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diff --git a/winsup/cygwin/regex/regex.7 b/winsup/cygwin/regex/regex.7 deleted file mode 100644 index 0fa180269..000000000 --- a/winsup/cygwin/regex/regex.7 +++ /dev/null @@ -1,235 +0,0 @@ -.TH REGEX 7 "25 Oct 1995" -.BY "Henry Spencer" -.SH NAME -regex \- POSIX 1003.2 regular expressions -.SH DESCRIPTION -Regular expressions (``RE''s), -as defined in POSIX 1003.2, come in two forms: -modern REs (roughly those of -.IR egrep ; -1003.2 calls these ``extended'' REs) -and obsolete REs (roughly those of -.IR ed ; -1003.2 ``basic'' REs). -Obsolete REs mostly exist for backward compatibility in some old programs; -they will be discussed at the end. -1003.2 leaves some aspects of RE syntax and semantics open; -`\(dg' marks decisions on these aspects that -may not be fully portable to other 1003.2 implementations. -.PP -A (modern) RE is one\(dg or more non-empty\(dg \fIbranches\fR, -separated by `|'. -It matches anything that matches one of the branches. -.PP -A branch is one\(dg or more \fIpieces\fR, concatenated. -It matches a match for the first, followed by a match for the second, etc. -.PP -A piece is an \fIatom\fR possibly followed -by a single\(dg `*', `+', `?', or \fIbound\fR. -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 0 or 1 matches of the atom. -.PP -A \fIbound\fR is `{' followed by an unsigned decimal integer, -possibly followed by `,' -possibly followed by another unsigned decimal integer, -always followed by `}'. -The integers must lie between 0 and RE_DUP_MAX (255\(dg) inclusive, -and if there are two of them, the first may not exceed the second. -An atom followed by a bound containing one integer \fIi\fR -and no comma matches -a sequence of exactly \fIi\fR matches of the atom. -An atom followed by a bound -containing one integer \fIi\fR and a comma matches -a sequence of \fIi\fR or more matches of the atom. -An atom followed by a bound -containing two integers \fIi\fR and \fIj\fR matches -a sequence of \fIi\fR through \fIj\fR (inclusive) matches of the atom. -.PP -An atom is a regular expression enclosed in `()' (matching a match for the -regular expression), -an empty set of `()' (matching the null string)\(dg, -a \fIbracket expression\fR (see below), `.' -(matching any single character), `^' (matching the null string at the -beginning of a line), `$' (matching the null string at the -end of a line), a `\e' followed by one of the characters -`^.[$()|*+?{\e' -(matching that character taken as an ordinary character), -a `\e' followed by any other character\(dg -(matching that character taken as an ordinary character, -as if the `\e' had not been present\(dg), -or a single character with no other significance (matching that character). -A `{' followed by a character other than a digit is an ordinary -character, not the beginning of a bound\(dg. -It is illegal to end an RE with `\e'. -.PP -A \fIbracket expression\fR is a list of characters enclosed in `[]'. -It normally matches any single character from the list (but see below). -If the list begins with `^', -it matches any single character -(but see below) \fInot\fR from the rest of the list. -If two characters in the list are separated by `\-', this is shorthand -for the full \fIrange\fR of characters between those two (inclusive) in the -collating sequence, -e.g. `[0\-9]' in ASCII matches any decimal digit. -It is illegal\(dg for two ranges to share an -endpoint, e.g. `a\-c\-e'. -Ranges are very collating-sequence-dependent, -and portable programs should avoid relying on them. -.PP -To include a literal `]' in the list, make it the first character -(following a possible `^'). -To include a literal `\-', make it the first or last character, -or the second endpoint of a range. -To use a literal `\-' as the first endpoint of a range, -enclose it in `[.' and `.]' to make it a collating element (see below). -With the exception of these and some combinations using `[' (see next -paragraphs), all other special characters, including `\e', lose their -special significance within a bracket expression. -.PP -Within a bracket expression, a collating element (a character, -a multi-character sequence that collates as if it were a single character, -or a collating-sequence name for either) -enclosed in `[.' and `.]' stands for the -sequence of characters of that collating element. -The sequence is a single element of the bracket expression's list. -A bracket expression containing a multi-character collating element -can thus match more than one character, -e.g. if the collating sequence includes a `ch' collating element, -then the RE `[[.ch.]]*c' matches the first five characters -of `chchcc'. -.PP -Within a bracket expression, a collating element enclosed in `[=' and -`=]' is an equivalence class, standing for the sequences of characters -of all collating elements equivalent to that one, including itself. -(If there are no other equivalent collating elements, -the treatment is as if the enclosing delimiters were `[.' and `.]'.) -For example, if o and \o'o^' are the members of an equivalence class, -then `[[=o=]]', `[[=\o'o^'=]]', and `[o\o'o^']' are all synonymous. -An equivalence class may not\(dg be an endpoint -of a range. -.PP -Within a bracket expression, the name of a \fIcharacter class\fR enclosed -in `[:' and `:]' stands for the list of all characters belonging to that -class. -Standard character class names are: -.PP -.RS -.nf -.ta 3c 6c 9c -alnum digit punct -alpha graph space -blank lower upper -cntrl print xdigit -.fi -.RE -.PP -These stand for the character classes defined in -.IR ctype (3). -A locale may provide others. -A character class may not be used as an endpoint of a range. -.PP -There are two special cases\(dg of bracket expressions: -the bracket expressions `[[:<:]]' and `[[:>:]]' match the null string at -the beginning and end of a word respectively. -A word is defined as a sequence of -word characters -which is neither preceded nor followed by -word characters. -A word character is an -.I alnum -character (as defined by -.IR ctype (3)) -or an underscore. -This is an extension, -compatible with but not specified by POSIX 1003.2, -and should be used with -caution in software intended to be portable to other systems. -.PP -In the event that an RE could match more than one substring of a given -string, -the RE matches the one starting earliest in the string. -If the RE could match more than one substring starting at that point, -it matches the longest. -Subexpressions also match the longest possible substrings, subject to -the constraint that the whole match be as long as possible, -with subexpressions starting earlier in the RE taking priority over -ones starting later. -Note that higher-level subexpressions thus take priority over -their lower-level component subexpressions. -.PP -Match lengths are measured in characters, not collating elements. -A null string is considered longer than no match at all. -For example, -`bb*' matches the three middle characters of `abbbc', -`(wee|week)(knights|nights)' matches all ten characters of `weeknights', -when `(.*).*' is matched against `abc' the parenthesized subexpression -matches all three characters, and -when `(a*)*' is matched against `bc' both the whole RE and the parenthesized -subexpression match the null string. -.PP -If case-independent matching is specified, -the effect is much as if all case distinctions had vanished from the -alphabet. -When an alphabetic that exists in multiple cases appears as an -ordinary character outside a bracket expression, it is effectively -transformed into a bracket expression containing both cases, -e.g. `x' becomes `[xX]'. -When it appears inside a bracket expression, all case counterparts -of it are added to the bracket expression, so that (e.g.) `[x]' -becomes `[xX]' and `[^x]' becomes `[^xX]'. -.PP -No particular limit is imposed on the length of REs\(dg. -Programs intended to be portable should not employ REs longer -than 256 bytes, -as an implementation can refuse to accept such REs and remain -POSIX-compliant. -.PP -Obsolete (``basic'') regular expressions differ in several respects. -`|', `+', and `?' are ordinary characters and there is no equivalent -for their functionality. -The delimiters for bounds are `\e{' and `\e}', -with `{' and `}' by themselves ordinary characters. -The parentheses for nested subexpressions are `\e(' and `\e)', -with `(' and `)' by themselves ordinary characters. -`^' is an ordinary character except at the beginning of the -RE or\(dg the beginning of a parenthesized subexpression, -`$' is an ordinary character except at the end of the -RE or\(dg the end of a parenthesized subexpression, -and `*' is an ordinary character if it appears at the beginning of the -RE or the beginning of a parenthesized subexpression -(after a possible leading `^'). -Finally, there is one new type of atom, a \fIback reference\fR: -`\e' followed by a non-zero decimal digit \fId\fR -matches the same sequence of characters -matched by the \fId\fRth parenthesized subexpression -(numbering subexpressions by the positions of their opening parentheses, -left to right), -so that (e.g.) `\e([bc]\e)\e1' matches `bb' or `cc' but not `bc'. -.SH SEE ALSO -regex(3) -.PP -POSIX 1003.2, section 2.8 (Regular Expression Notation). -.SH HISTORY -Written by Henry Spencer, based on the 1003.2 spec. -.SH BUGS -Having two kinds of REs is a botch. -.PP -The current 1003.2 spec says that `)' is an ordinary character in -the absence of an unmatched `('; -this was an unintentional result of a wording error, -and change is likely. -Avoid relying on it. -.PP -Back references are a dreadful botch, -posing major problems for efficient implementations. -They are also somewhat vaguely defined -(does -`a\e(\e(b\e)*\e2\e)*d' match `abbbd'?). -Avoid using them. -.PP -1003.2's specification of case-independent matching is vague. -The ``one case implies all cases'' definition given above -is current consensus among implementors as to the right interpretation. -.PP -The syntax for word boundaries is incredibly ugly. |