| Line 232: | Line 232: | ||
|} | |} | ||
| − | ''' | + | '''Assertions'''<br> |
| − | + | Besides ^ and $ , Perl regular expressions support the following zero-width assertions: | |
{| | {| | ||
| Line 247: | Line 247: | ||
|\B | |\B | ||
|Matches only when not at a word boundary. | |Matches only when not at a word boundary. | ||
| + | |- | ||
| + | |\A | ||
| + | |Matches beginning of the file. | ||
| + | |- | ||
| + | |\Z | ||
| + | |Matches position of last non-newline character in the file. | ||
| + | |- | ||
| + | |\z | ||
| + | |Matches end of the file. | ||
|} | |} | ||
UltraEdit supports Perl style regular expressions for search using the Boost C++ Libraries.
Note: in the following documentation, atom may refer to a single character, a marked sub-expression, or a character class.
In Perl regular expressions, all characters match themselves except for the following special characters:
| Character | Meaning |
|---|---|
| . | Matches any single character except new lines |
| ^ | Matches start of line (anchor) |
| $ | Matches end of line (anchor) |
| * | Matches 0 or more of the preceding atom |
| + | Matches 1 or more of the preceding atom |
| ? | Matches 0 or 1 of the preceding atom |
| [] | Matches any character in the set. For example [a-d] would match a, b, c, and d – but not e. |
| () | Tags the enclosed atom for backreferencing |
| {n} | Matches the previous atom n times. |
| | | "or" operand. For example dog|cat would match both "dog" and "cat." |
| \ | Escape character |
Marked sub-expressions
A section beginning ( and ending ) is a marked sub-expression. Whatever matched the sub-expression is split out in a separate field by the matching algorithms. Marked sub-expressions can also be repeated or referred to by a backreference.
Alternation
The | operator will match either of its arguments, so for example: abc|def will match either "abc" or "def". Parenthesis can be used to group alternations, for example: ab(d|ef) will match either of "abd" or "abef". Empty alternatives are not allowed (these are almost always a mistake), but if you really want an empty alternative use (?:) as a placeholder, for example:
Character sets
A character set is a bracket-expression starting with [ and ending with ], it defines a set of characters, and matches any single character that is a member of that set.
A bracket expression may contain any combination of the following:
Supported dcharacter class names (following the format [[:name:]])
| Name | POSIX-standard | Description |
|---|---|---|
| alnum | Yes | Any alpha-numeric character. |
| alpha | Yes | Any alphabetic character. |
| blank | Yes | Any whitespace character that is not a line separator. |
| cntrl | Yes | Any control character. |
| d | No | Any decimal digit |
| digit | Yes | Any decimal digit. |
| graph | Yes | Any graphical character. |
| l | No | Any lower case character. |
| lower | Yes | Any lower case character. |
| Yes | Any printable character. | |
| punct | Yes | Any punctuation character. |
| s | No | Any whitespace character. |
| space | Yes | Any whitespace character. |
| unicode | No | Any extended character whose code point is above 255 in value. |
| u | No | Any upper case character. |
| upper | Yes | Any upper case character. |
| w | No | Any word character (alphanumeric characters plus the underscore). |
| word | No | Any word character (alphanumeric characters plus the underscore). |
| xdigit | Yes | Any hexadecimal digit character. |
Escapes
Any special character preceded by an escape matches itself. The following escape sequences are also supported (all synonyms for single characters):
| Escape | Character |
|---|---|
| \a | '\a' |
| \e | 0x1B |
| \f | \f |
| \n | \n |
| \r | \r |
| \t | \t |
| \v | \v |
| \b | \b (but only inside a character class declaration). |
| \cX | An ASCII escape sequence - the character whose code point is X % 32 |
| \xdd | A hexadecimal escape sequence - matches the single character whose code point is 0xdd. |
| \x{dddd} | A hexadecimal escape sequence - matches the single character whose code point is 0xdddd. |
| \0ddd | An octal escape sequence - matches the single character whose code point is 0ddd. |
| \N{name} | Matches the single character which has the symbolic name name. For example \N{newline} matches the single character \n. |
"Single character" character classes
Any escaped character x, if x is the name of a character class shall match any character that is a member of that class, and any escaped character X, if x is the name of a character class, shall match any character not in that class. The following are supported by default:
| Escape sequence | Equivalent to |
|---|---|
| \d | [[:digit:]] |
| \l | [[:lower:]] |
| \s | [[:space:]] |
| \u | [[:upper:]] |
| \w | [[:word:]] |
| \D | [^[:digit:]] |
| \L | [^[:lower:]] |
| \S | [^[:space:]] |
| \U | [^[:upper:]] |
| \W | [^[:word:]] |
Assertions
Besides ^ and $ , Perl regular expressions support the following zero-width assertions:
| \< | Matches the start of a word. |
| \> | Matches the end of a word. |
| \b | Matches a word boundary (the start or end of a word). |
| \B | Matches only when not at a word boundary. |
| \A | Matches beginning of the file. |
| \Z | Matches position of last non-newline character in the file. |
| \z | Matches end of the file. |
For further information options on Perl regular please see:
See also:
UltraEdit Wiki