What is the status of fpc generics.collections.

Gennady Agranov11-24-2014 21:57 UTC

Hi,

I have found the old announcement about fpc-generics-collections, but all links are broken...

What is the status of this project?

Is it still downloadable?

Thank you,
Gennady
[fpc devel] Library announcement: Generics.Collections

Maciej Izak

Wed,
22 May 2013 12:45:20 -0700

Hi Free Pascal community!

I'm pleased to announce the generic library, compatible with Delphi Generics.Collections (almost ;) ).

Homepage
https://code.google.com/p/fpc-generics-collections/

SVN
http://fpc-generics-collections.googlecode.com/svn/trunk/

=== modules ===

Generics.Defaults
Generics.Collections
Generics.Helpers
Generics.Hashes

=== compatible classes ===

TEnumerator<T>
TEnumerable<T>
TList<T>
TQueue<T>
TStack<T>
TDictionary<TKey, TValue>
TObjectList<T: TObject>
TObjectStack<T: TObject>
TObjectDictionary<TKey, TValue>

=== renamed (because compiler limations/bug) ===

TArrayHelper<T> instead of TArray<T>

=== additional classes ===
************
TDictionary<TKey, TValue, TProbeSequence, THash, THashFactory> TObjectDictionary<TKey, TValue, TProbeSequence, THash, THashFactory>

TKey - key, TValue - value, THashFactory - hash factory :) TProbeSequence - TProbeSequence is special record for open addresing. To choose from a predefined:
TLinearProbing, TQuadraticProbing, TDoubleHashing, TFastLinearProbing, TFastQuadraticProbing, TFastDoubleHashing (fast version is without "mod")
more info at http://en.wikipedia.org/wiki/Open_addressing THash - type for hash (to reduce size of dictionary - can be UInt8, UInt16, UInt32 etc.)

For example, Delphi TDictionary version in this library is defined as: TDictionary<TKey, TValue> = class(TDictionary<TKey, TValue, TFastLinearProbing, UInt32, TDelphiHashFactory>);
************
TDictionaryList<TKey, TValue, TIndex, THash, THashFactory> class, that combines a TList and TDictionary

TKey - key, TValue - value, THashFactory - hash factory :) TIndex - type for index (to reduce size of dictionary - can be UInt8, UInt16, UInt32 etc.)
THash - type for hash (to reduce size of dictionary - can be UInt8, UInt16, UInt32 etc.)
************
Similar to TList, TDictionary and TDictionaryList, but uses normal operators instead of IEqualityComparer.

TFastList
TFastDictionary
TFastDictionaryList
************
TFastArrayHelper<T> - similar rules as above

=== not implemented ===

TThreadedQueue<T>

=== FAQ ===

1. How to use record as Key or Value in dictionary?

You need to wait for some compiler magic ( system functions GetReferenceToValue and GetValueSize described bolow) or add two methods to record:

    TRecord = record
      (* ... *)
      function GetValueSize: Integer; inline;
      function GetReferenceToValue: Pointer; inline;
    end;

2. How to use Pointer or some custom type as Key or Value in dictionary?

You need to wait for some compiler magic ( system functions GetReferenceToValue and GetValueSize described bolow) or use TValueHelper:

    uses
      Generics.Collections, Generics.Helpers;
    (* ... *)
      type
        TValueHelperPointer = TValueHelper<Pointer>;
      var
        d: TDictionary<TValueHelperPointer, string>;
      begin
        (* ... *)
        d.Add(nil, 'foo');

=== TODO ===

Comparer from Generics.Defaults can be optimized.

I have no knowledge of FPC compiler design, so i need a little help...

First thing : To finish my work I need critical compiler magic functions/feature. At first look mayby there is no sense for this functions but during work on Generic library it's necessary:

  function GetReferenceToValue(Value: T): Pointer; // for string types

return @s[1] or nil for empty string for Int32 return @i etc. returns a reference to the value, as

measured by human/programmer

  function GetValueSize(Value: T): Integer; // for string types return

Length(s), for Int32 returs 4 etc.

This functions should be implemented as operators (like Inc, Dec operators).

There is half-workaround/cripled solution as record/type helpers (module Generics.Helpers). Don't work for custom strings, and for custom "basic" types like:

  type MyStr = type string;
  type MyInt = type Int32;

Second thing: Bugs. Look at Critical - fix is needed to perform compatibility with Delphi and proper work.

Regards, HNB

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What is the status of fpc generics.collections.