strw_ltrimex.c

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/* enhanced ltrimw$ function */

#include "fb.h"

FBCALL FB_WCHAR *fb_WstrLTrimEx ( const FB_WCHAR *src, const FB_WCHAR *pattern )
{
        FB_WCHAR        *dst;
        ssize_t len;
        const FB_WCHAR *p = NULL;

    if( src == NULL ) {
        return NULL;
    }

    {
        ssize_t len_pattern = fb_wstr_Len( pattern );
        len = fb_wstr_Len( src );
        if( len >= len_pattern ) {
            if( len_pattern==1 ) {
                p = fb_wstr_SkipChar( src,
                                      len,
                                      *pattern );
                len = len - (ssize_t)(p - src);

            } else if( len_pattern != 0 ) {
                p = src;
                while (len >= len_pattern ) {
                    if( fb_wstr_Compare( p, pattern, len_pattern )!=0 )
                        break;
                    p += len_pattern;
                    len -= len_pattern;
                }
            }
        }
        }

        if( len > 0 )
        {
                /* alloc temp string */
        dst = fb_wstr_AllocTemp( len );
                if( dst != NULL )
                {
                        /* simple copy */
                        fb_wstr_Copy( dst, p, len );
                }
                else
                        dst = NULL;
    }
        else
                dst = NULL;

        return dst;
}