Major update: Column aliases. Columns are now identified in the context

of a view by an alias that can be modified.

src/hashtable.c

@@ -0,0 +1,197 @@
+/****************************************************************************
+ * Hash table source file	                                                *
+ ****************************************************************************/
+
+/**
+ * @file hashtable.c
+ * @author Celine Mercier
+ * @date July 26th 2016
+ * @brief Source file for hash table functions.
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include "string.h"
+
+#include "murmurhash2.h"
+#include "hashtable.h"
+
+
+// Create a new hashtable
+hashtable_p ht_create(size_t size)
+{
+	hashtable_p hashtable = NULL;
+	size_t		i;
+
+	// Allocate the table
+	hashtable = malloc(sizeof(hashtable_t));
+	if (hashtable == NULL)
+		return NULL;
+
+	// Allocate the head nodes
+	hashtable->table = malloc(size * sizeof(entry_p));
+	if (hashtable->table == NULL)
+		return NULL;
+
+	// Initialize the head nodes
+	for (i=0; i<size; i++)
+		hashtable->table[i] = NULL;
+
+	hashtable->size = size;
+
+	return hashtable;
+}
+
+
+// Create an entry
+entry_p ht_new_entry(const char* key, void* value)
+{
+	entry_p new_entry;
+
+	new_entry = malloc(sizeof(entry_t));
+	if (new_entry == NULL)
+		return NULL;
+
+	new_entry->key = strdup(key);
+	if (new_entry->key == NULL)
+		return NULL;
+
+	new_entry->value = value;
+
+	new_entry->next = NULL;
+
+	return new_entry;
+}
+
+
+// Delete an entry
+int ht_delete_entry(hashtable_p hashtable, const char* key)
+{
+	entry_p last  = NULL;
+	entry_p entry = NULL;
+	size_t  bin   = 0;
+
+	bin = murmurhash2(key, strlen(key), SEED);
+	bin = bin % hashtable->size;
+
+	// Step through the bin looking for the value
+	entry = hashtable->table[bin];
+
+	while ((entry != NULL) && (strcmp(key, entry->key ) != 0))
+	{
+		last = entry;
+		entry = entry->next;
+	}
+
+	if (entry == NULL)	// key not found
+		return -1;
+
+	// Link the entries before and after the entry
+	if (last != NULL)	// If not head node
+		last->next = entry->next;
+	else	// If head node
+		hashtable->table[bin] = entry->next;
+
+	// Free the entry
+	free(entry->key);
+	free(entry->value);
+	free(entry);
+
+	return 0;
+}
+
+
+// Set a new entry in the hash table. If the key is already in the table, the value is replaced by the new one
+int ht_set(hashtable_p hashtable, const char* key, void* value)
+{
+	size_t  bin       = 0;
+	entry_p new_entry = NULL;
+	entry_p next      = NULL;
+	entry_p last      = NULL;
+
+	if ((key == NULL) || (value == NULL))
+		return -1;
+
+	bin = murmurhash2(key, strlen(key), SEED);
+	bin = bin % hashtable->size;
+
+	next = hashtable->table[bin];
+
+	while ((next != NULL) && (strcmp(key, next->key) != 0))
+	{
+		last = next;
+		next = next->next;
+	}
+
+	// If the key is already in the table, the value is replaced
+	if ((next != NULL) && (strcmp(key, next->key) == 0))
+		new_entry->value = value;
+
+	// Else, create the new entry and link it at the end of the list
+	else
+	{
+		// Create the new entry
+		new_entry = ht_new_entry(key, value);
+		if (new_entry == NULL)
+			return -1;
+
+		// If it is the first entry of that bin, we're at the head node of the list, and we replace it with the new entry
+		if (last == NULL)
+			hashtable->table[bin] = new_entry;
+
+		// Else link the new entry at the end of the list
+		else
+			last->next = new_entry;
+	}
+	return 0;
+}
+
+
+// Retrieve a value from a hash table
+void* ht_get(hashtable_p hashtable, const char* key)
+{
+	size_t  bin = 0;
+	entry_p entry;
+
+	bin = murmurhash2(key, strlen(key), SEED);
+	bin = bin % hashtable->size;
+
+	// Step through the bin looking for the value
+	entry = hashtable->table[bin];
+
+	while ((entry != NULL) && (strcmp(key, entry->key ) != 0))
+		entry = entry->next;
+
+	if (entry == NULL)
+		return NULL;
+
+	else
+		return entry->value;
+}
+
+
+// Free the hash table
+void ht_free(hashtable_p hashtable)
+{
+	size_t  i;
+	entry_p entry;
+	entry_p next;
+
+	for (i=0; i < hashtable->size; i++)
+	{
+		next = hashtable->table[i];
+		while (next != NULL)
+		{
+			entry = next;
+			free(entry->key);
+			next = entry->next;
+			free(entry);
+		}
+	}
+	free(hashtable->table);
+	free(hashtable);
+}
+
+