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C++ Boost

Boost.Regex

match_flag_type

Boost.Regex Index




Synopsis

The type match_flag_type is an implementation defined bitmask type (17.3.2.1.2) that controls how a regular expression is matched against a character sequence.  The behavior of the format flags is descibed in more detail in the format syntax guide.

namespace boost{ namespace regex_constants{

typedef bitmask_type match_flag_type;

static const match_flag_type match_default = 0;
static const match_flag_type match_not_bob;
static const match_flag_type match_not_eob;
static const match_flag_type match_not_bol;
static const match_flag_type match_not_eol;
static const match_flag_type match_not_bow;
static const match_flag_type match_not_eow;
static const match_flag_type match_any;
static const match_flag_type match_not_null;
static const match_flag_type match_continuous;
static const match_flag_type match_partial;
static const match_flag_type match_single_line;
static const match_flag_type match_prev_avail;
static const match_flag_type match_not_dot_newline;
static const match_flag_type match_not_dot_null;

static const match_flag_type format_default = 0;
static const match_flag_type format_sed;
static const match_flag_type format_perl;
static const match_flag_type format_no_copy;
static const match_flag_type format_first_only;
static const match_flag_type format_all;

} // namespace regex_constants
} // namespace boost

Description

The type match_flag_type is an implementation defined bitmask type (17.3.2.1.2). When matching a regular expression against a sequence of characters [first, last) then setting its elements has the effects listed in the table below:

Element

Effect if set

match_default

Specifies that matching of regular expressions proceeds without any modification of the normal rules used in ECMA-262, ECMAScript Language Specification, Chapter 15 part 10, RegExp (Regular Expression) Objects (FWD.1)

match_not_bob Specifies that the expression "\A" should not match against the sub-sequence [first,first).
match_not_eob Specifies that the expressions "\z" and "\Z" should not match against the sub-sequence [last,last).

match_not_bol

Specifies that the expression "^" should not be matched against the sub-sequence [first,first).

match_not_eol

Specifies that the expression "$" should not be matched against the sub-sequence [last,last).

match_not_bow

Specifies that the expression "\b" should not be matched against the sub-sequence [first,first).

match_not_eow

Specifies that the expression "\b" should not be matched against the sub-sequence [last,last).

match_any

Specifies that if more than one match is possible then any match is an acceptable result.

match_not_null

Specifies that the expression can not be matched against an empty sequence.

match_continuous

Specifies that the expression must match a sub-sequence that begins at first.

match_partial

Specifies that if no match can be found, then it is acceptable to return a match [from, last) where from!=last, if there exists some sequence of characters [from,to) of which [from,last) is a prefix, and which would result in a full match.

match_extra Instructs the matching engine to retain all available capture information; if a capturing group is repeated then information about every repeat is available via match_results::captures() or sub_match_captures().
match_single_line Equivalent to Perl's s/ modifier; prevents ^ from matching after an embedded newline character (so that it only matches at the start of the text being matched), and $ from matching before an embedded newline (so that it only matches at the end of the text being matched).

match_prev_avail

Specifies that --first is a valid iterator position, when this flag is set then the flags match_not_bol and match_not_bow are ignored by the regular expression algorithms (RE.7) and iterators (RE.8).

match_not_dot_newline Specifies that the expression "." does not match a newline character.
match_not_dot_null Specified that the expression "." does not match a character null '\0'.

format_default

Specifies that when a regular expression match is to be replaced by a new string, that the new string is constructed using the rules used by the ECMAScript replace function in ECMA-262, ECMAScript Language Specification, Chapter 15 part 5.4.11 String.prototype.replace. (FWD.1). In addition during search and replace operations then all non-overlapping occurrences of the regular expression are located and replaced, and sections of the input that did not match the expression, are copied unchanged to the output string.

format_sed

Specifies that when a regular expression match is to be replaced by a new string, that the new string is constructed using the rules used by the Unix sed utility in IEEE Std 1003.1-2001, Portable Operating SystemInterface (POSIX ), Shells and Utilities..

format_perl

Specifies that when a regular expression match is to be replaced by a new string, that the new string is constructed using the same rules as Perl 5.

format_all Specifies that all syntax extensions are enabled, including conditional (?ddexpression1:expression2) replacements: see the format string guide for more details.

format_no_copy

When specified during a search and replace operation, then sections of the character container sequence being searched that do match the regular expression, are not copied to the output string.

format_first_only

When specified during a search and replace operation, then only the first occurrence of the regular expression is replaced.






Revised 04 Feb 2004

Copyright John Maddock 1998- 2004

Use, modification and distribution are subject to the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)