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+.TH PCRECPP 3 "08 January 2012" "PCRE 8.30"
+PCRE - Perl-compatible regular expressions.
+.B #include <pcrecpp.h>
+The C++ wrapper for PCRE was provided by Google Inc. Some additional
+functionality was added by Giuseppe Maxia. This brief man page was constructed
+from the notes in the \fIpcrecpp.h\fP file, which should be consulted for
+further details. Note that the C++ wrapper supports only the original 8-bit
+PCRE library. There is no 16-bit or 32-bit support at present.
+The "FullMatch" operation checks that supplied text matches a supplied pattern
+exactly. If pointer arguments are supplied, it copies matched sub-strings that
+match sub-patterns into them.
+ Example: successful match
+ pcrecpp::RE re("h.*o");
+ re.FullMatch("hello");
+ Example: unsuccessful match (requires full match):
+ pcrecpp::RE re("e");
+ !re.FullMatch("hello");
+ Example: creating a temporary RE object:
+ pcrecpp::RE("h.*o").FullMatch("hello");
+You can pass in a "const char*" or a "string" for "text". The examples below
+tend to use a const char*. You can, as in the different examples above, store
+the RE object explicitly in a variable or use a temporary RE object. The
+examples below use one mode or the other arbitrarily. Either could correctly be
+used for any of these examples.
+You must supply extra pointer arguments to extract matched subpieces.
+ Example: extracts "ruby" into "s" and 1234 into "i"
+ int i;
+ string s;
+ pcrecpp::RE re("(\e\ew+):(\e\ed+)");
+ re.FullMatch("ruby:1234", &s, &i);
+ Example: does not try to extract any extra sub-patterns
+ re.FullMatch("ruby:1234", &s);
+ Example: does not try to extract into NULL
+ re.FullMatch("ruby:1234", NULL, &i);
+ Example: integer overflow causes failure
+ !re.FullMatch("ruby:1234567891234", NULL, &i);
+ Example: fails because there aren't enough sub-patterns:
+ !pcrecpp::RE("\e\ew+:\e\ed+").FullMatch("ruby:1234", &s);
+ Example: fails because string cannot be stored in integer
+ !pcrecpp::RE("(.*)").FullMatch("ruby", &i);
+The provided pointer arguments can be pointers to any scalar numeric
+type, or one of:
+ string (matched piece is copied to string)
+ StringPiece (StringPiece is mutated to point to matched piece)
+ T (where "bool T::ParseFrom(const char*, int)" exists)
+ NULL (the corresponding matched sub-pattern is not copied)
+The function returns true iff all of the following conditions are satisfied:
+ a. "text" matches "pattern" exactly;
+ b. The number of matched sub-patterns is >= number of supplied
+ pointers;
+ c. The "i"th argument has a suitable type for holding the
+ string captured as the "i"th sub-pattern. If you pass in
+ void * NULL for the "i"th argument, or a non-void * NULL
+ of the correct type, or pass fewer arguments than the
+ number of sub-patterns, "i"th captured sub-pattern is
+ ignored.
+CAVEAT: An optional sub-pattern that does not exist in the matched
+string is assigned the empty string. Therefore, the following will
+return false (because the empty string is not a valid number):
+ int number;
+ pcrecpp::RE::FullMatch("abc", "[a-z]+(\e\ed+)?", &number);
+The matching interface supports at most 16 arguments per call.
+If you need more, consider using the more general interface
+\fBpcrecpp::RE::DoMatch\fP. See \fBpcrecpp.h\fP for the signature for
+NOTE: Do not use \fBno_arg\fP, which is used internally to mark the end of a
+list of optional arguments, as a placeholder for missing arguments, as this can
+lead to segfaults.
+You can use the "QuoteMeta" operation to insert backslashes before all
+potentially meaningful characters in a string. The returned string, used as a
+regular expression, will exactly match the original string.
+ Example:
+ string quoted = RE::QuoteMeta(unquoted);
+Note that it's legal to escape a character even if it has no special meaning in
+a regular expression -- so this function does that. (This also makes it
+identical to the perl function of the same name; see "perldoc -f quotemeta".)
+For example, "1.5-2.0?" becomes "1\e.5\e-2\e.0\e?".
+You can use the "PartialMatch" operation when you want the pattern
+to match any substring of the text.
+ Example: simple search for a string:
+ pcrecpp::RE("ell").PartialMatch("hello");
+ Example: find first number in a string:
+ int number;
+ pcrecpp::RE re("(\e\ed+)");
+ re.PartialMatch("x*100 + 20", &number);
+ assert(number == 100);
+By default, pattern and text are plain text, one byte per character. The UTF8
+flag, passed to the constructor, causes both pattern and string to be treated
+as UTF-8 text, still a byte stream but potentially multiple bytes per
+character. In practice, the text is likelier to be UTF-8 than the pattern, but
+the match returned may depend on the UTF8 flag, so always use it when matching
+UTF8 text. For example, "." will match one byte normally but with UTF8 set may
+match up to three bytes of a multi-byte character.
+ Example:
+ pcrecpp::RE_Options options;
+ options.set_utf8();
+ pcrecpp::RE re(utf8_pattern, options);
+ re.FullMatch(utf8_string);
+ Example: using the convenience function UTF8():
+ pcrecpp::RE re(utf8_pattern, pcrecpp::UTF8());
+ re.FullMatch(utf8_string);
+NOTE: The UTF8 flag is ignored if pcre was not configured with the
+ --enable-utf8 flag.
+PCRE defines some modifiers to change the behavior of the regular expression
+engine. The C++ wrapper defines an auxiliary class, RE_Options, as a vehicle to
+pass such modifiers to a RE class. Currently, the following modifiers are
+ modifier description Perl corresponding
+ PCRE_CASELESS case insensitive match /i
+ PCRE_MULTILINE multiple lines match /m
+ PCRE_DOTALL dot matches newlines /s
+ PCRE_DOLLAR_ENDONLY $ matches only at end N/A
+ PCRE_EXTRA strict escape parsing N/A
+ PCRE_EXTENDED ignore white spaces /x
+ PCRE_UTF8 handles UTF8 chars built-in
+ PCRE_UNGREEDY reverses * and *? N/A
+ PCRE_NO_AUTO_CAPTURE disables capturing parens N/A (*)
+(*) Both Perl and PCRE allow non capturing parentheses by means of the
+"?:" modifier within the pattern itself. e.g. (?:ab|cd) does not
+capture, while (ab|cd) does.
+For a full account on how each modifier works, please check the
+PCRE API reference page.
+For each modifier, there are two member functions whose name is made
+out of the modifier in lowercase, without the "PCRE_" prefix. For
+instance, PCRE_CASELESS is handled by
+ bool caseless()
+which returns true if the modifier is set, and
+ RE_Options & set_caseless(bool)
+which sets or unsets the modifier. Moreover, PCRE_EXTRA_MATCH_LIMIT can be
+accessed through the \fBset_match_limit()\fP and \fBmatch_limit()\fP member
+functions. Setting \fImatch_limit\fP to a non-zero value will limit the
+execution of pcre to keep it from doing bad things like blowing the stack or
+taking an eternity to return a result. A value of 5000 is good enough to stop
+stack blowup in a 2MB thread stack. Setting \fImatch_limit\fP to zero disables
+match limiting. Alternatively, you can call \fBmatch_limit_recursion()\fP
+which uses PCRE_EXTRA_MATCH_LIMIT_RECURSION to limit how much PCRE
+recurses. \fBmatch_limit()\fP limits the number of matches PCRE does;
+\fBmatch_limit_recursion()\fP limits the depth of internal recursion, and
+therefore the amount of stack that is used.
+Normally, to pass one or more modifiers to a RE class, you declare
+a \fIRE_Options\fP object, set the appropriate options, and pass this
+object to a RE constructor. Example:
+ RE_Options opt;
+ opt.set_caseless(true);
+ if (RE("HELLO", opt).PartialMatch("hello world")) ...
+RE_options has two constructors. The default constructor takes no arguments and
+creates a set of flags that are off by default. The optional parameter
+\fIoption_flags\fP is to facilitate transfer of legacy code from C programs.
+This lets you do
+ RE(pattern,
+ RE_Options(PCRE_CASELESS|PCRE_MULTILINE)).PartialMatch(str);
+However, new code is better off doing
+ RE(pattern,
+ RE_Options().set_caseless(true).set_multiline(true))
+ .PartialMatch(str);
+If you are going to pass one of the most used modifiers, there are some
+convenience functions that return a RE_Options class with the
+appropriate modifier already set: \fBCASELESS()\fP, \fBUTF8()\fP,
+If you need to set several options at once, and you don't want to go through
+the pains of declaring a RE_Options object and setting several options, there
+is a parallel method that give you such ability on the fly. You can concatenate
+several \fBset_xxxxx()\fP member functions, since each of them returns a
+reference to its class object. For example, to pass PCRE_CASELESS,
+PCRE_EXTENDED, and PCRE_MULTILINE to a RE with one statement, you may write:
+ RE(" ^ xyz \e\es+ .* blah$",
+ RE_Options()
+ .set_caseless(true)
+ .set_extended(true)
+ .set_multiline(true)).PartialMatch(sometext);
+The "Consume" operation may be useful if you want to repeatedly
+match regular expressions at the front of a string and skip over
+them as they match. This requires use of the "StringPiece" type,
+which represents a sub-range of a real string. Like RE, StringPiece
+is defined in the pcrecpp namespace.
+ Example: read lines of the form "var = value" from a string.
+ string contents = ...; // Fill string somehow
+ pcrecpp::StringPiece input(contents); // Wrap in a StringPiece
+ string var;
+ int value;
+ pcrecpp::RE re("(\e\ew+) = (\e\ed+)\en");
+ while (re.Consume(&input, &var, &value)) {
+ ...;
+ }
+Each successful call to "Consume" will set "var/value", and also
+advance "input" so it points past the matched text.
+The "FindAndConsume" operation is similar to "Consume" but does not
+anchor your match at the beginning of the string. For example, you
+could extract all words from a string by repeatedly calling
+ pcrecpp::RE("(\e\ew+)").FindAndConsume(&input, &word)
+By default, if you pass a pointer to a numeric value, the
+corresponding text is interpreted as a base-10 number. You can
+instead wrap the pointer with a call to one of the operators Hex(),
+Octal(), or CRadix() to interpret the text in another base. The
+CRadix operator interprets C-style "0" (base-8) and "0x" (base-16)
+prefixes, but defaults to base-10.
+ Example:
+ int a, b, c, d;
+ pcrecpp::RE re("(.*) (.*) (.*) (.*)");
+ re.FullMatch("100 40 0100 0x40",
+ pcrecpp::Octal(&a), pcrecpp::Hex(&b),
+ pcrecpp::CRadix(&c), pcrecpp::CRadix(&d));
+will leave 64 in a, b, c, and d.
+You can replace the first match of "pattern" in "str" with "rewrite".
+Within "rewrite", backslash-escaped digits (\e1 to \e9) can be
+used to insert text matching corresponding parenthesized group
+from the pattern. \e0 in "rewrite" refers to the entire matching
+text. For example:
+ string s = "yabba dabba doo";
+ pcrecpp::RE("b+").Replace("d", &s);
+will leave "s" containing "yada dabba doo". The result is true if the pattern
+matches and a replacement occurs, false otherwise.
+\fBGlobalReplace\fP is like \fBReplace\fP except that it replaces all
+occurrences of the pattern in the string with the rewrite. Replacements are
+not subject to re-matching. For example:
+ string s = "yabba dabba doo";
+ pcrecpp::RE("b+").GlobalReplace("d", &s);
+will leave "s" containing "yada dada doo". It returns the number of
+replacements made.
+\fBExtract\fP is like \fBReplace\fP, except that if the pattern matches,
+"rewrite" is copied into "out" (an additional argument) with substitutions.
+The non-matching portions of "text" are ignored. Returns true iff a match
+occurred and the extraction happened successfully; if no match occurs, the
+string is left unaffected.
+The C++ wrapper was contributed by Google Inc.
+Copyright (c) 2007 Google Inc.
+Last updated: 08 January 2012