structure: add BStringTrie

examples/CMakeLists.txt

@@ -74,3 +74,5 @@ if (BUILDING_ARPPROBE)
 endif ()
 
 add_executable(substring_test substring_test.c)
+
+add_executable(bstringtrie_test bstringtrie_test.c)

examples/bstringtrie_test.c

@@ -0,0 +1,53 @@
+#include <stdio.h>
+
+#include <misc/debug.h>
+#include <misc/array_length.h>
+#include <structure/BStringTrie.h>
+
+const char *strings[] = {
+    "hello", "world", "hell", "he", "war", "warning", "warned", "", "heap", "why", "not", "nowhere", "neither",
+    "normal", "how", "apple", "apear", "appreciate", "systematic", "systemic", "system", "self", "serious"
+};
+#define NUM_STRINGS B_ARRAY_LENGTH(strings)
+
+const char *other_strings[] = {
+    "warn", "wor", "helloo", "norma", "systems", "server", "no", "when", "nothing"
+};
+#define NUM_OTHER_STRINGS B_ARRAY_LENGTH(other_strings)
+
+int main ()
+{
+    int res;
+    
+    BStringTrie trie;
+    res = BStringTrie_Init(&trie);
+    ASSERT_FORCE(res);
+    
+    for (int i = 0; i < NUM_STRINGS; i++) {
+        res = BStringTrie_Set(&trie, strings[i], i);
+        ASSERT_FORCE(res);
+    }
+    
+    for (int i = 0; i < NUM_STRINGS; i++) {
+        int value = BStringTrie_Lookup(&trie, strings[i]);
+        ASSERT_FORCE(value == i);
+    }
+    
+    for (int i = 0; i < NUM_STRINGS; i++) {
+        res = BStringTrie_Set(&trie, strings[i], NUM_STRINGS - 1 - i);
+        ASSERT_FORCE(res);
+    }
+    
+    for (int i = 0; i < NUM_STRINGS; i++) {
+        int value = BStringTrie_Lookup(&trie, strings[i]);
+        ASSERT_FORCE(value == NUM_STRINGS - 1 - i);
+    }
+    
+    for (int i = 0; i < NUM_OTHER_STRINGS; i++) {
+        int value = BStringTrie_Lookup(&trie, other_strings[i]);
+        ASSERT_FORCE(value == BSTRINGTRIE_DEFAULT_VALUE);
+    }
+    
+    BStringTrie_Free(&trie);
+    return 0;
+}

structure/BStringTrie.h

@@ -0,0 +1,183 @@
+/**
+ * @file BStringTrie.h
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the author nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef BADVPN_BSTRINGTRIE_H
+#define BADVPN_BSTRINGTRIE_H
+
+#include <stddef.h>
+#include <limits.h>
+#include <string.h>
+
+#include <misc/debug.h>
+#include <misc/balloc.h>
+
+#define BSTRINGTRIE_DEFAULT_VALUE ((int)-1)
+
+#define BSTRINGTRIE_DEGREE (((size_t)1) << CHAR_BIT)
+
+struct BStringTrie__node {
+    int value[BSTRINGTRIE_DEGREE];
+    int link[BSTRINGTRIE_DEGREE];
+};
+
+typedef struct {
+    struct BStringTrie__node *arr;
+    size_t count;
+    size_t capacity;
+    int empty_value;
+} BStringTrie;
+
+static int BStringTrie_Init (BStringTrie *o) WARN_UNUSED;
+static void BStringTrie_Free (BStringTrie *o);
+static int BStringTrie_Set (BStringTrie *o, const char *key, int value) WARN_UNUSED;
+static int BStringTrie_Lookup (const BStringTrie *o, const char *key);
+
+// implementation follows
+
+static int BStringTrie__new_node (BStringTrie *o, int *out_nodeidx)
+{
+    ASSERT(o->count <= o->capacity)
+    ASSERT(o->capacity > 0)
+    ASSERT(out_nodeidx)
+    
+    if (o->count == o->capacity) {
+        if (o->capacity > SIZE_MAX / 2) {
+            return 0;
+        }
+        size_t newcap = 2 * o->capacity;
+        
+        struct BStringTrie__node *newarr = BAllocArray(newcap, sizeof(newarr[0]));
+        if (!newarr) {
+            return 0;
+        }
+        
+        memcpy(newarr, o->arr, o->count * sizeof(newarr[0]));
+        BFree(o->arr);
+        
+        o->arr = newarr;
+        o->capacity = newcap;
+    }
+    
+    struct BStringTrie__node *node = &o->arr[o->count];
+    
+    for (size_t i = 0; i < BSTRINGTRIE_DEGREE; i++) {
+        node->value[i] = BSTRINGTRIE_DEFAULT_VALUE;
+        node->link[i] = -1;
+    }
+    
+    *out_nodeidx = o->count;
+    o->count++;
+    
+    return 1;
+}
+
+static int BStringTrie_Init (BStringTrie *o)
+{
+    o->count = 0;
+    o->capacity = 1;
+    o->empty_value = BSTRINGTRIE_DEFAULT_VALUE;
+    
+    if (!(o->arr = BAllocArray(o->capacity, sizeof(o->arr[0])))) {
+        return 0;
+    }
+    
+    int idx0;
+    BStringTrie__new_node(o, &idx0);
+    
+    return 1;
+}
+
+static void BStringTrie_Free (BStringTrie *o)
+{
+    BFree(o->arr);
+}
+
+static int BStringTrie_Set (BStringTrie *o, const char *key, int value)
+{
+    ASSERT(key)
+    
+    if (!*key) {
+        o->empty_value = value;
+        return 1;
+    }
+    
+    const unsigned char *ukey = (const unsigned char *)key;
+    int nodeidx = 0;
+    
+    while (*(ukey + 1)) {
+        ASSERT(o->arr[nodeidx].link[*ukey] >= -1)
+        
+        int new_nodeidx;
+        
+        if (o->arr[nodeidx].link[*ukey] >= 0) {
+            new_nodeidx = o->arr[nodeidx].link[*ukey];
+        } else {
+            if (!BStringTrie__new_node(o, &new_nodeidx)) {
+                return 0;
+            }
+            o->arr[nodeidx].link[*ukey] = new_nodeidx;
+        }
+        
+        ASSERT(new_nodeidx >= 0)
+        ASSERT(new_nodeidx < o->count)
+        
+        nodeidx = new_nodeidx;
+        ukey++;
+    }
+    
+    o->arr[nodeidx].value[*ukey] = value;
+    
+    return 1;
+}
+
+static int BStringTrie_Lookup (const BStringTrie *o, const char *key)
+{
+    ASSERT(key)
+    
+    if (!*key) {
+        return o->empty_value;
+    }
+    
+    const unsigned char *ukey = (const unsigned char *)key;
+    int nodeidx = 0;
+    
+    while (*(ukey + 1)) {
+        nodeidx = o->arr[nodeidx].link[*ukey];
+        ASSERT(nodeidx >= -1)
+        if (nodeidx < 0) {
+            return -1;
+        }
+        ASSERT(nodeidx < o->count)
+        ukey++;
+    }
+    
+    return o->arr[nodeidx].value[*ukey];
+}
+
+#endif