Adobe COLDFUSION 9 Manual page 144

Developing applications

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DEVELOPING COLDFUSION 9 APPLICATIONS

The CFML Programming Language

The following table shows the character classes that ColdFusion supports. Regular expressions using these classes

match any Unicode character in the class, not just ASCII or ISO-8859 characters.

Character class

Any alphabetic character.

Any uppercase alphabetic character.

Any lowercase alphabetic character

Any digit. Same as \d.

Any alphabetic or numeric character.

Any hexadecimal digit. Same as [0-9A-Fa-f].

Space or a tab.

Any whitespace character. Same as \s.

Any alphanumeric, punctuation, or space character.

Any punctuation character

Any alphanumeric or punctuation character.

Any character not part of the character classes [:upper:], [:lower:], [:alpha:], [:digit:], [:punct:], [:graph:], [:print:], or

Any alphabetic or numeric character, plus the underscore (_). Same as \w

The ASCII characters, in the Hexadecimal range 0 - 7F

Using backreferences

You use parenthesis to group components of a regular expression into subexpressions. For example, the regular

expression "(ha)+" matches one or more occurrences of the string "ha".

ColdFusion performs an additional operation when using subexpressions; it automatically saves the characters in the

search string matched by a subexpression for later use within the regular expression. Referencing the saved

subexpression text is called backreferencing.

You can use backreferencing when searching for repeated words in a string, such as "the the" or "is is". The following

example uses backreferencing to find all repeated words in the search string and replace them with an asterisk:

REReplace("There is is coffee in the the kitchen",

"[ ]+([A-Za-z]+)[ ]+\1"," * ","ALL")

Using this regular expression, ColdFusion detects the two occurrences of "is" as well as the two occurrences of "the",

replaces them with an asterisk enclosed in spaces, and returns the following string:

There * coffee in * kitchen

You interpret the regular expression [ ]+([A-Za-z]+)[ ]+\1 as follows:

Use the subexpression ([A-Za-z]+) to search for character strings consisting of one or more letters, enclosed by one or

more spaces, [ ]+, followed by the same character string that matched the first subexpression, \1.

You reference the matched characters of a subexpression using a slash followed by a digit n (\n) where the first

subexpression in a regular expression is referenced as \1, the second as \2, and so on. The next section includes an

example using multiple backreferences.

Last updated 8/5/2010