'.
- Character
- . (A period)
- Matches any one character except the following characters.
- LINE FEED (U+000A), CARRIAGE RETURN (U+000D),
PARAGRAPH SEPARATOR (U+2029), LINE SEPARATOR (U+2028)
- This expression matches one code point in Unicode. It can match a pair of surrogates.
- When the "s" option is specified,
it matches any character including the above four characters.
- \e \f \n \r \t
- Matches ESCAPE (U+001B), FORM FEED (U+000C), LINE FEED (U+000A),
CARRIAGE RETURN (U+000D), HORIZONTAL TABULATION (U+0009)
- \cC
- Matches a control character.
The C must be one of '@', 'A'-'Z',
'[', '\', ']', '^', '_'.
It matches a control character of which the character code is less than
the character code of the C by 0x0040.
- For example, a \cJ matches a LINE FEED (U+000A),
and a \c[ matches an ESCAPE (U+001B).
- a non-meta character
- Matches the character.
- \ + a meta character
- Matches the meta character.
- \xHH \x{HHHH}
- Matches a character of which code point is HH (Hexadecimal) in Unicode.
You can write just 2 digits for \xHH, and
variable length digits for \x{HHHH}.
- \vHHHHHH
- Matches a character of which code point is HHHHHH (Hexadecimal) in Unicode.
- \g
- Matches a grapheme.
- It is equivalent to (?[\p{ASSIGNED}]-[\p{M}\p{C}])?(?:\p{M}|[\x{094D}\x{09CD}\x{0A4D}\x{0ACD}\x{0B3D}\x{0BCD}\x{0C4D}\x{0CCD}\x{0D4D}\x{0E3A}\x{0F84}]\p{L}|[\x{1160}-\x{11A7}]|[\x{11A8}-\x{11FF}]|[\x{FF9E}\x{FF9F}])*
- \X
- Matches a combining character sequence.
It is equivalent to (?:\PM\pM*)
- Character class
+ * - [R1R2...Rn] (without "," option)
+ *
- [R1,R2,...,Rn] (with "," option)
- Positive character class. It matches a character in ranges.
- Rn:
- A character (including \e \f \n \r \t \xHH \x{HHHH} \vHHHHHH)
This range matches the character.
- C1-C2
This range matches a character which has a code point that is >= C1's code point and <= C2's code point.
+ *
- A POSIX character class: [:alpha:] [:alnum:] [:ascii:] [:cntrl:] [:digit:] [:graph:] [:lower:] [:print:] [:punct:] [:space:] [:upper:] [:xdigit:],
+ * and negative POSIX character classes in Perl like [:^alpha:]
...
- \d \D \s \S \w \W \p{name} \P{name}
These expressions specifies the same ranges as the following expressions.
Enumerated ranges are merged (union operation).
[a-ec-z] is equivalent to [a-z]
- [^R1R2...Rn] (without a "," option)
- [^R1,R2,...,Rn] (with a "," option)
- Negative character class. It matches a character not in ranges.
- (?[ranges]op[ranges]op[ranges] ... )
(op is - or + or &.)
- Subtraction or union or intersection for character classes.
- For exmaple, (?[A-Z]-[CF]) is equivalent to [A-BD-EG-Z], and (?[0x00-0x7f]-[K]&[\p{Lu}]) is equivalent to [A-JL-Z].
- The result of this operations is a positive character class
even if an expression includes any negative character classes.
You have to take care on this in case-insensitive matching.
For instance, (?[^b]) is equivalent to [\x00-ac-\x{10ffff}],
which is equivalent to [^b] in case-sensitive matching.
But, in case-insensitive matching, (?[^b]) matches any character because
it includes 'B' and 'B' matches 'b'
though [^b] is processed as [^Bb].
- [R1R2...-[RnRn+1...]] (with an "X" option)
- Character class subtraction for the XML Schema.
You can use this syntax when you specify an "X" option.
- \d
- Equivalent to [0-9].
- When a "u" option is set, it is equivalent to
\p{Nd}.
- \D
- Equivalent to [^0-9]
- When a "u" option is set, it is equivalent to
\P{Nd}.
- \s
- Equivalent to [ \f\n\r\t]
- When a "u" option is set, it is equivalent to
[ \f\n\r\t\p{Z}].
- \S
- Equivalent to [^ \f\n\r\t]
- When a "u" option is set, it is equivalent to
[^ \f\n\r\t\p{Z}].
- \w
- Equivalent to [a-zA-Z0-9_]
- When a "u" option is set, it is equivalent to
[\p{Lu}\p{Ll}\p{Lo}\p{Nd}_].
- \W
- Equivalent to [^a-zA-Z0-9_]
- When a "u" option is set, it is equivalent to
[^\p{Lu}\p{Ll}\p{Lo}\p{Nd}_].
- \p{name}
- Matches one character in the specified General Category (the second field in UnicodeData.txt) or the specified Block.
The following names are available:
- Unicode General Categories:
-
L, M, N, Z, C, P, S, Lu, Ll, Lt, Lm, Lo, Mn, Me, Mc, Nd, Nl, No, Zs, Zl, Zp,
Cc, Cf, Cn, Co, Cs, Pd, Ps, Pe, Pc, Po, Sm, Sc, Sk, So,
- (Currently the Cn category includes U+10000-U+10FFFF characters)
- Unicode Blocks:
-
Basic Latin, Latin-1 Supplement, Latin Extended-A, Latin Extended-B,
IPA Extensions, Spacing Modifier Letters, Combining Diacritical Marks, Greek,
Cyrillic, Armenian, Hebrew, Arabic, Devanagari, Bengali, Gurmukhi, Gujarati,
Oriya, Tamil, Telugu, Kannada, Malayalam, Thai, Lao, Tibetan, Georgian,
Hangul Jamo, Latin Extended Additional, Greek Extended, General Punctuation,
Superscripts and Subscripts, Currency Symbols, Combining Marks for Symbols,
Letterlike Symbols, Number Forms, Arrows, Mathematical Operators,
Miscellaneous Technical, Control Pictures, Optical Character Recognition,
Enclosed Alphanumerics, Box Drawing, Block Elements, Geometric Shapes,
Miscellaneous Symbols, Dingbats, CJK Symbols and Punctuation, Hiragana,
Katakana, Bopomofo, Hangul Compatibility Jamo, Kanbun,
Enclosed CJK Letters and Months, CJK Compatibility, CJK Unified Ideographs,
Hangul Syllables, High Surrogates, High Private Use Surrogates, Low Surrogates,
Private Use, CJK Compatibility Ideographs, Alphabetic Presentation Forms,
Arabic Presentation Forms-A, Combining Half Marks, CJK Compatibility Forms,
Small Form Variants, Arabic Presentation Forms-B, Specials,
Halfwidth and Fullwidth Forms
- Others:
- ALL (Equivalent to [\u0000-\v10FFFF])
- ASSGINED (\p{ASSIGNED} is equivalent to \P{Cn})
- UNASSGINED
(\p{UNASSIGNED} is equivalent to \p{Cn})
- \P{name}
- Matches one character not in the specified General Category or the specified Block.
- Selection and Quantifier
- X|Y
- ...
- X*
- Matches 0 or more X.
- X+
- Matches 1 or more X.
- X?
- Matches 0 or 1 X.
- X{number}
- Matches number times.
- X{min,}
- ...
- X{min,max}
- ...
- X*?
- X+?
- X??
- X{min,}?
- X{min,max}?
- Non-greedy matching.
- Grouping, Capturing, and Back-reference
- (?:X)
- Grouping. "foo+" matches "foo" or "foooo".
If you want it matches "foofoo" or "foofoofoo",
you have to write "(?:foo)+".
- (X)
- Grouping with capturing.
It make a group and applications can know
where in target text a group matched with methods of a
Match
instance
after matches(String,Match)
.
The 0th group means whole of this regular expression.
The Nth gorup is the inside of the Nth left parenthesis.
For instance, a regular expression is
" *([^<:]*) +<([^>]*)> *"
and target text is
"From: TAMURA Kent <kent@trl.ibm.co.jp>":
Match.getCapturedText(0)
:
" TAMURA Kent <kent@trl.ibm.co.jp>"
Match.getCapturedText(1)
: "TAMURA Kent"
Match.getCapturedText(2)
: "kent@trl.ibm.co.jp"
- \1 \2 \3 \4 \5 \6 \7 \8 \9
-
- (?>X)
- Independent expression group. ................
- (?options:X)
- (?options-options2:X)
- ............................
- The options or the options2 consists of 'i' 'm' 's' 'w'.
Note that it can not contain 'u'.
- (?options)
- (?options-options2)
- ......
- These expressions must be at the beginning of a group.
- Anchor
- \A
- Matches the beginnig of the text.
- \Z
- Matches the end of the text, or before an EOL character at the end of the text,
or CARRIAGE RETURN + LINE FEED at the end of the text.
- \z
- Matches the end of the text.
- ^
- Matches the beginning of the text. It is equivalent to \A.
- When a "m" option is set,
it matches the beginning of the text, or after one of EOL characters (
LINE FEED (U+000A), CARRIAGE RETURN (U+000D), LINE SEPARATOR (U+2028),
PARAGRAPH SEPARATOR (U+2029).)
- $
- Matches the end of the text, or before an EOL character at the end of the text,
or CARRIAGE RETURN + LINE FEED at the end of the text.
- When a "m" option is set,
it matches the end of the text, or before an EOL character.
- \b
- Matches word boundary.
(See a "w" option)
- \B
- Matches non word boundary.
(See a "w" option)
- \<
- Matches the beginning of a word.
(See a "w" option)
- \>
- Matches the end of a word.
(See a "w" option)
- Lookahead and lookbehind
- (?=X)
- Lookahead.
- (?!X)
- Negative lookahead.
- (?<=X)
- Lookbehind.
- (Note for text capturing......)
- (?<!X)
- Negative lookbehind.
- Misc.
- (?(condition)yes-pattern|no-pattern),
- (?(condition)yes-pattern)
- ......
- (?#comment)
- Comment. A comment string consists of characters except ')'.
You can not write comments in character classes and before quantifiers.
BNF for the regular expression
regex ::= ('(?' options ')')? term ('|' term)*
term ::= factor+
factor ::= anchors | atom (('*' | '+' | '?' | minmax ) '?'? )?
| '(?#' [^)]* ')'
minmax ::= '{' ([0-9]+ | [0-9]+ ',' | ',' [0-9]+ | [0-9]+ ',' [0-9]+) '}'
atom ::= char | '.' | char-class | '(' regex ')' | '(?:' regex ')' | '\' [0-9]
| '\w' | '\W' | '\d' | '\D' | '\s' | '\S' | category-block | '\X'
| '(?>' regex ')' | '(?' options ':' regex ')'
| '(?' ('(' [0-9] ')' | '(' anchors ')' | looks) term ('|' term)? ')'
options ::= [imsw]* ('-' [imsw]+)?
anchors ::= '^' | '$' | '\A' | '\Z' | '\z' | '\b' | '\B' | '\<' | '\>'
looks ::= '(?=' regex ')' | '(?!' regex ')'
| '(?<=' regex ')' | '(?<!' regex ')'
char ::= '\\' | '\' [efnrtv] | '\c' [@-_] | code-point | character-1
category-block ::= '\' [pP] category-symbol-1
| ('\p{' | '\P{') (category-symbol | block-name
| other-properties) '}'
category-symbol-1 ::= 'L' | 'M' | 'N' | 'Z' | 'C' | 'P' | 'S'
category-symbol ::= category-symbol-1 | 'Lu' | 'Ll' | 'Lt' | 'Lm' | Lo'
| 'Mn' | 'Me' | 'Mc' | 'Nd' | 'Nl' | 'No'
| 'Zs' | 'Zl' | 'Zp' | 'Cc' | 'Cf' | 'Cn' | 'Co' | 'Cs'
| 'Pd' | 'Ps' | 'Pe' | 'Pc' | 'Po'
| 'Sm' | 'Sc' | 'Sk' | 'So'
block-name ::= (See above)
other-properties ::= 'ALL' | 'ASSIGNED' | 'UNASSIGNED'
character-1 ::= (any character except meta-characters)
char-class ::= '[' ranges ']'
| '(?[' ranges ']' ([-+&] '[' ranges ']')? ')'
ranges ::= '^'? (range ','?)+
range ::= '\d' | '\w' | '\s' | '\D' | '\W' | '\S' | category-block
| range-char | range-char '-' range-char
range-char ::= '\[' | '\]' | '\\' | '\' [,-efnrtv] | code-point | character-2
code-point ::= '\x' hex-char hex-char
| '\x{' hex-char+ '}'
| '\v' hex-char hex-char hex-char hex-char hex-char hex-char
hex-char ::= [0-9a-fA-F]
character-2 ::= (any character except \[]-,)
TODO
Version: $Id: RegularExpression.java,v 1.10 2005/03/22 03:26:24 mrglavas Exp $
Author: TAMURA Kent <kent@trl.ibm.co.jp>
UNKNOWN:
Method Summary |
boolean | equals(Object obj)
Return true if patterns are the same and the options are equivalent. |
int | getNumberOfGroups()
Return the number of regular expression groups.
|
String | getOptions()
Returns a option string.
|
String | getPattern()
|
int | hashCode()
|
boolean | matches(char[] target)
Checks whether the target text contains this pattern or not.
|
boolean | matches(char[] target, int start, int end)
Checks whether the target text contains this pattern
in specified range or not.
|
boolean | matches(char[] target, Match match)
Checks whether the target text contains this pattern or not.
|
boolean | matches(char[] target, int start, int end, Match match)
Checks whether the target text contains this pattern
in specified range or not.
|
boolean | matches(String target)
Checks whether the target text contains this pattern or not.
|
boolean | matches(String target, int start, int end)
Checks whether the target text contains this pattern
in specified range or not.
|
boolean | matches(String target, Match match)
Checks whether the target text contains this pattern or not.
|
boolean | matches(String target, int start, int end, Match match)
Checks whether the target text contains this pattern
in specified range or not.
|
boolean | matches(CharacterIterator target)
Checks whether the target text contains this pattern or not.
|
boolean | matches(CharacterIterator target, Match match)
Checks whether the target text contains this pattern or not.
|
void | setPattern(String newPattern)
|
void | setPattern(String newPattern, String options)
|
String | toString()
Represents this instence in String. |
public RegularExpression(String regex)
Creates a new RegularExpression instance.
Parameters: regex A regular expression
Throws: org.apache.xerces.utils.regex.ParseException regex is not conforming to the syntax.
public RegularExpression(String regex, String options)
Creates a new RegularExpression instance with options.
Parameters: regex A regular expression options A String consisted of "i" "m" "s" "u" "w" "," "X"
Throws: org.apache.xerces.utils.regex.ParseException regex is not conforming to the syntax.
public boolean equals(Object obj)
Return true if patterns are the same and the options are equivalent.
public int getNumberOfGroups()
Return the number of regular expression groups.
This method returns 1 when the regular expression has no capturing-parenthesis.
public String getOptions()
Returns a option string.
The order of letters in it may be different from a string specified
in a constructor or
setPattern()
.
See Also: RegularExpression RegularExpression
public String getPattern()
public int hashCode()
public boolean matches(char[] target)
Checks whether the
target text
contains this pattern or not.
Returns: true if the target is matched to this regular expression.
public boolean matches(char[] target, int start, int end)
Checks whether the
target text
contains this pattern
in specified range or not.
Parameters: start Start offset of the range. end End offset +1 of the range.
Returns: true if the target is matched to this regular expression.
public boolean matches(char[] target,
Match match)
Checks whether the
target text
contains this pattern or not.
Parameters: match A Match instance for storing matching result.
Returns: Offset of the start position in target; or -1 if not match.
public boolean matches(char[] target, int start, int end,
Match match)
Checks whether the
target text
contains this pattern
in specified range or not.
Parameters: start Start offset of the range. end End offset +1 of the range. match A Match instance for storing matching result.
Returns: Offset of the start position in target; or -1 if not match.
public boolean matches(String target)
Checks whether the
target text
contains this pattern or not.
Returns: true if the target is matched to this regular expression.
public boolean matches(String target, int start, int end)
Checks whether the
target text
contains this pattern
in specified range or not.
Parameters: start Start offset of the range. end End offset +1 of the range.
Returns: true if the target is matched to this regular expression.
public boolean matches(String target,
Match match)
Checks whether the
target text
contains this pattern or not.
Parameters: match A Match instance for storing matching result.
Returns: Offset of the start position in target; or -1 if not match.
public boolean matches(String target, int start, int end,
Match match)
Checks whether the
target text
contains this pattern
in specified range or not.
Parameters: start Start offset of the range. end End offset +1 of the range. match A Match instance for storing matching result.
Returns: Offset of the start position in target; or -1 if not match.
public boolean matches(CharacterIterator target)
Checks whether the
target text
contains this pattern or not.
Returns: true if the target is matched to this regular expression.
public boolean matches(CharacterIterator target,
Match match)
Checks whether the
target text
contains this pattern or not.
Parameters: match A Match instance for storing matching result.
Returns: Offset of the start position in target; or -1 if not match.
public void setPattern(String newPattern)
public void setPattern(String newPattern, String options)
public String toString()
Represents this instence in String.
Copyright B) 1999-2005 Apache XML Project. All Rights Reserved.