Visara Master Console Center Scripting Guide - Manual (Page 60)

Chapter 4 Regular Expressions
Scripting Guide 60
Bracket
Expression
Rule Description
Equivalence
Class Expression
Specifies a set of collating elements that all sort to the
same primary location. An equivalence class is
enclosed in bracket-equal “[= =]” delimiters. An
equivalence class generally is designed to deal with
primary-secondary sorting, that is, for languages like
French that define groups of characters as sorting to
the same primary location and then having a tie-
breaking secondary sort.
For example, if x, y, and z are collating elements that
belong to the same equivalence class, the bracket
expressions “[[=x=]a]”, “[[=y=]a]”, and “[[=z=]a]” are
equivalent to [xyza]. Here we use x, y, and z as variables
representing characters in the same equivalence class. In
a typical example, x might be the collating element e
while y and z are the characters è and é respectively. If
the collating element within [= =] delimiters does not
belong to an equivalence class, the equivalence class
expression is treated as a collating symbol; that is, the
delimiters are ignored.
Range
Expression A set of collating elements that falls between two
elements in the current collation sequence, inclusively.
It is expressed as starting and ending points separated
by a hyphen “-”. For example, the RE “1[a-d]2”, which
includes the bracket expression “[a-d]” containing the
range expression a through d, represents a pattern that
will match any of these strings: 1a2, 1b2, 1c2, and 1d2.
Range expressions depend on collating sequences.
A construction such as [a-d-g] is invalid.
A hyphen or right bracket may be represented as
collating symbols, ‘[.-.]’ or ‘[.].]’, anywhere in a bracket
expression. Otherwise, if both ‘-‘ and ‘]’ are required in
a bracket expression, the bracket must be first (after an
optional initial ^) and the hyphen last.
The hyphen character loses its special meaning in a
bracket expression if it occurs first (after an initial ‘^’, if
any), last, or as an ending range point in a range
expression. Examples:
[-df] and [df-] are equivalent and match any of the
characters d, f, or -
[^-df] and [^df-] are equivalent and match any
characters except d, f and -
[&-] matches any character between & and - inclusive
[-;] matches any characters between - and ; inclusive
[A--] is invalid, because A follows - in the collation
sequence
Table 9. Bracket Expression Rules.