first draft of hash table implementation

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 254 insertions, 0 deletions

diff --git a/src/libmdsserver/hash-table.h b/src/libmdsserver/hash-table.h
new file mode 100644
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+++ b/src/libmdsserver/hash-table.h
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+/**
+ * mds — A micro-display server
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef MDS_LIBMDSSERVER_HASH_TABLE_H
+#define MDS_LIBMDSSERVER_HASH_TABLE_H
+
+
+#include <stdlib.h>
+
+
+/**
+ * Hash table entry
+ */
+typedef struct hash_entry
+{
+  /**
+   * A key
+   */
+  void* key;
+  
+  /**
+   * The value associated with the key
+   */
+  void* value;
+  
+  /**
+   * The truncated hash value of the key
+   */
+  long hash;
+  
+  /**
+   * The next entry in the bucket
+   */
+  struct hash_entry* next;
+  
+} hash_entry_t;
+
+
+/**
+ * Value lookup table based on hash value, that do not support `NULL` keys nor `NULL` values
+ */
+typedef struct hash_table
+{
+  /**
+   * The table's capacity, i.e. the number of buckets
+   */
+  size_t capacity;
+  
+  /**
+   * Entry buckets
+   */
+  hash_entry_t** buckets;
+  
+  /**
+   * When, in the ratio of entries comparied to the capacity, to grow the table
+   */
+  float load_factor;
+  
+  /**
+   * When, in the number of entries, to grow the table
+   */
+  size_t threshold;
+  
+  /**
+   * The number of entries stored in the table
+   */
+  size_t size;
+  
+  /**
+   * Check whether two values are equal
+   * 
+   * If this function pointer is `NULL`, the identity is used
+   * 
+   * Be aware, this variable cannot be marshalled
+   * 
+   * @param   value_a  The first value
+   * @param   value_b  The second value
+   * @return           Whether the values are equals
+   */
+  int (*value_comparator)(const void* value_a, const void* value_b);
+  
+  /**
+   * Check whether two keys are equal
+   * 
+   * If this function pointer is `NULL`, the identity is used
+   * 
+   * Be aware, this variable cannot be marshalled
+   * 
+   * @param   key_a  The first key
+   * @param   key_b  The second key
+   * @return         Whether the keys are equals
+   */
+  int (*key_comparator)(const void* key_a, const void* key_b);
+  
+  /**
+   * Calculate the hash of a key
+   * 
+   * If this function pointer is `NULL`, the identity hash is used
+   * 
+   * Be aware, this variable cannot be marshalled
+   * 
+   * @param   key  The key
+   * @return       The hash of the key
+   */
+  long (*hasher)(const void* key);
+  
+} hash_table_t;
+
+
+
+/**
+ * Create a hash table
+ * 
+ * @param   this              Memory slot in which to store the new hash table
+ * @param   initial_capacity  The initial capacity of the table
+ * @param   load_factor       The load factor of the table, i.e. when to grow the table
+ * @return                    Non-zero on error, `errno` will have been set accordingly
+ */
+int hash_table_create_fine_tuned(hash_table_t* restrict this, size_t initial_capacity, float load_factor);
+
+/**
+ * Create a hash table
+ * 
+ * @param   this:hash_table_t*       Memory slot in which to store the new hash table
+ * @param   initial_capacity:size_t  The initial capacity of the table
+ * @return  :int                     Non-zero on error, `errno` will have been set accordingly
+ */
+#define hash_table_create_tuned(this, initial_capacity)  \
+  hash_table_create_fine_tuned(this, initial_capacity, 0.75)
+
+/**
+ * Create a hash table
+ * 
+ * @param   this:hash_table_t*  Memory slot in which to store the new hash table
+ * @return  :int                Non-zero on error, `errno` will have been set accordingly
+ */
+#define hash_table_create(this)  \
+  hash_table_create_tuned(this, 16)
+
+/**
+ * Clone a hash table
+ * 
+ * @param   this  The hash table to clone
+ * @param   out   Memory slot in which to store the new hash table
+ * @return        Non-zero on error, `errno` will have been set accordingly
+ */
+int hash_table_clone(const hash_table_t* restrict this, hash_table_t* restrict out);
+
+/**
+ * Release all resources in a hash table, should
+ * be done even if construction fails
+ * 
+ * @param  this    The hash table
+ * @param  values  Whether to free all stored values
+ * @param  keys    Whether to free all stored keys
+ */
+void hash_table_destroy(hash_table_t* restrict this, int values, int keys);
+
+/**
+ * Check whether a value is stored in the table
+ * 
+ * @param   this   The hash table
+ * @param   value  The value
+ * @return         Whether the value is stored in the table
+ */
+int hash_table_contains_value(const hash_table_t* restrict this, void* restrict value) __attribute__((pure));
+
+/**
+ * Check whether a key is used in the table
+ * 
+ * @param   this  The hash table
+ * @param   key   The key
+ * @return        Whether the key is used
+ */
+int hash_table_contains_key(const hash_table_t* restrict this, void* restrict key) __attribute__((pure));
+
+/**
+ * Look up a value in the table
+ * 
+ * @param   this  The hash table
+ * @param   key   The key associated with the value
+ * @return        The value associated with the key, `NULL` i the key was not used
+ */
+void* hash_table_get(const hash_table_t* restrict this, const void* restrict key);
+
+/**
+ * Add an entry to the table
+ * 
+ * @param   this   The hash table
+ * @param   key    The key of the entry to add
+ * @param   value  The value of the entry to add
+ * @return         The previous value associated with the key, `NULL` i the key was not used
+ */
+void* hash_table_put(hash_table_t* restrict this, void* restrict key, void* restrict value);
+
+/**
+ * Remove an entry in the table
+ * 
+ * @param   this  The hash table
+ * @param   key   The key of the entry to remove
+ * @return        The previous value associated with the key, `NULL` i the key was not used
+ */
+void* hash_table_remove(hash_table_t* restrict this, const void* restrict key);
+
+/**
+ * Remove all entries in the table
+ * 
+ * @param  this  The hash table
+ */
+void hash_table_clear(hash_table_t* restrict this);
+
+/**
+ * Calculate the buffer size need to marshal a hash table
+ * 
+ * @param   this  The hash table
+ * @return        The number of bytes to allocate to the output buffer
+ */
+size_t hash_table_marshal_size(const hash_table_t* restrict this) __attribute__((pure));
+
+/**
+ * Marshals a hash table
+ * 
+ * @param  this  The hash table
+ * @param  data  Output buffer for the marshalled data
+ */
+void hash_table_marshal(const hash_table_t* restrict this, char* restrict data);
+
+/**
+ * Unmarshals a hash table
+ * 
+ * @param   this  Memory slot in which to store the new hash table
+ * @param   data  In buffer with the marshalled data
+ * @return        Non-zero one error, errno will be set accordingly.
+ *                Destroy the list on error.
+ */
+int hash_table_unmarshal(hash_table_t* restrict this, char* restrict data);
+
+
+#endif
+