doc/html/pcrecpp.html

<html>
<head>
<title>pcrecpp specification</title>
</head>
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
<h1>pcrecpp man page</h1>
<p>
Return to the <a href="index.html">PCRE index page</a>.
</p>
<p>
This page is part of the PCRE HTML documentation. It was generated automatically
from the original man page. If there is any nonsense in it, please consult the
man page, in case the conversion went wrong.
<br>
<ul>
<li><a name="TOC1" href="#SEC1">SYNOPSIS OF C++ WRAPPER</a>
<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
<li><a name="TOC3" href="#SEC3">MATCHING INTERFACE</a>
<li><a name="TOC4" href="#SEC4">QUOTING METACHARACTERS</a>
<li><a name="TOC5" href="#SEC5">PARTIAL MATCHES</a>
<li><a name="TOC6" href="#SEC6">UTF-8 AND THE MATCHING INTERFACE</a>
<li><a name="TOC7" href="#SEC7">PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE</a>
<li><a name="TOC8" href="#SEC8">SCANNING TEXT INCREMENTALLY</a>
<li><a name="TOC9" href="#SEC9">PARSING HEX/OCTAL/C-RADIX NUMBERS</a>
<li><a name="TOC10" href="#SEC10">REPLACING PARTS OF STRINGS</a>
<li><a name="TOC11" href="#SEC11">AUTHOR</a>
<li><a name="TOC12" href="#SEC12">REVISION</a>
</ul>
<br><a name="SEC1" href="#TOC1">SYNOPSIS OF C++ WRAPPER</a><br>
<P>
<b>#include &#60;pcrecpp.h&#62;</b>
</P>
<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
<P>
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 <i>pcrecpp.h</i> 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 support at present.
</P>
<br><a name="SEC3" href="#TOC1">MATCHING INTERFACE</a><br>
<P>
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.
<pre>
  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");
</pre>
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.
</P>
<P>
You must supply extra pointer arguments to extract matched subpieces.
<pre>
  Example: extracts "ruby" into "s" and 1234 into "i"
     int i;
     string s;
     pcrecpp::RE re("(\\w+):(\\d+)");
     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("\\w+:\\d+").FullMatch("ruby:1234", &s);

  Example: fails because string cannot be stored in integer
     !pcrecpp::RE("(.*)").FullMatch("ruby", &i);
</pre>
The provided pointer arguments can be pointers to any scalar numeric
type, or one of:
<pre>
   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)
</pre>
The function returns true iff all of the following conditions are satisfied:
<pre>
  a. "text" matches "pattern" exactly;

  b. The number of matched sub-patterns is &#62;= 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.
</pre>
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):
<pre>
   int number;
   pcrecpp::RE::FullMatch("abc", "[a-z]+(\\d+)?", &number);
</pre>
The matching interface supports at most 16 arguments per call.
If you need more, consider using the more general interface
<b>pcrecpp::RE::DoMatch</b>. See <b>pcrecpp.h</b> for the signature for
<b>DoMatch</b>.
</P>
<P>
NOTE: Do not use <b>no_arg</b>, 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.
</P>
<br><a name="SEC4" href="#TOC1">QUOTING METACHARACTERS</a><br>
<P>
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.
<pre>
  Example:
     string quoted = RE::QuoteMeta(unquoted);
</pre>
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\.5\-2\.0\?".
</P>
<br><a name="SEC5" href="#TOC1">PARTIAL MATCHES</a><br>
<P>
You can use the "PartialMatch" operation when you want the pattern
to match any substring of the text.
<pre>
  Example: simple search for a string:
     pcrecpp::RE("ell").PartialMatch("hello");

  Example: find first number in a string:
     int number;
     pcrecpp::RE re("(\\d+)");
     re.PartialMatch("x*100 + 20", &number);
     assert(number == 100);
</PRE>
</P>
<br><a name="SEC6" href="#TOC1">UTF-8 AND THE MATCHING INTERFACE</a><br>
<P>
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.
<pre>
  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);
</pre>
NOTE: The UTF8 flag is ignored if pcre was not configured with the
<pre>
      --enable-utf8 flag.
</PRE>
</P>
<br><a name="SEC7" href="#TOC1">PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE</a><br>
<P>
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
supported:
<pre>
   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 whitespaces          /x
   PCRE_UTF8             handles UTF8 chars          built-in
   PCRE_UNGREEDY         reverses * and *?           N/A
   PCRE_NO_AUTO_CAPTURE  disables capturing parens   N/A (*)
</pre>
(*) 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.
</P>
<P>
For a full account on how each modifier works, please check the
PCRE API reference page.
</P>
<P>
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
<pre>
  bool caseless()
</pre>
which returns true if the modifier is set, and
<pre>
  RE_Options & set_caseless(bool)
</pre>
which sets or unsets the modifier. Moreover, PCRE_EXTRA_MATCH_LIMIT can be
accessed through the <b>set_match_limit()</b> and <b>match_limit()</b> member
functions. Setting <i>match_limit</i> 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 <i>match_limit</i> to zero disables
match limiting. Alternatively, you can call <b>match_limit_recursion()</b>
which uses PCRE_EXTRA_MATCH_LIMIT_RECURSION to limit how much PCRE
recurses. <b>match_limit()</b> limits the number of matches PCRE does;
<b>match_limit_recursion()</b> limits the depth of internal recursion, and
therefore the amount of stack that is used.
</P>
<P>
Normally, to pass one or more modifiers to a RE class, you declare
a <i>RE_Options</i> object, set the appropriate options, and pass this
object to a RE constructor. Example:
<pre>
   RE_Options opt;
   opt.set_caseless(true);
   if (RE("HELLO", opt).PartialMatch("hello world")) ...
</pre>
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
<i>option_flags</i> is to facilitate transfer of legacy code from C programs.
This lets you do
<pre>
   RE(pattern,
     RE_Options(PCRE_CASELESS|PCRE_MULTILINE)).PartialMatch(str);
</pre>
However, new code is better off doing
<pre>
   RE(pattern,
     RE_Options().set_caseless(true).set_multiline(true))
       .PartialMatch(str);
</pre>
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: <b>CASELESS()</b>, <b>UTF8()</b>,
<b>MULTILINE()</b>, <b>DOTALL</b>(), and <b>EXTENDED()</b>.
</P>
<P>
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 <b>set_xxxxx()</b> 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:
<pre>
   RE(" ^ xyz \\s+ .* blah$",
     RE_Options()
       .set_caseless(true)
       .set_extended(true)
       .set_multiline(true)).PartialMatch(sometext);

</PRE>
</P>
<br><a name="SEC8" href="#TOC1">SCANNING TEXT INCREMENTALLY</a><br>
<P>
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.
<pre>
  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("(\\w+) = (\\d+)\n");
     while (re.Consume(&input, &var, &value)) {
       ...;
     }
</pre>
Each successful call to "Consume" will set "var/value", and also
advance "input" so it points past the matched text.
</P>
<P>
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
<pre>
  pcrecpp::RE("(\\w+)").FindAndConsume(&input, &word)
</PRE>
</P>
<br><a name="SEC9" href="#TOC1">PARSING HEX/OCTAL/C-RADIX NUMBERS</a><br>
<P>
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.
<pre>
  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));
</pre>
will leave 64 in a, b, c, and d.
</P>
<br><a name="SEC10" href="#TOC1">REPLACING PARTS OF STRINGS</a><br>
<P>
You can replace the first match of "pattern" in "str" with "rewrite".
Within "rewrite", backslash-escaped digits (\1 to \9) can be
used to insert text matching corresponding parenthesized group
from the pattern. \0 in "rewrite" refers to the entire matching
text. For example:
<pre>
  string s = "yabba dabba doo";
  pcrecpp::RE("b+").Replace("d", &s);
</pre>
will leave "s" containing "yada dabba doo". The result is true if the pattern
matches and a replacement occurs, false otherwise.
</P>
<P>
<b>GlobalReplace</b> is like <b>Replace</b> except that it replaces all
occurrences of the pattern in the string with the rewrite. Replacements are
not subject to re-matching. For example:
<pre>
  string s = "yabba dabba doo";
  pcrecpp::RE("b+").GlobalReplace("d", &s);
</pre>
will leave "s" containing "yada dada doo". It returns the number of
replacements made.
</P>
<P>
<b>Extract</b> is like <b>Replace</b>, 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.
</P>
<br><a name="SEC11" href="#TOC1">AUTHOR</a><br>
<P>
The C++ wrapper was contributed by Google Inc.
<br>
Copyright &copy; 2007 Google Inc.
<br>
</P>
<br><a name="SEC12" href="#TOC1">REVISION</a><br>
<P>
Last updated: 08 January 2012
<br>
<p>
Return to the <a href="index.html">PCRE index page</a>.
</p>
1	nigel	77	<html>
2			<head>
3			<title>pcrecpp specification</title>
4			</head>
5			<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6			<h1>pcrecpp man page</h1>
7			<p>
8			Return to the <a href="index.html">PCRE index page</a>.
9			</p>
10	ph10	111	<p>
11	nigel	77	This page is part of the PCRE HTML documentation. It was generated automatically
12			from the original man page. If there is any nonsense in it, please consult the
13			man page, in case the conversion went wrong.
14	ph10	111	<br>
15	nigel	77	<ul>
16			<li><a name="TOC1" href="#SEC1">SYNOPSIS OF C++ WRAPPER</a>
17			<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
18			<li><a name="TOC3" href="#SEC3">MATCHING INTERFACE</a>
19	nigel	93	<li><a name="TOC4" href="#SEC4">QUOTING METACHARACTERS</a>
20			<li><a name="TOC5" href="#SEC5">PARTIAL MATCHES</a>
21			<li><a name="TOC6" href="#SEC6">UTF-8 AND THE MATCHING INTERFACE</a>
22			<li><a name="TOC7" href="#SEC7">PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE</a>
23			<li><a name="TOC8" href="#SEC8">SCANNING TEXT INCREMENTALLY</a>
24			<li><a name="TOC9" href="#SEC9">PARSING HEX/OCTAL/C-RADIX NUMBERS</a>
25			<li><a name="TOC10" href="#SEC10">REPLACING PARTS OF STRINGS</a>
26			<li><a name="TOC11" href="#SEC11">AUTHOR</a>
27	ph10	99	<li><a name="TOC12" href="#SEC12">REVISION</a>
28	nigel	77	</ul>
29			<br><a name="SEC1" href="#TOC1">SYNOPSIS OF C++ WRAPPER</a><br>
30			<P>
31			<b>#include <pcrecpp.h></b>
32			</P>
33			<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
34			<P>
35	nigel	81	The C++ wrapper for PCRE was provided by Google Inc. Some additional
36			functionality was added by Giuseppe Maxia. This brief man page was constructed
37			from the notes in the <i>pcrecpp.h</i> file, which should be consulted for
38	ph10	903	further details. Note that the C++ wrapper supports only the original 8-bit
39	ph10	869	PCRE library. There is no 16-bit support at present.
40	nigel	77	</P>
41			<br><a name="SEC3" href="#TOC1">MATCHING INTERFACE</a><br>
42			<P>
43			The "FullMatch" operation checks that supplied text matches a supplied pattern
44			exactly. If pointer arguments are supplied, it copies matched sub-strings that
45			match sub-patterns into them.
46			<pre>
47			Example: successful match
48			pcrecpp::RE re("h.*o");
49			re.FullMatch("hello");
50
51			Example: unsuccessful match (requires full match):
52			pcrecpp::RE re("e");
53			!re.FullMatch("hello");
54
55			Example: creating a temporary RE object:
56			pcrecpp::RE("h.*o").FullMatch("hello");
57			</pre>
58			You can pass in a "const char*" or a "string" for "text". The examples below
59			tend to use a const char*. You can, as in the different examples above, store
60			the RE object explicitly in a variable or use a temporary RE object. The
61			examples below use one mode or the other arbitrarily. Either could correctly be
62			used for any of these examples.
63			</P>
64			<P>
65			You must supply extra pointer arguments to extract matched subpieces.
66			<pre>
67			Example: extracts "ruby" into "s" and 1234 into "i"
68			int i;
69			string s;
70			pcrecpp::RE re("(\\w+):(\\d+)");
71			re.FullMatch("ruby:1234", &s, &i);
72
73			Example: does not try to extract any extra sub-patterns
74			re.FullMatch("ruby:1234", &s);
75
76			Example: does not try to extract into NULL
77			re.FullMatch("ruby:1234", NULL, &i);
78
79			Example: integer overflow causes failure
80			!re.FullMatch("ruby:1234567891234", NULL, &i);
81
82			Example: fails because there aren't enough sub-patterns:
83			!pcrecpp::RE("\\w+:\\d+").FullMatch("ruby:1234", &s);
84
85			Example: fails because string cannot be stored in integer
86			!pcrecpp::RE("(.*)").FullMatch("ruby", &i);
87			</pre>
88			The provided pointer arguments can be pointers to any scalar numeric
89			type, or one of:
90			<pre>
91			string (matched piece is copied to string)
92			StringPiece (StringPiece is mutated to point to matched piece)
93			T (where "bool T::ParseFrom(const char*, int)" exists)
94			NULL (the corresponding matched sub-pattern is not copied)
95			</pre>
96			The function returns true iff all of the following conditions are satisfied:
97			<pre>
98			a. "text" matches "pattern" exactly;
99
100			b. The number of matched sub-patterns is >= number of supplied
101			pointers;
102
103			c. The "i"th argument has a suitable type for holding the
104			string captured as the "i"th sub-pattern. If you pass in
105	ph10	286	void * NULL for the "i"th argument, or a non-void * NULL
106			of the correct type, or pass fewer arguments than the
107	nigel	77	number of sub-patterns, "i"th captured sub-pattern is
108			ignored.
109			</pre>
110	nigel	93	CAVEAT: An optional sub-pattern that does not exist in the matched
111			string is assigned the empty string. Therefore, the following will
112			return false (because the empty string is not a valid number):
113			<pre>
114			int number;
115			pcrecpp::RE::FullMatch("abc", "[a-z]+(\\d+)?", &number);
116			</pre>
117	nigel	77	The matching interface supports at most 16 arguments per call.
118			If you need more, consider using the more general interface
119			<b>pcrecpp::RE::DoMatch</b>. See <b>pcrecpp.h</b> for the signature for
120			<b>DoMatch</b>.
121			</P>
122	ph10	392	<P>
123			NOTE: Do not use <b>no_arg</b>, which is used internally to mark the end of a
124			list of optional arguments, as a placeholder for missing arguments, as this can
125			lead to segfaults.
126			</P>
127	nigel	93	<br><a name="SEC4" href="#TOC1">QUOTING METACHARACTERS</a><br>
128	nigel	77	<P>
129	nigel	93	You can use the "QuoteMeta" operation to insert backslashes before all
130			potentially meaningful characters in a string. The returned string, used as a
131			regular expression, will exactly match the original string.
132			<pre>
133			Example:
134			string quoted = RE::QuoteMeta(unquoted);
135			</pre>
136			Note that it's legal to escape a character even if it has no special meaning in
137			a regular expression -- so this function does that. (This also makes it
138			identical to the perl function of the same name; see "perldoc -f quotemeta".)
139			For example, "1.5-2.0?" becomes "1\.5\-2\.0\?".
140			</P>
141			<br><a name="SEC5" href="#TOC1">PARTIAL MATCHES</a><br>
142			<P>
143	nigel	77	You can use the "PartialMatch" operation when you want the pattern
144			to match any substring of the text.
145			<pre>
146			Example: simple search for a string:
147			pcrecpp::RE("ell").PartialMatch("hello");
148
149			Example: find first number in a string:
150			int number;
151			pcrecpp::RE re("(\\d+)");
152			re.PartialMatch("x*100 + 20", &number);
153			assert(number == 100);
154			</PRE>
155			</P>
156	nigel	93	<br><a name="SEC6" href="#TOC1">UTF-8 AND THE MATCHING INTERFACE</a><br>
157	nigel	77	<P>
158			By default, pattern and text are plain text, one byte per character. The UTF8
159			flag, passed to the constructor, causes both pattern and string to be treated
160			as UTF-8 text, still a byte stream but potentially multiple bytes per
161			character. In practice, the text is likelier to be UTF-8 than the pattern, but
162			the match returned may depend on the UTF8 flag, so always use it when matching
163			UTF8 text. For example, "." will match one byte normally but with UTF8 set may
164			match up to three bytes of a multi-byte character.
165			<pre>
166			Example:
167			pcrecpp::RE_Options options;
168			options.set_utf8();
169			pcrecpp::RE re(utf8_pattern, options);
170			re.FullMatch(utf8_string);
171
172			Example: using the convenience function UTF8():
173			pcrecpp::RE re(utf8_pattern, pcrecpp::UTF8());
174			re.FullMatch(utf8_string);
175			</pre>
176			NOTE: The UTF8 flag is ignored if pcre was not configured with the
177			<pre>
178			--enable-utf8 flag.
179			</PRE>
180			</P>
181	nigel	93	<br><a name="SEC7" href="#TOC1">PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE</a><br>
182	nigel	77	<P>
183	nigel	81	PCRE defines some modifiers to change the behavior of the regular expression
184			engine. The C++ wrapper defines an auxiliary class, RE_Options, as a vehicle to
185			pass such modifiers to a RE class. Currently, the following modifiers are
186			supported:
187			<pre>
188			modifier description Perl corresponding
189
190			PCRE_CASELESS case insensitive match /i
191			PCRE_MULTILINE multiple lines match /m
192			PCRE_DOTALL dot matches newlines /s
193			PCRE_DOLLAR_ENDONLY $ matches only at end N/A
194			PCRE_EXTRA strict escape parsing N/A
195			PCRE_EXTENDED ignore whitespaces /x
196			PCRE_UTF8 handles UTF8 chars built-in
197			PCRE_UNGREEDY reverses * and *? N/A
198			PCRE_NO_AUTO_CAPTURE disables capturing parens N/A (*)
199			</pre>
200			(*) Both Perl and PCRE allow non capturing parentheses by means of the
201			"?:" modifier within the pattern itself. e.g. (?:ab\|cd) does not
202			capture, while (ab\|cd) does.
203			</P>
204			<P>
205			For a full account on how each modifier works, please check the
206			PCRE API reference page.
207			</P>
208			<P>
209			For each modifier, there are two member functions whose name is made
210			out of the modifier in lowercase, without the "PCRE_" prefix. For
211			instance, PCRE_CASELESS is handled by
212			<pre>
213			bool caseless()
214			</pre>
215			which returns true if the modifier is set, and
216			<pre>
217			RE_Options & set_caseless(bool)
218			</pre>
219	nigel	87	which sets or unsets the modifier. Moreover, PCRE_EXTRA_MATCH_LIMIT can be
220	nigel	81	accessed through the <b>set_match_limit()</b> and <b>match_limit()</b> member
221			functions. Setting <i>match_limit</i> to a non-zero value will limit the
222			execution of pcre to keep it from doing bad things like blowing the stack or
223			taking an eternity to return a result. A value of 5000 is good enough to stop
224			stack blowup in a 2MB thread stack. Setting <i>match_limit</i> to zero disables
225	nigel	87	match limiting. Alternatively, you can call <b>match_limit_recursion()</b>
226			which uses PCRE_EXTRA_MATCH_LIMIT_RECURSION to limit how much PCRE
227			recurses. <b>match_limit()</b> limits the number of matches PCRE does;
228			<b>match_limit_recursion()</b> limits the depth of internal recursion, and
229			therefore the amount of stack that is used.
230	nigel	81	</P>
231			<P>
232			Normally, to pass one or more modifiers to a RE class, you declare
233			a <i>RE_Options</i> object, set the appropriate options, and pass this
234			object to a RE constructor. Example:
235			<pre>
236	ph10	654	RE_Options opt;
237	nigel	81	opt.set_caseless(true);
238			if (RE("HELLO", opt).PartialMatch("hello world")) ...
239			</pre>
240			RE_options has two constructors. The default constructor takes no arguments and
241			creates a set of flags that are off by default. The optional parameter
242			<i>option_flags</i> is to facilitate transfer of legacy code from C programs.
243			This lets you do
244			<pre>
245			RE(pattern,
246			RE_Options(PCRE_CASELESS\|PCRE_MULTILINE)).PartialMatch(str);
247			</pre>
248			However, new code is better off doing
249			<pre>
250			RE(pattern,
251			RE_Options().set_caseless(true).set_multiline(true))
252			.PartialMatch(str);
253			</pre>
254			If you are going to pass one of the most used modifiers, there are some
255			convenience functions that return a RE_Options class with the
256			appropriate modifier already set: <b>CASELESS()</b>, <b>UTF8()</b>,
257			<b>MULTILINE()</b>, <b>DOTALL</b>(), and <b>EXTENDED()</b>.
258			</P>
259			<P>
260			If you need to set several options at once, and you don't want to go through
261			the pains of declaring a RE_Options object and setting several options, there
262			is a parallel method that give you such ability on the fly. You can concatenate
263			several <b>set_xxxxx()</b> member functions, since each of them returns a
264			reference to its class object. For example, to pass PCRE_CASELESS,
265			PCRE_EXTENDED, and PCRE_MULTILINE to a RE with one statement, you may write:
266			<pre>
267			RE(" ^ xyz \\s+ .* blah$",
268			RE_Options()
269			.set_caseless(true)
270			.set_extended(true)
271			.set_multiline(true)).PartialMatch(sometext);
272
273			</PRE>
274			</P>
275	nigel	93	<br><a name="SEC8" href="#TOC1">SCANNING TEXT INCREMENTALLY</a><br>
276	nigel	81	<P>
277	nigel	77	The "Consume" operation may be useful if you want to repeatedly
278			match regular expressions at the front of a string and skip over
279			them as they match. This requires use of the "StringPiece" type,
280			which represents a sub-range of a real string. Like RE, StringPiece
281			is defined in the pcrecpp namespace.
282			<pre>
283			Example: read lines of the form "var = value" from a string.
284			string contents = ...; // Fill string somehow
285			pcrecpp::StringPiece input(contents); // Wrap in a StringPiece
286	ph10	583
287	nigel	77	string var;
288			int value;
289			pcrecpp::RE re("(\\w+) = (\\d+)\n");
290			while (re.Consume(&input, &var, &value)) {
291			...;
292			}
293			</pre>
294			Each successful call to "Consume" will set "var/value", and also
295			advance "input" so it points past the matched text.
296			</P>
297			<P>
298			The "FindAndConsume" operation is similar to "Consume" but does not
299			anchor your match at the beginning of the string. For example, you
300			could extract all words from a string by repeatedly calling
301			<pre>
302			pcrecpp::RE("(\\w+)").FindAndConsume(&input, &word)
303			</PRE>
304			</P>
305	nigel	93	<br><a name="SEC9" href="#TOC1">PARSING HEX/OCTAL/C-RADIX NUMBERS</a><br>
306	nigel	77	<P>
307			By default, if you pass a pointer to a numeric value, the
308			corresponding text is interpreted as a base-10 number. You can
309			instead wrap the pointer with a call to one of the operators Hex(),
310			Octal(), or CRadix() to interpret the text in another base. The
311			CRadix operator interprets C-style "0" (base-8) and "0x" (base-16)
312			prefixes, but defaults to base-10.
313			<pre>
314			Example:
315			int a, b, c, d;
316			pcrecpp::RE re("(.) (.) (.) (.)");
317			re.FullMatch("100 40 0100 0x40",
318			pcrecpp::Octal(&a), pcrecpp::Hex(&b),
319			pcrecpp::CRadix(&c), pcrecpp::CRadix(&d));
320			</pre>
321			will leave 64 in a, b, c, and d.
322			</P>
323	nigel	93	<br><a name="SEC10" href="#TOC1">REPLACING PARTS OF STRINGS</a><br>
324	nigel	77	<P>
325			You can replace the first match of "pattern" in "str" with "rewrite".
326			Within "rewrite", backslash-escaped digits (\1 to \9) can be
327			used to insert text matching corresponding parenthesized group
328			from the pattern. \0 in "rewrite" refers to the entire matching
329			text. For example:
330			<pre>
331			string s = "yabba dabba doo";
332			pcrecpp::RE("b+").Replace("d", &s);
333			</pre>
334			will leave "s" containing "yada dabba doo". The result is true if the pattern
335			matches and a replacement occurs, false otherwise.
336			</P>
337			<P>
338			<b>GlobalReplace</b> is like <b>Replace</b> except that it replaces all
339			occurrences of the pattern in the string with the rewrite. Replacements are
340			not subject to re-matching. For example:
341			<pre>
342			string s = "yabba dabba doo";
343			pcrecpp::RE("b+").GlobalReplace("d", &s);
344			</pre>
345			will leave "s" containing "yada dada doo". It returns the number of
346			replacements made.
347			</P>
348			<P>
349			<b>Extract</b> is like <b>Replace</b>, except that if the pattern matches,
350			"rewrite" is copied into "out" (an additional argument) with substitutions.
351			The non-matching portions of "text" are ignored. Returns true iff a match
352			occurred and the extraction happened successfully; if no match occurs, the
353			string is left unaffected.
354			</P>
355	nigel	93	<br><a name="SEC11" href="#TOC1">AUTHOR</a><br>
356	nigel	77	<P>
357			The C++ wrapper was contributed by Google Inc.
358			<br>
359	ph10	123	Copyright © 2007 Google Inc.
360	ph10	99	<br>
361			</P>
362			<br><a name="SEC12" href="#TOC1">REVISION</a><br>
363			<P>
364	ph10	869	Last updated: 08 January 2012
365	ph10	99	<br>
366	nigel	77	<p>
367			Return to the <a href="index.html">PCRE index page</a>.
368			</p>
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