From 8447522dc230a9ce2187f648acd4385396c85f54 Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Wed, 21 Dec 2016 01:07:47 -0800
Subject: [PATCH] Add and implement a hash table.

---
 CMakeLists.txt |   2 +-
 include/ht.h   |  39 +++++++++++++++
 src/ht.c       | 129 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 169 insertions(+), 1 deletion(-)
 create mode 100644 include/ht.h
 create mode 100644 src/ht.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 42907ae..c4f2349 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ project(libds)
 
 include_directories(include)
 
-add_library(ds src/libds.c src/vec.c)
+add_library(ds src/libds.c src/vec.c src/ht.c)
 add_executable(libds src/main.c)
 
 target_link_libraries(libds ds)
diff --git a/include/ht.h b/include/ht.h
new file mode 100644
index 0000000..bbab4f7
--- /dev/null
+++ b/include/ht.h
@@ -0,0 +1,39 @@
+#ifndef LIBDS_HT_HEADER
+#define LIBDS_HT_HEADER
+
+#define LIBDS_HT_SIZE 32
+
+#include "libds.h"
+
+struct ht_node_s {
+    void* key;
+    void* data;
+    struct ht_node_s*  next;
+};
+
+struct ht_s {
+    struct ht_node_s* data[LIBDS_HT_SIZE];
+    unsigned int (*hash_func)(void*);
+    int (*cmp_func)(void*, void*);
+    void* (*copy_func)(void*);
+    void (*free_func)(void*);
+};
+
+typedef struct ht_node_s ht_node;
+typedef struct ht_s ht;
+
+unsigned int ht_default_hash_func(void*);
+int  ht_default_cmp_func(void*, void*);
+void*  ht_default_copy_func(void*);
+void ht_default_free_func(void*);
+
+void ht_init(ht*);
+void ht_free(ht*);
+
+libds_result ht_put(ht*, void*, void*);
+void* ht_get(ht*, void*);
+void ht_remove(ht*, void*);
+
+int ht_foreach(ht*, void*, compare_func, foreach_func, ...);
+
+#endif
diff --git a/src/ht.c b/src/ht.c
new file mode 100644
index 0000000..3347953
--- /dev/null
+++ b/src/ht.c
@@ -0,0 +1,129 @@
+#include "ht.h"
+#include <string.h>
+#include <stdlib.h>
+
+unsigned int ht_default_hash_func(void* data){
+    const unsigned int fnv_prime = 16777619;
+    const unsigned int fnv_offset_basis = 2166136261;
+    unsigned int hash;
+    char* string;
+    hash = fnv_offset_basis;
+    string = data;
+    while (*string) {
+        hash = hash * fnv_prime;
+        hash = hash ^ (*(string++));
+    }
+    return hash;
+}
+int ht_default_cmp_func(void* a, void* b){
+    return strcmp(a, b) == 0;
+}
+void* ht_default_copy_func(void* from) {
+    void* copy = malloc(sizeof(char) * (strlen(from) + 1));
+    if(copy) {
+        strcpy(copy, from);
+    }
+    return copy;
+}
+void ht_default_free_func(void* data){
+    free(data);
+}
+
+void ht_init(ht* ht){
+    ht->cmp_func = ht_default_cmp_func;
+    ht->copy_func = ht_default_copy_func;
+    ht->free_func = ht_default_free_func;
+    ht->hash_func = ht_default_hash_func;
+    memset(ht->data, 0, sizeof(ht->data));
+}
+void ht_free(ht* ht){
+    int index = 0;
+    for(; index < LIBDS_HT_SIZE; index++){
+        ht_node* head = ht->data[index];
+        while(head){
+            ht_node* to_delete = head;
+            head = head->next;
+            ht->free_func(to_delete->key);
+            free(to_delete);
+        }
+    }
+}
+
+libds_result ht_put(ht* ht, void* key, void* data){
+    libds_result result = SUCCESS;
+    ht_node* new_node = NULL;
+    unsigned int key_int = ht->hash_func(key) % LIBDS_HT_SIZE;
+
+
+    new_node = malloc(sizeof(*new_node));
+    if(new_node) {
+        new_node->data = data;
+        new_node->key = ht->copy_func(key);
+        if(new_node->key == NULL){
+            result = MALLOC;
+        }
+    } else {
+        result = MALLOC;
+    }
+
+    if(result != SUCCESS) {
+        if(new_node) {
+            free(new_node);
+            new_node = NULL;
+        }
+    } else {
+        new_node->next = ht->data[key_int];
+        ht->data[key_int] = new_node;
+    }
+
+    return result;
+}
+void* ht_get(ht* ht, void* key) {
+    void* data = NULL;
+    ht_node* search_node;
+    unsigned int key_int = ht->hash_func(key) % LIBDS_HT_SIZE;
+
+    search_node =  ht->data[key_int];
+    while(search_node && data == NULL){
+        if(ht->cmp_func(search_node->key, key)) {
+            data = search_node->data;
+        }
+        search_node = search_node->next;
+    }
+
+    return data;
+}
+void ht_remove(ht* ht, void* key){
+    ht_node** search_ptr;
+    unsigned int key_int = ht->hash_func(key) % LIBDS_HT_SIZE;
+
+    search_ptr = &ht->data[key_int];
+    while(*search_ptr){
+        if(ht->cmp_func((*search_ptr)->key, key)){
+            ht_node* to_delete = *search_ptr;
+            *search_ptr = (*search_ptr)->next;
+            ht->free_func(to_delete->key);
+            free(to_delete);
+        } else {
+            search_ptr = &(*search_ptr)->next;
+        }
+    }
+}
+
+int ht_foreach(ht* ht, void* data, compare_func compare, foreach_func foreach, ...){
+    int index = 0;
+    int return_code = 0;
+    va_list args;
+    for(; index < LIBDS_HT_SIZE && return_code == 0; index++){
+        ht_node* search_node = ht->data[index];
+        while(search_node && return_code == 0){
+            if(compare(data, search_node->data)) {
+                va_start(args, foreach);
+                return_code = foreach(search_node->data, args);
+                va_end(args);
+            }
+            search_node = search_node->next;
+        }
+    }
+    return return_code;
+}
\ No newline at end of file