ext/Intl: add support for determining layout character/line orientation of a locale

[LamentXU123]

Description

Similar to #18345. The ICU4C has uloc_getCharacterOrientation and uloc_getLineOrientation to determine this.

Currently we have isrighttoleft which only returns true or false depends on whether it's RTL or LTR in a locale.

The uloc_getCharacterOrientation method comparing to isrighttoleft returns RTL LTR or UNKNOWN constants instead of true and false. And the uloc_getLineOrientation method returns TTB(Top to Bottom) or BTT(Bottom to top) constants.

Now I think the uloc_getLineOrientation method provides something unique to the intl code base and is quite useful for people to determine the line orientation of a locale. Also I'd prefer uloc_getCharacterOrientation in more complicated senecios since it:

• returns UNKNOWN instead of false when the given locale has a undefined orientation
• returns INTL constants instead of true/false

It would be great to expose this ICU capability to PHP code. I am happy to work on this later if we agreed on this feature.

[devnexen]

Let me ask. Your arguments are

locale-aware character direction is useful when deciding whether content should default to LTR(left to right) or RTL(right to left)

right ?

can't you address it with the very feature you reference to ? or do you mean uloc_getCharacterOrientation ?

[LamentXU123]

can't you address it with the very feature you reference to ? or do you mean uloc_getCharacterOrientation ?

Ah yes. Made a mistake here.

[alecpl]

How about https://www.php.net/manual/en/locale.isrighttoleft.php

[LamentXU123]

I am aware before, please review the original post I updated again seems like I don't make things clear at the beginning :)

[devnexen]

to be honest, I m not yet convinced how useful uloc_getCharacterOrientation is. Locale::isRightToLeft() already covers what userland needs (dir, mirroring, alignment). The orientation pair only helps for real layout work ; vertical writing-mode, caret, bidi runs, and that s not done at the PHP level. CLDR is basically LTR/TTB or RTL/TTB anyway so getCharacterOrientation would just duplicate isRightToLeft.

[LamentXU123]

The impact of those two APIs is quite little. People is already doing the line orientation in CSS.

I initially think the intl extension has the goal of exposing ICU APIs to users but it turns out it doesn't. Well this make adding those changes useless, not every un-exposed API in ICU has the value of being added into the extension.

Anyways, there are still some un-exposed APIs. See if those two could be justified instead: Locale::getDisplayKeyword() and Locale::getDisplayKeywordValue() since we already have Locale::getDisplayLanguage(), Locale::getDisplayRegion(), and Locale::getDisplayVariant()

[devnexen]

Those have better chance to be accepted, filling little gaps.

[devnexen]

It is almost borderline RFC, but I would recommend to discuss it internally (internal ML) before putting efforts into it.

[LamentXU123]

Let's go through a RFC process of this :) They are at least new functions and we don't need to rush this feature. Closing this issue, thanks!