qrealka · May 7, 2024 12:07 · Oct 21, 2014
diff --git a/Makefile b/Makefile
@@ -0,0 +1,11 @@
+CFLAGS = -std=c99 -Wall
+
+main : main.o
+
+.PHONY : test clean
+
+test : main
+	./$^ "*regex*" "*vtable*" < main.c
+
+clean :
+	$(RM) main *.o
diff --git a/main.c b/main.c
@@ -0,0 +1,223 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <regex.h>
+#include <stdbool.h>
+#include <fnmatch.h>
+#include <stddef.h>
+
+#define container_of(ptr, type, member) \
+    ((type *)((char *)(ptr) - offsetof(type, member)))
+
+/* Filter API */
+
+struct filter {
+    struct filter_vtable *vtable;
+};
+
+struct filter_vtable {
+    bool (*match)(struct filter *, const char *);
+    void (*free)(struct filter *);
+    struct filter *(*clone)(struct filter *);
+};
+
+bool filter_match(struct filter *filter, const char *string)
+{
+    return filter->vtable->match(filter, string);
+}
+
+void filter_free(struct filter *filter)
+{
+    return filter->vtable->free(filter);
+}
+
+struct filter *filter_clone(struct filter *filter)
+{
+    return filter->vtable->clone(filter);
+}
+
+/* Regex Filter */
+
+struct filter *filter_regex_create(const char *pattern);
+
+struct filter_regex {
+    regex_t regex;
+    const char *pattern;
+    struct filter filter;
+};
+
+static bool
+method_match_regex(struct filter *f, const char *string)
+{
+    struct filter_regex *regex = container_of(f, struct filter_regex, filter);
+    return regexec(&regex->regex, string, 0, NULL, 0) == 0;
+}
+
+static void
+method_free_regex(struct filter *f)
+{
+    struct filter_regex *regex = container_of(f, struct filter_regex, filter);
+    regfree(&regex->regex);
+    free(f);
+}
+
+static struct filter *
+method_clone_regex(struct filter *f)
+{
+    struct filter_regex *regex = container_of(f, struct filter_regex, filter);
+    return filter_regex_create(regex->pattern);
+}
+
+struct filter_vtable filter_regex_vtable = {
+    method_match_regex, method_free_regex, method_clone_regex
+};
+
+struct filter *filter_regex_create(const char *pattern)
+{
+    struct filter_regex *regex = malloc(sizeof(*regex));
+    regex->pattern = pattern;
+    regcomp(&regex->regex, pattern, REG_EXTENDED);
+    regex->filter.vtable = &filter_regex_vtable;
+    return &regex->filter;
+}
+
+/* Glob Filter */
+
+struct filter *filter_glob_create(const char *pattern);
+
+struct filter_glob {
+    struct filter filter;
+    const char *pattern;
+};
+
+static bool
+method_match_glob(struct filter *f, const char *string)
+{
+    struct filter_glob *glob = (struct filter_glob *) f;
+    return fnmatch(glob->pattern, string, 0) == 0;
+}
+
+static void
+method_free_glob(struct filter *f)
+{
+    free(f);
+}
+
+static struct filter *
+method_clone_glob(struct filter *f)
+{
+    struct filter_glob *glob = (struct filter_glob *) f;
+    return filter_glob_create(glob->pattern);
+}
+
+struct filter_vtable filter_glob_vtable = {
+    method_match_glob, method_free_glob, method_clone_glob
+};
+
+struct filter *filter_glob_create(const char *pattern)
+{
+    struct filter_glob *glob = malloc(sizeof(*glob));
+    glob->pattern = pattern;
+    glob->filter.vtable = &filter_glob_vtable;
+    return &glob->filter;
+}
+
+/* AND Filter */
+
+struct filter *filter_and(struct filter *a, struct filter *b);
+
+struct filter_and {
+    struct filter filter;
+    struct filter *sub[2];
+};
+
+static bool
+method_match_and (struct filter *f, const char *s)
+{
+    struct filter_and *and = (struct filter_and *) f;
+    return filter_match(and->sub[0], s) && filter_match(and->sub[1], s);
+}
+
+static void
+method_free_and(struct filter *f)
+{
+    struct filter_and *and = (struct filter_and *) f;
+    filter_free(and->sub[0]);
+    filter_free(and->sub[1]);
+    free(f);
+}
+
+static struct filter *
+method_clone_and(struct filter *f)
+{
+    struct filter_and *and = (struct filter_and *) f;
+    return filter_and(filter_clone(and->sub[0]), filter_clone(and->sub[1]));
+}
+
+struct filter_vtable filter_and_vtable = {
+    method_match_and, method_free_and, method_clone_and
+};
+
+struct filter *filter_and(struct filter *a, struct filter *b)
+{
+    struct filter_and *and = malloc(sizeof(*and));
+    and->sub[0] = a;
+    and->sub[1] = b;
+    and->filter.vtable = &filter_and_vtable;
+    return &and->filter;
+}
+
+/* Constant Filters */
+
+static bool
+method_match_any(struct filter *f, const char *string)
+{
+    return true;
+}
+
+static bool
+method_match_none(struct filter *f, const char *string)
+{
+    return false;
+}
+
+static void
+method_free_noop(struct filter *f)
+{
+}
+
+static struct
+filter *method_clone_noop(struct filter *f)
+{
+    return f;
+}
+
+struct filter_vtable filter_any_vtable = {
+    method_match_any, method_free_noop, method_clone_noop
+};
+
+struct filter_vtable filter_none_vtable = {
+    method_match_none, method_free_noop, method_clone_noop
+};
+
+struct filter FILTER_ANY  = { &filter_any_vtable };
+struct filter FILTER_NONE = { &filter_none_vtable };
+
+/* Test Program */
+
+void pass_match(FILE *input, FILE *output, struct filter *filter)
+{
+    char line[4096];
+    while (fgets(line, sizeof(line), input))
+        if (filter_match(filter, line))
+            fputs(line, output);
+}
+
+int main(int argc, char **argv)
+{
+    struct filter *filter = &FILTER_ANY;
+    for (char **p = argv + 1; *p; p++)
+        filter = filter_and(filter, filter_glob_create(*p));
+    pass_match(stdin, stdout, filter);
+    filter_free(filter);
+    return 0;
+}