HashOf is a Cardinal function used to calculate and return the 32-bit hash value for the String in Key. HashOf examines all bytes values in Key (in reverse order). When CaseSensitive is set to False, the characters are converted to their uppercase equivalent for use in the hashing algorithm. Range and overflow checking are disabled in the HashOf method.

HashOf is used in the Add method to calculate the HashValue stored in the PStringHashItem entry for the hash item. It is also used in the Find method to get the hash value to locate in the storage for the List.

Insert is a method used to store the pointer in Item to the internal storage in List. Insert re-allocates the memory used for List to include the addition space needed for the new item.

Index contains the ordinal position in List where the PStringHashItem instance is stored. Index must be in the range 0..Count. When Index has the value in Count, Insert behaves like an Append operation in the List. The value Index is adjusted if it exceeds either range limit.

When Index is not the newly added position (Count), the memory for existing entries in List are shifted upward by the size of the hash item in Item. The pointer in Item is stored in List at the ordinal position in Index.

Inserts increments the value in the Count property for the newly added item in the container.

Insert is used to implement the Add method.

Create is the constructor for the class instance. It sets the value in the CaseSensitive property to the value specified in the CaseSensitivity argument. Create calls the inherited (empty) constructor prior to exiting from the method.

Destroy is the overridden destructor for the class instance. It calls the Clear method to remove free any hash items and the storage allocated in List. Destroy calls the inherited method prior to exit.

Add is an overloaded Integer function used to store a hash item (and optional data associated with item) in the List for the container. The return value contains the ordinal position in List where the hash item was stored.

S is a String with the key used to construct the hash value.

ItemData is an untyped pointer to the optional data associated with the key.

Add allocates a new PStringHashItem instance used to represent the hash item in ItemData. Values in S and itemData are stored in the instance. HashOf is called to get the 32-bit hash value stored in the instance.

Hash items in List are stored in hash value order. When Count has a non-zero value, the hash value for the new entry is used to locate the position in List where the new entry is stored. When Count is 0, the item is always stored at position 0 in List.

Use Remove to delete a hash item in List with a given key value.

Use Find to get the position in List for a hash item with a given key value.

Use the Data property to get an untyped pointer to the arbitrary data associated with the given key value. The pointer must be cast to the type needed in the application.

Use List to access the PStringHashItemList using an ordinal position in the storage.

Clear is a method used to free resources allocated for the hash items, and the memory allocated for the List property.

Clear calls Dispose for each of the PStringHashItem instances stored in List to free the memory allocated for the typed pointer. Clear calls FreeMem to free the memory allocated for the List property, and sets the member reference to Nil.

The value in Count is set to 0 to indicate that the List is empty.

Clear is called from the Destroy method when the class instance is freed.

Find is an Integer function used to the position in List where the hash item with the specified Key value is stored. The return value contains the ordinal position for the hash item in List, or -1 when a hash item is not found for the key value in S.

S contains the key value for the hash item locates in the method. HashOf is called to get the 32-bit hash value, and BinarySearch is called to locate the hash value in List.

An overloaded variant provides an untyped pointer in Data that is also used to locate the hash item. If the value in Data does not match the stored value in List, other candidates with the same hash value are considered. A match is found when the Key and Data for the hash item are the same. Otherwise, the return value is set to -1 to indicate that a match was not found.

Find is used in the Remove method, and to implement indexed access for the Data property.

Remove is a method used to remove a hash item in List with the specified key value (and optional data).

S contains the key value to locate in the List.

Data is an untyped Pointer to the optional data associated with the key value.

Remove calls the Find method to get the ordinal position in List where the hash item is stored, or -1 when a hash item with the key (and optional data) is not found. The position is used as the return value for the method.

When a hash item was located, the Dispose routine is called to free the memory allocated for the typed Pointer to the hash item. Delete is called to remove the PHashStringItem instance and re-order the memory for hash items after the position in List. The Count property is decremented to reflect the new size for the List.

CaseSensitive is a Boolean property which indicates the case for the key values in hash items. The default value for the property is set to the argument passed to the Create constructor.

When set to False, key values are converted to their uppercase equivalent when hash values are calculate in the HashOf method. When set to True, the existing case for the key value is used.

The value in CaseSensitive must be set before hash items are added to the List. Setting a new value for the property when Count has a non-zero value causes an EListError Exception to be raised.

CaseSensitive is used in the Find method to ensure that the search uses the same logic employed when the hash item was created.

Count is a read-only Integer property which contains the number of hash items stored in List. The value is maintained when the Add, Insert, Remove, Delete, or Clear methods are called.

Count establishes the upper limit for indexed access to values in the List property; index values must be in the range 0..Count-1.

Data is an indexed Pointer property which provides access to the storage for a hash item by its key value. The untyped Pointer in the property values is arbitrary data associated with the key value, and must be cast to the type expected in an application.

The Find method is called when reading or writing a value in the property. Finds gets the position where the hash item is stored in List using the setting in the CaseSensitive property. If the value in S does not exist when reading a property value, Nil is returned. If the value in S does not exist when writing a property value, the Add method is called to create a new hash item in List with the key in S.

Data is the default property for the container, and the value used in an enumerator for the class instance.

List is a read-only indexed PStringHashItemList property which provides access to the storage used in the container. Resources in List are allocated and freed in methods like Add, Remove, Delete, and Clear.

The value is a Pointer to the first memory block allocated for the PHashStringItem instances stored in the container. The property values are accessed using the ordinal position for a given hash item.

Since the property value is a Pointer, it must be dereferenced to access the member values for a given hash item. For example: