• Marcel (7/7) Feb 12 2020 Hello!
• user1234 (6/13) Feb 12 2020 alias Concatenated = AliasSeq!(TList1, TList2);
• H. S. Teoh (6/13) Feb 12 2020 [...]
• Paul Backus (4/8) Feb 12 2020 It's an open-addressed hash table. If you want to see all the
• Steven Schveighoffer (8/17) Feb 13 2020 For some background, collisions used to be handled via a BST, which

Marcel <marcelpi97 gmail.com> writes:

Hello!
I have two questions:

1- How can I concatenate two type sequences?

2- How is the builtin associative array implemented? I think I 
read somewhere it's implemented like C++'s std::unordered_map but 
with BSTs instead of DLists for handling collisions: is this 
correct?

user1234 <user1234 12.de> writes:

On Wednesday, 12 February 2020 at 20:58:49 UTC, Marcel wrote:
 Hello!
 I have two questions:

 1- How can I concatenate two type sequences?

alias Concatenated = AliasSeq!(TList1, TList2);

or maybe

alias Concatenated = AliasSeq!(TList1[0..$], TList2[0..$]);

since I don't remember if they nest or not.

 2- How is the builtin associative array implemented? I think I 
 read somewhere it's implemented like C++'s std::unordered_map 
 but with BSTs instead of DLists for handling collisions: is 
 this correct?

see druntime source.

"H. S. Teoh" <hsteoh quickfur.ath.cx> writes:

On Wed, Feb 12, 2020 at 09:05:22PM +0000, user1234 via Digitalmars-d-learn
wrote:
 On Wednesday, 12 February 2020 at 20:58:49 UTC, Marcel wrote:
 Hello!
 I have two questions:
 
 1- How can I concatenate two type sequences?

 
 alias Concatenated = AliasSeq!(TList1, TList2);

[...]

This is correct. They always auto-expand, and thus do not nest.


T

-- 
Let X be the set not defined by this sentence...

Paul Backus <snarwin gmail.com> writes:

On Wednesday, 12 February 2020 at 20:58:49 UTC, Marcel wrote:
 2- How is the builtin associative array implemented? I think I 
 read somewhere it's implemented like C++'s std::unordered_map 
 but with BSTs instead of DLists for handling collisions: is 
 this correct?

It's an open-addressed hash table. If you want to see all the 
details, the source is here:

https://github.com/dlang/druntime/blob/v2.090.1/src/rt/aaA.d

Steven Schveighoffer <schveiguy gmail.com> writes:

On 2/12/20 5:47 PM, Paul Backus wrote:
 On Wednesday, 12 February 2020 at 20:58:49 UTC, Marcel wrote:
 2- How is the builtin associative array implemented? I think I read 
 somewhere it's implemented like C++'s std::unordered_map but with BSTs 
 instead of DLists for handling collisions: is this correct?

 
 It's an open-addressed hash table. If you want to see all the details, 
 the source is here:
 
 https://github.com/dlang/druntime/blob/v2.090.1/src/rt/aaA.d

For some background, collisions used to be handled via a BST, which 
required all AA keys to provide opCmp in addition to opEquals and toHash.

It was changed some time ago (maybe like 8 years ago? Can't remember) to 
be open addressed hash, thus removing the requirement for opCmp.

This is probably why you read something about the old implementation 
using BST.

-Steve