The AwkSyntax structure implements the AWK syntax for regular expressions.
The syntax is defined on pp. 28-30 of The AWK Programming Language,
by Aho, Kernighan and Weinberger. The syntax has been extended with interval
syntax, which was added as part of the POSIX standard.
Synopsis
structure AwkSyntax : REGEXP_PARSER
Description
The meta characters are: "\" "^" "$" "." "[" "]" "|" "(" ")" "*" "+" "?"
Atomic REs:
c matches the character c (for non-metacharacters c)
"^" matches the empty string at the beginning of a line
"$" matches the empty string at the end of a line
"." matches any single character (except \000 and \n)
Escape sequences:
"\b" matches backspace
"\f" matches formfeed
"\n" matches newline (linefeed)
"\r" matches carriage return
"\t" matches tab
"\"ddd matches the character with octal code ddd.
"\"c matches the character c (e.g., \\ for \, \" for ")
"\x"dd matches the character with hex code dd.
Character classes:
[...] matches any character in "..."
[^...] a complemented character list, which matches any character not
in the list "..."
Compound regular expressions, where A and B are REs:
A|B matches A or B
AB matches A followed by B
A? matches zero or one As
A* matches zero or more As
A+ matches one or more As
A{n} matches n copies of A
A{n,} matches n or more copies of A
A{n,m} matches from n to m copies of A
(A) matches A