C

Regular Expression with Multiple Matches and Named Capture Groups

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

#include <C_CkStringBuilder.h>
#include <C_CkJsonObject.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkStringBuilder sb;
    BOOL crlf;
    const char *pattern;
    HCkJsonObject json;
    int timeoutMs;
    int numMatches;
    int idx_first;
    int idx_last;
    int i;
    int matchCount;

    success = FALSE;

    sb = CkStringBuilder_Create();
    crlf = TRUE;
    CkStringBuilder_AppendLine(sb,"Name: John Smith",crlf);
    CkStringBuilder_AppendLine(sb,"Name: Jack Johnson",crlf);
    CkStringBuilder_AppendLine(sb,"Name: Mary Adams",crlf);

    printf("%s\n",CkStringBuilder_getAsString(sb));

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

    pattern = "Name:\\s+(?<first>\\w+)\\s+(?<last>\\w+)";
    json = CkJsonObject_Create();
    CkJsonObject_putEmitCompact(json,FALSE);

    timeoutMs = 2000;
    numMatches = CkStringBuilder_RegexMatch(sb,pattern,json,timeoutMs);
    if (numMatches < 0) {
        // Probably an error in the regular expression.
        // Suggestion: Use AI to help create and/or diagnose regular expressions.
        printf("%s\n",CkStringBuilder_lastErrorText(sb));
        CkStringBuilder_Dispose(sb);
        CkJsonObject_Dispose(json);
        return;
    }

    // Examine the matches:
    printf("%s\n",CkJsonObject_emit(json));

    // 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 = CkJsonObject_IntOf(json,"named.first");
    idx_last = CkJsonObject_IntOf(json,"named.last");

    i = 0;
    matchCount = CkJsonObject_SizeOfArray(json,"match");
    while (i < matchCount) {
        printf("Match %d:\n",i + 1);
        CkJsonObject_putI(json,i);

        CkJsonObject_putJ(json,idx_first);
        printf("first: %s\n",CkJsonObject_stringOf(json,"match[i].group[j].cap"));

        CkJsonObject_putJ(json,idx_last);
        printf("first: %s\n",CkJsonObject_stringOf(json,"match[i].group[j].cap"));

        printf("\n");
        i = i + 1;
    }

    // Output is: 

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


    CkStringBuilder_Dispose(sb);
    CkJsonObject_Dispose(json);

    }