ceph/src/boost/libs/regex/doc/standards.qbk

   1 [/
   2   Copyright 2006-2007 John Maddock.
   3   Distributed under the Boost Software License, Version 1.0.
   4   (See accompanying file LICENSE_1_0.txt or copy at
   5   http://www.boost.org/LICENSE_1_0.txt).
   6 ]
   7
   8
   9 [section:standards Standards Conformance]
  10
  11 [h4 C++]
  12
  13 Boost.Regex is intended to conform to the [tr1].
  14
  15 [h4 ECMAScript / JavaScript]
  16
  17 All of the ECMAScript regular expression syntax features are supported, except that:
  18
  19 The escape sequence \\u matches any upper case character (the same as \[\[:upper:\]\])
  20 rather than a Unicode escape sequence; use \\x{DDDD} for Unicode escape sequences.
  21
  22 [h4 Perl]
  23
  24 Almost all Perl features are supported, except for:
  25
  26 (?{code})       Not implementable in a compiled strongly typed language.
  27
  28 (??{code})      Not implementable in a compiled strongly typed language.
  29
  30 (*VERB) The [@http://perldoc.perl.org/perlre.html#Special-Backtracking-Control-Verbs
  31 backtracking control verbs] are not recognised or implemented at this time.
  32
  33 In addition the following features behave slightly differently from Perl:
  34
  35 ^ $ \Z  These recognise any line termination sequence, and not just \\n: see the Unicode requirements below.
  36
  37 [h4 POSIX]
  38
  39 All the POSIX basic and extended regular expression features are supported,
  40 except that:
  41
  42 No character collating names are recognized except those specified in the
  43 POSIX standard for the C locale, unless they are explicitly registered with the
  44 traits class.
  45
  46 Character equivalence classes ( \[\[\=a\=\]\] etc) are probably buggy except on Win32.
  47 Implementing this feature requires knowledge of the format of the string sort
  48 keys produced by the system; if you need this, and the default implementation
  49 doesn't work on your platform, then you will need to supply a custom traits class.
  50
  51 [h4 Unicode]
  52
  53 The following comments refer to
  54 [@http://unicode.org/reports/tr18/ Unicode Technical Standard #18: Unicode
  55 Regular Expressions version 11].
  56
  57 [table
  58 [[Item][Feature][Support]]
  59 [[1.1][Hex Notation][Yes: use \x{DDDD} to refer to code point UDDDD.]]
  60 [[1.2][Character Properties][All the names listed under the General Category Property are supported.  Script names and Other Names are not currently supported.]]
  61 [[1.3][Subtraction and Intersection][Indirectly support by forward-lookahead:
  62
  63 `(?=[[:X:]])[[:Y:]]`
  64
  65 Gives the intersection of character properties X and Y.
  66
  67 `(?![[:X:]])[[:Y:]]`
  68
  69 Gives everything in Y that is not in X (subtraction).]]
  70 [[1.4][Simple Word Boundaries][Conforming: non-spacing marks are included in the set of word characters.]]
  71 [[1.5][Caseless Matching][Supported, note that at this level, case transformations are 1:1, many to many case folding operations are not supported (for example "'''&#xDF;'''" to "SS").]]
  72 [[1.6][Line Boundaries][Supported, except that "." matches only one character of "\\r\\n". Other than that word boundaries match correctly; including not matching in the middle of a "\\r\\n" sequence.]]
  73 [[1.7][Code Points][Supported: provided you use the u32* algorithms, then UTF-8, UTF-16 and UTF-32 are all treated as sequences of 32-bit code points.]]
  74 [[2.1][Canonical Equivalence][Not supported: it is up to the user of the library to convert all text into the same canonical form as the regular expression.]]
  75 [[2.2][Default Grapheme Clusters][Not supported.]]
  76 [[2.3Default Word Boundaries][Not supported.]]
  77 [[2.4][Default Loose Matches][Not Supported.]]
  78 [[2.5][Named Properties][Supported: the expression "\[\[:name:\]\]" or \\N{name} matches the named character "name".]]
  79 [[2.6][Wildcard properties][Not Supported.]]
  80 [[3.1][Tailored Punctuation.][Not Supported.]]
  81 [[3.2][Tailored Grapheme Clusters][Not Supported.]]
  82 [[3.3][Tailored Word Boundaries.][Not Supported.]]
  83 [[3.4][Tailored Loose Matches][Partial support: \[\[\=c\=\]\] matches characters with the same primary equivalence class as "c".]]
  84 [[3.5][Tailored Ranges][Supported: \[a-b\] matches any character that collates in the range a to b, when the expression is constructed with the collate flag set.]]
  85 [[3.6][Context Matches][Not Supported.]]
  86 [[3.7][Incremental Matches][Supported: pass the flag `match_partial` to the regex algorithms.]]
  87 [[3.8][Unicode Set Sharing][Not Supported.]]
  88 [[3.9][Possible Match Sets][Not supported, however this information is used internally to optimise the matching of regular expressions, and return quickly if no match is possible.]]
  89 [[3.10][Folded Matching][Partial Support:  It is possible to achieve a similar effect by using a custom regular expression traits class.]]
  90 [[3.11][Custom Submatch Evaluation][Not Supported.]]
  91 ]
  92
  93 [endsect]
  94