Visual FoxPro

Regular Expression with Multiple Matches and Named Capture Groups

See more Regular Expressions Examples

Demonstrates regular expressions with named capture groups and multiple matches. Visual FoxPro

LOCAL lnSuccess
LOCAL loSb
LOCAL lnCrlf
LOCAL lcPattern
LOCAL loJson
LOCAL lnTimeoutMs
LOCAL lnNumMatches
LOCAL lnIdx_first
LOCAL lnIdx_last
LOCAL i
LOCAL lnMatchCount

lnSuccess = 0

loSb = CreateObject('Chilkat.StringBuilder')
lnCrlf = 1
loSb.AppendLine("Name: John Smith",lnCrlf)
loSb.AppendLine("Name: Jack Johnson",lnCrlf)
loSb.AppendLine("Name: Mary Adams",lnCrlf)

? loSb.GetAsString()

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

lcPattern = "Name:\s+(?<first>\w+)\s+(?<last>\w+)"
loJson = CreateObject('Chilkat.JsonObject')
loJson.EmitCompact = 0

lnTimeoutMs = 2000
lnNumMatches = loSb.RegexMatch(lcPattern,loJson,lnTimeoutMs)
IF (lnNumMatches < 0) THEN
    * Probably an error in the regular expression.
    * Suggestion: Use AI to help create and/or diagnose regular expressions.
    ? loSb.LastErrorText
    RELEASE loSb
    RELEASE loJson
    CANCEL
ENDIF

* Examine the matches:
? loJson.Emit()

* 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:

lnIdx_first = loJson.IntOf("named.first")
lnIdx_last = loJson.IntOf("named.last")

i = 0
lnMatchCount = loJson.SizeOfArray("match")
DO WHILE i < lnMatchCount
    ? "Match " + STR(i + 1) + ":"
    loJson.I = i

    loJson.J = lnIdx_first
    ? "first: " + loJson.StringOf("match[i].group[j].cap")

    loJson.J = lnIdx_last
    ? "first: " + loJson.StringOf("match[i].group[j].cap")

    ? ""
    i = i + 1
ENDDO

* Output is: 

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

RELEASE loSb
RELEASE loJson