Proposal: container/heap: add Peek function

[leonxu0]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

1.7.1

What operating system and processor architecture are you using (go env)?

linux

What did you do?

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

piece of code :
todo := &PushTaskList{}
todo.init("todo")
heap.Init(todo)
heap.Push(todo, &PushTask{v:"1",stime:9,ktime:5,priority:9})
heap.Push(todo, &PushTask{v:"2",stime:3,ktime:1,priority:10})
heap.Push(todo, &PushTask{v:"3",stime:5,ktime:7,priority:12})
heap.Push(todo, &PushTask{v:"4",stime:11,ktime:3,priority:11})
for todo.Len() > 0 {
pt := heap.Front(todo)
pt.print()
if pt.priority > 11 {
heap.Pop(todo)
}
}

What did you expect to see?

i need a function for container/heap to return the first element but not pop it.

What did you see instead?

no such function, i can't check the first element without using the heap.Pop() function, which in some case i should not call.

[odeke-em]

I've updated the title to make this a request for a Peek function https://en.wikipedia.org/wiki/Peek_(data_type_operation)

[minux]

Unless you're developing code that takes a heap.Interface, usually you have access to the slice representation, and the minimum item is at index 0. Therefore, I don't think Peek is very important.

[odeke-em]

Yeah, @minux's words were also echoed on this golang-nuts mailing list post https://groups.google.com/forum/#!topic/golang-nuts/sy1p8SfyPoY.

[leonxu0]

@odeke-em @minux thanks! problem solved!