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hash_table.cpp@1:10330bce85cb, 2020-10-23 (annotated)

Committer:
DCchico
Date:
Fri Oct 23 16:18:39 2020 -0400
Revision:
1:10330bce85cb
Child:
2:4947d6a82971
shell-code

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DCchico 1:10330bce85cb 1 /*
DCchico 1:10330bce85cb 2 Student Name:
DCchico 1:10330bce85cb 3 Date:
DCchico 1:10330bce85cb 4
DCchico 1:10330bce85cb 5 =======================
DCchico 1:10330bce85cb 6 ECE 2035 Project 2-1:
DCchico 1:10330bce85cb 7 =======================
DCchico 1:10330bce85cb 8 This file provides definition for the structs and functions declared in the
DCchico 1:10330bce85cb 9 header file. It also contains helper functions that are not accessible from
DCchico 1:10330bce85cb 10 outside of the file.
DCchico 1:10330bce85cb 11
DCchico 1:10330bce85cb 12 FOR FULL CREDIT, BE SURE TO TRY MULTIPLE TEST CASES and DOCUMENT YOUR CODE.
DCchico 1:10330bce85cb 13
DCchico 1:10330bce85cb 14 ===================================
DCchico 1:10330bce85cb 15 Naming conventions in this file:
DCchico 1:10330bce85cb 16 ===================================
DCchico 1:10330bce85cb 17 1. All struct names use camel case where the first letter is capitalized.
DCchico 1:10330bce85cb 18 e.g. "HashTable", or "HashTableEntry"
DCchico 1:10330bce85cb 19
DCchico 1:10330bce85cb 20 2. Variable names with a preceding underscore "_" will not be called directly.
DCchico 1:10330bce85cb 21 e.g. "_HashTable", "_HashTableEntry"
DCchico 1:10330bce85cb 22
DCchico 1:10330bce85cb 23 Recall that in C, we have to type "struct" together with the name of the struct
DCchico 1:10330bce85cb 24 in order to initialize a new variable. To avoid this, in hash_table.h
DCchico 1:10330bce85cb 25 we use typedef to provide new "nicknames" for "struct _HashTable" and
DCchico 1:10330bce85cb 26 "struct _HashTableEntry". As a result, we can create new struct variables
DCchico 1:10330bce85cb 27 by just using:
DCchico 1:10330bce85cb 28 - "HashTable myNewTable;"
DCchico 1:10330bce85cb 29 or
DCchico 1:10330bce85cb 30 - "HashTableEntry myNewHashTableEntry;"
DCchico 1:10330bce85cb 31
DCchico 1:10330bce85cb 32 The preceding underscore "_" simply provides a distinction between the names
DCchico 1:10330bce85cb 33 of the actual struct defition and the "nicknames" that we use to initialize
DCchico 1:10330bce85cb 34 new structs.
DCchico 1:10330bce85cb 35 [See Hidden Definitions section for more information.]
DCchico 1:10330bce85cb 36
DCchico 1:10330bce85cb 37 3. Functions, their local variables and arguments are named with camel case, where
DCchico 1:10330bce85cb 38 the first letter is lower-case.
DCchico 1:10330bce85cb 39 e.g. "createHashTable" is a function. One of its arguments is "numBuckets".
DCchico 1:10330bce85cb 40 It also has a local variable called "newTable".
DCchico 1:10330bce85cb 41
DCchico 1:10330bce85cb 42 4. The name of a struct member is divided by using underscores "_". This serves
DCchico 1:10330bce85cb 43 as a distinction between function local variables and struct members.
DCchico 1:10330bce85cb 44 e.g. "num_buckets" is a member of "HashTable".
DCchico 1:10330bce85cb 45
DCchico 1:10330bce85cb 46 */
DCchico 1:10330bce85cb 47
DCchico 1:10330bce85cb 48 /****************************************************************************
DCchico 1:10330bce85cb 49 * Include the Public Interface
DCchico 1:10330bce85cb 50 *
DCchico 1:10330bce85cb 51 * By including the public interface at the top of the file, the compiler can
DCchico 1:10330bce85cb 52 * enforce that the function declarations in the the header are not in
DCchico 1:10330bce85cb 53 * conflict with the definitions in the file. This is not a guarantee of
DCchico 1:10330bce85cb 54 * correctness, but it is better than nothing!
DCchico 1:10330bce85cb 55 ***************************************************************************/
DCchico 1:10330bce85cb 56 #include "hash_table.h"
DCchico 1:10330bce85cb 57
DCchico 1:10330bce85cb 58
DCchico 1:10330bce85cb 59 /****************************************************************************
DCchico 1:10330bce85cb 60 * Include other private dependencies
DCchico 1:10330bce85cb 61 *
DCchico 1:10330bce85cb 62 * These other modules are used in the implementation of the hash table module,
DCchico 1:10330bce85cb 63 * but are not required by users of the hash table.
DCchico 1:10330bce85cb 64 ***************************************************************************/
DCchico 1:10330bce85cb 65 #include <stdlib.h> // For malloc and free
DCchico 1:10330bce85cb 66 #include <stdio.h> // For printf
DCchico 1:10330bce85cb 67
DCchico 1:10330bce85cb 68
DCchico 1:10330bce85cb 69 /****************************************************************************
DCchico 1:10330bce85cb 70 * Hidden Definitions
DCchico 1:10330bce85cb 71 *
DCchico 1:10330bce85cb 72 * These definitions are not available outside of this file. However, because
DCchico 1:10330bce85cb 73 * the are forward declared in hash_table.h, the type names are
DCchico 1:10330bce85cb 74 * available everywhere and user code can hold pointers to these structs.
DCchico 1:10330bce85cb 75 ***************************************************************************/
DCchico 1:10330bce85cb 76 /**
DCchico 1:10330bce85cb 77 * This structure represents an a hash table.
DCchico 1:10330bce85cb 78 * Use "HashTable" instead when you are creating a new variable. [See top comments]
DCchico 1:10330bce85cb 79 */
DCchico 1:10330bce85cb 80 struct _HashTable {
DCchico 1:10330bce85cb 81 /** The array of pointers to the head of a singly linked list, whose nodes
DCchico 1:10330bce85cb 82 are HashTableEntry objects */
DCchico 1:10330bce85cb 83 HashTableEntry** buckets;
DCchico 1:10330bce85cb 84
DCchico 1:10330bce85cb 85 /** The hash function pointer */
DCchico 1:10330bce85cb 86 HashFunction hash;
DCchico 1:10330bce85cb 87
DCchico 1:10330bce85cb 88 /** The number of buckets in the hash table */
DCchico 1:10330bce85cb 89 unsigned int num_buckets;
DCchico 1:10330bce85cb 90 };
DCchico 1:10330bce85cb 91
DCchico 1:10330bce85cb 92 /**
DCchico 1:10330bce85cb 93 * This structure represents a hash table entry.
DCchico 1:10330bce85cb 94 * Use "HashTableEntry" instead when you are creating a new variable. [See top comments]
DCchico 1:10330bce85cb 95 */
DCchico 1:10330bce85cb 96 struct _HashTableEntry {
DCchico 1:10330bce85cb 97 /** The key for the hash table entry */
DCchico 1:10330bce85cb 98 unsigned int key;
DCchico 1:10330bce85cb 99
DCchico 1:10330bce85cb 100 /** The value associated with this hash table entry */
DCchico 1:10330bce85cb 101 void* value;
DCchico 1:10330bce85cb 102
DCchico 1:10330bce85cb 103 /**
DCchico 1:10330bce85cb 104 * A pointer pointing to the next hash table entry
DCchico 1:10330bce85cb 105 * NULL means there is no next entry (i.e. this is the tail)
DCchico 1:10330bce85cb 106 */
DCchico 1:10330bce85cb 107 HashTableEntry* next;
DCchico 1:10330bce85cb 108 };
DCchico 1:10330bce85cb 109
DCchico 1:10330bce85cb 110
DCchico 1:10330bce85cb 111 /****************************************************************************
DCchico 1:10330bce85cb 112 * Private Functions
DCchico 1:10330bce85cb 113 *
DCchico 1:10330bce85cb 114 * These functions are not available outside of this file, since they are not
DCchico 1:10330bce85cb 115 * declared in hash_table.h.
DCchico 1:10330bce85cb 116 ***************************************************************************/
DCchico 1:10330bce85cb 117 /**
DCchico 1:10330bce85cb 118 * createHashTableEntry
DCchico 1:10330bce85cb 119 *
DCchico 1:10330bce85cb 120 * Helper function that creates a hash table entry by allocating memory for it on
DCchico 1:10330bce85cb 121 * the heap. It initializes the entry with key and value, initialize pointer to
DCchico 1:10330bce85cb 122 * the next entry as NULL, and return the pointer to this hash table entry.
DCchico 1:10330bce85cb 123 *
DCchico 1:10330bce85cb 124 * @param key The key corresponds to the hash table entry
DCchico 1:10330bce85cb 125 * @param value The value stored in the hash table entry
DCchico 1:10330bce85cb 126 * @return The pointer to the hash table entry
DCchico 1:10330bce85cb 127 */
DCchico 1:10330bce85cb 128 static HashTableEntry* createHashTableEntry(unsigned int key, void* value) {
DCchico 1:10330bce85cb 129
DCchico 1:10330bce85cb 130 }
DCchico 1:10330bce85cb 131
DCchico 1:10330bce85cb 132 /**
DCchico 1:10330bce85cb 133 * findItem
DCchico 1:10330bce85cb 134 *
DCchico 1:10330bce85cb 135 * Helper function that checks whether there exists the hash table entry that
DCchico 1:10330bce85cb 136 * contains a specific key.
DCchico 1:10330bce85cb 137 *
DCchico 1:10330bce85cb 138 * @param hashTable The pointer to the hash table.
DCchico 1:10330bce85cb 139 * @param key The key corresponds to the hash table entry
DCchico 1:10330bce85cb 140 * @return The pointer to the hash table entry, or NULL if key does not exist
DCchico 1:10330bce85cb 141 */
DCchico 1:10330bce85cb 142 static HashTableEntry* findItem(HashTable* hashTable, unsigned int key) {
DCchico 1:10330bce85cb 143
DCchico 1:10330bce85cb 144 }
DCchico 1:10330bce85cb 145
DCchico 1:10330bce85cb 146 /****************************************************************************
DCchico 1:10330bce85cb 147 * Public Interface Functions
DCchico 1:10330bce85cb 148 *
DCchico 1:10330bce85cb 149 * These functions implement the public interface as specified in the header
DCchico 1:10330bce85cb 150 * file, and make use of the private functions and hidden definitions in the
DCchico 1:10330bce85cb 151 * above sections.
DCchico 1:10330bce85cb 152 ****************************************************************************/
DCchico 1:10330bce85cb 153 // The createHashTable is provided for you as a starting point.
DCchico 1:10330bce85cb 154 HashTable* createHashTable(HashFunction hashFunction, unsigned int numBuckets) {
DCchico 1:10330bce85cb 155 // The hash table has to contain at least one bucket. Exit gracefully if
DCchico 1:10330bce85cb 156 // this condition is not met.
DCchico 1:10330bce85cb 157 if (numBuckets==0) {
DCchico 1:10330bce85cb 158 printf("Hash table has to contain at least 1 bucket...\n");
DCchico 1:10330bce85cb 159 exit(1);
DCchico 1:10330bce85cb 160 }
DCchico 1:10330bce85cb 161
DCchico 1:10330bce85cb 162 // Allocate memory for the new HashTable struct on heap.
DCchico 1:10330bce85cb 163 HashTable* newTable = (HashTable*)malloc(sizeof(HashTable));
DCchico 1:10330bce85cb 164
DCchico 1:10330bce85cb 165 // Initialize the components of the new HashTable struct.
DCchico 1:10330bce85cb 166 newTable->hash = hashFunction;
DCchico 1:10330bce85cb 167 newTable->num_buckets = numBuckets;
DCchico 1:10330bce85cb 168 newTable->buckets = (HashTableEntry**)malloc(numBuckets*sizeof(HashTableEntry*));
DCchico 1:10330bce85cb 169
DCchico 1:10330bce85cb 170 // As the new buckets are empty, init each bucket as NULL.
DCchico 1:10330bce85cb 171 unsigned int i;
DCchico 1:10330bce85cb 172 for (i=0; i<numBuckets; ++i) {
DCchico 1:10330bce85cb 173 newTable->buckets[i] = NULL;
DCchico 1:10330bce85cb 174 }
DCchico 1:10330bce85cb 175
DCchico 1:10330bce85cb 176 // Return the new HashTable struct.
DCchico 1:10330bce85cb 177 return newTable;
DCchico 1:10330bce85cb 178 }
DCchico 1:10330bce85cb 179
DCchico 1:10330bce85cb 180 void destroyHashTable(HashTable* hashTable) {
DCchico 1:10330bce85cb 181
DCchico 1:10330bce85cb 182 }
DCchico 1:10330bce85cb 183
DCchico 1:10330bce85cb 184 void* insertItem(HashTable* hashTable, unsigned int key, void* value) {
DCchico 1:10330bce85cb 185 }
DCchico 1:10330bce85cb 186
DCchico 1:10330bce85cb 187 void* getItem(HashTable* hashTable, unsigned int key) {
DCchico 1:10330bce85cb 188
DCchico 1:10330bce85cb 189 }
DCchico 1:10330bce85cb 190
DCchico 1:10330bce85cb 191 void* removeItem(HashTable* hashTable, unsigned int key) {
DCchico 1:10330bce85cb 192
DCchico 1:10330bce85cb 193 }
DCchico 1:10330bce85cb 194
DCchico 1:10330bce85cb 195 void deleteItem(HashTable* hashTable, unsigned int key) {
DCchico 1:10330bce85cb 196
DCchico 1:10330bce85cb 197 }