IDE regular expressions

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Normal regular expression

Metacharacters:

   \   Quote the next metacharacter
   ^   Match the beginning of the line
   .   Match any character (except newline). Example: 'a.c' matches 'abc', 'aBC', 'axc', 'a3c', 'a$c', etc.
   $   Match the end of the line (or before newline at the end)
   |   Alternation
   ()  Grouping. For example: (abc)+ matches 'abc' or 'abcabc' or 'abcabcabc' etc.
   []  Character class. For example [abc], [a-z], [a-zA-Z0-9_]
   [^] Reversed character class. For example [^a-z]

Quantifiers:

   *      Match 0 or more times
   +      Match 1 or more times
   ?      Match 1 or 0 times
   {n}    Match exactly n times
   {n,}   Match at least n times
   {n,m}  Match at least n but not more than m times

Curly brackets in any other context is treated as a regular character. The ``* is equivalent to {0,}, the ``+ to {1,} and the ``? to {0,1}.

By default, a quantifier is greedy, that means, it will match as many times as possible. To match the minimum number of times possible, append a ``?.

   *?     Match 0 or more times
   +?     Match 1 or more times
   ??     Match 0 or 1 time
   {n}?   Match exactly n times
   {n,}?  Match at least n times
   {n,m}? Match at least n but not more than m times

Simple Syntax

Some IDE dialogs provide a checkbox to choose between simple syntax and regular expressions. The simple syntax is often shorter for common file name filters.

Technically it does this:

  The following characters are replaced with
  . -> \.
  * -> .*
  ? -> .
  , -> |
  ; -> |
  
  Finally enclose by ^( )$

Examples for simple syntax

  • *.pas - matches all file names ending with .pas, like Unit1.pas or Some.txt.pas. Default is to match case sensitive. So it does not fit unit1.PAS.
  • *.pas;*.pp;*p - matches all files like unit1.pas, 678.pp or %.p
  • unit*.pas - matches all files beginning with unit and ending with .pas like unit1.pas and unit.pas.
  • unit?.pas - matches all files beginning with unit, ending with .pas and exactly one like arbitrary character in between like unit1.pas and unit2.pas.

Quoted symbols

The backslash '\' can be used to treat special characters like '.' as normal character or to get some special ranges.

  \. matches a point '.'
  \d matches a number character '0'..'9'
  \D matches a non number character
  \s matches a space character ' ',#9,#10,#12,#13
  \S matches a non space character
  \w matches a word character 'a'..'z','A'..'Z','0'..'9','_'
  \W matches a non word character
  \b word boundary
  \B not word boundary
  \A begin of line
  \Z end of line

Search and Replace with regular expressions

The find dialogs support regular expressions for finding and replacing. Each found pattern grouped in round brackets can be used by a $1, ..., $9 variable

For example:

  • Find expression: a(.*)c
  • Replace expression: A$1C
  • Text: 'abc aLazc'

The $1 will be replaced with the found text, that matches the first bracket.

  • Result: 'AbC ALazC'

You can also use the following special chars in the *replace* term

\n
Inserts a Linebreak
\l \u
Lower or Uppercases the *next* Char. Use this in front of $n. \u$1 Will insert the match from the first brackets, but with its first char made uppercase
\L \U
Lower or Uppercase the *full* text of the next $n. The $n must follow immediately