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// NSString-FBAdditions.m

// FriBidi

// Created by Ofri Wolfus on 22/08/06.

#import "NSString-FBAdditions.h"

#import "fribidi.h"

#import "ConvertUTF.h"

@implementation NSString (FBAdditions)

* This method attempts to determine the base writing direction of our string.

* We do this by looping through our characters until we find the first one that knows its writing direction.

* This method will usually get the right direction, unless someone accidentally put a random letter at the

* beginning of the string, which has a different writing direction.

* But since this will be the user's fault, he'll have to deal with it :)

* Anyhow, AppKit also uses this method when displaying bidi text.

- (NSWritingDirection)baseWritingDirection {

unsigned int len = [self length];

unsigned int i;

FriBidiChar *f, fch;

UTF16 *u, uch;

NSWritingDirection dir = NSWritingDirectionNatural;

* Loop through all our characters, one by one, until we find one which knows its writing direction.

* Note: If our string begins with lots of universal characters (characters without a direction), this

* could get very inefficient.

for (i = 0U; i < len; i++) {

FriBidiCharType type;

// Get a single character

uch = (UTF16)CFStringGetCharacterAtIndex((CFStringRef)self, i);

u = &uch;

f = &fch;

// Convert our UniChar (which is UTF16) to FriBidiChar (which is UTF32)

if (ConvertUTF16toUTF32((const UTF16**)&u, (u + 1), &f, (f + 1), lenientConversion) == conversionOK) {

// Get the type of our character

type = fribidi_get_type(fch);

// LTR char?

if (!(type & FRIBIDI_MASK_RTL)) {

dir = NSWritingDirectionLeftToRight;

break;

}

// RTL char?

if (type & FRIBIDI_MASK_RTL) {

dir = NSWritingDirectionRightToLeft;

break;

}

return dir;

}

@end