Ruby

Regular Expression with Multiple Matches and Named Capture Groups

See more Regular Expressions Examples

Demonstrates regular expressions with named capture groups and multiple matches. Ruby

require 'chilkat'

success = false

sb = Chilkat::CkStringBuilder.new()
crlf = true
sb.AppendLine("Name: John Smith",crlf)
sb.AppendLine("Name: Jack Johnson",crlf)
sb.AppendLine("Name: Mary Adams",crlf)

print sb.getAsString() + "\n";

# We have the following string:
# Name: John Smith
# Name: Jack Johnson
# Name: Mary Adams

pattern = "Name:\\s+(?<first>\\w+)\\s+(?<last>\\w+)"
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": "Name: John Smith",
#           "idx": 0,
#           "len": 16
#         },
#         {
#           "cap": "John",
#           "idx": 6,
#           "len": 4
#         },
#         {
#           "cap": "Smith",
#           "idx": 11,
#           "len": 5
#         }
#       ]
#     },
#     {
#       "group": [
#         {
#           "cap": "Name: Jack Johnson",
#           "idx": 18,
#           "len": 18
#         },
#         {
#           "cap": "Jack",
#           "idx": 24,
#           "len": 4
#         },
#         {
#           "cap": "Johnson",
#           "idx": 29,
#           "len": 7
#         }
#       ]
#     },
#     {
#       "group": [
#         {
#           "cap": "Name: Mary Adams",
#           "idx": 38,
#           "len": 16
#         },
#         {
#           "cap": "Mary",
#           "idx": 44,
#           "len": 4
#         },
#         {
#           "cap": "Adams",
#           "idx": 49,
#           "len": 5
#         }
#       ]
#     }
#   ]
# }

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

idx_first = json.IntOf("named.first")
idx_last = json.IntOf("named.last")

i = 0
matchCount = json.SizeOfArray("match")
while i < matchCount
    print "Match " + (i + 1).to_s() + ":" + "\n";
    json.put_I(i)

    json.put_J(idx_first)
    print "first: " + json.stringOf("match[i].group[j].cap") + "\n";

    json.put_J(idx_last)
    print "first: " + json.stringOf("match[i].group[j].cap") + "\n";

    print "" + "\n";
    i = i + 1
end

# Output is: 

# Match 1:
# first: John
# first: Smith
# 
# Match 2:
# first: Jack
# first: Johnson
# 
# Match 3:
# first: Mary
# first: Adams