MACROMEDIA ColdFusion MX, Develop Manual

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Using backreferences 153
Using backreferences in replacement strings
You can use backreferences in the replacement string of both the
REReplace
and
REReplaceNoCase
functions. For example, to replace the first repeated word in a text string with
a single word, use the following syntax:
REReplace("There is is a cat in in the kitchen",
"([A-Za-z ]+)\1","\1")
This results in the sentence:
“There is a cat in in the kitchen”
You can use the optional fourth parameter to
REReplace
, scope , to replace all repeated words, as in
the following code:
REReplace("There is is a cat in in the kitchen",
"([A-Za-z ]+)\1","\1","ALL")
This results in the following string:
“There is a cat in the kitchen”
The next example uses two backreferences to reverse the order of the words "apples" and "pears"
in a sentence:
<cfset astring = "apples and pears, apples and pears, apples and pears">
<cfset newString = REReplace("#astring#", "(apples) and (pears)",
"\2 and \1","ALL")>
In this example, you reference the subexpression (apples) as \1 and the subexpression (pears) as \2.
The
REReplace
function returns the string:
"pears and apples, pears and apples, pears and apples"
Note: To use backreferences in either the search string or the replace string, you must use
parentheses within the regular expression to create the corresponding subexpression. Otherwise,
ColdFusion throws an exception.
Using backreferences to perform case conversions in replacement
strings
The
REReplace
and
REReplaceNoCase
functions support special characters in replacement
strings to convert replacement characters to uppercase or lowercase. The following table describes
these special characters:
To include a literal \u, or other code, in a replacement string, escape it with another backslash; for
example \\u .
Special
character Description
\u Converts the next character to uppercase.
\l Converts the next character to lowercase.
\U Converts all characters to uppercase until encountering \E.
\L Converts all characters to lowercase until encountering \E.
\E End \U or \L.