Simplify Join and speedup joining arrays of numbers.

Simplify Join and speedup joining arrays of numbers.

[Lasse Reichstein, 2011-01-10 10:51:44]

LGTM

http://codereview.chromium.org/6173004/diff/2001/src/array.js
File src/array.js (right):

http://codereview.chromium.org/6173004/diff/2001/src/array.js#newcode121
src/array.js:121: return convert(e);
How about checking against undefined after the IS_STRING test?
Or does it happen so rarely that it doesn't matter anyway?

http://codereview.chromium.org/6173004/diff/2001/src/array.js#newcode132
src/array.js:132: if (!(e == null)) {
Use IS_NULL_OR_UNDEFINED (which reduces to this but better explains the type
coercion).

http://codereview.chromium.org/6173004/diff/2001/src/array.js#newcode157
src/array.js:157: }
How about:
if (IS_NUMBER(e)) { 
  e = %_NumberToString(e);
} else if (!IS_STRING(e)) {
  e = convert(e);
}
elements[i] = e;


or 

if (!IS_STRING(e)) {
  if (IS_NUMBER(e)) {
    e = %_NumberToString(e);
  } else if (IS_NULL_OR_UNDEFINED(e)) {
    e = ''
  } else {
    e = convert(e);
  }
}
elements[i] = e;

[sandholm, 2011-01-10 11:40:52]

http://codereview.chromium.org/6173004/diff/2001/src/array.js
File src/array.js (right):

http://codereview.chromium.org/6173004/diff/2001/src/array.js#newcode121
src/array.js:121: return convert(e);
On 2011/01/10 10:51:44, Lasse Reichstein wrote:
> How about checking against undefined after the IS_STRING test?
> Or does it happen so rarely that it doesn't matter anyway?

Doesn't matter.

http://codereview.chromium.org/6173004/diff/2001/src/array.js#newcode132
src/array.js:132: if (!(e == null)) {
On 2011/01/10 10:51:44, Lasse Reichstein wrote:
> Use IS_NULL_OR_UNDEFINED (which reduces to this but better explains the type
> coercion).

I changed this back to IS_UNDEFINED after all.

http://codereview.chromium.org/6173004/diff/2001/src/array.js#newcode157
src/array.js:157: }
On 2011/01/10 10:51:44, Lasse Reichstein wrote:
> How about:
> if (IS_NUMBER(e)) { 
>   e = %_NumberToString(e);
> } else if (!IS_STRING(e)) {
>   e = convert(e);
> }
> elements[i] = e;
> 
> 
> or 
> 
> if (!IS_STRING(e)) {
>   if (IS_NUMBER(e)) {
>     e = %_NumberToString(e);
>   } else if (IS_NULL_OR_UNDEFINED(e)) {
>     e = ''
>   } else {
>     e = convert(e);
>   }
> }
> elements[i] = e;

I want the expected path (IS_NUMBER) to be as fast as possible. With these
rewrites I'll have two assignments instead of one in that case. I tried running
alternative one and it is a bit slower (1%).