Support searching by regexp (brute force only).

Mostly for compatibility completeness.

diff --git a/plocate.cpp b/plocate.cpp
index 5b9db1807b6d1862b4520eddd961677103e782ff..9f3928b1a8349e8db0e57d82bb31fd8df59171ef 100644 (file)
--- a/plocate.cpp
+++ b/plocate.cpp
@@ -47,6 +47,8 @@ bool ignore_case = false;
 bool only_count = false;
 bool print_nul = false;
 bool use_debug = false;
+bool patterns_are_regex = false;
+bool use_extended_regex = false;
 int64_t limit_matches = numeric_limits<int64_t>::max();
 
 class Serializer {
@@ -96,7 +98,7 @@ void Serializer::release_current()
 
 struct Needle {
        enum { STRSTR,
-              REGEX,  // Not currently used.
+              REGEX,
               GLOB } type;
        string str;  // Filled in no matter what.
        regex_t re;  // For REGEX.
@@ -400,11 +402,17 @@ void do_search_file(const vector<Needle> &needles, const char *filename)
        dprintf("Corpus init done after %.1f ms.\n", 1e3 * duration<float>(steady_clock::now() - start).count());
 
        vector<TrigramDisjunction> trigram_groups;
-       for (const Needle &needle : needles) {
-               if (needle.str.size() < 3)
-                       continue;
-               parse_trigrams(needle.str, ignore_case, &trigram_groups);
+       if (patterns_are_regex) {
+               // We could parse the regex to find trigrams that have to be there
+               // (there are actually known algorithms to deal with disjunctions
+               // and such, too), but for now, we just go brute force.
+               // Using locate with regexes is pretty niche.
+       } else {
+               for (const Needle &needle : needles) {
+                       parse_trigrams(needle.str, ignore_case, &trigram_groups);
+               }
        }
+
        unique_sort(
                &trigram_groups,
                [](const TrigramDisjunction &a, const TrigramDisjunction &b) { return a.trigram_alternatives < b.trigram_alternatives; },
@@ -573,6 +581,26 @@ string unescape_glob_to_plain_string(const string &needle)
        return unescaped;
 }
 
+regex_t compile_regex(const string &needle)
+{
+       regex_t re;
+       int flags = REG_NOSUB;
+       if (ignore_case) {
+               flags |= REG_ICASE;
+       }
+       if (use_extended_regex) {
+               flags |= REG_EXTENDED;
+       }
+       int err = regcomp(&re, needle.c_str(), flags);
+       if (err != 0) {
+               char errbuf[256];
+               regerror(err, &re, errbuf, sizeof(errbuf));
+               fprintf(stderr, "Error when compiling regex '%s': %s\n", needle.c_str(), errbuf);
+               exit(1);
+       }
+       return re;
+}
+
 void usage()
 {
        printf(
@@ -584,6 +612,8 @@ void usage()
                "  -i, --ignore-case      search case-insensitively\n"
                "  -l, --limit LIMIT      stop after LIMIT matches\n"
                "  -0, --null             delimit matches by NUL instead of newline\n"
+               "  -r, --regexp           interpret patterns as basic regexps (slow)\n"
+               "      --regex            interpret patterns as extended regexps (slow)\n"
                "      --help             print this help\n"
                "      --version          print version information\n");
 }
@@ -600,6 +630,7 @@ void version()
 
 int main(int argc, char **argv)
 {
+       constexpr int EXTENDED_REGEX = 1000;
        static const struct option long_options[] = {
                { "help", no_argument, 0, 'h' },
                { "count", no_argument, 0, 'c' },
@@ -608,6 +639,8 @@ int main(int argc, char **argv)
                { "limit", required_argument, 0, 'l' },
                { "null", no_argument, 0, '0' },
                { "version", no_argument, 0, 'V' },
+               { "regexp", no_argument, 0, 'r' },
+               { "regex", no_argument, 0, EXTENDED_REGEX },
                { "debug", no_argument, 0, 'D' },  // Not documented.
                { 0, 0, 0, 0 }
        };
@@ -639,6 +672,13 @@ int main(int argc, char **argv)
                case '0':
                        print_nul = true;
                        break;
+               case 'r':
+                       patterns_are_regex = true;
+                       break;
+               case EXTENDED_REGEX:
+                       patterns_are_regex = true;
+                       use_extended_regex = true;
+                       break;
                case 'D':
                        use_debug = true;
                        break;
@@ -665,6 +705,7 @@ int main(int argc, char **argv)
                Needle needle;
                needle.str = argv[i];
 
+
                // See if there are any wildcard characters, which indicates we should treat it
                // as an (anchored) glob.
                bool any_wildcard = false;
@@ -675,7 +716,10 @@ int main(int argc, char **argv)
                        }
                }
 
-               if (any_wildcard) {
+               if (patterns_are_regex) {
+                       needle.type = Needle::REGEX;
+                       needle.re = compile_regex(needle.str);
+               } else if (any_wildcard) {
                        needle.type = Needle::GLOB;
                } else if (ignore_case) {
                        // strcasestr() doesn't handle locales correctly (even though LSB