DEELX supports Perl compatible regular expression syntax. The basic patterns in DEELX are the same as it in most engines.
Common characters
Alphas, numbers, the underscore and punctuations with no special definition are "common chars".
Simple escaped characters
Some nonprinting characters which we know.
Quoted characters (\Q...\E)
Quote (disable) pattern metacharacters from \Q till \E.
Character sets
Can match any one but only one character of a certain set of characters.
Custom defined character sets
Use square [ ] to define a custom character set.
Repeat quantifier
Make another expression repeat matching many times.
Character boundary
A condition of the position, does not match any character.
Alternative expressions
Use "|" to separate expressions, match any one and only one of them.
Group
Use bracket ( ) to enclose sub-expressions into a single element.
Named group
Name a group, then get what captured through the name.
Backward reference
Refer to what a certain group captured.
