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authorMax Kellermann <max@duempel.org>2008-09-08 11:46:04 +0200
committerMax Kellermann <max@duempel.org>2008-09-08 11:46:04 +0200
commit2b8040b42524dad68ea85c45a4be25909a03eb5c (patch)
treef14c109213bc54e0623362fd02951c7cb5b18a46
parent3f6fe915ebff003b907bc0c70502d21691b50095 (diff)
downloadmpd-2b8040b42524dad68ea85c45a4be25909a03eb5c.tar.gz
mpd-2b8040b42524dad68ea85c45a4be25909a03eb5c.tar.xz
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added string set library
"struct strset" is a hashed string set: you can add strings to this library, and it stores them as a set of unique strings. You can get the size of the set, and you can enumerate through all values. This will be used to replace the linear tagTracker library.
-rw-r--r--src/Makefile.am2
-rw-r--r--src/strset.c144
-rw-r--r--src/strset.h49
3 files changed, 195 insertions, 0 deletions
diff --git a/src/Makefile.am b/src/Makefile.am
index 30408288c..5a5439bfc 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -92,6 +92,7 @@ mpd_headers = \
tag_save.h \
tagTracker.h \
utf8.h \
+ strset.h \
utils.h \
volume.h \
ioops.h \
@@ -158,6 +159,7 @@ mpd_SOURCES = \
tag_print.c \
tag_save.c \
tagTracker.c \
+ strset.c \
utils.c \
volume.c \
utf8.c \
diff --git a/src/strset.c b/src/strset.c
new file mode 100644
index 000000000..6bf61a4b2
--- /dev/null
+++ b/src/strset.c
@@ -0,0 +1,144 @@
+/* the Music Player Daemon (MPD)
+ * Copyright (C) 2008 Max Kellermann <max@duempel.org>
+ * This project's homepage is: http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "strset.h"
+#include "utils.h"
+#include "os_compat.h"
+
+#define NUM_SLOTS 16384
+
+struct strset_slot {
+ struct strset_slot *next;
+ const char *value;
+};
+
+struct strset {
+ unsigned size;
+
+ struct strset_slot *current_slot;
+ unsigned next_slot;
+
+ struct strset_slot slots[NUM_SLOTS];
+};
+
+static unsigned calc_hash(const char *p) {
+ unsigned hash = 5381;
+
+ assert(p != NULL);
+
+ while (*p != 0)
+ hash = (hash << 5) + hash + *p++;
+
+ return hash;
+}
+
+mpd_malloc struct strset *strset_new(void)
+{
+ struct strset *set = xcalloc(1, sizeof(*set));
+ return set;
+}
+
+void strset_free(struct strset *set)
+{
+ unsigned i;
+
+ for (i = 0; i < NUM_SLOTS; ++i) {
+ struct strset_slot *slot = set->slots[i].next, *next;
+
+ while (slot != NULL) {
+ next = slot->next;
+ free(slot);
+ slot = next;
+ }
+ }
+
+ free(set);
+}
+
+void strset_add(struct strset *set, const char *value)
+{
+ struct strset_slot *base_slot
+ = &set->slots[calc_hash(value) % NUM_SLOTS];
+ struct strset_slot *slot = base_slot;
+
+ if (base_slot->value == NULL) {
+ /* empty slot - put into base_slot */
+ assert(base_slot->next == NULL);
+
+ base_slot->value = value;
+ ++set->size;
+ return;
+ }
+
+ for (slot = base_slot->next; slot != NULL; slot = slot->next)
+ if (strcmp(slot->value, value) == 0)
+ /* found it - do nothing */
+ return;
+
+ /* insert it into the slot chain */
+ slot = xmalloc(sizeof(*slot));
+ slot->next = base_slot->next;
+ slot->value = value;
+ base_slot->next = slot;
+ ++set->size;
+}
+
+int strset_get(const struct strset *set, const char *value)
+{
+ const struct strset_slot *slot = &set->slots[calc_hash(value)];
+
+ if (slot->value == NULL)
+ return 0;
+
+ for (slot = slot->next; slot != NULL; slot = slot->next)
+ if (strcmp(slot->value, value) == 0)
+ /* found it - do nothing */
+ return 1;
+
+ return 0;
+}
+
+unsigned strset_size(const struct strset *set)
+{
+ return set->size;
+}
+
+void strset_rewind(struct strset *set)
+{
+ set->current_slot = NULL;
+ set->next_slot = 0;
+}
+
+const char *strset_next(struct strset *set)
+{
+ if (set->current_slot != NULL && set->current_slot->next != NULL) {
+ set->current_slot = set->current_slot->next;
+ return set->current_slot->value;
+ }
+
+ while (set->next_slot < NUM_SLOTS &&
+ set->slots[set->next_slot].value == NULL)
+ ++set->next_slot;
+
+ if (set->next_slot >= NUM_SLOTS)
+ return NULL;
+
+ set->current_slot = &set->slots[set->next_slot++];
+ return set->current_slot->value;
+}
+
diff --git a/src/strset.h b/src/strset.h
new file mode 100644
index 000000000..41ef0e1bd
--- /dev/null
+++ b/src/strset.h
@@ -0,0 +1,49 @@
+/* the Music Player Daemon (MPD)
+ * Copyright (C) 2008 Max Kellermann <max@duempel.org>
+ * This project's homepage is: http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+/**
+ * "struct strset" is a hashed string set: you can add strings to this
+ * library, and it stores them as a set of unique strings. You can
+ * get the size of the set, and you can enumerate through all values.
+ *
+ * It is important to note that the strset does not copy the string
+ * values - it stores the exact pointers it was given in strset_add().
+ */
+
+#ifndef STRSET_H
+#define STRSET_H
+
+#include "gcc.h"
+
+struct strset;
+
+mpd_malloc struct strset *strset_new(void);
+
+void strset_free(struct strset *set);
+
+void strset_add(struct strset *set, const char *value);
+
+int strset_get(const struct strset *set, const char *value);
+
+unsigned strset_size(const struct strset *set);
+
+void strset_rewind(struct strset *set);
+
+const char *strset_next(struct strset *set);
+
+#endif