Sparse currently has a memory efficient implementation for lists
of pointers to some objects.
These are used for 2 different purposes:
- either for a simple set of objects
- either as a sequence (ordered) of objects.
There is also another similar need:
- a map of object (aka: dictionnary, table, ...)
where the only needed operations are:
- add a new element (with it's key)
- lookup an element via it's key
- replace the element corresponding to a key
The implementation done in this patch is a very simple one
based on list of blocks of key-value pairs.
The idea being to later switch to a dynamic structure using
a hash-table as soon as the number of element reach some threshold.
However, these hash-table are only needed for some huge input files
(the current implementation is no worse than walking through
the ptrlists).
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
Makefile | 1 +
ptrmap.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
ptrmap.h | 12 +++++++
3 files changed, 122 insertions(+)
create mode 100644 ptrmap.c
create mode 100644 ptrmap.h
diff --git a/Makefile b/Makefile
index 0976ee818..43bbaa9bc 100644
--- a/Makefile
+++ b/Makefile
@@ -53,6 +53,7 @@ LIB_OBJS += optimize.o
LIB_OBJS += parse.o
LIB_OBJS += pre-process.o
LIB_OBJS += ptrlist.o
+LIB_OBJS += ptrmap.o
LIB_OBJS += scope.o
LIB_OBJS += show-parse.o
LIB_OBJS += simplify.o
diff --git a/ptrmap.c b/ptrmap.c
new file mode 100644
index 000000000..ff07e19a1
--- /dev/null
+++ b/ptrmap.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Stupid implementation of pointer -> pointer map.
+ *
+ * Copyright (c) 2017 Luc Van Oostenryck.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "ptrmap.h"
+#include "allocate.h"
+#include <stddef.h>
+
+#define MAP_NR 7
+
+struct ptrpair {
+ void *key;
+ void *val;
+};
+struct ptrmap {
+ struct ptrmap *next;
+ int nr;
+ struct ptrpair pairs[MAP_NR];
+};
+
+DECLARE_ALLOCATOR(ptrmap);
+ALLOCATOR(ptrmap, "ptrmap");
+
+void __ptrmap_add(struct ptrmap **mapp, void *key, void *val)
+{
+ struct ptrmap *head = *mapp;
+ struct ptrmap *newmap;
+ struct ptrmap *map;
+ struct ptrpair *pair;
+ int nr;
+
+ if ((map = head)) {
+ struct ptrmap *next = map->next;
+ if (next) // head is full
+ map = next;
+ if ((nr = map->nr) < MAP_NR)
+ goto oldmap;
+ }
+
+ // need a new block
+ newmap = __alloc_ptrmap(0);
+ if (!head) {
+ *mapp = newmap;
+ } else {
+ newmap->next = head->next;
+ head->next = newmap;
+ }
+ map = newmap;
+ nr = 0;
+
+oldmap:
+ pair = &map->pairs[nr];
+ pair->key = key;
+ pair->val = val;
+ map->nr = ++nr;
+}
+
+void *__ptrmap_lookup(struct ptrmap *map, void *key)
+{
+ for (; map; map = map->next) {
+ int i, n = map->nr;
+ for (i = 0; i < n; i++) {
+ struct ptrpair *pair = &map->pairs[i];
+ if (pair->key == key)
+ return pair->val;
+ }
+ }
+ return NULL;
+}
+
+void __ptrmap_update(struct ptrmap **mapp, void *key, void *val)
+{
+ struct ptrmap *map = *mapp;
+
+ for (; map; map = map->next) {
+ int i, n = map->nr;
+ for (i = 0; i < n; i++) {
+ struct ptrpair *pair = &map->pairs[i];
+ if (pair->key == key) {
+ if (pair->val != val)
+ pair->val = val;
+ return;
+ }
+ }
+ }
+
+ __ptrmap_add(mapp, key, val);
+}
diff --git a/ptrmap.h b/ptrmap.h
new file mode 100644
index 000000000..070db15e2
--- /dev/null
+++ b/ptrmap.h
@@ -0,0 +1,12 @@
+#ifndef PTRMAP_H
+#define PTRMAP_H
+
+struct ptrmap;
+
+
+/* ptrmap.c */
+void __ptrmap_add(struct ptrmap **mapp, void *key, void *val);
+void __ptrmap_update(struct ptrmap **mapp, void *key, void *val);
+void *__ptrmap_lookup(struct ptrmap *map, void *key);
+
+#endif
--
2.16.2
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