The following topic is based on the public domain document located on http://www.scintilla.org/SciTERegEx.html
Regular Expressions (RegEx) can be used for searching for patterns rather than literals.
For example, using the following posix-mode Regular Expression, it is possible to search for variables in property files which look like $(name.subname)
This Regular Expression can be read like this:
Replacement with regular expressions allows for complex transformations with the use of tagged expressions.
For example, pairs of numbers separated by a comma could be reordered by replacing the posix-mode regular expression
The first RegEx means: Match one or more digits between 0 and 9 before the comma and one or more digits between 0 and 9 after the comma.
In non-posix mode, the same would be written as
The replacement RegEx \2, \1 means: Take the second matched expression and put it before the comma, then place the first matched expression after the comma.
The first posix mode RegEx could even be written as
which also means any number of digits before the comma and any number of digits after the comma.
Regular expression syntax depends on the parameter
If set to 0 (default), the Regular Expression syntax uses the old Unix style where \( and \) mark capturing sections while ( and ) represent themselves.
If set to 1, the RegEx syntax uses the more common style where opening and closing parentheses ( and ) mark capturing sections while \( and \) are plain parentheses.
matches the character following it, except:
\a,\b,\f,\n,\r,\t,\v match the corresponding C escape char, respectively BEL, BS, FF, LF, CR, TAB and VT; Note that \r and \n are never matched because in Scintilla, regular expression searches are made line per line (stripped of end-of-line chars).
if not in posix mode, when followed by a left or right round bracket (see [7]);
Backslash is used as an escape character for all other meta-characters, and itself.
matches one of the characters in the set.
If the first character in the set is ^, it matches the characters NOT in the set, i.e. complements the set.
A shorthand S-E (start dash end) is used to specify a set of characters S up to E, inclusive.
The special characters ]and-have no special meaning if they appear as the first chars in the set. To include both, put - first: [-]A-Z], or just add a backslash before each of them, like [A-Z\]\-]
a regular expression starting with a \< construct and/or ending with a \> construct, restricts the pattern matching to the beginning of a word, and/or the end of a word. A word is defined to be a character string beginning and/or ending with the characters A-Z a-z 0-9 and _. The Editor extends this definition by user setting. The word must also be preceded and/or followed by any character outside those mentioned.
Most of this documentation was originally written by Ozan S. Yigit. Additions by Neil Hodgson and Philippe Lhoste. All of this document is in the public domain.