Windows PowerShell command on Get-command pcrecpp

Manual Pages for UNIX Operating System command usage for man pcrecpp

Introduction to Library Functions PCRECPP(3)

NAME

PCRE - Perl-compatible regular expressions.

SYNOPSIS OF C++ WRAPPER

#include

DESCRIPTION

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

pcrecpp.h file, which should be consulted for further

details. MATCHING INTERFACE The "FullMatch" operation checks that supplied text matches

a supplied pattern exactly. If pointer arguments are sup-

plied, 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("(\\w+):(\\d+)");

re.FullMatch("ruby:1234", &s, &i);

Example: does not try to extract any extra sub-patterns

re.FullMatch("ruby:1234", &s); SunOS 5.10 Last change: 1 Introduction to Library Functions PCRECPP(3) 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);

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 condi-

tions are satisfied: a. "text" matches "pattern" exactly;

b. The number of matched sub-patterns is >= number of sup-

plied pointers; c. The "i"th argument has a suitable type for holding the

string captured as the "i"th sub-pattern. If you pass

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]+(\\d+)?", &number);

The matching interface supports at most 16 arguments per call. If you need more, consider using the more general

interface pcrecpp::RE::DoMatch. See pcrecpp.h for the

SunOS 5.10 Last change: 2 Introduction to Library Functions PCRECPP(3) signature for DoMatch. QUOTING METACHARACTERS 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 func-

tion of the same name; see "perldoc -f quotemeta".) For

example, "1.5-2.0?" becomes "1\.5\-2\.0\?".

PARTIAL MATCHES 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("(\\d+)");

re.PartialMatch("x*100 + 20", &number); assert(number == 100);

UTF-8 AND THE MATCHING INTERFACE

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());

SunOS 5.10 Last change: 3 Introduction to Library Functions PCRECPP(3)

re.FullMatch(utf8_string);

NOTE: The UTF8 flag is ignored if pcre was not configured with the

--enable-utf8 flag.

PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE PCRE defines some modifiers to change the behavior of the

regular expression engine. The C++ wrapper defines an auxi-

liary class, RE_Options, as a vehicle to pass such modifiers

to a RE class. Currently, the following modifiers are sup-

ported: 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-

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

set_match_limit() and match_limit() member functions. Set-

ting match_limit to a non-zero value will limit the execu-

tion 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 SunOS 5.10 Last change: 4 Introduction to Library Functions PCRECPP(3)

stack. Setting match_limit to zero disables match limiting.

Alternatively, you can call match_limit_recursion() which

uses PCRE_EXTRA_MATCH_LIMIT_RECURSION to limit how much PCRE

recurses. match_limit() limits the number of matches PCRE

does; match_limit_recursion() 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 RE_Options 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 option_flags is to facil-

itate 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:

CASELESS(), UTF8(), MULTILINE(), DOTALL(), and EXTENDED(). 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 con-

catenate several set_xxxxx() 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 \\s+ .* blah$",

RE_Options()

.set_caseless(true)

.set_extended(true)

.set_multiline(true)).PartialMatch(sometext);

SunOS 5.10 Last change: 5 Introduction to Library Functions PCRECPP(3) SCANNING TEXT INCREMENTALLY

The "Consume" operation may be useful if you want to repeat-

edly 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("(\\w+) = (\\d+)\n");

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("(\\w+)").FindAndConsume(&input, &word)

PARSING HEX/OCTAL/C-RADIX NUMBERS

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. SunOS 5.10 Last change: 6 Introduction to Library Functions PCRECPP(3) REPLACING PARTS OF STRINGS 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: 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. GlobalReplace is like Replace 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. Extract is like Replace, 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 extrac-

tion happened successfully; if no match occurs, the string is left unaffected. AUTHOR The C++ wrapper was contributed by Google Inc. Copyright (c) 2007 Google Inc. REVISION Last updated: 12 November 2007

ATTRIBUTES

See attributes(5) for descriptions of the following attri-

butes: SunOS 5.10 Last change: 7 Introduction to Library Functions PCRECPP(3)

_______________________________________

| ATTRIBUTE TYPE | ATTRIBUTE VALUE|

|____________________|__________________|_

| Availability | library/pcre |