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Diff for /src/lib/libc/regex/re_format.7 between version 1.10 and 1.11

version 1.10, 2013/01/25 11:51:42 version 1.11, 2015/08/22 14:04:54
Line 83  and obsolete REs (roughly those of
Line 83  and obsolete REs (roughly those of
 Obsolete REs mostly exist for backward compatibility in some old programs;  Obsolete REs mostly exist for backward compatibility in some old programs;
 they will be discussed at the end.  they will be discussed at the end.
 1003.2 leaves some aspects of RE syntax and semantics open;  1003.2 leaves some aspects of RE syntax and semantics open;
 `#' marks decisions on these aspects that  `(*)' marks decisions on these aspects that
 may not be fully portable to other 1003.2 implementations.  may not be fully portable to other 1003.2 implementations.
 .Pp  .Pp
 A (modern) RE is one# or more non-empty#  A (modern) RE is one(*) or more non-empty(*)
 .Em branches ,  .Em branches ,
 separated by `|'.  separated by `|'.
 It matches anything that matches one of the branches.  It matches anything that matches one of the branches.
 .Pp  .Pp
 A branch is one# or more  A branch is one(*) or more
 .Em pieces ,  .Em pieces ,
 concatenated.  concatenated.
 It matches a match for the first, followed by a match for the second, etc.  It matches a match for the first, followed by a match for the second, etc.
Line 99  It matches a match for the first, follow
Line 99  It matches a match for the first, follow
 A piece is an  A piece is an
 .Em atom  .Em atom
 possibly followed  possibly followed
 by a single# `*', `+', `?', or  by a single(*) `*', `+', `?', or
 .Em bound .  .Em bound .
 An atom followed by `*' matches a sequence of 0 or more matches of the atom.  An atom followed by `*' matches a sequence of 0 or more matches of the atom.
 An atom followed by `+' matches a sequence of 1 or more matches of the atom.  An atom followed by `+' matches a sequence of 1 or more matches of the atom.
Line 110  A
Line 110  A
 is `{' followed by an unsigned decimal integer, possibly followed by `,'  is `{' followed by an unsigned decimal integer, possibly followed by `,'
 possibly followed by another unsigned decimal integer,  possibly followed by another unsigned decimal integer,
 always followed by `}'.  always followed by `}'.
 The integers must lie between 0 and RE_DUP_MAX (255#) inclusive,  The integers must lie between 0 and RE_DUP_MAX (255(*)) inclusive,
 and if there are two of them, the first may not exceed the second.  and if there are two of them, the first may not exceed the second.
 An atom followed by a bound containing one integer  An atom followed by a bound containing one integer
 .Em i  .Em i
Line 133  through
Line 133  through
 (inclusive) matches of the atom.  (inclusive) matches of the atom.
 .Pp  .Pp
 An atom is a regular expression enclosed in `()' (matching a match for the  An atom is a regular expression enclosed in `()' (matching a match for the
 regular expression), an empty set of `()' (matching the null string)#, a  regular expression), an empty set of `()' (matching the null string)(*), a
 .Em bracket expression  .Em bracket expression
 (see below), `.' (matching any single character),  (see below), `.' (matching any single character),
 `^' (matching the null string at the beginning of a line),  `^' (matching the null string at the beginning of a line),
 `$' (matching the null string at the end of a line),  `$' (matching the null string at the end of a line),
 a `\e' followed by one of the characters `^.[$()|*+?{\e'  a `\e' followed by one of the characters `^.[$()|*+?{\e'
 (matching that character taken as an ordinary character),  (matching that character taken as an ordinary character),
 a `\e' followed by any other character#  a `\e' followed by any other character(*)
 (matching that character taken as an ordinary character,  (matching that character taken as an ordinary character,
 as if the `\e' had not been present#),  as if the `\e' had not been present(*)),
 or a single character with no other significance (matching that character).  or a single character with no other significance (matching that character).
 A `{' followed by a character other than a digit is an ordinary  A `{' followed by a character other than a digit is an ordinary
 character, not the beginning of a bound#.  character, not the beginning of a bound(*).
 It is illegal to end an RE with `\e'.  It is illegal to end an RE with `\e'.
 .Pp  .Pp
 A  A
Line 161  for the full
Line 161  for the full
 .Em range  .Em range
 of characters between those two (inclusive) in the collating sequence,  of characters between those two (inclusive) in the collating sequence,
 e.g. `[0-9]' in ASCII matches any decimal digit.  e.g. `[0-9]' in ASCII matches any decimal digit.
 It is illegal# for two ranges to share an endpoint, e.g. `a-c-e'.  It is illegal(*) for two ranges to share an endpoint, e.g. `a-c-e'.
 Ranges are very collating-sequence-dependent,  Ranges are very collating-sequence-dependent,
 and portable programs should avoid relying on them.  and portable programs should avoid relying on them.
 .Pp  .Pp
Line 194  of all collating elements equivalent to 
Line 194  of all collating elements equivalent to 
 the treatment is as if the enclosing delimiters were `[.' and `.]'.)  the treatment is as if the enclosing delimiters were `[.' and `.]'.)
 For example, if o and '\(^o' are the members of an equivalence class,  For example, if o and '\(^o' are the members of an equivalence class,
 then `[[=o=]]', `[[=\(^o'=]]', and `[o\(^o']' are all synonymous.  then `[[=o=]]', `[[=\(^o'=]]', and `[o\(^o']' are all synonymous.
 An equivalence class may not# be an endpoint  An equivalence class may not(*) be an endpoint
 of a range.  of a range.
 .Pp  .Pp
 Within a bracket expression, the name of a  Within a bracket expression, the name of a
Line 214  These stand for the character classes de
Line 214  These stand for the character classes de
 A locale may provide others.  A locale may provide others.
 A character class may not be used as an endpoint of a range.  A character class may not be used as an endpoint of a range.
 .Pp  .Pp
 There are two special cases# of bracket expressions:  There are two special cases(*) of bracket expressions:
 the bracket expressions `[[:\*[Lt]:]]' and `[[:\*[Gt]:]]' match  the bracket expressions `[[:\*[Lt]:]]' and `[[:\*[Gt]:]]' match
 the null string at the beginning and end of a word respectively.  the null string at the beginning and end of a word respectively.
 A word is defined as a sequence of word characters  A word is defined as a sequence of word characters
Line 260  When it appears inside a bracket express
Line 260  When it appears inside a bracket express
 of it are added to the bracket expression, so that (e.g.) `[x]'  of it are added to the bracket expression, so that (e.g.) `[x]'
 becomes `[xX]' and `[^x]' becomes `[^xX]'.  becomes `[xX]' and `[^x]' becomes `[^xX]'.
 .Pp  .Pp
 No particular limit is imposed on the length of REs#.  No particular limit is imposed on the length of REs(*).
 Programs intended to be portable should not employ REs longer  Programs intended to be portable should not employ REs longer
 than 256 bytes,  than 256 bytes,
 as an implementation can refuse to accept such REs and remain  as an implementation can refuse to accept such REs and remain
Line 274  with `{' and `}' by themselves ordinary 
Line 274  with `{' and `}' by themselves ordinary 
 The parentheses for nested subexpressions are `\e(' and `\e)',  The parentheses for nested subexpressions are `\e(' and `\e)',
 with `(' and `)' by themselves ordinary characters.  with `(' and `)' by themselves ordinary characters.
 `^' is an ordinary character except at the beginning of the  `^' is an ordinary character except at the beginning of the
 RE or# the beginning of a parenthesized subexpression,  RE or(*) the beginning of a parenthesized subexpression,
 `$' is an ordinary character except at the end of the  `$' is an ordinary character except at the end of the
 RE or# the end of a parenthesized subexpression,  RE or(*) the end of a parenthesized subexpression,
 and `*' is an ordinary character if it appears at the beginning of the  and `*' is an ordinary character if it appears at the beginning of the
 RE or the beginning of a parenthesized subexpression  RE or the beginning of a parenthesized subexpression
 (after a possible leading `^').  (after a possible leading `^').
Legend:
Removed from v.1.10  
changed lines
  Added in v.1.11
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