WCPattern * p = WCPattern::compile(L"a*b"); WCMatcher * m = p->createWCMatcher(L"aaaaaab"); if (m->matches()) ...However, if you do not need to use a pattern more than once, it is often times okay to use the WCPattern's static methods insteads. An example looks like this:
if (WCPattern::matches(L"a*b", L"aaaab")) { ... }
This class does not currently support unicode. The unicode update for this
class is coming soon.
This class is partially immutable. It is completely safe to call createWCMatcher
concurrently in different threads, but the other functions (e.g. split) should
not be called concurrently on the same WCPattern.
| Construct | Matches |
| Characters | |
x
|
The character x
|
\\
|
The character \
|
\0nn
|
The character with octal ASCII value nn
|
\0nnn
|
The character with octal ASCII value nnn
|
\xhh
|
The character with hexadecimal ASCII value hh
|
\t
|
A tab character |
\r
|
A carriage return character |
\n
|
A new-line character |
| Character Classes | |
[abc]
|
Either a, b, or c
|
[^abc]
|
Any character but a, b, or c
|
[a-zA-Z]
|
Any character ranging from a thru z, or
A thru Z
|
[^a-zA-Z]
|
Any character except those ranging from a thru
z, or A thru Z
|
[a\-z]
|
Either a, -, or z
|
[a-z[A-Z]]
|
Same as [a-zA-Z]
|
[a-z&&[g-i]]
|
Any character in the intersection of a-z and
g-i
|
[a-z&&[^g-i]]
|
Any character in a-z and not in g-i
|
| Prefefined character classes | |
.
|
Any character. Multiline matching must be compiled into the pattern for
. to match a \r or a \n.
Even if multiline matching is enabled, . will not
match a \r\n, only a \r or a \n.
|
\d
|
[0-9]
|
\D
|
[^\d]
|
\s
|
[ \t\r\n\x0B]
|
\S
|
[^\s]
|
\w
|
[a-zA-Z0-9_]
|
\W
|
[^\w]
|
| POSIX character classes | |
\p{Lower}
|
[a-z]
|
\p{Upper}
|
[A-Z]
|
\p{ASCII}
|
[\x00-\x7F]
|
\p{Alpha}
|
[a-zA-Z]
|
\p{Digit}
|
[0-9]
|
\p{Alnum}
|
[\w&&[^_]]
|
\p{Punct}
|
[!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~]
|
\p{XDigit}
|
[a-fA-F0-9]
|
| Boundary Matches | |
^
|
The beginning of a line. Also matches the beginning of input. |
$
|
The end of a line. Also matches the end of input. |
\b
|
A word boundary |
\B
|
A non word boundary |
\A
|
The beginning of input |
\G
|
The end of the previous match. Ensures that a "next" match will only happen if it begins with the character immediately following the end of the "current" match. |
\Z
|
The end of input. Will also match if there is a single trailing
\r\n, a single trailing \r, or a single
trailing \n.
|
\z
|
The end of input |
| Greedy Quantifiers | |
x?
|
x, either zero times or one time |
x*
|
x, zero or more times |
x+
|
x, one or more times |
x{n}
|
x, exactly n times |
x{n,}
|
x, at least n times
|
x{,m}
|
x, at most m times
|
x{n,m}
|
x, at least n times and at most
m times
|
| Possessive Quantifiers | |
x?+
|
x, either zero times or one time |
x*+
|
x, zero or more times |
x++
|
x, one or more times |
x{n}+
|
x, exactly n times |
x{n,}+
|
x, at least n times
|
x{,m}+
|
x, at most m times
|
x{n,m}+
|
x, at least n times and at most
m times
|
| Reluctant Quantifiers | |
x??
|
x, either zero times or one time |
x*?
|
x, zero or more times |
x+?
|
x, one or more times |
x{n}?
|
x, exactly n times |
x{n,}?
|
x, at least n times
|
x{,m}?
|
x, at most m times
|
x{n,m}?
|
x, at least n times and at most
m times
|
| Operators | |
xy
|
x then y
|
x|y
|
x or y
|
(x)
|
x as a capturing group
|
| Quoting | |
\Q
|
Nothing, but treat every character (including \s) literally until a
matching \E
|
\E
|
Nothing, but ends its matching \Q
|
| Special Constructs | |
(?:x)
|
x, but not as a capturing group
|
(?=x)
|
x, via positive lookahead. This means that the
expression will match only if it is trailed by x.
It will not "eat" any of the characters matched by
x.
|
(?!x)
|
x, via negative lookahead. This means that the
expression will match only if it is not trailed by
x. It will not "eat" any of the characters
matched by x.
|
(?<=x)
|
x, via positive lookbehind. x
cannot contain any quantifiers.
|
(?x)
|
x, via negative lookbehind. x
cannot contain any quantifiers.
|
(?>x)
|
x{1}+
|
| Registered Expression Matching | |
{x}
|
The registered pattern x
|
The backslash character ((wchar_t)'\') serves to introduce escaped constructs, as defined in the table above, as well as to quote characters that otherwise would be interpreted as unescaped constructs. Thus the expression \\ matches a single backslash and \{ matches a left brace.
It is an error to use a backslash prior to any alphabetic character that does not denote an escaped construct; these are reserved for future extensions to the regular-expression language. A backslash may be used prior to a non-alphabetic character regardless of whether that character is part of an unescaped construct.
It is necessary to double backslashes in string literals that represent regular expressions to protect them from interpretation by a compiler. The string literal "\b", for example, matches a single backspace character when interpreted as a regular expression, while "\\b" matches a word boundary. The string litera "\(hello\)" is illegal and leads to a compile-time error; in order to match the string (hello) the string literal "\\(hello\\)" must be used.
Character classes may appear within other character classes, and may be composed by the union operator (implicit) and the intersection operator (&&). The union operator denotes a class that contains every character that is in at least one of its operand classes. The intersection operator denotes a class that contains every character that is in both of its operand classes.
The precedence of character-class operators is as follows, from highest to lowest:
1 Literal escape \x 2 Range a-z 3 Grouping [...] 4 Intersection [a-z&&[aeiou]] 5 Union [a-e][i-u]
Note that a different set of metacharacters are in effect inside
a character class than outside a character class. For instance, the
regular expression . loses its special meaning inside a
character class, while the expression - becomes a range
forming metacharacter.
Capturing groups are numbered by counting their opening parentheses from
left to right. In the expression ((A)(B(C))), for example, there
are four such groups: Group zero always stands for the entire expression.
Capturing groups are so named because, during a match, each subsequence
of the input sequence that matches such a group is saved. The captured
subsequence may be used later in the expression, via a back reference, and
may also be retrieved from the matcher once the match operation is complete.
The captured input associated with a group is always the subsequence
that the group most recently matched. If a group is evaluated a second time
because of quantification then its previously-captured value, if any, will
be retained if the second evaluation fails. Matching the string
L"aba" against the expression (a(b)?)+, for example, leaves
group two set to L"b". All captured input is discarded at the
beginning of each match.
Groups beginning with (? are pure, non-capturing groups
that do not capture text and do not count towards the group total.
Coming Soon.
The Perl constructs not supported by this class: The conditional constructs (?{X}) and
(?(condition)X|Y),
The embedded code constructs (?{code})
and (??{code}), The embedded comment syntax (?#comment), and The preprocessing operations \l \u,
\L, and \U. Embedded flags Constructs supported by this class but not by Perl: Possessive quantifiers, which greedily match as much as they can
and do not back off, even when doing so would allow the overall match to
succeed. Character-class union and intersection as described
above. Notable differences from Perl: In Perl, \1 through \9 are always interpreted
as back references; a backslash-escaped number greater than 9 is
treated as a back reference if at least that many subexpressions exist,
otherwise it is interpreted, if possible, as an octal escape. In this
class octal escapes must always begin with a zero. In this class,
\1 through \9 are always interpreted as back
references, and a larger number is accepted as a back reference if at
least that many subexpressions exist at that point in the regular
expression, otherwise the parser will drop digits until the number is
smaller or equal to the existing number of groups or it is one digit.
Perl uses the g flag to request a match that resumes
where the last match left off. This functionality is provided implicitly
by the Perl is forgiving about malformed matching constructs, as in the
expression *a, as well as dangling brackets, as in the
expression abc], and treats them as literals. This
class also strict and will not compile a pattern when dangling characters
are encountered. For a more precise description of the behavior of regular expression
constructs, please see
Mastering Regular Expressions, 2nd Edition, Jeffrey E. F. Friedl,
O'Reilly and Associates, 2002.
End Text Extracted And Modified From java.util.regex.WCPattern documentation
which would replace
@param pattern The pattern for which to search
@param str The string to search
@param mode The special mode requested of the
Multiple calls to
Groups and capturing
1
((A)(B(C))) 2
(A) 3
(B(C)) 4
(C) WC support
Comparison to Perl 5
WCPattern engine performs traditional NFA-based matching
with ordered alternation as occurs in Perl 5.
WCMatcher class: Repeated invocations of the
find method will resume where the last match left off,
unless the matcher is reset.
@author Jeffery Stuart
@since March 2003, Stable Since November 2004
@version 1.07.00
@memo A class used to represent "PERL 5"-ish regular expressions
*/
class WCPattern
{
friend class WCMatcher;
friend class NFAUNode;
friend class NFAQuantifierUNode;
private:
/**
This constructor should not be called directly. Those wishing to use the
WCPattern class should instead use the {@link compile compile} method.
@param rhs The pattern to compile
@memo Creates a new pattern from the regular expression in rhs.
*/
WCPattern(const bkstring & rhs);
protected:
/**
This currently is not used, so don't try to do anything with it.
@memo Holds all the compiled patterns for quick access.
*/
static std::maperror is no longer used.
*/
bool error;
/**
Used during compilation to keep track of the current index into
{@link pattern pattern}. Once the pattern is successfully
compiled, error is no longer used.
*/
int curInd;
/**
The number of capture groups this contains.
*/
int groupCount;
/**
The number of non-capture groups this contains.
*/
int nonCapGroupCount;
/**
The flags specified when this was compiled.
*/
unsigned long flags;
protected:
/**
Raises an error during compilation. Compilation will cease at that point
and compile will return NULL.
*/
void raiseError();
/**
Convenience function for registering a node in nodes.
@param node The node to register
@return The registered node
*/
NFAUNode * registerNode(NFAUNode * node);
/**
Calculates the union of two strings. This function will first sort the
strings and then use a simple selection algorithm to find the union.
@param s1 The first "class" to union
@param s2 The second "class" to union
@return A new string containing all unique characters. Each character
must have appeared in one or both of s1 and
s2.
*/
bkstring classUnion (bkstring s1, bkstring s2) const;
/**
Calculates the intersection of two strings. This function will first sort
the strings and then use a simple selection algorithm to find the
intersection.
@param s1 The first "class" to intersect
@param s2 The second "class" to intersect
@return A new string containing all unique characters. Each character
must have appeared both s1 and s2.
*/
bkstring classIntersect (bkstring s1, bkstring s2) const;
/**
Calculates the negation of a string. The negation is the set of all
characters between \x00 and \xFF not
contained in s1.
@param s1 The "class" to be negated.
@param s2 The second "class" to intersect
@return A new string containing all unique characters. Each character
must have appeared both s1 and s2.
*/
bkstring classNegate (bkstring s1) const;
/**
Creates a new "class" representing the range from low thru
hi. This function will wrap if low >
hi. This is a feature, not a buf. Sometimes it is useful
to be able to say [\x70-\x10] instead of [\x70-\x7F\x00-\x10].
@param low The beginning character
@param hi The ending character
@return A new string containing all the characters from low thru hi.
*/
bkstring classCreateRange(wchar_t low, wchar_t hi) const;
/**
Extracts a decimal number from the substring of member-variable
{@link pattern pattern} starting at start and
ending at end.
@param start The starting index in {@link pattern pattern}
@param end The last index in {@link pattern pattern}
@return The decimal number in {@link pattern pattern}
*/
int getInt(int start, int end);
/**
Parses a {n,m} string out of the member-variable
{@link pattern pattern} stores the result in sNum
and eNum.
@param sNum Output parameter. The minimum number of matches required
by the curly quantifier are stored here.
@param eNum Output parameter. The maximum number of matches allowed
by the curly quantifier are stored here.
@return Success/Failure. Fails when the curly does not have the proper
syntax
*/
bool quantifyCurly(int & sNum, int & eNum);
/**
Tries to quantify the currently parsed group. If the group being parsed
is indeed quantified in the member-variable
{@link pattern pattern}, then the NFA is modified accordingly.
@param start The starting node of the current group being parsed
@param stop The ending node of the current group being parsed
@param gn The group number of the current group being parsed
@return The node representing the starting node of the group. If the
group becomes quantified, then this node is not necessarily
a GroupHead node.
*/
NFAUNode * quantifyGroup(NFAUNode * start, NFAUNode * stop, const int gn);
/**
Tries to quantify the last parsed expression. If the character was indeed
quantified, then the NFA is modified accordingly.
@param newNode The recently created expression node
@return The node representing the last parsed expression. If the
expression was quantified, return value != newNode
*/
NFAUNode * quantify(NFAUNode * newNode);
/**
Parses the current class being examined in
{@link pattern pattern}.
@return A string of unique characters contained in the current class being
parsed
*/
bkstring parseClass();
/**
Parses the current POSIX class being examined in
{@link pattern pattern}.
@return A string of unique characters representing the POSIX class being
parsed
*/
bkstring parsePosix();
/**
Returns a string containing the octal character being parsed
@return The string contained the octal value being parsed
*/
bkstring parseOctal();
/**
Returns a string containing the hex character being parsed
@return The string contained the hex value being parsed
*/
bkstring parseHex();
/**
Returns a new node representing the back reference being parsed
@return The new node representing the back reference being parsed
*/
NFAUNode * parseBackref();
/**
Parses the escape sequence currently being examined. Determines if the
escape sequence is a class, a single character, or the beginning of a
quotation sequence.
@param inv Output parameter. Whether or not to invert the returned class
@param quo Output parameter. Whether or not this sequence starts a
quotation.
@return The characters represented by the class
*/
bkstring parseEscape(bool & inv, bool & quo);
/**
Parses a supposed registered pattern currently under compilation. If the
sequence of characters does point to a registered pattern, then the
registered pattern is appended to *end. The registered pattern
is parsed with the current compilation flags.
@param end The ending node of the thus-far compiled pattern
@return The new end node of the current pattern
*/
NFAUNode * parseRegisteredWCPattern(NFAUNode ** end);
/**
Parses a lookbehind expression. Appends the necessary nodes
*end.
@param pos Positive or negative look behind
@param end The ending node of the current pattern
@return The new end node of the current pattern
*/
NFAUNode * parseBehind(const bool pos, NFAUNode ** end);
/**
Parses the current expression and tacks on nodes until a \E is found.
@return The end of the current pattern
*/
NFAUNode * parseQuote();
/**
Parses {@link pattern pattern}. This function is called
recursively when an or (|) or a group is encountered.
@param inParen Are we currently parsing inside a group
@param inOr Are we currently parsing one side of an or (|)
@param end The end of the current expression
@return The starting node of the NFA constructed from this parse
*/
NFAUNode * parse(const bool inParen = 0, const bool inOr = 0, NFAUNode ** end = NULL);
public:
/// We should match regardless of case
const static unsigned long CASE_INSENSITIVE;
/// We are implicitly quoted
const static unsigned long LITERAL;
/// @memo We should treat a . as [\x00-\x7F]
const static unsigned long DOT_MATCHES_ALL;
/** ^ and $ should anchor to the beginning and
ending of lines, not all input
*/
const static unsigned long MULTILINE_MATCHING;
/** When enabled, only instances of \n are recognized as
line terminators
*/
const static unsigned long UNIX_LINE_MODE;
/// The absolute minimum number of matches a quantifier can match (0)
const static int MIN_QMATCH;
/// The absolute maximum number of matches a quantifier can match (0x7FFFFFFF)
const static int MAX_QMATCH;
public:
/**
Call this function to compile a regular expression into a
WCPattern object. Special values can be assigned to
mode when certain non-standard behaviors are expected from
the WCPattern object.
@param pattern The regular expression to compile
@param mode A bitwise or of flags signalling what special behaviors are
wanted from this WCPattern object
@return If successful, compile returns a WCPattern
pointer. Upon failure, compile returns
NULL
*/
static WCPattern * compile (const bkstring & pattern,
const unsigned long mode = 0);
/**
Dont use this function. This function will compile a pattern, and cache
the result. This will eventually be used as an optimization when people
just want to call static methods using the same pattern over and over
instead of first compiling the pattern and then using the compiled
instance for matching.
@param pattern The regular expression to compile
@param mode A bitwise or of flags signalling what special behaviors are
wanted from this WCPattern object
@return If successful, compileAndKeep returns a
WCPattern pointer. Upon failure, compile
returns NULL.
*/
static WCPattern * compileAndKeep (const bkstring & pattern,
const unsigned long mode = 0);
/**
Searches through replace and replaces all substrings matched
by pattern with str. str may
contain backreferences (e.g. \1) to capture groups. A typical
invocation looks like:
WCPattern::replace(L"(a+)b(c+)", L"abcccbbabcbabc", L"\\2b\\1");
abcccbbabcbabc with
cccbabbcbabcba.
@param pattern The regular expression
@param str The replacement text
@param replacementText The string in which to perform replacements
@param mode The special mode requested of the WCPattern
during the replacement process
@return The text with the replacement string substituted where necessary
*/
static bkstring replace (const bkstring & pattern,
const bkstring & str,
const bkstring & replacementText,
const unsigned long mode = 0);
/**
Splits the specified string over occurrences of the specified pattern.
Empty strings can be optionally ignored. The number of strings returned is
configurable. A typical invocation looks like:
bkstring str(strSize, 0);
@param pattern The regular expression
@param replace The string to split
@param keepEmptys Whether or not to keep empty strings
@param limit The maximum number of splits to make
@param mode The special mode requested of the
FILE * fp = fopen(fileName, "r");
fread((char*)str.data(), strSize * 2, 1, fp);
fclose(fp);
std::vector<bkstring> lines = WCPattern::split(L"[\r\n]+", str, true);
WCPattern
during the split process
@return All substrings of str split across pattern.
*/
static std::vectora* can be matched by an empty string, so
instead you should pass a+ since at least one character must
be matched. A typical invocation of findAll looks like:
std::vector<td::string> numbers = WCPattern::findAll(L"\\d+", string);
WCPattern
during the find process
@return All instances of pattern in str
*/
static std::vectorWCPattern
during the replacement process
@return True if str is recognized by pattern
*/
static bool matches (const bkstring & pattern,
const bkstring & str,
const unsigned long mode = 0);
/**
Registers a pattern under a specific name for use in later compilations.
A typical invocation and later use looks like:
WCPattern::registerWCPattern(L"ip", L"(?:\\d{1,3}\\.){3}\\d{1,3}");
WCPattern * p1 = WCPattern::compile(L"{ip}:\\d+");
WCPattern * p2 = WCPattern::compile(L"Connection from ({ip}) on port \\d+");
registerWCPattern with the same
name will result in the pattern getting overwritten.
@param name The name to give to the pattern
@param pattern The pattern to register
@param mode Any special flags to use when compiling pattern
@return Success/Failure. Fails only if pattern has invalid
syntax
*/
static bool registerWCPattern(const bkstring & name,
const bkstring & pattern,
const unsigned long mode = 0);
/**
Clears the pattern registry
*/
static void unregisterWCPatterns();
/**
Don't use
*/
static void clearWCPatternCache();
/**
Searches through a string for the nth match of the
given pattern in the string. Match indeces start at zero, not one.
A typical invocation looks like this:
std::pair<bkstring, int> match = WCPattern::findNthMatch(L"\\d{1,3}", L"192.168.1.101:22", 1);
wprintf(L"%s %i\n", match.first.c_str(), match.second);
Output: 168 4
@param pattern The pattern for which to search
@param str The string to search
@param matchNum Which match to find
@param mode Any special flags to use during the matching process
@return A string and an integer. The string is the string matched. The
integer is the starting location of the matched string in
str. You can check for success/failure by making sure
that the integer returned is greater than or equal to zero.
*/
static std::pair