Implement a trie, sans removal.

src/trie.c

@@ -0,0 +1,92 @@
+#include "trie.h"
+#include <stdlib.h>
+#include "util.h"
+
+void libab_trie_init(libab_trie* trie) {
+    trie->head = NULL;
+    ll_init(&trie->empty_list);
+}
+
+void _libab_trie_free(libab_trie_node* to_free) {
+    if(to_free == NULL) return;
+    _libab_trie_free(to_free->next);
+    _libab_trie_free(to_free->child);
+    ll_free(&to_free->values);
+    free(to_free);
+}
+
+libab_result _libab_trie_put(libab_trie_node** node, const char* key, void* value) {
+    libab_result result = LIBAB_SUCCESS;
+    if((*node = malloc(sizeof(**node)))) {
+        (*node)->key = *key;
+        (*node)->next = NULL;
+        ll_init(&(*node)->values);
+
+        if(*(key + 1)) {
+            result = _libab_trie_put(&(*node)->child, key + 1, value);
+        } else {
+            (*node)->child = NULL;
+            result = libab_convert_ds_result(ll_append(&(*node)->values, value));
+        }
+    } else {
+        result = LIBAB_MALLOC;
+    }
+
+    if(result != LIBAB_SUCCESS) {
+        free(*node);
+        *node = NULL;
+    }
+
+    return result;
+}
+
+libab_result _libab_trie_add(libab_trie_node* node, void* value) {
+    return libab_convert_ds_result(ll_append(&node->values, value));
+}
+
+libab_result libab_trie_put(libab_trie* trie, const char* key, void* value) {
+    libab_result result = LIBAB_SUCCESS;
+    libab_trie_node** current = &trie->head;
+    char search;
+    while(*key) {
+        search = *key;
+        while(*current && (*current)->key != search) {
+            current = &(*current)->next;
+        }
+        if(*current) {
+            if(*(key + 1)) {
+                current = &(*current)->child;
+            } else {
+                result = _libab_trie_add(*current, value);
+            }
+            key++;
+        } else {
+            result = _libab_trie_put(current, key, value);
+            break;
+        }
+    }
+    return result;
+}
+
+const ll* libab_trie_get(libab_trie* trie, const char* key) {
+    libab_trie_node* current = trie->head;
+    while(current && *key) {
+        while(current && current->key != *key) {
+            current = current->next;
+        }
+        if(current == NULL) break;
+        
+        if(*(key + 1)) {
+            current = current->child;
+            key++;
+        } else {
+            return &current->values;
+        }
+    }
+    return &trie->empty_list;
+}
+
+void libab_trie_free(libab_trie* trie) {
+    _libab_trie_free(trie->head);   
+    trie->head = NULL;
+}