Bug 59151 – Provide default constructors for HashMap iterators

• Component: WebCore Misc.
• Status: RESOLVED FIXED

[Vitaly Repeshko]

[WTF] Provide default constructors for HashMap iterators

[Vitaly Repeshko]

Created attachment 90625 [details]
patch

[Adam Barth]

Comment on attachment 90625 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=90625&action=review

> Source/JavaScriptCore/wtf/HashTable.h:1123
> +        HashTableConstIteratorAdapter() {}

Do we need to initialize m_impl to anything (like null) or does it do that itself?

[Adam Barth]

+mjs for WTF foo.

[Vitaly Repeshko]

(In reply to comment #2)
> (From update of attachment 90625 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=90625&action=review
> 
> > Source/JavaScriptCore/wtf/HashTable.h:1123
> > +        HashTableConstIteratorAdapter() {}
> 
> Do we need to initialize m_impl to anything (like null) or does it do that itself?

Unlike the adapter it has a default constructor. So I don't think it should be initialized.

[Sam Weinig]

Why are these needed? What will they be used for?

[Vitaly Repeshko]

(In reply to comment #5)
> Why are these needed? What will they be used for?

Right now you can't declare a variable or class field of type HashMap::iterator without immediately initializing it. This is inconsistent with wtf::Vector and STL iterators.

My specific intended usage for them is to implement a lightweight iterator over EventTarget's listeners. EventTarget has a map of vectors. So the listener iterator simply combines a map iterator and an index. The problem is that the listener map is optional and the map iterator can't be initialized when it's NULL without using some dummy map.

[Adam Barth]

I asked Vitaly to post this as a separate patch because the folks who would review this patch might not be the same folks who would be interested in reviewing the rest of his change.

[Adam Barth]

Comment on attachment 90625 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=90625&action=review

> Source/JavaScriptCore/ChangeLog:7
> +

I would add some more explanation here about why you're making this change (i.e., that you plan to use it in another patch shortly).

[Vitaly Repeshko]

	M	Source/JavaScriptCore/ChangeLog
	M	Source/JavaScriptCore/wtf/HashTable.h
Committed r84687