Add hash map

1 files changed, 191 insertions, 0 deletions

diff --git a/src/std/hash_map.c b/src/std/hash_map.c
new file mode 100644
index 0000000..1ffca90
--- /dev/null
+++ b/src/std/hash_map.c
@@ -0,0 +1,191 @@
+#include "../../include/std/hash_map.h"
+#include "../../include/std/scoped_allocator.h"
+#include "../../include/std/mem.h"
+#include <assert.h>
+
+/*
+Basic hash map implementation. TODO: Improve performance
+*/
+
+#define HASH_MAP_INITIAL_SIZE 16
+
+typedef struct HashMapBucketNode HashMapBucketNode;
+
+typedef struct {
+    HashMapBucketNode *start;
+} HashMapBucket;
+
+static void bucket_node_set_next(HashMapBucketNode *self, HashMapBucketNode *next) {
+    am_memcpy(self, &next, sizeof(next));
+}
+
+static HashMapBucketNode* bucket_node_get_next(HashMapBucketNode *self) {
+    HashMapBucketNode *next;
+    am_memcpy(&next, self, sizeof(HashMapBucketNode*));
+    return next;
+}
+
+static void bucket_node_set_key(HashMapBucketNode *self, BufferView key) {
+    u32 key_size;
+    key_size = (u32)key.size;
+    am_memcpy((char*)self + sizeof(HashMapBucketNode*), &key_size, sizeof(u32));
+    am_memcpy((char*)self + sizeof(HashMapBucketNode*) + sizeof(u32), key.data, key_size);
+}
+
+static BufferView bucket_node_get_key(HashMapBucketNode *self) {
+    BufferView key;
+    u32 key_size;
+    am_memcpy(&key_size, (char*)self + sizeof(HashMapBucketNode*), sizeof(u32));
+    key.size = key_size;
+    key.data = (char*)self + sizeof(HashMapBucketNode*) + sizeof(u32);
+    return key;
+}
+
+static void bucket_node_set_value(HashMapBucketNode *self, void *value, usize type_size) {
+    u32 key_size;
+    am_memcpy(&key_size, (char*)self + sizeof(HashMapBucketNode*), sizeof(key_size));
+    am_memcpy((char*)self + sizeof(HashMapBucketNode*) + sizeof(u32) + key_size, value, type_size);
+}
+
+static void* bucket_node_get_value(HashMapBucketNode *self) {
+    u32 key_size;
+    void *value;
+    am_memcpy(&key_size, (char*)self + sizeof(HashMapBucketNode*), sizeof(key_size));
+    value = (char*)self + sizeof(HashMapBucketNode*) + sizeof(u32) + key_size;
+    return value;
+}
+
+int hash_map_init(HashMap *self, ScopedAllocator *allocator, usize type_size, 
+                  HashMapCompare compare_func, HashMapHash hash_func) {
+    assert(compare_func);
+    assert(hash_func);
+    self->allocator = allocator;
+    self->type_size = type_size;
+    self->num_elements = 0;
+    self->compare_func = compare_func;
+    self->hash_func = hash_func;
+    return_if_error(buffer_init(&self->buckets, self->allocator));
+    assert(self->buckets.size == 0);
+    return_if_error(buffer_append(&self->buckets, NULL, sizeof(HashMapBucket) * HASH_MAP_INITIAL_SIZE));
+    am_memset(self->buckets.data, 0, self->buckets.size);
+    return 0;
+}
+
+static CHECK_RESULT int hash_map_bucket_add(HashMap *self, HashMapBucket *bucket, BufferView key, void *value) {
+    HashMapBucketNode *new_bucket_node;
+    return_if_error(scoped_allocator_alloc(self->allocator, 
+                                           sizeof(HashMapBucketNode*) + sizeof(u32) + key.size + self->type_size,
+                                           (void**)&new_bucket_node));
+    bucket_node_set_next(new_bucket_node, bucket->start);
+    bucket_node_set_key(new_bucket_node, key);
+    bucket_node_set_value(new_bucket_node, value, self->type_size);
+    bucket->start = new_bucket_node;
+    return 0;
+}
+
+static void hash_map_reorder_buckets(HashMap *self, usize end_index) {
+    HashMapBucket *bucket;
+    HashMapBucket *bucket_end;
+    usize bucket_size;
+    usize index;
+
+    bucket = (HashMapBucket*)self->buckets.data;
+    bucket_end = ((HashMapBucket*)self->buckets.data) + end_index;
+    bucket_size = buffer_get_size(&self->buckets, HashMapBucket);
+    index = 0;
+
+    for(; bucket != bucket_end; ++bucket, ++index) {
+        HashMapBucketNode *prev_bucket_node;
+        HashMapBucketNode *bucket_node;
+        prev_bucket_node = NULL;
+        for(bucket_node = bucket->start; bucket_node; bucket_node_get_next(bucket_node)) {
+            BufferView bucket_key;
+            usize bucket_index;
+
+            /* Node between current and previous has been removed, chain previous and current */
+            if(prev_bucket_node && !bucket_node_get_next(prev_bucket_node))
+                bucket_node_set_next(prev_bucket_node, bucket_node);
+
+            bucket_key = bucket_node_get_key(bucket_node);
+            bucket_index = self->hash_func((const u8*)bucket_key.data, bucket_key.size) % bucket_size;
+            if(bucket_index != index) {
+                /* Add node to new bucket */
+                HashMapBucket *new_bucket;
+                new_bucket = ((HashMapBucket*)self->buckets.data) + bucket_index;
+                bucket_node_set_next(bucket_node, new_bucket->start);
+                new_bucket->start = bucket_node;
+                /* Mark bucket node to be removed from previous bucket */
+                bucket_node_set_next(prev_bucket_node, NULL);
+            } else {
+                prev_bucket_node = bucket_node;
+            }
+        }
+    }
+}
+
+static CHECK_RESULT int hash_map_increase_buckets(HashMap *self) {
+    usize prev_size;
+    usize bytes_to_append;
+    prev_size = buffer_get_size(&self->buckets, HashMapBucket);
+    bytes_to_append = prev_size * 1.5;
+    return_if_error(buffer_append(&self->buckets, NULL, bytes_to_append));
+    am_memset(self->buckets.data + prev_size, 0, prev_size + bytes_to_append);
+    hash_map_reorder_buckets(self, prev_size);
+    return 0;
+}
+
+int hash_map_insert(HashMap *self, BufferView key, void *value) {
+    usize bucket_index;
+    usize bucket_size;
+    HashMapBucket *bucket;
+
+    bucket_size = buffer_get_size(&self->buckets, HashMapBucket);
+    if(self->num_elements == bucket_size) {
+        return_if_error(hash_map_increase_buckets(self));
+        bucket_size = buffer_get_size(&self->buckets, HashMapBucket);
+    }
+
+    bucket_index = self->hash_func((const u8*)key.data, key.size) % bucket_size;
+    bucket = ((HashMapBucket*)self->buckets.data) + bucket_index;
+    return_if_error(hash_map_bucket_add(self, bucket, key, value));
+    ++self->num_elements;
+    return 0;
+}
+
+bool hash_map_get(HashMap *self, BufferView key, void *value) {
+    usize bucket_size;
+    usize bucket_index;
+    HashMapBucket *bucket;
+    HashMapBucketNode *bucket_node;
+
+    bucket_size = buffer_get_size(&self->buckets, HashMapBucket);
+    bucket_index = self->hash_func((const u8*)key.data, key.size) % bucket_size;
+
+    bucket = ((HashMapBucket*)self->buckets.data) + bucket_index;
+    for(bucket_node = bucket->start; bucket_node; bucket_node_get_next(bucket_node)) {
+        BufferView bucket_key;
+        bucket_key = bucket_node_get_key(bucket_node);
+        bucket_index = self->hash_func((const u8*)bucket_key.data, bucket_key.size) % bucket_size;
+        bucket_index %= bucket_size;
+        if(self->compare_func(value, bucket_node_get_value(bucket_node)) == 0)
+            return bool_true;
+    }
+
+    return bool_false;
+}
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+
+int hash_compare_string(const void *a, const void *b) {
+    const BufferView *lhs;
+    const BufferView *rhs;
+    int mem_diff;
+
+    lhs = a;
+    rhs = b;
+    mem_diff = am_memcmp(lhs->data, rhs->data, MIN(lhs->size, rhs->size));
+    if(mem_diff == 0)
+        return (int)lhs->size - (int)rhs->size;
+    else
+        return mem_diff;
+}