From: Holden Glova <dsafari@...>
Date: 2002-05-17T20:22:51+09:00
Subject: Re: Shifting array element & regex on array element

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On Fri, 17 May 2002 22:45, Yohanes Santoso wrote:
> In implementing a buffer gap mechanism, I was wondering if there is
> any efficient way to shift elements in an array.
>
> Suppose that I have 80000 elements in an array. I would like to insert
> a new element between the 1st and 2nd elements by making the 2nd
> element be the 3rd and so on.
>
> In C, the way to do this is to do bcopy/memmove or
> something like while (--1 >= 0) *--to = *--from;
>
> The way I am implementing right now is:
> 80000.downto(2) {|i| array[i+1]=array[i]}
>
> 1. Is this as efficient as it gets? It looks fast enough so far.

Perhaps ugly? But it works.

irb(main):015:0> array = [1, 3, 4, 5]
[1, 3, 4, 5]
irb(main):023:0> array[0..0] + [2] + array[1..-1]
[1, 2, 3, 4, 5]

> The next future of the buffer is that it supports regex. Ruby's
> standard Regex class can't operate over array, especially array with a
> gap.
>
> 2. Anyone know of a Regex library that can operate over an array (either
>    Ruby's Array or C's array (unsigned char*) ) with a gap?
>
> TIA,
> YS.

I'm not sure what you mean here.

- -- 
Signed,
Holden Glova
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