Ruby Requires Chilkat v11.1.0+

Regular Expression with Named Capture Groups

See more Regular Expressions Examples

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)

or

(?'name'pattern)

Example

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

Applied to:

"John Smith"

Produces:

• first: John
• last: Smith

Ruby

require 'chilkat'

success = false

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

sb = Chilkat::CkStringBuilder.new()
sb.Append(subject)

json = Chilkat::CkJsonObject.new()
json.put_EmitCompact(false)

timeoutMs = 2000
numMatches = sb.RegexMatch(pattern,json,timeoutMs)
if (numMatches < 0)
    #  Probably an error in the regular expression.
    #  Suggestion: Use AI to help create and/or diagnose regular expressions.
    print sb.lastErrorText() + "\n";
    exit
end

#  Examine the matches:
print json.emit() + "\n";

#  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.put_I(json.IntOf("named.first"))
print "first: " + json.stringOf("match[0].group[i].cap") + "\n";

json.put_I(json.IntOf("named.last"))
print "last: " + json.stringOf("match[0].group[i].cap") + "\n";

#  Output is: 

#  first: John
#  last: Smith