Classic ASP

Regular Expression with Named Capture Groups

Demonstrates regular expressions with named capture groups.

See the sample code below.

Note: Chilkat uses PCRE2. See PCRE2 Regular Expressions
Also see: PCRE2 Performance

In PCRE2, named capture groups allow you to assign a name to a capturing group, making it easier to reference by name instead of number.

Syntax

(?<name>pattern)

(?'name'pattern)

Example

(?<first>\w+)\s+(?<last>\w+)

Applied to:

"John Smith"

Produces:

first: John
last: Smith

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Classic ASP

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

subject = "John Smith"
pattern = "(?<first>\w+)\s+(?<last>\w+)"

set sb = Server.CreateObject("Chilkat.StringBuilder")
success = sb.Append(subject)

set json = Server.CreateObject("Chilkat.JsonObject")
json.EmitCompact = 0

timeoutMs = 2000
numMatches = sb.RegexMatch(pattern,json,timeoutMs)
If (numMatches < 0) Then
    ' Probably an error in the regular expression.
    ' Suggestion: Use AI to help create and/or diagnose regular expressions.
    Response.Write "<pre>" & Server.HTMLEncode( sb.LastErrorText) & "</pre>"
    Response.End
End If

' Examine the matches:
Response.Write "<pre>" & Server.HTMLEncode( json.Emit()) & "</pre>"

' Here is the JSON showing the matches.
' Important:  Capture group 0 always contains the entire match — that is, the portion of the input string that matches the full regular expression.

' {
'   "named": {
'     "first": 1,
'     "last": 2
'   },
'   "match": [
'     {
'       "group": [
'         {
'           "cap": "John Smith",
'           "idx": 0,
'           "len": 10
'         },
'         {
'           "cap": "John",
'           "idx": 0,
'           "len": 4
'         },
'         {
'           "cap": "Smith",
'           "idx": 5,
'           "len": 5
'         }
'       ]
'     }
'   ]
' }

' The capture group index is obtained by looking up the name in the JSON result.
' For example:

json.I = json.IntOf("named.first")
Response.Write "<pre>" & Server.HTMLEncode( "first: " & json.StringOf("match[0].group[i].cap")) & "</pre>"

json.I = json.IntOf("named.last")
Response.Write "<pre>" & Server.HTMLEncode( "last: " & json.StringOf("match[0].group[i].cap")) & "</pre>"

' Output is: 

' first: John
' last: Smith

%>
</body>
</html>