REMatch: Easier Regular Expression Handling in ColdFusion

• « Blog post
• Demo
• Source code

Demo

Input:

reMatch(strRegex, strString, [intStart], [strScope], [boolReturnLenPos], [boolCaseSensitive])

Output:

array
1	struct LEN 3 POS 1 VALUE aaa
2	struct LEN 1 POS 10 VALUE a

Source Code

Note: The code below contains four additional UDFs (reMatchNoCase, match, matchNoCase, and reEscape) which cannot be tested using the above demo.

<!--- UDFs by Steven Levithan ---> <cffunction name="reMatch" output="false"> <cfargument name="regex" type="string" required="yes" /> <cfargument name="string" type="string" required="yes" /> <cfargument name="start" type="numeric" required="no" default="1" /> <cfargument name="scope" type="string" required="no" default="ONE" /> <cfargument name="returnLenPos" type="boolean" required="no" default="FALSE" /> <cfargument name="caseSensitive" type="boolean" required="no" default="TRUE" /> <cfset var thisMatch = "" /> <cfset var matchInfo = structNew() /> <cfset var matches = arrayNew(1) /> <!--- Set the time before entering the loop ---> <cfset var timeout = now() /> <!--- Build the matches array. Continue looping until additional instances of regex are not found. If scope is "ONE", the loop will end after the first iteration ---> <cfloop condition="TRUE"> <!--- By using returnSubExpressions (the fourth reFind argument), the position and length of the first match is captured in arrays named len and pos ---> <cfif caseSensitive> <cfset thisMatch = reFind(regex, string, start, TRUE) /> <cfelse> <cfset thisMatch = reFindNoCase(regex, string, start, TRUE) /> </cfif> <!--- If a match was not found, end the loop ---> <cfif thisMatch.pos[1] EQ 0> <cfbreak /> <!--- If a match was found, and extended info was requested, append a struct containing the value, length, and position of the match to the matches array ---> <cfelseif returnLenPos> <cfset matchInfo.value = mid(string, thisMatch.pos[1], thisMatch.len[1]) /> <cfset matchInfo.len = thisMatch.len[1] /> <cfset matchInfo.pos = thisMatch.pos[1] /> <cfset arrayAppend(matches, duplicate(matchInfo)) /> <!--- Otherwise, just append the match value to the matches array ---> <cfelse> <cfset arrayAppend(matches, mid(string, thisMatch.pos[1], thisMatch.len[1])) /> </cfif> <!--- If only the first match was requested, end the loop ---> <cfif scope EQ "ONE"> <cfbreak /> <!--- If the match length was greater than zero ---> <cfelseif thisMatch.pos[1] + thisMatch.len[1] GT start> <!--- Set the start position for the next iteration of the loop to the end position of the match ---> <cfset start = thisMatch.pos[1] + thisMatch.len[1] /> <!--- If the match was zero length ---> <cfelse> <!--- Advance the start position for the next iteration of the loop by one, to avoid infinite iteration ---> <cfset start = start + 1 /> </cfif> <!--- If the loop has run for 20 seconds, throw an error, to mitigate against overlong processing. However, note that even one pass using a poorly-written regex which triggers catastrophic backtracking could take longer than 20 seconds ---> <cfif dateDiff("s", timeout, now()) GTE 20> <cfthrow message="Processing too long. Optimize regular expression for better performance" /> </cfif> </cfloop> <cfif scope EQ "ONE"> <cfparam name="matches[1]" default="" /> <cfreturn matches[1] /> <cfelse> <cfreturn matches /> </cfif> </cffunction> <!--- Case-insensitive version of reMatch() ---> <cffunction name="reMatchNoCase" output="false"> <cfargument name="regex" type="string" required="yes" /> <cfargument name="string" type="string" required="yes" /> <cfargument name="start" type="numeric" required="no" default="1" /> <cfargument name="scope" type="string" required="no" default="ONE" /> <cfargument name="returnLenPos" type="boolean" required="no" default="FALSE" /> <cfreturn reMatch(regex, string, start, scope, returnLenPos, FALSE) /> </cffunction> <!--- Non-regex version of reMatch() ---> <cffunction name="match" output="false"> <cfargument name="substring" type="string" required="yes" /> <cfargument name="string" type="string" required="yes" /> <cfargument name="start" type="numeric" required="no" default="1" /> <cfargument name="scope" type="string" required="no" default="ONE" /> <cfargument name="returnLenPos" type="boolean" required="no" default="FALSE" /> <cfreturn reMatch(reEscape(substring), string, start, scope, returnLenPos, TRUE) /> </cffunction> <!--- Case-insensitive version of match() ---> <cffunction name="matchNoCase" output="false"> <cfargument name="substring" type="string" required="yes" /> <cfargument name="string" type="string" required="yes" /> <cfargument name="start" type="numeric" required="no" default="1" /> <cfargument name="scope" type="string" required="no" default="ONE" /> <cfargument name="returnLenPos" type="boolean" required="no" default="FALSE" /> <cfreturn reMatch(reEscape(substring), string, start, scope, returnLenPos, FALSE) /> </cffunction> <!--- Escape special regular expression characters (.,*,+,?,^,$,{,},(,),|,[,],\) within a string by preceding them with a forward slash (\). This allows safely using literal strings within regular expressions ---> <cffunction name="reEscape" returntype="string" output="false"> <cfargument name="string" type="string" required="yes" /> <cfreturn reReplace(string, "[.*+?^${}()|[\]\\]", "\\\0", "ALL") /> </cffunction>