Extend Iterable instead of implementing it.

Extend Iterable instead of implementing it.

This way all Iterables inherit the functions defined in Iterable.
Make Iterable a const class.
Add methods for the one Iterable that cannot extend.

Committed: https://code.google.com/p/dart/source/detail?r=14962

[sra1, 2012-11-15 01:02:17]

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/tree/nodes.dart (right):

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/tree/nodes.dart:475: List result = new
List();
new List() -> []

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart
File sdk/lib/core/iterable.dart (right):

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart...
sdk/lib/core/iterable.dart:35: // skeleton. It will be changed to become lazy
soon.
How will it be lazy?

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart...
sdk/lib/core/iterable.dart:36: List result = new List();
Any reason to use new List() when the more concise [] means the same?

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart...
sdk/lib/core/iterable.dart:54: List result = new List<E>();
Ditto <E>[]

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart...
sdk/lib/core/iterable.dart:86: Dynamic reduce(var initialValue,
Dynamic -> dynamic ?

[floitsch, 2012-11-15 01:27:27]

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/tree/nodes.dart (right):

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/tree/nodes.dart:475: List result = new
List();
On 2012/11/15 01:02:18, sra1 wrote:
> new List() -> []

Done.

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart
File sdk/lib/core/iterable.dart (right):

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart...
sdk/lib/core/iterable.dart:35: // skeleton. It will be changed to become lazy
soon.
On 2012/11/15 01:02:18, sra1 wrote:
> How will it be lazy?

Have a look here:
https://chromiumcodereview.appspot.com/11366111/

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart...
sdk/lib/core/iterable.dart:36: List result = new List();
On 2012/11/15 01:02:18, sra1 wrote:
> Any reason to use new List() when the more concise [] means the same?

Done.

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart...
sdk/lib/core/iterable.dart:54: List result = new List<E>();
On 2012/11/15 01:02:18, sra1 wrote:
> Ditto <E>[]

Done.

https://codereview.chromium.org/11363252/diff/1014/sdk/lib/core/iterable.dart...
sdk/lib/core/iterable.dart:86: Dynamic reduce(var initialValue,
On 2012/11/15 01:02:18, sra1 wrote:
> Dynamic -> dynamic ?

Done.

[Anders Johnsen, 2012-11-15 10:31:14]

LGTM

[Ivan Posva, 2012-11-26 18:13:01]

Here is a general comment about style and choosing implements over extends. 

-Ivan

https://codereview.chromium.org/11363252/diff/2014/sdk/lib/utf/utf16.dart
File sdk/lib/utf/utf16.dart (right):

https://codereview.chromium.org/11363252/diff/2014/sdk/lib/utf/utf16.dart#new...
sdk/lib/utf/utf16.dart:218: class IterableUtf16Decoder extends Iterable<int> {
Please remember by extending rather than implementing you add unnecessary type
arguments on the class extending the parameterized interface.

This ripples all the way down into the implementation causing you to allocate
two objects (object and its type arguments) for each new IterableUtf16Decoder.

[floitsch, 2012-11-28 14:16:01]

Addressed Ivan's comments in https://codereview.chromium.org/11416240/

https://codereview.chromium.org/11363252/diff/2014/sdk/lib/utf/utf16.dart
File sdk/lib/utf/utf16.dart (right):

https://codereview.chromium.org/11363252/diff/2014/sdk/lib/utf/utf16.dart#new...
sdk/lib/utf/utf16.dart:218: class IterableUtf16Decoder extends Iterable<int> {
On 2012/11/26 18:13:01, Ivan Posva wrote:
> Please remember by extending rather than implementing you add unnecessary type
> arguments on the class extending the parameterized interface.
> 
> This ripples all the way down into the implementation causing you to allocate
> two objects (object and its type arguments) for each new IterableUtf16Decoder.

Added TODO.

[Lasse Reichstein Nielsen, 2012-11-28 21:29:35]

https://codereview.chromium.org/11363252/diff/2014/sdk/lib/utf/utf16.dart
File sdk/lib/utf/utf16.dart (right):

https://codereview.chromium.org/11363252/diff/2014/sdk/lib/utf/utf16.dart#new...
sdk/lib/utf/utf16.dart:218: class IterableUtf16Decoder extends Iterable<int> {
Is there any way that this could be made cheaper?
E.g., when the class and its superclass always have the same type
parameterization, and since type parameters are final on the object, could it be
stored only once?