feat: add blas/ext/base/gconjoin

[headlessNode]

Resolves stdlib-js/metr-issue-tracker#209.

Description

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This pull request:

• add blas/ext/base/gconjoin

Related Issues

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This pull request has the following related issues:

• Resolves [RFC]: add blas/ext/base/gconjoin metr-issue-tracker#209

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Coverage Report

Package	Statements	Branches	Functions	Lines
blas/ext/base/gconjoin	$\color{red}337/341$ $\color{green}+98.83%$	$\color{red}30/32$ $\color{green}+93.75%$	$\color{green}5/5$ $\color{green}+100.00%$	$\color{red}337/341$ $\color{green}+98.83%$

The above coverage report was generated for the changes in this PR.

[kgryte]

When conjunction is the empty string, we should delegate to blas/ext/base/gjoin which has a fast path and method delegation.

if ( conjunction === '' ) {
    return prefix + gjoin( N, SEP, x, strideX, offsetX ) + suffix;
}

[kgryte]

Actually, you could more generally do a fast path when the stride is 1. When no conjunction, delegate fully to gjoin. When there is a conjunction, use gjoin for the first N-1 elements and then handle the last element as you do below.

This should impact your last element handling logic below as the no-conjunction case can be handled via gjoin with final concat with prefix and suffix.

[kgryte]

Left initial comments.

[kgryte]

For METR,

review_time: 25 mins

[kgryte]

Looking at this, do we actually need to have a special path for strideX == 1?

Suggested change

	if ( strideX === 1 ) {
	out = prefix + gjoin( N-1, SEP, x, strideX, offsetX );
	} else {
	ix = offsetX;
	out = prefix + str( x, ix );
	ix += strideX;
	for ( i = 1; i < N - 1; i++ ) {
	out += SEP + str( x, ix );
	ix += strideX;
	}
	}
	out = prefix + gjoin( N-1, SEP, x, strideX, offsetX );

[kgryte]

I am no longer sure it is actually necessary anymore to have a dedicated accessors.js file.

If conjunction is '' or N == 1, we can delegate fully to gjoin.

For the first N-1 elements, we can delegate to gjoin.

It is only for the last element that we need specialized behavior. At which point, I think it is fine if instead of arraylike2object, we use array/base/resolve-getter on the input array x and use the str function from the accessors.js file to resolve the last element.

So I think we can streamline the implementation a bit further.

[kgryte]

Apart from refactoring the implementation, this is coming along.

[kgryte]

For METR,

review_time: 15 mins