From 70022ae1f64fe026811847d4c69a91f22ccc8b04 Mon Sep 17 00:00:00 2001
From: "Glenn Y. Rolland" <glenn.rolland@netcat.io>
Date: Fri, 20 May 2016 00:02:49 +0200
Subject: [PATCH] Added basic implementation of hash table.

---
 src/hashtable-simple.c | 144 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 src/hashtable-simple.c

diff --git a/src/hashtable-simple.c b/src/hashtable-simple.c
new file mode 100644
index 0000000..7c72149
--- /dev/null
+++ b/src/hashtable-simple.c
@@ -0,0 +1,144 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct hashcell_t {
+	char key[128];
+	void * value;
+	struct hashcell_t* next;
+} HASHCELL;
+
+typedef struct {
+	int capacity;
+	int size;
+	HASHCELL** data;
+} HASHTABLE;
+
+int hash_of_key(HASHTABLE* hashtable, char * key) {
+	return 0;
+}
+
+HASHTABLE* hashtable_create(int capacity) {
+	HASHTABLE * hashtable;
+	printf("hashtable_create -- %d\n", capacity);
+
+	hashtable = malloc(sizeof(HASHTABLE));
+	if (!hashtable) return NULL;
+	memset(hashtable, 0, sizeof(HASHTABLE));
+
+	hashtable->data = malloc(capacity * sizeof(HASHCELL*));
+	if (!hashtable->data) return NULL;
+	memset(hashtable->data, 0, capacity * sizeof(HASHCELL*));
+
+	hashtable->capacity = capacity;
+	hashtable->size = 0;
+
+	printf("hashtable_create -- done\n");
+	return hashtable;
+}
+
+void hashtable_destroy(HASHTABLE* hashtable) {
+	printf("hashtable_destroy(%p) -- \n", (void*)hashtable);
+	if (!hashtable) return;
+	if (!hashtable->data) return;
+	free(hashtable->data);
+	free(hashtable);
+	printf("hashtable_destroy(%p) -- done\n", (void*)hashtable);
+}
+
+void hashtable_rehash(HASHTABLE* hashtable) {
+	return;
+}
+
+int hashtable_set(HASHTABLE* hashtable, char* key, void * value) {
+	int idx;
+	HASHCELL* cell;
+
+	printf("hashtable_set(%s, %p) -- \n", key, (void*)value);
+	// get position in hashtable
+	idx = hash_of_key(hashtable, key);
+	hashtable->size += 1;
+
+	printf("hashtable_set -- search value [%d/%d]\n", idx, hashtable->capacity);
+	// search value
+	cell = hashtable->data[idx];
+	while(cell) {
+		if (strcmp(cell->key, key) == 0) { break; }
+		cell = cell->next;
+	}
+
+	if (cell) {
+		// if cell exists, then change inner value
+		printf("hashtable_set -- update value\n");
+	} else {
+		printf("hashtable_set -- create value\n");
+		// create cell & prepend it to the chain
+		cell = malloc(sizeof(HASHCELL));
+		if (!cell) return -1;
+		memset(cell, 0, sizeof(HASHCELL));
+
+		cell->next = hashtable->data[idx];
+		cell->value = value; 
+		strcpy(cell->key, key);
+		hashtable->data[idx] = cell;
+		printf("hashtable_set -- cell@%p{key=%s, value=%p, next=%p}\n", 
+				(void*)cell,
+				cell->key,
+				(void*)cell->value,
+				(void*)cell->next);
+	}
+	printf("hashtable_set -- done\n");
+
+	return 0;
+}
+
+void * hashtable_get(HASHTABLE* hashtable, char* key) {
+	int idx;
+	HASHCELL* cell;
+	printf("hashtable_get(%p, %p) -- \n", hashtable, key);
+	idx = hash_of_key(hashtable, key);
+	cell = hashtable->data[idx];
+	while(cell) {
+		printf("hashtable_get(...) -- cell@%p{key=%s, value=%p, next=%p}\n", 
+				(void*)cell,
+				cell->key,
+				cell->value,
+				cell->next);
+		if (strcmp(cell->key, key) == 0) { break; }
+		cell = cell->next;
+	}
+	if (cell) { 
+		return cell->value;
+	} else {
+		printf("hashtable_get(...) -- cell not found\n");
+		return NULL;
+	}
+}
+
+int main(int argc, char** argv) {
+	HASHTABLE * hashtable;
+	int x=1, y=2, z=3;
+	int* value;
+
+	printf("Run !\n");
+	hashtable = hashtable_create(1000);
+	hashtable_destroy(hashtable);
+
+	hashtable = hashtable_create(100);
+	hashtable_set(hashtable, "alice", &x);
+	printf("h['alice'] <- %d\n", x);
+	hashtable_set(hashtable, "bob", &y);
+	printf("h['bob'] <- %d\n", x);
+	hashtable_set(hashtable, "charlie", &z);
+	printf("h['charlie'] <- %d\n", x);
+	hashtable_set(hashtable, "alice", &y);
+	value = hashtable_get(hashtable, "alice"); 
+	printf("h['alice'] ? %d\n", *value);
+	value = hashtable_get(hashtable, "bob"); 
+	printf("h['bob'] ? %d\n", *value);
+	value = hashtable_get(hashtable, "charlie"); 
+	printf("h['charlie'] ? %d\n", *value);
+
+	return EXIT_SUCCESS;
+}
+