strset

include/lang2/strset.h

@@ -0,0 +1,21 @@
+#ifndef L2_STRSET_H
+#define L2_STRSET_H
+
+#include <stdlib.h>
+
+struct l2_strset {
+	size_t next;
+	size_t len;
+	size_t size;
+	size_t mask;
+	char **keys;
+	size_t *vals;
+};
+
+void l2_strset_init(struct l2_strset *set);
+void l2_strset_free(struct l2_strset *set);
+size_t l2_strset_put_move(struct l2_strset *set, char **str);
+size_t l2_strset_put_copy(struct l2_strset *set, const char *str);
+size_t l2_strset_get(struct l2_strset *set, const char *str);
+
+#endif

src/strset.c

@@ -0,0 +1,122 @@
+#include "strset.h"
+
+#include <string.h>
+
+// sdbm from http://www.cse.yorku.ca/~oz/hash.html;
+// there are probably better algorithms out there
+static size_t hash(const void *ptr) {
+	const unsigned char *str = ptr;
+	size_t h = 0;
+	int c;
+
+	while ((c = *(str++)) != 0) {
+		h = c + (h << 6) + (h << 16) - h;
+	}
+
+	return h;
+}
+
+void grow(struct l2_strset *set) {
+	struct l2_strset old = *set;
+	set->len = 0;
+	set->size *= 2;
+	set->mask = (set->mask << 1) | set->mask;
+
+	set->keys = calloc(set->size, sizeof(*set->keys));
+	set->vals = calloc(set->size, sizeof(*set->vals));
+
+	for (size_t i = 0; i < old.size; ++i) {
+		char *oldkey = old.keys[i];
+		if (oldkey == NULL) {
+			continue;
+		}
+
+		size_t h = hash(old.keys[i]);
+		for (size_t j = 0; ; ++j) {
+			size_t index = (h + j) & set->mask;
+			char *k = set->keys[index];
+			if (k == NULL || strcmp(oldkey, k) != 0) {
+				continue;
+			}
+
+			set->keys[index] = oldkey;
+			set->vals[index] = old.vals[i];
+			break;
+		}
+	}
+
+	free(old.keys);
+	free(old.vals);
+}
+
+void l2_strset_init(struct l2_strset *set) {
+	set->next = 1;
+	set->len = 0;
+	set->size = 16;
+	set->mask = 0x0f;
+	set->keys = calloc(set->size, sizeof(*set->keys));
+	set->vals = calloc(set->size, sizeof(*set->vals));
+}
+
+void l2_strset_free(struct l2_strset *set) {
+	for (size_t i = 0; i < set->size; ++i) {
+		free(set->keys[i]);
+	}
+
+	free(set->keys);
+	free(set->vals);
+}
+
+size_t l2_strset_put_move(struct l2_strset *set, char **str) {
+	if (set->len >= set->size / 2) {
+		grow(set);
+	}
+
+	size_t h = hash(*str);
+	for (size_t i = 0; ; ++i) {
+		size_t index = (h + i) & set->mask;
+		char *k = set->keys[index];
+		if (k == NULL) {
+			set->keys[index] = *str;
+			set->vals[index] = set->next++;
+			*str = NULL;
+			return set->vals[index];
+		} else if (strcmp(*str, k) == 0) {
+			free(*str);
+			*str = NULL;
+			return set->vals[index];
+		}
+	}
+}
+
+size_t l2_strset_put_copy(struct l2_strset *set, const char *str) {
+	if (set->len >= set->size / 2) {
+		grow(set);
+	}
+
+	size_t h = hash(str);
+	for (size_t i = 0; ; ++i) {
+		size_t index = (h + i) & set->mask;
+		char *k = set->keys[index];
+		if (k == NULL) {
+			set->keys[index] = strdup(str);
+			set->vals[index] = set->next++;
+			return set->vals[index];
+		} else if (strcmp(str, k) == 0) {
+			return set->vals[index];
+		}
+	}
+}
+
+size_t l2_strset_get(struct l2_strset *set, const char *str) {
+	size_t h = hash(str);
+	for (size_t i = 0; ; ++i) {
+		size_t index = (h + i) & set->mask;
+		char *k = set->keys[index];
+		if (k == NULL) {
+			return 0;
+		} else if (strcmp(str, k) == 0) {
+			return set->vals[index];
+		}
+	}
+}