Lua Requires Chilkat v11.1.0+

Regular Expression with Multiple Matches and Capture Groups

See more Regular Expressions Examples

Demonstrates a regular expression with multiple matches and capture groups for each match.

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

Lua

local chilkat = require("chilkat")

local success = false

local pattern = "Name:\\s+(\\w+)\\s+(\\w+),\\s+Email:\\s+(\\S+)"

local sb = chilkat.StringBuilder.new()
local crlf = true
sb:append_line("Name: John Smith, Email: john.smith@example.com", crlf)
sb:append_line("Name: Jack Johnson, Email: jack.johnson@example.com", crlf)
sb:append_line("Name: Mary Adams, Email: mary.adams@example.com", crlf)

print(sb:get_as_string())

-- We have the following string:
-- Name: John Smith, Email: john.smith@example.com
-- Name: Jack Johnson, Email: jack.johnson@example.com
-- Name: Mary Adams, Email: mary.adams@example.com

local json = chilkat.JsonObject.new()
json.emit_compact = false

local timeoutMs = 2000
local numMatches = sb:regex_match(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.
    print(sb.last_error_text)
    return
end

-- Examine the matches:
print(json:emit())

-- This is the JSON with the match information.
-- See the JSON parsing code below to get the matched capture group values.

-- {
--   "match": [
--     {
--       "group": [
--         {
--           "cap": "Name: John Smith, Email: john.smith@example.com",
--           "idx": 0,
--           "len": 47
--         },
--         {
--           "cap": "John",
--           "idx": 6,
--           "len": 4
--         },
--         {
--           "cap": "Smith",
--           "idx": 11,
--           "len": 5
--         },
--         {
--           "cap": "john.smith@example.com",
--           "idx": 25,
--           "len": 22
--         }
--       ]
--     },
--     {
--       "group": [
--         {
--           "cap": "Name: Jack Johnson, Email: jack.johnson@example.com",
--           "idx": 49,
--           "len": 51
--         },
--         {
--           "cap": "Jack",
--           "idx": 55,
--           "len": 4
--         },
--         {
--           "cap": "Johnson",
--           "idx": 60,
--           "len": 7
--         },
--         {
--           "cap": "jack.johnson@example.com",
--           "idx": 76,
--           "len": 24
--         }
--       ]
--     },
--     {
--       "group": [
--         {
--           "cap": "Name: Mary Adams, Email: mary.adams@example.com",
--           "idx": 102,
--           "len": 47
--         },
--         {
--           "cap": "Mary",
--           "idx": 108,
--           "len": 4
--         },
--         {
--           "cap": "Adams",
--           "idx": 113,
--           "len": 5
--         },
--         {
--           "cap": "mary.adams@example.com",
--           "idx": 127,
--           "len": 22
--         }
--       ]
--     }
--   ]
-- }

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

local cap = ""
local i = 0
local matchCount = json:size_of_array("match")
while i < matchCount do
    print("Match " .. (i + 1) .. ":")
    json.i = i
    local j = 0
    local numCaptureGroups = json:size_of_array("match[i].group")
    while j < numCaptureGroups do
        json.j = j
        cap = json:string_of("match[i].group[j].cap")
        print(j .. ": " .. cap)
        j = j + 1
    end

    i = i + 1
end

-- Capture group 0 always contains the entire match — that is, the portion of the input string that matches the full regular expression.

-- Output

-- Match 1:
-- 0: Name: John Smith, Email: john.smith@example.com
-- 1: John
-- 2: Smith
-- 3: john.smith@example.com
-- Match 2:
-- 0: Name: Jack Johnson, Email: jack.johnson@example.com
-- 1: Jack
-- 2: Johnson
-- 3: jack.johnson@example.com
-- Match 3:
-- 0: Name: Mary Adams, Email: mary.adams@example.com
-- 1: Mary
-- 2: Adams
-- 3: mary.adams@example.com