| /************************************************* |
| * PCRE DEMONSTRATION PROGRAM * |
| *************************************************/ |
| |
| /* This is a demonstration program to illustrate the most straightforward ways |
| of calling the PCRE regular expression library from a C program. See the |
| pcresample documentation for a short discussion ("man pcresample" if you have |
| the PCRE man pages installed). |
| |
| In Unix-like environments, if PCRE is installed in your standard system |
| libraries, you should be able to compile this program using this command: |
| |
| gcc -Wall pcredemo.c -lpcre -o pcredemo |
| |
| If PCRE is not installed in a standard place, it is likely to be installed with |
| support for the pkg-config mechanism. If you have pkg-config, you can compile |
| this program using this command: |
| |
| gcc -Wall pcredemo.c `pkg-config --cflags --libs libpcre` -o pcredemo |
| |
| If you do not have pkg-config, you may have to use this: |
| |
| gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \ |
| -R/usr/local/lib -lpcre -o pcredemo |
| |
| Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and |
| library files for PCRE are installed on your system. Only some operating |
| systems (e.g. Solaris) use the -R option. |
| |
| Building under Windows: |
| |
| If you want to statically link this program against a non-dll .a file, you must |
| define PCRE_STATIC before including pcre.h, otherwise the pcre_malloc() and |
| pcre_free() exported functions will be declared __declspec(dllimport), with |
| unwanted results. So in this environment, uncomment the following line. */ |
| |
| /* #define PCRE_STATIC */ |
| |
| #include <stdio.h> |
| #include <string.h> |
| #include <pcre.h> |
| |
| #define OVECCOUNT 30 /* should be a multiple of 3 */ |
| |
| |
| int main(int argc, char **argv) |
| { |
| pcre *re; |
| const char *error; |
| char *pattern; |
| char *subject; |
| unsigned char *name_table; |
| unsigned int option_bits; |
| int erroffset; |
| int find_all; |
| int crlf_is_newline; |
| int namecount; |
| int name_entry_size; |
| int ovector[OVECCOUNT]; |
| int subject_length; |
| int rc, i; |
| int utf8; |
| |
| |
| /************************************************************************** |
| * First, sort out the command line. There is only one possible option at * |
| * the moment, "-g" to request repeated matching to find all occurrences, * |
| * like Perl's /g option. We set the variable find_all to a non-zero value * |
| * if the -g option is present. Apart from that, there must be exactly two * |
| * arguments. * |
| **************************************************************************/ |
| |
| find_all = 0; |
| for (i = 1; i < argc; i++) |
| { |
| if (strcmp(argv[i], "-g") == 0) find_all = 1; |
| else break; |
| } |
| |
| /* After the options, we require exactly two arguments, which are the pattern, |
| and the subject string. */ |
| |
| if (argc - i != 2) |
| { |
| printf("Two arguments required: a regex and a subject string\n"); |
| return 1; |
| } |
| |
| pattern = argv[i]; |
| subject = argv[i+1]; |
| subject_length = (int)strlen(subject); |
| |
| |
| /************************************************************************* |
| * Now we are going to compile the regular expression pattern, and handle * |
| * and errors that are detected. * |
| *************************************************************************/ |
| |
| re = pcre_compile( |
| pattern, /* the pattern */ |
| 0, /* default options */ |
| &error, /* for error message */ |
| &erroffset, /* for error offset */ |
| NULL); /* use default character tables */ |
| |
| /* Compilation failed: print the error message and exit */ |
| |
| if (re == NULL) |
| { |
| printf("PCRE compilation failed at offset %d: %s\n", erroffset, error); |
| return 1; |
| } |
| |
| |
| /************************************************************************* |
| * If the compilation succeeded, we call PCRE again, in order to do a * |
| * pattern match against the subject string. This does just ONE match. If * |
| * further matching is needed, it will be done below. * |
| *************************************************************************/ |
| |
| rc = pcre_exec( |
| re, /* the compiled pattern */ |
| NULL, /* no extra data - we didn't study the pattern */ |
| subject, /* the subject string */ |
| subject_length, /* the length of the subject */ |
| 0, /* start at offset 0 in the subject */ |
| 0, /* default options */ |
| ovector, /* output vector for substring information */ |
| OVECCOUNT); /* number of elements in the output vector */ |
| |
| /* Matching failed: handle error cases */ |
| |
| if (rc < 0) |
| { |
| switch(rc) |
| { |
| case PCRE_ERROR_NOMATCH: printf("No match\n"); break; |
| /* |
| Handle other special cases if you like |
| */ |
| default: printf("Matching error %d\n", rc); break; |
| } |
| pcre_free(re); /* Release memory used for the compiled pattern */ |
| return 1; |
| } |
| |
| /* Match succeded */ |
| |
| printf("\nMatch succeeded at offset %d\n", ovector[0]); |
| |
| |
| /************************************************************************* |
| * We have found the first match within the subject string. If the output * |
| * vector wasn't big enough, say so. Then output any substrings that were * |
| * captured. * |
| *************************************************************************/ |
| |
| /* The output vector wasn't big enough */ |
| |
| if (rc == 0) |
| { |
| rc = OVECCOUNT/3; |
| printf("ovector only has room for %d captured substrings\n", rc - 1); |
| } |
| |
| /* Show substrings stored in the output vector by number. Obviously, in a real |
| application you might want to do things other than print them. */ |
| |
| for (i = 0; i < rc; i++) |
| { |
| char *substring_start = subject + ovector[2*i]; |
| int substring_length = ovector[2*i+1] - ovector[2*i]; |
| printf("%2d: %.*s\n", i, substring_length, substring_start); |
| } |
| |
| |
| /************************************************************************** |
| * That concludes the basic part of this demonstration program. We have * |
| * compiled a pattern, and performed a single match. The code that follows * |
| * shows first how to access named substrings, and then how to code for * |
| * repeated matches on the same subject. * |
| **************************************************************************/ |
| |
| /* See if there are any named substrings, and if so, show them by name. First |
| we have to extract the count of named parentheses from the pattern. */ |
| |
| (void)pcre_fullinfo( |
| re, /* the compiled pattern */ |
| NULL, /* no extra data - we didn't study the pattern */ |
| PCRE_INFO_NAMECOUNT, /* number of named substrings */ |
| &namecount); /* where to put the answer */ |
| |
| if (namecount <= 0) printf("No named substrings\n"); else |
| { |
| unsigned char *tabptr; |
| printf("Named substrings\n"); |
| |
| /* Before we can access the substrings, we must extract the table for |
| translating names to numbers, and the size of each entry in the table. */ |
| |
| (void)pcre_fullinfo( |
| re, /* the compiled pattern */ |
| NULL, /* no extra data - we didn't study the pattern */ |
| PCRE_INFO_NAMETABLE, /* address of the table */ |
| &name_table); /* where to put the answer */ |
| |
| (void)pcre_fullinfo( |
| re, /* the compiled pattern */ |
| NULL, /* no extra data - we didn't study the pattern */ |
| PCRE_INFO_NAMEENTRYSIZE, /* size of each entry in the table */ |
| &name_entry_size); /* where to put the answer */ |
| |
| /* Now we can scan the table and, for each entry, print the number, the name, |
| and the substring itself. */ |
| |
| tabptr = name_table; |
| for (i = 0; i < namecount; i++) |
| { |
| int n = (tabptr[0] << 8) | tabptr[1]; |
| printf("(%d) %*s: %.*s\n", n, name_entry_size - 3, tabptr + 2, |
| ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]); |
| tabptr += name_entry_size; |
| } |
| } |
| |
| |
| /************************************************************************* |
| * If the "-g" option was given on the command line, we want to continue * |
| * to search for additional matches in the subject string, in a similar * |
| * way to the /g option in Perl. This turns out to be trickier than you * |
| * might think because of the possibility of matching an empty string. * |
| * What happens is as follows: * |
| * * |
| * If the previous match was NOT for an empty string, we can just start * |
| * the next match at the end of the previous one. * |
| * * |
| * If the previous match WAS for an empty string, we can't do that, as it * |
| * would lead to an infinite loop. Instead, a special call of pcre_exec() * |
| * is made with the PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED flags set. * |
| * The first of these tells PCRE that an empty string at the start of the * |
| * subject is not a valid match; other possibilities must be tried. The * |
| * second flag restricts PCRE to one match attempt at the initial string * |
| * position. If this match succeeds, an alternative to the empty string * |
| * match has been found, and we can print it and proceed round the loop, * |
| * advancing by the length of whatever was found. If this match does not * |
| * succeed, we still stay in the loop, advancing by just one character. * |
| * In UTF-8 mode, which can be set by (*UTF8) in the pattern, this may be * |
| * more than one byte. * |
| * * |
| * However, there is a complication concerned with newlines. When the * |
| * newline convention is such that CRLF is a valid newline, we want must * |
| * advance by two characters rather than one. The newline convention can * |
| * be set in the regex by (*CR), etc.; if not, we must find the default. * |
| *************************************************************************/ |
| |
| if (!find_all) /* Check for -g */ |
| { |
| pcre_free(re); /* Release the memory used for the compiled pattern */ |
| return 0; /* Finish unless -g was given */ |
| } |
| |
| /* Before running the loop, check for UTF-8 and whether CRLF is a valid newline |
| sequence. First, find the options with which the regex was compiled; extract |
| the UTF-8 state, and mask off all but the newline options. */ |
| |
| (void)pcre_fullinfo(re, NULL, PCRE_INFO_OPTIONS, &option_bits); |
| utf8 = option_bits & PCRE_UTF8; |
| option_bits &= PCRE_NEWLINE_CR|PCRE_NEWLINE_LF|PCRE_NEWLINE_CRLF| |
| PCRE_NEWLINE_ANY|PCRE_NEWLINE_ANYCRLF; |
| |
| /* If no newline options were set, find the default newline convention from the |
| build configuration. */ |
| |
| if (option_bits == 0) |
| { |
| int d; |
| (void)pcre_config(PCRE_CONFIG_NEWLINE, &d); |
| /* Note that these values are always the ASCII ones, even in |
| EBCDIC environments. CR = 13, NL = 10. */ |
| option_bits = (d == 13)? PCRE_NEWLINE_CR : |
| (d == 10)? PCRE_NEWLINE_LF : |
| (d == (13<<8 | 10))? PCRE_NEWLINE_CRLF : |
| (d == -2)? PCRE_NEWLINE_ANYCRLF : |
| (d == -1)? PCRE_NEWLINE_ANY : 0; |
| } |
| |
| /* See if CRLF is a valid newline sequence. */ |
| |
| crlf_is_newline = |
| option_bits == PCRE_NEWLINE_ANY || |
| option_bits == PCRE_NEWLINE_CRLF || |
| option_bits == PCRE_NEWLINE_ANYCRLF; |
| |
| /* Loop for second and subsequent matches */ |
| |
| for (;;) |
| { |
| int options = 0; /* Normally no options */ |
| int start_offset = ovector[1]; /* Start at end of previous match */ |
| |
| /* If the previous match was for an empty string, we are finished if we are |
| at the end of the subject. Otherwise, arrange to run another match at the |
| same point to see if a non-empty match can be found. */ |
| |
| if (ovector[0] == ovector[1]) |
| { |
| if (ovector[0] == subject_length) break; |
| options = PCRE_NOTEMPTY_ATSTART | PCRE_ANCHORED; |
| } |
| |
| /* Run the next matching operation */ |
| |
| rc = pcre_exec( |
| re, /* the compiled pattern */ |
| NULL, /* no extra data - we didn't study the pattern */ |
| subject, /* the subject string */ |
| subject_length, /* the length of the subject */ |
| start_offset, /* starting offset in the subject */ |
| options, /* options */ |
| ovector, /* output vector for substring information */ |
| OVECCOUNT); /* number of elements in the output vector */ |
| |
| /* This time, a result of NOMATCH isn't an error. If the value in "options" |
| is zero, it just means we have found all possible matches, so the loop ends. |
| Otherwise, it means we have failed to find a non-empty-string match at a |
| point where there was a previous empty-string match. In this case, we do what |
| Perl does: advance the matching position by one character, and continue. We |
| do this by setting the "end of previous match" offset, because that is picked |
| up at the top of the loop as the point at which to start again. |
| |
| There are two complications: (a) When CRLF is a valid newline sequence, and |
| the current position is just before it, advance by an extra byte. (b) |
| Otherwise we must ensure that we skip an entire UTF-8 character if we are in |
| UTF-8 mode. */ |
| |
| if (rc == PCRE_ERROR_NOMATCH) |
| { |
| if (options == 0) break; /* All matches found */ |
| ovector[1] = start_offset + 1; /* Advance one byte */ |
| if (crlf_is_newline && /* If CRLF is newline & */ |
| start_offset < subject_length - 1 && /* we are at CRLF, */ |
| subject[start_offset] == '\r' && |
| subject[start_offset + 1] == '\n') |
| ovector[1] += 1; /* Advance by one more. */ |
| else if (utf8) /* Otherwise, ensure we */ |
| { /* advance a whole UTF-8 */ |
| while (ovector[1] < subject_length) /* character. */ |
| { |
| if ((subject[ovector[1]] & 0xc0) != 0x80) break; |
| ovector[1] += 1; |
| } |
| } |
| continue; /* Go round the loop again */ |
| } |
| |
| /* Other matching errors are not recoverable. */ |
| |
| if (rc < 0) |
| { |
| printf("Matching error %d\n", rc); |
| pcre_free(re); /* Release memory used for the compiled pattern */ |
| return 1; |
| } |
| |
| /* Match succeded */ |
| |
| printf("\nMatch succeeded again at offset %d\n", ovector[0]); |
| |
| /* The match succeeded, but the output vector wasn't big enough. */ |
| |
| if (rc == 0) |
| { |
| rc = OVECCOUNT/3; |
| printf("ovector only has room for %d captured substrings\n", rc - 1); |
| } |
| |
| /* As before, show substrings stored in the output vector by number, and then |
| also any named substrings. */ |
| |
| for (i = 0; i < rc; i++) |
| { |
| char *substring_start = subject + ovector[2*i]; |
| int substring_length = ovector[2*i+1] - ovector[2*i]; |
| printf("%2d: %.*s\n", i, substring_length, substring_start); |
| } |
| |
| if (namecount <= 0) printf("No named substrings\n"); else |
| { |
| unsigned char *tabptr = name_table; |
| printf("Named substrings\n"); |
| for (i = 0; i < namecount; i++) |
| { |
| int n = (tabptr[0] << 8) | tabptr[1]; |
| printf("(%d) %*s: %.*s\n", n, name_entry_size - 3, tabptr + 2, |
| ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]); |
| tabptr += name_entry_size; |
| } |
| } |
| } /* End of loop to find second and subsequent matches */ |
| |
| printf("\n"); |
| pcre_free(re); /* Release memory used for the compiled pattern */ |
| return 0; |
| } |
| |
| /* End of pcredemo.c */ |