���� JFIF  XX �� �� �     $.' ",#(7),01444'9=82<.342  2!!22222222222222222222222222222222222222222222222222�� ��" �� 4     ��   �� �,�PG"Z_�4�˷����kjز�Z�,F+��_z�,�© �����zh6�٨�ic�fu��� #ډb���_�N� ?� �wQ���5-�~�I���8��� �TK<5o�Iv-� ����k�_U_����� ~b�M��d��� �Ӝ�U�Hh��?]��E�w��Q���k�{��_}qFW7HTՑ��Y��F� ?_�'ϔ��_�Ջt� �=||I �� 6�έ"�����D���/[�k�9�� �Y�8 ds|\���Ҿp6�Ҵ���]��.����6� z<�v��@]�i% �� $j��~ �g��J>��no����pM[me�i$[�� �� s�o�ᘨ�˸ nɜG-�ĨU�ycP� 3.DB�li�;� �hj���x 7Z^�N�h��� ���N3u{�:j �x�힞��#M &��jL P@ _���� P�� &��o8 ������9 �����@Sz 6�t7#O�ߋ � s}Yf�T� ��lmr����Z)'N��k�۞p ����w\�T ȯ?�8` �O��i{wﭹW�[�r�� ��Q4F�׊�� �3m&L�=��h3� ���z~��#� \�l :�F,j@�� ʱ�wQT����8�"kJO��� 6�֚l���� }��� R�>ډK���]��y����&����p�}b�� ;N�1�m�r$� |��7�>e�@ B�TM*-i H��g�D�)� E�m�|�ؘbҗ�a ��Ҿ���� t4��� o���G��*oCN�rP���Q��@z,|?W[0 �����:�n,j WiE��W� �$~/�hp\��?��{(�0���+�Y8rΟ�+����>S-S�� ��VN;� }�s?.����� w �9��˟<���Mq4�Wv' ��{)0�1mB ��V����W[� ����8�/<� �%���wT^�5���b��)iM� p g�N�&ݝ� �VO~� q���u���9� ����!��J27��� �$ O-���! �: �%H��� ـ ����y�ΠM=t{!S�� oK8������ t<����è :a�� ����[���� �ա�H���~��w��Qz`�p o�^ �� ��Q��n�  �,uu�C� $ ^���,� �����8�#��:�6��e�|~� ��!�3� 3.�\0�� q��o�4`.|� ����y�Q�`~;�d�ׯ,��O�Zw�������`73�v�܋�< ���Ȏ�� ـ4k��5�K�a�u�=9Yd��$>x�A�&�� j0� ���vF��� Y� |�y��� ~�6�@c��1vOp �Ig�� ��4��l�OD� ��L����� R���c���j�_�uX 6��3?nk��Wy�f;^*B� ��@ �~a�`��Eu������ +� �� 6�L��.ü>��}y���}_�O�6�͐�:�Yr G�X��kG�� ���l^w�� �~㒶sy� �Iu�!� W ��X��N�7BV��O��!X�2����wvG�R�f�T#�����t�/?���%8�^�W�aT ��G�cL�M���I��(J����1~�8�?aT ���]����AS�E��(��*E}� 2�� #I/�׍qz��^t�̔��� b�Yz4x ���t�){ OH� �+(E��A&�N�������XT��o��"�XC�� '���)}�J�z�p� ��~5�}�^����+�6����w��c��Q�| Lp�d�H��}�(�.|����k��c4^� "�����Z?ȕ ��a< �L�!0 39C� �Eu� C�F�Ew�ç ;�n?�*o���B�8�bʝ���'#Rqf�� �M}7����]��� �s2tcS{�\icTx;�\��7K���P ���ʇ Z O-��~�� c>"��?�� �����P ��E��O�8��@�8��G��Q�g�a�Վ���󁶠 �䧘��_%#r�>� 1�z�a�� eb��qcP ѵ��n���#L��� =��׀t� L�7�` ��V��� A{�C:�g���e@ �w1 Xp 3�c3�ġ���� p��M"'-�@n4���fG� �B3�DJ�8[Jo�ߐ���gK)ƛ��$���� � ��8�3�����+���� �����6�ʻ���� ���S�kI�*KZlT _`�� �?��K� ���QK�d ����B`�s}�>���` ��*�>��,*@J�d�oF*� ���弝��O}�k��s��]��y�ߘ ��c1G�V���<=�7��7����6 �q�PT��tXԀ�!9*4�4Tހ 3XΛex�46�� �Y��D ����� �BdemDa����\�_l,� �G�/���֌7���Y�](�xTt^%�GE�����4�}bT ���ڹ�����; Y)���B�Q��u��>J/J � ⮶.�XԄ��j�ݳ� +E��d ��r�5�_D �1 �� o�� �B�x�΢�#� ��<��W�����8���R6�@ g�M�.��� dr�D��>(otU��@ x=��~v���2� ӣ�d�oBd ��3�eO�6�㣷�� ���ݜ 6��6Y��Qz`�� S��{���\P �~z m5{J/L��1������<�e�ͅPu� b�]�ϔ ���'�� ����f�b� Zpw��c`"��i���BD@:)ִ�:�]��h v�E� w���T�l ��P� ��"Ju�}��وV J��G6��. J/�Qgl߭�e�����@�z�Zev2u� )]կ��� ��7x�� �s�M�-<ɯ�c��r� v�����@��$�ޮ}lk���a�� �'����>x��O\�Z Fu>��� ��ck#��&:��`�$ �ai�>2Δ����l���oF[h� �lE�ܺ�Π k:)���` �� $[6�����9�����kOw�\|��� 8}������ބ:��񶐕� �I�A1/� =�2[�,�!��.}gN#�u����b ��� ~� �݊��}34q��� �d�E��L c��$ ��"�[q�U�硬g^��%B � z���r�p J�ru%v\h 1Y�ne` ǥ:g�� �pQM~�^� Xi� ��`S�:V2 9.�P���V� ?B�k�� AEvw%�_�9C�Q����wKekP ؠ�\� ;Io d�{ ߞo�c1eP��� �\� `����E=���@K<�Y�� �eڼ�J ���w����{av�F�'�M�@ /J��+9p ���|]���� �Iw &` ��8���& M�hg ��[�{ ��Xj�� %��Ӓ� $��(��� �ʹN��� <>�I���RY� ��K2�NPlL�ɀ )��&e� ���B+ь����( � �JTx ���_?EZ� }@ 6�U���뙢ط�z��dWI� n` D����噥�[��uV��"�G& Ú����2 g�}&m� �?ċ �"����Om#� ������� � ��{� ON��"S�X ��Ne��ysQ���@ Fn��Vg��� dX�~nj� ]J�<�K]: ��FW�� b�������62 �=��5f����JKw� �bf�X� 55��~J �%^� ���:�-�QIE��P��v�nZum� z � ~ə ���� ���ة����;�f��\v��� g�8�1��f2 4;�V���ǔ�)��� �9���1\�� c��v�/'Ƞ�w����� ��$�4�R-��t�� �� e�6�/�ġ �̕Ecy�J���u�B���<�W�ַ~�w[B1L۲�-JS΂�{���΃���� ��A��20�c# �� @    0!1@AP"#2Q`$3V�%45a6�FRUq���   � ���^7ׅ,$n� ������+��F�`��2X'��0vM��p�L=������ 5��8������u�p~���.�`r�����\��� O��,ư�0oS ��_�M�����l���4�kv\JSd���x���SW�<��Ae�IX����������$I���w�:S���y���›R��9�Q[���,�5�;�@]�%���u�@ *ro�lbI �� ��+���%m:�͇ZV�����u�̉����θau<�fc�.����{�4Ա� �Q����*�Sm��8\ujqs]{kN���)qO�y�_*dJ�b�7���yQqI&9�ԌK!�M}�R�;�� ����S�T���1���i[U�ɵz�]��U)V�S6���3$K{� ߊ<�(� E]Զ[ǼENg�����'�\?#)Dkf��J���o��v���'�%ƞ�&K�u� !��b�35LX�Ϸ��63$K�a�;�9>,R��W��3�3� d�JeTYE.Mϧ��-�o�j3+y��y^�c�������VO�9NV\nd�1 ��!͕_)a�v;����թ�M�lWR1��)El��P;��yوÏ�u 3�k�5Pr6<�⒲l�!˞*��u־�n�!�l:����UNW ��%��Chx8vL'��X�@��*��)���̮��ˍ��� � ��D-M�+J�U�kvK����+�x8��cY������?�Ԡ��~3mo��|�u@[XeY�C�\Kp�x8�oC�C�&����N�~3-H���� ��MX�s�u<`���~"WL��$8ξ��3���a�)|:@�m�\���^�`�@ҷ)�5p+��6���p�%i)P M���ngc�����#0Aruz���RL+xSS?���ʮ}()#�t��mˇ!��0}}y����<�e� �-ή�Ԩ��X������ MF���ԙ~l L.3���}�V뽺�v��� ��멬��Nl�)�2����^�Iq��a��M��qG��T�����c3#������3U�Ǎ���}��לS�|qa��ڃ�+���-��2�f����/��bz��ڐ�� �ݼ[2�ç����k�X�2�* �Z�d���J�G����M*9W���s{��w���T��x��y,�in�O�v��]���n����P�$� JB@=4�OTI�n��e�22a\����q�d���%�$��(���:���: /*�K[PR�fr\nڙdN���F�n�$�4� [�� U�zƶ����� �mʋ���,�ao�u 3�z� �x��Kn����\[��VFmbE;�_U��&V�Gg�]L�۪&#n%�$ɯ� dG���D�TI=�%+AB�Ru#��b4�1�»x�cs�YzڙJG��f��Il� �d�eF'T� iA��T���uC�$����Y��H?����[!G`}���ͪ� �纤Hv\������j�Ex�K���!���OiƸ�Yj�+u-<���'q����uN�*�r\��+�]���<�wOZ.fp�ێ��,-*)V?j-kÊ#�`�r��dV����(�ݽBk�����G�ƛk�QmUڗe��Z���f}|����8�8��a���i��3'J�����~G_�^���d�8w������ R�`(�~�.��u���l�s+g�bv���W���lGc}��u���afE~1�Ue������Z�0�8�=e�� f@/�jqEKQQ�J� �oN��J���W5~M>$6�Lt�;$ʳ{���^��6�{����v6���ķܰg�V�cnn �~z�x�«�,2�u�?cE+Ș�H؎�%�Za�)���X>uW�Tz�Nyo����s���FQƤ��$��*�&�LLXL)�1�" L��eO��ɟ�9=���:t��Z���c��Ž���Y?�ӭV�wv�~,Y��r�ۗ�|�y��GaF�����C�����.�+� ���v1���fήJ�����]�S��T��B��n5sW}y�$��~z�'�c ��8 ��� ,! �p��VN�S��N�N�q��y8z˱�A��4��*��'������2n<�s���^ǧ˭P�Jޮɏ�U�G�L�J�*#��<�V��t7�8����TĜ>��i}K%,���)[��z�21z ?�N�i�n1?T�I�R#��m-�����������������1����lA�`��fT5+��ܐ�c�q՝��ʐ��,���3�f2U�եmab��#ŠdQ�y>\��)�SLY����w#��.���ʑ�f��� ,"+�w�~�N�'�c�O�3F�������N<���)j��&��,-� �љ���֊�_�zS���TǦ����w�>��?�������n��U仆�V���e�����0���$�C�d���rP �m�׈e�Xm�Vu� �L��.�bֹ��� �[Դaզ���*��\y�8�Է:�Ez\�0�Kq�C b��̘��cө���Q��=0Y��s�N��S.��� 3.���O�o:���#���v7�[#߫ ��5�܎�L���Er4���9n��COWlG�^��0k�%<���ZB���aB_���������'=��{i�v�l�$�uC���mƎҝ{�c㱼�y]���W�i ��ߧc��m�H� m�"�"�����;Y�ߝ�Z�Ǔ�����:S#��|}�y�,/k�Ld� TA�(�AI$+I3��;Y*���Z��}|��ӧO��d�v��..#:n��f>�>���ȶI�TX��� 8��y����"d�R�|�)0���=���n4��6ⲑ�+��r<�O�܂~zh�z����7ܓ�HH�Ga롏���nCo�>������a ���~]���R���̲c?�6(�q�;5%� |�uj�~z8R =X��I�V=�|{v�Gj\gc��q����z�؋%M�ߍ����1y��#��@f^���^�>N��� ��#x#۹��6�Y~�?�dfPO��{��P�4��V��u1E1J �*|���%�� �JN��`eWu�zk M6���q t[�� ��g�G���v��WIG��u_ft����5�j�"�Y�:T��ɐ���*�;� e5���4����q$C��2d�}���� _S�L#m�Yp��O�.�C�;��c����Hi#֩%+) �Ӎ��ƲV���SYź��g |���tj��3�8���r|���V��1#;.SQ�A[���S������#���`n�+���$��$ I �P\[�@�s��(�ED�z���P��])8�G#��0B��[ى��X�II�q<��9�~[Z멜�Z�⊔IWU&A>�P~�#��dp<�?����7���c��'~���5 ��+$���lx@�M�dm��n<=e�dyX��?{�|Aef ,|n3�<~z�ƃ�uۧ�����P��Y,�ӥQ�*g�#먙R�\���;T��i,��[9Qi歉����c>]9�� ��"�c��P�� �Md?٥��If�ت�u��k��/����F��9�c*9��Ǎ:�ØF���z�n*�@|I�ށ9����N3{'��[�'ͬ�Ҳ4��#}��!�V� Fu��,�,mTIk���v C�7v���B�6k�T9��1�*l� '~��ƞF��lU��'�M ����][ΩũJ_�{�i�I�n��$�� �L�� j��O�dx�����kza۪��#�E��Cl����x˘�o�����V���ɞ�ljr��)�/,�߬h�L��#��^��L�ф�,íMƁe�̩�NB�L�����iL����q�}��(��q��6IçJ$�W�E$��:������=#����(�K�B����zђ <��K(�N�۫K�w��^O{!����) �H���>x�������lx�?>Պ�+�>�W���,Ly!_�D���Ō�l���Q�!�[ �S����J��1��Ɛ�Y}��b,+�Lo�x�ɓ)����=�y�oh�@�꥟/��I��ѭ=��P�y9��� �ۍYӘ�e+�p�Jnϱ?V\SO%�(�t� ���=?MR�[Ș�����d�/ ��n�l��B�7j� ��!�;ӥ�/�[-���A�>� dN�sLj ��,ɪv��=1c�.SQ�O3�U���ƀ�ܽ�E����������̻��9G�ϷD�7(�}��Ävӌ\� y�_0[w ���<΍>����a_��[0+�L��F.�޺��f�>oN�T����q;���y\��bՃ��y�jH�<|q-eɏ�_?_9+P���Hp$�����[ux�K w�Mw��N�ی'$Y2�=��q���KB��P��~�� ����Yul:�[<����F1�2�O���5=d����]Y�sw:���Ϯ���E��j,_Q��X��z`H1,#II ��d�wr��P˂@�ZJV����y$�\y�{}��^~���[:N����ߌ�U�������O��d�����ؾe��${p>G��3c���Ė�lʌ�� ת��[��`ϱ�-W����dg�I��ig2��� ��}s ��ؤ(%#sS@���~���3�X�nRG�~\jc3�v��ӍL��M[JB�T��s3}��j�Nʖ��W����;7� �ç?=X�F=-�=����q�ߚ���#���='�c��7���ڑW�I(O+=:uxq�������������e2�zi+�kuG�R��������0�&e�n���iT^J����~\jy���p'dtG��s����O��3����9* �b#Ɋ�� p������[Bws�T�>d4�ۧs���nv�n���U���_�~,�v����ƜJ1��s�� �QIz�� )�(lv8M���U=�;����56��G���s#�K���MP�=��LvyGd��}�VwWBF�'�à �?MH�U�g2�� ����!�p�7Q��j��ڴ����=��j�u��� Jn�A s���uM������e��Ɔ�Ҕ�!) '��8Ϣ�ٔ� �ޝ(��Vp���צ֖d=�IC�J�Ǡ{q������kԭ�߸���i��@K����u�|�p=..�*+����x�����z[Aqġ#s2a�Ɗ���RR�)*HRsi�~�a &f��M��P����-K�L@��Z��Xy�'x�{}��Zm+���:�)�) IJ�-i�u���� ���ܒH��'� L(7�y�GӜq���� j��� 6ߌg1�g�o���,kر���tY�?W,���p���e���f�OQS��!K�۟cҒA�|ս�j�>��=⬒��˧L[�� �߿2JaB~R��u�:��Q�] �0H~���]�7��Ƽ�I���( }��cq '�ήET���q�?f�ab���ӥvr� �)o��-Q��_'����ᴎo��K������;��V���o��%���~OK ����*��b�f:���-ťIR��`B�5!RB@���ï�� �u �̯e\�_U�_������� g�ES��3������� QT��a�� ��x����U<~�c?�*�#]�MW,[8O�a�x��]�1bC|踤�P��lw5V%�)�{t�<��d��5���0i�XSU��m:��Z�┵�i�"��1�^B�-��P�hJ��&)O��*�D��c�W��vM��)����}���P��ܗ-q����\mmζZ-l@�}��a��E�6��F�@��&Sg@���ݚ�M����� ȹ 4����#p�\H����dYDo�H���"��\��..R�B�H�z_�/5˘����6��KhJR��P�mƶi�m���3� ,#c�co��q�a)*P t����R�m�k�7x�D�E�\Y�閣_X�<���~�)���c[[�BP����6�Yq���S��0����%_����;��Àv�~�| VS؇ ��'O0��F0��\���U�-�d@�����7�SJ*z��3n��y��P����O��������� m�~�P�3|Y��ʉr#�C�<�G~�.,! ���bqx���h~0=��!ǫ�jy����l� O,�[B��~��|9��ٱ����Xly�#�i�B��g%�S��������tˋ���e���ې��\[d�t)��.+u�|1 ������#�~Oj����hS�%��i.�~X���I�H�m��0n���c�1uE�q��cF�RF�o���7� �O�ꮧ� ���ۛ{��ʛi5�rw?׌#Qn�TW��~?y$��m\�\o����%W� ?=>S�N@�� �Ʈ���R����N�)�r"C�:��:����� �����#��qb��Y�. �6[��2K����2u�Ǧ�HYR��Q�MV��� �G�$��Q+.>�����nNH��q�^��� ����q��mM��V��D�+�-�#*�U�̒ ���p욳��u:�������IB���m� ��PV@O���r[b= �� ��1U�E��_Nm�yKbN�O���U�}�the�`�|6֮P>�\2�P�V���I�D�i�P�O;�9�r�mAHG�W�S]��J*�_�G��+kP�2����Ka�Z���H�'K�x�W�MZ%�O�YD�Rc+o��?�q��Ghm��d�S�oh�\�D�|:W������UA�Qc yT�q� �����~^�H��/��#p�CZ���T�I�1�ӏT����4��"�ČZ�����}��`w�#�*,ʹ�� ��0�i��課�Om�*�da��^gJ݅{���l�e9uF#T�ֲ��̲�ٞC"�q���ߍ ոޑ�o#�XZTp����@ o�8��(jd��xw�]�,f���`~� |,s��^����f�1���t��|��m�򸄭/ctr��5s��7�9Q�4�H1꠲BB@ l9@���C�����+�wp�xu�£Yc�9��?`@#�o�mH�s2��)�=��2�.�l����jg�9$�Y�S�%*L������R�Y������7Z���,*=�䷘$�������arm�o�ϰ���UW.|�r�uf����IGw�t����Zwo��~5 ��YյhO+=8fF�)�W�7�L9lM�̘·Y���֘YLf�큹�pRF���99.A �"wz��=E\Z���'a� 2��Ǚ�#;�'}�G���*��l��^"q��+2FQ� hj��kŦ��${���ޮ-�T�٭cf�|�3#~�RJ����t��$b�(R��(����r���dx� >U b�&9,>���%E\� Ά�e�$��'�q't��*�א���ެ�b��-|d���SB�O�O��$�R+�H�)�܎�K��1m`;�J�2�Y~9��O�g8=vqD`K[�F)k�[���1m޼c��n���]s�k�z$@��)!I �x՝"v��9=�ZA=`Ɠi �:�E��)` 7��vI��}d�YI�_ �o�:ob���o ���3Q��&D&�2=�� �Ά��;>�h����y.*ⅥS������Ӭ�+q&����j|UƧ��� �}���J0��WW< ۋS�)jQR�j���Ư��rN)�Gű�4Ѷ(�S)Ǣ�8��i��W52���No˓� ۍ%�5brOn�L�;�n��\G����=�^U�dI���8$�&���h��'���+�(������cȁ߫k�l��S^���cƗjԌE�ꭔ��gF���Ȓ��@���}O���*;e�v�WV���YJ\�]X'5��ղ�k�F��b 6R�o՜m��i N�i���� >J����?��lPm�U��}>_Z&�KK��q�r��I�D�Չ~�q�3fL�:S�e>���E���-G���{L�6p�e,8��������QI��h��a�Xa��U�A'���ʂ���s�+טIjP�-��y�8ۈZ?J$��W�P� ��R�s�]��|�l(�ԓ��sƊi��o(��S0 ��Y� 8�T97.�����WiL��c�~�dxc�E|�2!�X�K�Ƙਫ਼�$((�6�~|d9u+�qd�^3�89��Y�6L�.I�����?���iI�q���9�)O/뚅����O���X��X�V��ZF[�یgQ�L��K1���RҖr@v�#��X�l��F���Нy�S�8�7�kF!A��sM���^rkp�jP�DyS$N���q�� nxҍ!U�f�!eh�i�2�m ���`�Y�I�9r�6� �TF���C}/�y�^���Η���5d�'��9A-��J��>{�_l+�`��A���[�'��յ�ϛ#w:݅�%��X�}�&�PSt�Q�"�-��\縵�/����$Ɨh�Xb�*�y��BS����;W�ջ_mc�����vt?2}1�;qS�d�d~u:2k5�2�R�~�z+|HE!)�Ǟl��7`��0�<�,�2*���Hl-��x�^����'_TV�gZA�'j� ^�2Ϊ��N7t�����?w�� �x1��f��Iz�C-Ȗ��K�^q�;���-W�DvT�7��8�Z�������� hK�(P:��Q- �8�n�Z���܃e貾�<�1�YT<�,�����"�6{ / �?�͟��|1�:�#g��W�>$����d��J��d�B�� =��jf[��%rE^��il:��B���x���Sּ�1հ��,�=��*�7 fcG��#q� �eh?��2�7�����,�!7x��6�n�LC�4x��},Geǝ�tC.��vS �F�43��zz\��;QYC,6����~;RYS/6���|2���5���v��T��i����������mlv��������&� �nRh^ejR�LG�f���? �ۉҬܦƩ��|��Ȱ����>3����!v��i�ʯ�>�v��オ�X3e���_1z�Kȗ\<������!�8���V��]��?b�k41�Re��T�q��mz��TiOʦ�Z��Xq���L������q"+���2ۨ��8}�&N7XU7Ap�d�X��~�׿��&4e�o�F��� �H�� ��O���č�c�� 懴�6���͉��+)��v;j��ݷ�� �UV�� i��� j���Y9GdÒJ1��詞�����V?h��l�� ��l�cGs�ځ�������y�Ac���� �\V3�? �� ܙg�>qH�S,�E�W�[�㺨�uch�⍸�O�}���a��>�q�6�n6� ���N6�q�� ���� N    ! 1AQaq�0@����"2BRb�#Pr���3C`��Scst���$4D���%Td��  ? � ��N����a��3��m���C���w��������xA�m�q�m��� m������$����4n淿t'��C"w��zU=D�\R+w�p+Y�T�&�պ@��ƃ��3ޯ?�Aﶂ��aŘ���@-�����Q�=���9D��ռ�ѻ@��M�V��P��܅�G5�f�Y<�u=,EC)�<�Fy'�"�&�չ�X~f��l�KԆV��?�� �W�N����=(� �;���{�r����ٌ�Y���h{�١������jW����P���Tc�����X�K�r��}���w�R��%��?���E��m�� �Y�q|����\lEE4� ��r���}�lsI�Y������f�$�=�d�yO����p�����yBj8jU�o�/�S��?�U��*������ˍ�0����� �u�q�m [�?f����a�� )Q�>����6#������� ?����0UQ����,IX���(6ڵ[�DI�MNލ�c&���υ�j\��X�R|,4��� j������T�hA�e��^���d���b<����n�� �즇�=!���3�^�`j�h�ȓr��jẕ�c�,ٞX����-����a�ﶔ���#�$��]w�O��Ӫ�1y%��L�Y<�wg#�ǝ�̗`�x�xa�t�w��»1���o7o5��>�m뭛C���Uƃߜ}�C���y1Xνm�F8�jI���]����H���ۺиE@I�i;r�8ӭ���� V�F�Շ| ��&?�3|x�B�MuS�Ge�=Ӕ�#BE5G�� ���Y!z��_e��q�р/W>|-�Ci߇�t�1ޯќd�R3�u��g�=0 5��[?�#͏��q�cf���H��{ ?u�=?�?ǯ���}Z��z���hmΔ�BFTW�����<�q� (v� ��!��z���iW]*�J�V�z��gX֧A�q�&��/w���u�gYӘa���; �i=����g:��?2�dž6�ى�k�4�>�Pxs����}������G�9� �3 ���)gG�R<>r h�$��'nc�h�P��Bj��J�ҧH� -��N1���N��?��~��}-q!=��_2hc�M��l�vY%UE�@|�v����M2�.Y[|y�"Eï��K�ZF,�ɯ?,q�?v�M 80jx�"�;�9vk�����+ ֧�� �ȺU��?�%�vcV��mA�6��Qg^M��� �A}�3�nl� QRN�l8�kkn�'�����(��M�7m9و�q���%ޟ���*h$Zk"��$�9��: �?U8�Sl��,,|ɒ��xH(ѷ����Gn�/Q�4�P��G�%��Ա8�N��!� �&�7�;���eKM7�4��9R/%����l�c>�x;������>��C�:�����t��h?aKX�bhe�ᜋ^�$�Iհ �hr7%F$�E��Fd���t��5���+�(M6�t����Ü�UU|zW�=a�Ts�Tg������dqP�Q����b'�m���1{|Y����X�N��b �P~��F^F:����k6�"�j!�� �I�r�`��1&�-$�Bevk:y���#y w��I0��x��=D�4��tU���P�ZH��ڠ底taP��6����b>�xa� ���Q�#� WeF��ŮNj�p�J* mQ�N��� �*I�-*�ȩ�F�g�3 �5��V�ʊ�ɮ�a��5F���O@{���NX��?����H�]3��1�Ri_u��������ѕ�� ����0��� F��~��:60�p�͈�S��qX#a�5>���`�o&+�<2�D����: �������ڝ�$�nP���*)�N�|y�Ej�F�5ټ�e���ihy�Z �>���k�bH�a�v��h�-#���!�Po=@k̆IEN��@��}Ll?j�O������߭�ʞ���Q|A07x���wt!xf���I2?Z��<ץ�T���cU�j��]�� 陎Ltl �}5�ϓ��$�,��O�mˊ�;�@O��jE��j(�ا,��LX���LO���Ц�90�O �.����a��nA���7������j4 ��W��_ٓ���zW�jcB������y՗+EM�)d���N�g6�y1_x��p�$Lv :��9�"z��p���ʙ$��^��JԼ*�ϭ����o���=x�Lj�6�J��u82�A�H�3$�ٕ@�=Vv�]�'�qEz�;I˼��)��=��ɯ���x �/�W(V���p�����$ �m�������u�����񶤑Oqˎ�T����r��㠚x�sr�GC��byp�G��1ߠ�w e�8�$⿄����/�M{*}��W�]˷.�CK\�ުx���/$�WP w���r� |i���&�}�{�X� �>��$-��l���?-z���g����lΆ���(F���h�vS*���b���߲ڡn,|)mrH[���a�3�ר�[1��3o_�U�3�TC�$��(�=�)0�kgP���� ��u�^=��4 �WYCҸ:��vQ�ר�X�à��tk�m,�t*��^�,�}D*� �"(�I��9R����>`�`��[~Q]�#af��i6l��8���6�:,s�s�N6�j"�A4���IuQ��6E,�GnH��zS�HO�uk�5$�I�4��ؤ�Q9�@��C����wp �BGv[]�u�Ov��� 0I4���\��y�����Q�Ѹ��~>Z��8�T��a��q�ޣ;z��a���/��S��I:�ܫ_�|������>=Z����8:�S��U�I�J��"IY���8%b8���H��:�QO�6�;7�I�S��J��ҌAά3��>c���E+&jf$eC+�z�;��V����� �r���ʺ������my�e���aQ�f&��6�ND ��.:��NT�vm�<- u���ǝ\MvZY�N�NT��-A�>jr!S��n�O 1�3�Ns�%�3D@���`������ܟ 1�^c<���� �a�ɽ�̲�Xë#�w�|y�cW�=�9I*H8�p�^(4���՗�k��arOcW�tO�\�ƍR��8����'�K���I�Q�����?5�>[�}��yU�ײ -h��=��% q�ThG�2�)���"ו3]�!kB��*p�FDl�A���,�eEi�H�f�Ps�����5�H:�Փ~�H�0Dت�D�I����h�F3�������c��2���E��9�H��5�zԑ�ʚ�i�X�=:m�xg�hd(�v����׊�9iS��O��d@0ڽ���:�p�5�h-��t�&���X�q�ӕ,��ie�|���7A�2���O%P��E��htj��Y1��w�Ѓ!����  ���� ࢽ��My�7�\�a�@�ţ�J �4�Ȼ�F�@o�̒?4�wx��)��]�P��~�����u�����5�����7X ��9��^ܩ�U;Iꭆ 5 �������eK2�7(�{|��Y׎ �V��\"���Z�1� Z�����}��(�Ǝ"�1S���_�vE30>���p;� ΝD��%x�W�?W?v����o�^V�i�d��r[��/&>�~`�9Wh��y�;���R�� � ;;ɮT��?����r$�g1�K����A��C��c��K��l:�'��3 c�ﳯ*"t8�~l��)���m��+U,z��`( �>yJ�?����h>��]��v��ЍG*�{`��;y]��I�T� ;c��NU�fo¾h���/$���|NS���1�S�"�H��V���T���4��uhǜ�]�v;���5�͠x��'C\�SBpl���h}�N����� A�Bx���%��ޭ�l��/����T��w�ʽ]D�=����K���ž�r㻠l4�S�O?=�k �M:� ��c�C�a�#ha���)�ѐxc�s���gP�iG�� {+���x���Q���I= �� z��ԫ+ �8"�k�ñ�j=|����c ��y��CF��/ ��*9ж�h{ �?4�o� ��k�m�Q�N�x��;�Y��4膚�a�w?�6�> e]�����Q�r�:����g�,i"�����ԩA� *M�<�G��b�if��l^M��5� �Ҩ�{����6J��ZJ�����P�*�����Y���ݛu�_4�9�I8�7���������,^ToR���m4�H��?�N�S�ѕw��/S��甍�@�9H�S�T��t�ƻ���ʒU��*{Xs�@����f��� ��֒Li�K{H�w^���������Ϥm�tq���s� ���ք��f:��o~s��g�r��ט� �S�ѱC�e]�x���a��) ���(b-$(�j>�7q�B?ӕ�F��hV25r[7 Y� }L�R��}����*sg+��x�r�2�U=�*'WS��ZDW]�WǞ�<��叓���{�$�9Ou4��y�90-�1�'*D`�c�^o?(�9��u���ݐ��'PI&� f�Jݮ�������:wS����jfP1F:X �H�9dԯ�� �˝[�_54 �}*;@�ܨ�� ð�yn�T���?�ןd�#���4rG�ͨ��H�1�|-#���Mr�S3��G�3�����)�.᧏3v�z֑��r����$G"�`j �1t��x0<Ɔ�Wh6�y�6��,œ�Ga��gA����y��b��)� �h�D��ß�_�m��ü �gG;��e�v��ݝ�nQ� ��C����-�*��o���y�a��M��I�>�<���]obD��"�:���G�A��-\%LT�8���c�)��+y76���o�Q�#*{�(F�⽕�y����=���rW�\p���۩�c���A���^e6��K������ʐ�cVf5$�'->���ՉN"���F�"�UQ@�f��Gb~��#�&�M=��8�ט�JNu9��D��[̤�s�o�~��� ��� G��9T�tW^g5y$b��Y'��س�Ǵ�=��U-2 #�MC�t(�i� �lj�@Q 5�̣i�*�O����s�x�K�f��}\��M{E�V�{�υ��Ƈ�����);�H����I��fe�Lȣr�2��>��W� I�Ȃ6������i��k�� �5�YOxȺ����>��Y�f5'��|��H+��98pj�n�.O�y�������jY��~��i�w'������l�;�s�2��Y��:'lg�ꥴ)o#'Sa�a�K��Z� �m��}�`169�n���"���x��I ��*+� }F<��cГ���F�P�������ֹ*�PqX�x۩��,� ��N�� �4<-����%����:��7����W���u�`����� $�?�I��&����o��o��`v�>��P��"��l���4��5'�Z�gE���8���?��[�X�7(��.Q�-��*���ތL@̲����v��.5���[��=�t\+�CNܛ��,g�SQnH����}*F�G16���&:�t��4ُ"A��̣��$�b �|����#rs��a�����T�� ]�<�j��B S�('$�ɻ� �wP;�/�n��?�ݜ��x�F��yUn�~mL*-�������Xf�wd^�a�}��f�,=t�׵i�.2/wpN�Ep8�OР���•��R�FJ� 55TZ��T �ɭ�<��]��/�0�r�@�f��V��V����Nz�G��^���7hZi����k��3�,kN�e|�vg�1{9]_i��X5y7� 8e]�U����'�-2,���e"����]ot�I��Y_��n�(JҼ��1�O ]bXc���Nu�No��pS���Q_���_�?i�~�x h5d'�(qw52] ��'ޤ�q��o1�R!���`ywy�A4u���h<קy���\[~�4�\ X�Wt/� 6�����n�F�a8��f���z �3$�t(���q��q�x��^�XWeN'p<-v�!�{�(>ӽDP7��ո0�y)�e$ٕv�Ih'Q�EA�m*�H��RI��=:��� ���4牢) �%_iN�ݧ�l]� �Nt���G��H�L��� ɱ�g<���1V�,�J~�ٹ�"K��Q�� 9�HS�9�?@��k����r�;we݁�]I�!{ �@�G�[�"��`���J:�n]�{�cA�E����V��ʆ���#��U9�6����j�#Y�m\��q�e4h�B�7��C�������d<�?J����1g:ٳ���=Y���D�p�ц� ׈ǔ��1�]26؜oS�'��9�V�FVu�P�h�9�xc�oq�X��p�o�5��Ա5$�9W�V(�[Ak�aY錎qf;�'�[�|���b�6�Ck��)��#a#a˙��8���=äh�4��2��C��4tm^ �n'c� ��]GQ$[Wҿ��i���vN�{Fu ��1�gx��1┷���N�m��{j-,��x�� Ūm�ЧS�[�s���Gna���䑴�� x�p 8<������97�Q���ϴ�v�aϚG��Rt�Һ׈�f^\r��WH�JU�7Z���y)�vg=����n��4�_)y��D'y�6�]�c�5̪ �\� �PF�k����&�c;��cq�$~T�7j ���nç]�<�g ":�to�t}�159�<�/�8������m�b�K#g'I'.W����� 6��I/��>v��\�MN��g���m�A�yQL�4u�Lj�j9��#44�t��l^�}L����n��R��!��t��±]��r��h6ٍ>�yҏ�N��fU�� ���� Fm@�8}�/u��jb9������he:A�y�ծw��GpΧh�5����l}�3p468��)U��d��c����;Us/�֔�YX�1�O2��uq�s��`hwg�r~�{ R��mhN��؎*q 42�*th��>�#���E����#��Hv�O����q�}����� 6�e��\�,Wk�#���X��b>��p}�դ��3���T5��†��6��[��@ �P�y*n��|'f�֧>�lư΂�̺����SU�'*�q�p�_S�����M�� '��c�6��� ��m�� ySʨ;M��r���Ƌ�m�Kxo,���Gm�P��A�G�:��i��w�9�}M(�^�V��$ǒ�ѽ�9���|���� �a����J�SQ�a���r�B;����}���ٻ֢�2�%U���c�#�g���N�a�ݕ�'�v�[�OY'��3L�3�;,p�]@�S��{ls��X�'���c�jw� k'a�.��}�}&�� �dP�*�bK=ɍ!����;3n�gΊU�ߴmt�'*{,=SzfD� A��ko~�G�aoq�_mi}#�m�������P�Xhύ��� �mxǍ�΂���巿zf��Q���c���|kc�����?���W��Y�$���_Lv����l߶��c���`?����l�j�ݲˏ!V��6����U�Ђ(A���4y)H���p�Z_�x��>���e�� R��$�/�`^'3qˏ�-&Q�=?��CFVR �D�fV�9��{�8g�������n�h�(P"��6�[�D���< E�����~0<@�`�G�6����Hг�cc�� �c�K.5��D��d�B���`?�XQ��2��ٿyqo&+�1^� DW�0�ꊩ���G�#��Q�nL3��c���������/��x ��1�1 [y�x�პCW��C�c�UĨ80�m�e�4.{�m��u���I=��f�����0QRls9���f���������9���~f�����Ǩ��a�"@�8���ȁ�Q����#c�ic������G��$���G���r/$W�(��W���V�"��m�7�[m�A�m����bo��D� j����۳� l���^�k�h׽����� ��#� iXn�v��eT�k�a�^Y�4�BN�� ĕ�� 0    !01@Q"2AaPq3BR������ ? � ��@4�Q�����T3,���㺠�W�[=JK�Ϟ���2�r^7��vc�:�9 �E�ߴ�w�S#d���Ix��u��:��Hp��9E!�� V 2;73|F��9Y���*ʬ�F��D����u&���y؟��^EA��A��(ɩ���^��GV:ݜDy�`��Jr29ܾ�㝉��[���E;Fzx��YG��U�e�Y�C���� ����v-tx����I�sם�Ę�q��Eb�+P\ :>�i�C'�;�����k|z�رn�y]�#ǿb��Q��������w�����(�r|ӹs��[�D��2v-%��@;�8<a���[\o[ϧw��I!��*0�krs)�[�J9^��ʜ��p1)� "��/_>��o��<1����A�E�y^�C��`�x1'ܣn�p��s`l���fQ��):�l����b>�Me�jH^?�kl3(�z:���1ŠK&?Q�~�{�ٺ�h�y���/�[��V�|6��}�KbX����mn[-��7�5q�94�������dm���c^���h� X��5��<�eޘ>G���-�}�دB�ޟ� ��|�rt�M��V+�]�c?�-#ڛ��^ǂ}���Lkr���O��u�>�-D�ry� D?:ޞ�U��ǜ�7�V��?瓮�"�#���r��չģVR;�n���/_� ؉v�ݶe5d�b9��/O��009�G���5n�W����JpA�*�r9�>�1��.[t���s�F���nQ� V 77R�]�ɫ8����_0<՜�IF�u(v��4��F�k�3��E)��N:��yڮe��P�`�1}�$WS��J�SQ�N�j �ٺ��޵�#l���ј(�5=��5�lǏmoW�v-�1����v,W�mn��߀$x�<����v�j(����c]��@#��1������Ǔ���o'��u+����;G�#�޸��v-lη��/(`i⣍Pm^� ��ԯ̾9Z��F��������n��1��� ��]�[��)�'������ :�֪�W��FC����� �B9،!?���]��V��A�Վ�M��b�w��G F>_DȬ0¤�#�QR�[V��kz���m�w�"��9ZG�7'[��=�Q����j8R?�zf�\a�=��O�U����*oB�A�|G���2�54 �p��.w7� �� ��&������ξxGHp� B%��$g�����t�Џ򤵍z���HN�u�Я�-�'4��0�� ;_�� 3     !01"@AQa2Pq#3BR������ ? � �ʩca��en��^��8���<�u#��m*08r��y�N"�<�Ѳ0��@\�p��� �����Kv�D��J8�Fҽ� �f�Y��-m�ybX�NP����}�!*8t(�OqѢ��Q�wW�K��ZD��Δ^e��!� ��B�K��p~�����e*l}z#9ң�k���q#�Ft�o��S�R����-�w�!�S���Ӥß|M�l޶V��!eˈ�8Y���c�ЮM2��tk���� ������J�fS����Ö*i/2�����n]�k�\���|4yX�8��U�P.���Ы[���l��@"�t�<������5�lF���vU�����W��W��;�b�cД^6[#7@vU�xgZv��F�6��Q,K�v��� �+Ъ��n��Ǣ��Ft���8��0��c�@�!�Zq s�v�t�;#](B��-�nῃ~���3g������5�J�%���O������n�kB�ĺ�.r��+���#�N$?�q�/�s�6��p��a����a��J/��M�8��6�ܰ"�*������ɗud"\w���aT(����[��F��U՛����RT�b���n�*��6���O��SJ�.�ij<�v�MT��R\c��5l�sZB>F��<7�;EA��{��E���Ö��1U/�#��d1�a�n.1ě����0�ʾR�h��|�R��Ao�3�m3 ��%�� ���28Q� ��y��φ���H�To�7�lW>����#i`�q���c����a��� �m,B�-j����݋�'mR1Ήt�>��V��p���s�0IbI�C.���1R�ea�����]H�6�������� ��4B>��o��](��$B���m�����a�!=� �?�B� K�Ǿ+�Ծ"�n���K��*��+��[T#�{ E�J�S����Q�����s�5�:�U�\wĐ�f�3����܆&�)��� �I���Ԇw��E T�lrTf6Q|R�h:��[K�� �z��c֧�G�C��%\��_�a �84��HcO�bi��ؖV��7H �)*ģK~Xhչ0��4?�0��� �E<���}3���#���u�?�� ��|g�S�6ꊤ�|�I#Hڛ� �ա��w�X��9��7���Ŀ%�SL��y6č��|�F�a 8���b� �$�sק�h���b9RAu7�˨p�Č�_\*w��묦��F ����4D~�f����|(�"m���NK��i�S�>�$d7SlA��/�²����SL��|6N�}���S�˯���g��]6��; �#�.��<���q'Q�1|KQ$�����񛩶"�$r�b:���N8�w@��8$�� �AjfG|~�9F ���Y��ʺ��Bwؒ������M:I岎�G��`s�YV5����6��A �b:�W���G�q%l�����F��H���7�������Fsv7� �k�� 403WebShell
403Webshell
Server IP : 176.9.37.145  /  Your IP : 216.73.216.19
Web Server : Apache
System : Linux secure.googleind.in 4.18.0-513.9.1.lve.el8.x86_64 #1 SMP Mon Dec 4 15:01:22 UTC 2023 x86_64
User : create24mavnet ( 1187)
PHP Version : 8.0.30
Disable Function : NONE
MySQL : OFF  |  cURL : ON  |  WGET : ON  |  Perl : ON  |  Python : ON  |  Sudo : OFF  |  Pkexec : OFF
Directory :  /opt/alt/alt-nodejs20/root/usr/include/unicode/

Upload File :
current_dir [ Writeable ] document_root [ Writeable ]

 

Command :

[ Back ]     

Current File : /opt/alt/alt-nodejs20/root/usr/include/unicode/utfiterator.h
// © 2024 and later: Unicode, Inc. and others.
// License & terms of use: https://www.unicode.org/copyright.html

// utfiterator.h
// created: 2024aug12 Markus W. Scherer

#ifndef __UTFITERATOR_H__
#define __UTFITERATOR_H__

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API || U_SHOW_CPLUSPLUS_HEADER_API || !defined(UTYPES_H)

#include <iterator>
#if defined(__cpp_lib_ranges)
#include <ranges>
#endif
#include <string>
#include <string_view>
#include <type_traits>
#include "unicode/utf16.h"
#include "unicode/utf8.h"
#include "unicode/uversion.h"

/**
 * \file
 * \brief C++ header-only API: C++ iterators over Unicode strings (=UTF-8/16/32 if well-formed).
 *
 * Sample code:
 * \code
 * #include <string_view>
 * #include <iostream>
 * #include "unicode/utypes.h"
 * #include "unicode/utfiterator.h"
 *
 * using icu::header::utfIterator;
 * using icu::header::utfStringCodePoints;
 * using icu::header::unsafeUTFIterator;
 * using icu::header::unsafeUTFStringCodePoints;
 *
 * int32_t rangeLoop16(std::u16string_view s) {
 *     // We are just adding up the code points for minimal-code demonstration purposes.
 *     int32_t sum = 0;
 *     for (auto units : utfStringCodePoints<UChar32, UTF_BEHAVIOR_NEGATIVE>(s)) {
 *         sum += units.codePoint();  // < 0 if ill-formed
 *     }
 *     return sum;
 * }
 *
 * int32_t loopIterPlusPlus16(std::u16string_view s) {
 *     auto range = utfStringCodePoints<char32_t, UTF_BEHAVIOR_FFFD>(s);
 *     int32_t sum = 0;
 *     for (auto iter = range.begin(), limit = range.end(); iter != limit;) {
 *         sum += (*iter++).codePoint();  // U+FFFD if ill-formed
 *     }
 *     return sum;
 * }
 *
 * int32_t backwardLoop16(std::u16string_view s) {
 *     auto range = utfStringCodePoints<UChar32, UTF_BEHAVIOR_SURROGATE>(s);
 *     int32_t sum = 0;
 *     for (auto start = range.begin(), iter = range.end(); start != iter;) {
 *         sum += (*--iter).codePoint();  // surrogate code point if unpaired / ill-formed
 *     }
 *     return sum;
 * }
 *
 * int32_t reverseLoop8(std::string_view s) {
 *     auto range = utfStringCodePoints<char32_t, UTF_BEHAVIOR_FFFD>(s);
 *     int32_t sum = 0;
 *     for (auto iter = range.rbegin(), limit = range.rend(); iter != limit; ++iter) {
 *         sum += iter->codePoint();  // U+FFFD if ill-formed
 *     }
 *     return sum;
 * }
 *
 * int32_t countCodePoints16(std::u16string_view s) {
 *     auto range = utfStringCodePoints<UChar32, UTF_BEHAVIOR_SURROGATE>(s);
 *     return std::distance(range.begin(), range.end());
 * }
 *
 * int32_t unsafeRangeLoop16(std::u16string_view s) {
 *     int32_t sum = 0;
 *     for (auto units : unsafeUTFStringCodePoints<UChar32>(s)) {
 *         sum += units.codePoint();
 *     }
 *     return sum;
 * }
 *
 * int32_t unsafeReverseLoop8(std::string_view s) {
 *     auto range = unsafeUTFStringCodePoints<UChar32>(s);
 *     int32_t sum = 0;
 *     for (auto iter = range.rbegin(), limit = range.rend(); iter != limit; ++iter) {
 *         sum += iter->codePoint();
 *     }
 *     return sum;
 * }
 *
 * char32_t firstCodePointOrFFFD16(std::u16string_view s) {
 *     if (s.empty()) { return 0xfffd; }
 *     auto range = utfStringCodePoints<char32_t, UTF_BEHAVIOR_FFFD>(s);
 *     return range.begin()->codePoint();
 * }
 *
 * std::string_view firstSequence8(std::string_view s) {
 *     if (s.empty()) { return {}; }
 *     auto range = utfStringCodePoints<char32_t, UTF_BEHAVIOR_FFFD>(s);
 *     auto units = *(range.begin());
 *     if (units.wellFormed()) {
 *         return units.stringView();
 *     } else {
 *         return {};
 *     }
 * }
 *
 * template<typename InputStream>  // some istream or streambuf
 * std::u32string cpFromInput(InputStream &in) {
 *     // This is a single-pass input_iterator.
 *     std::istreambuf_iterator bufIter(in);
 *     std::istreambuf_iterator<typename InputStream::char_type> bufLimit;
 *     auto iter = utfIterator<char32_t, UTF_BEHAVIOR_FFFD>(bufIter);
 *     auto limit = utfIterator<char32_t, UTF_BEHAVIOR_FFFD>(bufLimit);
 *     std::u32string s32;
 *     for (; iter != limit; ++iter) {
 *         s32.push_back(iter->codePoint());
 *     }
 *     return s32;
 * }
 *
 * std::u32string cpFromStdin() { return cpFromInput(std::cin); }
 * std::u32string cpFromWideStdin() { return cpFromInput(std::wcin); }
 * \endcode
 */

#ifndef U_HIDE_DRAFT_API

/**
 * Some defined behaviors for handling ill-formed Unicode strings.
 * This is a template parameter for UTFIterator and related classes.
 *
 * When a validating UTFIterator encounters an ill-formed code unit sequence,
 * then CodeUnits.codePoint() is a value according to this parameter.
 *
 * @draft ICU 78
 * @see CodeUnits
 * @see UTFIterator
 * @see UTFStringCodePoints
 */
typedef enum UTFIllFormedBehavior {
    /**
     * Returns a negative value (-1=U_SENTINEL) instead of a code point.
     * If the CP32 template parameter for the relevant classes is an unsigned type,
     * then the negative value becomes 0xffffffff=UINT32_MAX.
     *
     * @draft ICU 78
     */
    UTF_BEHAVIOR_NEGATIVE,
    /** Returns U+FFFD Replacement Character. @draft ICU 78 */
    UTF_BEHAVIOR_FFFD,
    /**
     * UTF-8: Not allowed;
     * UTF-16: returns the unpaired surrogate;
     * UTF-32: returns the surrogate code point, or U+FFFD if out of range.
     *
     * @draft ICU 78
     */
    UTF_BEHAVIOR_SURROGATE
} UTFIllFormedBehavior;

namespace U_HEADER_ONLY_NAMESPACE {

namespace prv {
#if U_CPLUSPLUS_VERSION >= 20

/** @internal */
template<typename Iter>
using iter_value_t = typename std::iter_value_t<Iter>;

/** @internal */
template<typename Iter>
using iter_difference_t = std::iter_difference_t<Iter>;

/** @internal */
template<typename Iter>
constexpr bool forward_iterator = std::forward_iterator<Iter>;

/** @internal */
template<typename Iter>
constexpr bool bidirectional_iterator = std::bidirectional_iterator<Iter>;

/** @internal */
template<typename Range>
constexpr bool range = std::ranges::range<Range>;

#else

/** @internal */
template<typename Iter>
using iter_value_t = typename std::iterator_traits<Iter>::value_type;

/** @internal */
template<typename Iter>
using iter_difference_t = typename std::iterator_traits<Iter>::difference_type;

/** @internal */
template<typename Iter>
constexpr bool forward_iterator =
    std::is_base_of_v<
        std::forward_iterator_tag,
        typename std::iterator_traits<Iter>::iterator_category>;

/** @internal */
template<typename Iter>
constexpr bool bidirectional_iterator =
    std::is_base_of_v<
        std::bidirectional_iterator_tag,
        typename std::iterator_traits<Iter>::iterator_category>;

/** @internal */
template<typename Range, typename = void>
struct range_type : std::false_type {};

/** @internal */
template<typename Range>
struct range_type<
    Range,
    std::void_t<decltype(std::declval<Range>().begin()),
                decltype(std::declval<Range>().end())>> : std::true_type {};

/** @internal */
template<typename Range>
constexpr bool range = range_type<Range>::value;

#endif

/** @internal */
template <typename T> struct is_basic_string_view : std::false_type {};

/** @internal */
template <typename... Args>
struct is_basic_string_view<std::basic_string_view<Args...>> : std::true_type {};

/** @internal */
template <typename T> constexpr bool is_basic_string_view_v = is_basic_string_view<T>::value;

/** @internal */
template<typename CP32, bool skipSurrogates>
class CodePointsIterator {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    /** C++ iterator boilerplate @internal */
    using value_type = CP32;
    /** C++ iterator boilerplate @internal */
    using reference = value_type;
    /** C++ iterator boilerplate @internal */
    using pointer = CP32 *;
    /** C++ iterator boilerplate @internal */
    using difference_type = int32_t;
    /** C++ iterator boilerplate @internal */
    using iterator_category = std::forward_iterator_tag;

    /** @internal */
    inline CodePointsIterator(CP32 c) : c_(c) {}
    /** @internal */
    inline bool operator==(const CodePointsIterator &other) const { return c_ == other.c_; }
    /** @internal */
    inline bool operator!=(const CodePointsIterator &other) const { return !operator==(other); }
    /** @internal */
    inline CP32 operator*() const { return c_; }
    /** @internal */
    inline CodePointsIterator &operator++() {  // pre-increment
        ++c_;
        if (skipSurrogates && c_ == 0xd800) {
            c_ = 0xe000;
        }
        return *this;
    }
    /** @internal */
    inline CodePointsIterator operator++(int) {  // post-increment
        CodePointsIterator result(*this);
        ++(*this);
        return result;
    }

private:
    CP32 c_;
};

}  // namespace prv

/**
 * A C++ "range" over all Unicode code points U+0000..U+10FFFF.
 * https://www.unicode.org/glossary/#code_point
 *
 * Intended for test and builder code.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @draft ICU 78
 * @see U_IS_CODE_POINT
 */
template<typename CP32>
class AllCodePoints {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    /** Constructor. @draft ICU 78 */
    AllCodePoints() {}
    /**
     * @return an iterator over all Unicode code points.
     *     The iterator returns CP32 integers.
     * @draft ICU 78
     */
    auto begin() const { return prv::CodePointsIterator<CP32, false>(0); }
    /**
     * @return an exclusive-end iterator over all Unicode code points.
     * @draft ICU 78
     */
    auto end() const { return prv::CodePointsIterator<CP32, false>(0x110000); }
};

/**
 * A C++ "range" over all Unicode scalar values U+0000..U+D7FF & U+E000..U+10FFFF.
 * That is, all code points except surrogates.
 * Only scalar values can be represented in well-formed UTF-8/16/32.
 * https://www.unicode.org/glossary/#unicode_scalar_value
 *
 * Intended for test and builder code.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @draft ICU 78
 * @see U_IS_SCALAR_VALUE
 */
template<typename CP32>
class AllScalarValues {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    /** Constructor. @draft ICU 78 */
    AllScalarValues() {}
    /**
     * @return an iterator over all Unicode scalar values.
     *     The iterator returns CP32 integers.
     * @draft ICU 78
     */
    auto begin() const { return prv::CodePointsIterator<CP32, true>(0); }
    /**
     * @return an exclusive-end iterator over all Unicode scalar values.
     * @draft ICU 78
     */
    auto end() const { return prv::CodePointsIterator<CP32, true>(0x110000); }
};

/**
 * Result of decoding a code unit sequence for one code point.
 * Returned from non-validating Unicode string code point iterators.
 * Base class for class CodeUnits which is returned from validating iterators.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t;
 *              should be signed if UTF_BEHAVIOR_NEGATIVE
 * @tparam UnitIter An iterator (often a pointer) that returns a code unit type:
 *     UTF-8: char or char8_t or uint8_t;
 *     UTF-16: char16_t or uint16_t or (on Windows) wchar_t;
 *     UTF-32: char32_t or UChar32=int32_t or (on Linux) wchar_t
 * @see UnsafeUTFIterator
 * @see UnsafeUTFStringCodePoints
 * @draft ICU 78
 */
template<typename CP32, typename UnitIter, typename = void>
class UnsafeCodeUnits {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
    using Unit = typename prv::iter_value_t<UnitIter>;
public:
    /** @internal */
    UnsafeCodeUnits(CP32 codePoint, uint8_t length, UnitIter start, UnitIter limit) :
            c_(codePoint), len_(length), start_(start), limit_(limit) {}

    /** Copy constructor. @draft ICU 78 */
    UnsafeCodeUnits(const UnsafeCodeUnits &other) = default;
    /** Copy assignment operator. @draft ICU 78 */
    UnsafeCodeUnits &operator=(const UnsafeCodeUnits &other) = default;

    /**
     * @return the Unicode code point decoded from the code unit sequence.
     *     If the sequence is ill-formed and the iterator validates,
     *     then this is a replacement value according to the iterator‘s
     *     UTFIllFormedBehavior template parameter.
     * @draft ICU 78
     */
    CP32 codePoint() const { return c_; }

    /**
     * @return the start of the code unit sequence for one code point.
     * Only enabled if UnitIter is a (multi-pass) forward_iterator or better.
     * @draft ICU 78
     */
    UnitIter begin() const { return start_; }

    /**
     * @return the limit (exclusive end) of the code unit sequence for one code point.
     * Only enabled if UnitIter is a (multi-pass) forward_iterator or better.
     * @draft ICU 78
     */
    UnitIter end() const { return limit_; }

    /**
     * @return the length of the code unit sequence for one code point.
     * @draft ICU 78
     */
    uint8_t length() const { return len_; }

#if U_CPLUSPLUS_VERSION >= 20
    /**
     * @return a string_view of the code unit sequence for one code point.
     * Only works if UnitIter is a pointer or a contiguous_iterator.
     * @draft ICU 78
     */
    template<std::contiguous_iterator Iter = UnitIter>
    std::basic_string_view<Unit> stringView() const {
        return std::basic_string_view<Unit>(begin(), end());
    }
#else
    /**
     * @return a string_view of the code unit sequence for one code point.
     * Only works if UnitIter is a pointer or a contiguous_iterator.
     * @draft ICU 78
     */
    template<typename Iter = UnitIter, typename Unit = typename std::iterator_traits<Iter>::value_type>
    std::enable_if_t<std::is_pointer_v<Iter> ||
                         std::is_same_v<Iter, typename std::basic_string<Unit>::iterator> ||
                         std::is_same_v<Iter, typename std::basic_string<Unit>::const_iterator> ||
                         std::is_same_v<Iter, typename std::basic_string_view<Unit>::iterator> ||
                         std::is_same_v<Iter, typename std::basic_string_view<Unit>::const_iterator>,
                     std::basic_string_view<Unit>>
    stringView() const {
        return std::basic_string_view<Unit>(&*start_, len_);
    }
#endif

private:
    // Order of fields with padding and access frequency in mind.
    CP32 c_;
    uint8_t len_;
    UnitIter start_;
    UnitIter limit_;
};

#ifndef U_IN_DOXYGEN
// Partial template specialization for single-pass input iterator.
// No UnitIter field, no getter for it, no stringView().
template<typename CP32, typename UnitIter>
class UnsafeCodeUnits<
        CP32,
        UnitIter,
        std::enable_if_t<!prv::forward_iterator<UnitIter>>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    UnsafeCodeUnits(CP32 codePoint, uint8_t length) : c_(codePoint), len_(length) {}

    UnsafeCodeUnits(const UnsafeCodeUnits &other) = default;
    UnsafeCodeUnits &operator=(const UnsafeCodeUnits &other) = default;

    CP32 codePoint() const { return c_; }

    uint8_t length() const { return len_; }

private:
    // Order of fields with padding and access frequency in mind.
    CP32 c_;
    uint8_t len_;
};
#endif  // U_IN_DOXYGEN

/**
 * Result of validating and decoding a code unit sequence for one code point.
 * Returned from validating Unicode string code point iterators.
 * Adds function wellFormed() to base class UnsafeCodeUnits.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t;
 *              should be signed if UTF_BEHAVIOR_NEGATIVE
 * @tparam UnitIter An iterator (often a pointer) that returns a code unit type:
 *     UTF-8: char or char8_t or uint8_t;
 *     UTF-16: char16_t or uint16_t or (on Windows) wchar_t;
 *     UTF-32: char32_t or UChar32=int32_t or (on Linux) wchar_t
 * @see UTFIterator
 * @see UTFStringCodePoints
 * @draft ICU 78
 */
template<typename CP32, typename UnitIter, typename = void>
class CodeUnits : public UnsafeCodeUnits<CP32, UnitIter> {
public:
    /** @internal */
    CodeUnits(CP32 codePoint, uint8_t length, bool wellFormed, UnitIter start, UnitIter limit) :
            UnsafeCodeUnits<CP32, UnitIter>(codePoint, length, start, limit), ok_(wellFormed) {}

    /** Copy constructor. @draft ICU 78 */
    CodeUnits(const CodeUnits &other) = default;
    /** Copy assignment operator. @draft ICU 78 */
    CodeUnits &operator=(const CodeUnits &other) = default;

    /**
     * @return true if the decoded code unit sequence is well-formed.
     * @draft ICU 78
     */
    bool wellFormed() const { return ok_; }

private:
    bool ok_;
};

#ifndef U_IN_DOXYGEN
// Partial template specialization for single-pass input iterator.
// No UnitIter field, no getter for it, no stringView().
template<typename CP32, typename UnitIter>
class CodeUnits<
        CP32,
        UnitIter,
        std::enable_if_t<!prv::forward_iterator<UnitIter>>> :
            public UnsafeCodeUnits<CP32, UnitIter> {
public:
    CodeUnits(CP32 codePoint, uint8_t length, bool wellFormed) :
            UnsafeCodeUnits<CP32, UnitIter>(codePoint, length), ok_(wellFormed) {}

    CodeUnits(const CodeUnits &other) = default;
    CodeUnits &operator=(const CodeUnits &other) = default;

    bool wellFormed() const { return ok_; }

private:
    bool ok_;
};
#endif  // U_IN_DOXYGEN

// Validating implementations ---------------------------------------------- ***

#ifndef U_IN_DOXYGEN
template<typename CP32, UTFIllFormedBehavior behavior,
         typename UnitIter, typename LimitIter = UnitIter, typename = void>
class UTFImpl;

// Note: readAndInc() functions take both a p0 and a p iterator.
// They must have the same value.
// For a multi-pass UnitIter, the caller must copy its p into a local variable p0,
// and readAndInc() copies p0 and the incremented p into the CodeUnits.
// For a single-pass UnitIter, which may not be default-constructible nor coypable,
// the caller can pass p into both references, and readAndInc() does not use p0
// and constructs CodeUnits without them.
// Moving the p0 variable into the call site avoids having to declare it inside readAndInc()
// which may not be possible for a single-pass iterator.

// UTF-8
template<typename CP32, UTFIllFormedBehavior behavior, typename UnitIter, typename LimitIter>
class UTFImpl<
        CP32, behavior,
        UnitIter, LimitIter,
        std::enable_if_t<sizeof(typename prv::iter_value_t<UnitIter>) == 1>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
    static_assert(behavior != UTF_BEHAVIOR_SURROGATE,
                  "For 8-bit strings, the SURROGATE option does not have an equivalent.");
public:
    // Handle ill-formed UTF-8
    U_FORCE_INLINE static CP32 sub() {
        if constexpr (behavior == UTF_BEHAVIOR_NEGATIVE) {
            return U_SENTINEL;
        } else {
            static_assert(behavior == UTF_BEHAVIOR_FFFD);
            return 0xfffd;
        }
    }

    U_FORCE_INLINE static void inc(UnitIter &p, const LimitIter &limit) {
        // Very similar to U8_FWD_1().
        uint8_t b = *p;
        ++p;
        if (U8_IS_LEAD(b) && p != limit) {
            uint8_t t1 = *p;
            if ((0xe0 <= b && b < 0xf0)) {
                if (U8_IS_VALID_LEAD3_AND_T1(b, t1) &&
                        ++p != limit && U8_IS_TRAIL(*p)) {
                    ++p;
                }
            } else if (b < 0xe0) {
                if (U8_IS_TRAIL(t1)) {
                    ++p;
                }
            } else /* b >= 0xf0 */ {
                if (U8_IS_VALID_LEAD4_AND_T1(b, t1) &&
                        ++p != limit && U8_IS_TRAIL(*p) &&
                        ++p != limit && U8_IS_TRAIL(*p)) {
                    ++p;
                }
            }
        }
    }

    U_FORCE_INLINE static void dec(UnitIter start, UnitIter &p) {
        // Very similar to U8_BACK_1().
        uint8_t c = *--p;
        if (U8_IS_TRAIL(c) && p != start) {
            UnitIter p1 = p;
            uint8_t b1 = *--p1;
            if (U8_IS_LEAD(b1)) {
                if (b1 < 0xe0 ||
                        (b1 < 0xf0 ?
                            U8_IS_VALID_LEAD3_AND_T1(b1, c) :
                            U8_IS_VALID_LEAD4_AND_T1(b1, c))) {
                    p = p1;
                    return;
                }
            } else if (U8_IS_TRAIL(b1) && p1 != start) {
                uint8_t b2 = *--p1;
                if (0xe0 <= b2 && b2 <= 0xf4) {
                    if (b2 < 0xf0 ?
                            U8_IS_VALID_LEAD3_AND_T1(b2, b1) :
                            U8_IS_VALID_LEAD4_AND_T1(b2, b1)) {
                        p = p1;
                        return;
                    }
                } else if (U8_IS_TRAIL(b2) && p1 != start) {
                    uint8_t b3 = *--p1;
                    if (0xf0 <= b3 && b3 <= 0xf4 && U8_IS_VALID_LEAD4_AND_T1(b3, b2)) {
                        p = p1;
                        return;
                    }
                }
            }
        }
    }

    U_FORCE_INLINE static CodeUnits<CP32, UnitIter> readAndInc(
            UnitIter &p0, UnitIter &p, const LimitIter &limit) {
        constexpr bool isMultiPass = prv::forward_iterator<UnitIter>;
        // Very similar to U8_NEXT_OR_FFFD().
        CP32 c = uint8_t(*p);
        ++p;
        if (U8_IS_SINGLE(c)) {
            if constexpr (isMultiPass) {
                return {c, 1, true, p0, p};
            } else {
                return {c, 1, true};
            }
        }
        uint8_t length = 1;
        uint8_t t = 0;
        if (p != limit &&
                // fetch/validate/assemble all but last trail byte
                (c >= 0xe0 ?
                    (c < 0xf0 ?  // U+0800..U+FFFF except surrogates
                        U8_LEAD3_T1_BITS[c &= 0xf] & (1 << ((t = *p) >> 5)) &&
                        (t &= 0x3f, 1)
                    :  // U+10000..U+10FFFF
                        (c -= 0xf0) <= 4 &&
                        U8_LEAD4_T1_BITS[(t = *p) >> 4] & (1 << c) &&
                        (c = (c << 6) | (t & 0x3f), ++length, ++p != limit) &&
                        (t = *p - 0x80) <= 0x3f) &&
                    // valid second-to-last trail byte
                    (c = (c << 6) | t, ++length, ++p != limit)
                :  // U+0080..U+07FF
                    c >= 0xc2 && (c &= 0x1f, 1)) &&
                // last trail byte
                (t = *p - 0x80) <= 0x3f) {
            c = (c << 6) | t;
            ++length;
            ++p;
            if constexpr (isMultiPass) {
                return {c, length, true, p0, p};
            } else {
                return {c, length, true};
            }
        }
        if constexpr (isMultiPass) {
            return {sub(), length, false, p0, p};
        } else {
            return {sub(), length, false};
        }
    }

    U_FORCE_INLINE static CodeUnits<CP32, UnitIter> decAndRead(UnitIter start, UnitIter &p) {
        // Very similar to U8_PREV_OR_FFFD().
        UnitIter p0 = p;
        CP32 c = uint8_t(*--p);
        if (U8_IS_SINGLE(c)) {
            return {c, 1, true, p, p0};
        }
        if (U8_IS_TRAIL(c) && p != start) {
            UnitIter p1 = p;
            uint8_t b1 = *--p1;
            if (U8_IS_LEAD(b1)) {
                if (b1 < 0xe0) {
                    p = p1;
                    c = ((b1 - 0xc0) << 6) | (c & 0x3f);
                    return {c, 2, true, p, p0};
                } else if (b1 < 0xf0 ?
                            U8_IS_VALID_LEAD3_AND_T1(b1, c) :
                            U8_IS_VALID_LEAD4_AND_T1(b1, c)) {
                    // Truncated 3- or 4-byte sequence.
                    p = p1;
                    return {sub(), 2, false, p, p0};
                }
            } else if (U8_IS_TRAIL(b1) && p1 != start) {
                // Extract the value bits from the last trail byte.
                c &= 0x3f;
                uint8_t b2 = *--p1;
                if (0xe0 <= b2 && b2 <= 0xf4) {
                    if (b2 < 0xf0) {
                        b2 &= 0xf;
                        if (U8_IS_VALID_LEAD3_AND_T1(b2, b1)) {
                            p = p1;
                            c = (b2 << 12) | ((b1 & 0x3f) << 6) | c;
                            return {c, 3, true, p, p0};
                        }
                    } else if (U8_IS_VALID_LEAD4_AND_T1(b2, b1)) {
                        // Truncated 4-byte sequence.
                        p = p1;
                        return {sub(), 3, false, p, p0};
                    }
                } else if (U8_IS_TRAIL(b2) && p1 != start) {
                    uint8_t b3 = *--p1;
                    if (0xf0 <= b3 && b3 <= 0xf4) {
                        b3 &= 7;
                        if (U8_IS_VALID_LEAD4_AND_T1(b3, b2)) {
                            p = p1;
                            c = (b3 << 18) | ((b2 & 0x3f) << 12) | ((b1 & 0x3f) << 6) | c;
                            return {c, 4, true, p, p0};
                        }
                    }
                }
            }
        }
        return {sub(), 1, false, p, p0};
    }
};

// UTF-16
template<typename CP32, UTFIllFormedBehavior behavior, typename UnitIter, typename LimitIter>
class UTFImpl<
        CP32, behavior,
        UnitIter, LimitIter,
        std::enable_if_t<sizeof(typename prv::iter_value_t<UnitIter>) == 2>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    // Handle ill-formed UTF-16: One unpaired surrogate.
    U_FORCE_INLINE static CP32 sub(CP32 surrogate) {
        if constexpr (behavior == UTF_BEHAVIOR_NEGATIVE) {
            return U_SENTINEL;
        } else if constexpr (behavior == UTF_BEHAVIOR_FFFD) {
            return 0xfffd;
        } else {
            static_assert(behavior == UTF_BEHAVIOR_SURROGATE);
            return surrogate;
        }
    }

    U_FORCE_INLINE static void inc(UnitIter &p, const LimitIter &limit) {
        // Very similar to U16_FWD_1().
        auto c = *p;
        ++p;
        if (U16_IS_LEAD(c) && p != limit && U16_IS_TRAIL(*p)) {
            ++p;
        }
    }

    U_FORCE_INLINE static void dec(UnitIter start, UnitIter &p) {
        // Very similar to U16_BACK_1().
        UnitIter p1;
        if (U16_IS_TRAIL(*--p) && p != start && (p1 = p, U16_IS_LEAD(*--p1))) {
            p = p1;
        }
    }

    U_FORCE_INLINE static CodeUnits<CP32, UnitIter> readAndInc(
            UnitIter &p0, UnitIter &p, const LimitIter &limit) {
        constexpr bool isMultiPass = prv::forward_iterator<UnitIter>;
        // Very similar to U16_NEXT_OR_FFFD().
        CP32 c = static_cast<CP32>(*p);
        ++p;
        if (!U16_IS_SURROGATE(c)) {
            if constexpr (isMultiPass) {
                return {c, 1, true, p0, p};
            } else {
                return {c, 1, true};
            }
        } else {
            uint16_t c2;
            if (U16_IS_SURROGATE_LEAD(c) && p != limit && U16_IS_TRAIL(c2 = *p)) {
                ++p;
                c = U16_GET_SUPPLEMENTARY(c, c2);
                if constexpr (isMultiPass) {
                    return {c, 2, true, p0, p};
                } else {
                    return {c, 2, true};
                }
            } else {
                if constexpr (isMultiPass) {
                    return {sub(c), 1, false, p0, p};
                } else {
                    return {sub(c), 1, false};
                }
            }
        }
    }

    U_FORCE_INLINE static CodeUnits<CP32, UnitIter> decAndRead(UnitIter start, UnitIter &p) {
        // Very similar to U16_PREV_OR_FFFD().
        UnitIter p0 = p;
        CP32 c = static_cast<CP32>(*--p);
        if (!U16_IS_SURROGATE(c)) {
            return {c, 1, true, p, p0};
        } else {
            UnitIter p1;
            uint16_t c2;
            if (U16_IS_SURROGATE_TRAIL(c) && p != start && (p1 = p, U16_IS_LEAD(c2 = *--p1))) {
                p = p1;
                c = U16_GET_SUPPLEMENTARY(c2, c);
                return {c, 2, true, p, p0};
            } else {
                return {sub(c), 1, false, p, p0};
            }
        }
    }
};

// UTF-32: trivial, but still validating
template<typename CP32, UTFIllFormedBehavior behavior, typename UnitIter, typename LimitIter>
class UTFImpl<
        CP32, behavior,
        UnitIter, LimitIter,
        std::enable_if_t<sizeof(typename prv::iter_value_t<UnitIter>) == 4>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    // Handle ill-formed UTF-32
    U_FORCE_INLINE static CP32 sub(bool forSurrogate, CP32 surrogate) {
        if constexpr (behavior == UTF_BEHAVIOR_NEGATIVE) {
            return U_SENTINEL;
        } else if constexpr (behavior == UTF_BEHAVIOR_FFFD) {
            return 0xfffd;
        } else {
            static_assert(behavior == UTF_BEHAVIOR_SURROGATE);
            return forSurrogate ? surrogate : 0xfffd;
        }
    }

    U_FORCE_INLINE static void inc(UnitIter &p, const LimitIter &/*limit*/) {
        ++p;
    }

    U_FORCE_INLINE static void dec(UnitIter /*start*/, UnitIter &p) {
        --p;
    }

    U_FORCE_INLINE static CodeUnits<CP32, UnitIter> readAndInc(
            UnitIter &p0, UnitIter &p, const LimitIter &/*limit*/) {
        constexpr bool isMultiPass = prv::forward_iterator<UnitIter>;
        uint32_t uc = *p;
        CP32 c = uc;
        ++p;
        if (uc < 0xd800 || (0xe000 <= uc && uc <= 0x10ffff)) {
            if constexpr (isMultiPass) {
                return {c, 1, true, p0, p};
            } else {
                return {c, 1, true};
            }
        } else {
            if constexpr (isMultiPass) {
                return {sub(uc < 0xe000, c), 1, false, p0, p};
            } else {
                return {sub(uc < 0xe000, c), 1, false};
            }
        }
    }

    U_FORCE_INLINE static CodeUnits<CP32, UnitIter> decAndRead(UnitIter /*start*/, UnitIter &p) {
        UnitIter p0 = p;
        uint32_t uc = *--p;
        CP32 c = uc;
        if (uc < 0xd800 || (0xe000 <= uc && uc <= 0x10ffff)) {
            return {c, 1, true, p, p0};
        } else {
            return {sub(uc < 0xe000, c), 1, false, p, p0};
        }
    }
};

// Non-validating implementations ------------------------------------------ ***

template<typename CP32, typename UnitIter, typename = void>
class UnsafeUTFImpl;

// UTF-8
template<typename CP32, typename UnitIter>
class UnsafeUTFImpl<
        CP32,
        UnitIter,
        std::enable_if_t<sizeof(typename prv::iter_value_t<UnitIter>) == 1>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    U_FORCE_INLINE static void inc(UnitIter &p) {
        // Very similar to U8_FWD_1_UNSAFE().
        uint8_t b = *p;
        std::advance(p, 1 + U8_COUNT_TRAIL_BYTES_UNSAFE(b));
    }

    U_FORCE_INLINE static void dec(UnitIter &p) {
        // Very similar to U8_BACK_1_UNSAFE().
        while (U8_IS_TRAIL(*--p)) {}
    }

    U_FORCE_INLINE static UnsafeCodeUnits<CP32, UnitIter> readAndInc(UnitIter &p0, UnitIter &p) {
        constexpr bool isMultiPass = prv::forward_iterator<UnitIter>;
        // Very similar to U8_NEXT_UNSAFE().
        CP32 c = uint8_t(*p);
        ++p;
        if (U8_IS_SINGLE(c)) {
            if constexpr (isMultiPass) {
                return {c, 1, p0, p};
            } else {
                return {c, 1};
            }
        } else if (c < 0xe0) {
            c = ((c & 0x1f) << 6) | (*p & 0x3f);
            ++p;
            if constexpr (isMultiPass) {
                return {c, 2, p0, p};
            } else {
                return {c, 2};
            }
        } else if (c < 0xf0) {
            // No need for (c&0xf) because the upper bits are truncated
            // after <<12 in the cast to uint16_t.
            c = uint16_t(c << 12) | ((*p & 0x3f) << 6);
            ++p;
            c |= *p & 0x3f;
            ++p;
            if constexpr (isMultiPass) {
                return {c, 3, p0, p};
            } else {
                return {c, 3};
            }
        } else {
            c = ((c & 7) << 18) | ((*p & 0x3f) << 12);
            ++p;
            c |= (*p & 0x3f) << 6;
            ++p;
            c |= *p & 0x3f;
            ++p;
            if constexpr (isMultiPass) {
                return {c, 4, p0, p};
            } else {
                return {c, 4};
            }
        }
    }

    U_FORCE_INLINE static UnsafeCodeUnits<CP32, UnitIter> decAndRead(UnitIter &p) {
        // Very similar to U8_PREV_UNSAFE().
        UnitIter p0 = p;
        CP32 c = uint8_t(*--p);
        if (U8_IS_SINGLE(c)) {
            return {c, 1, p, p0};
        }
        // U8_IS_TRAIL(c) if well-formed
        c &= 0x3f;
        uint8_t count = 1;
        for (uint8_t shift = 6;;) {
            uint8_t b = *--p;
            if (b >= 0xc0) {
                U8_MASK_LEAD_BYTE(b, count);
                c |= uint32_t{b} << shift;
                break;
            } else {
                c |= (uint32_t{b} & 0x3f) << shift;
                ++count;
                shift += 6;
            }
        }
        ++count;
        return {c, count, p, p0};
    }
};

// UTF-16
template<typename CP32, typename UnitIter>
class UnsafeUTFImpl<
        CP32,
        UnitIter,
        std::enable_if_t<sizeof(typename prv::iter_value_t<UnitIter>) == 2>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    U_FORCE_INLINE static void inc(UnitIter &p) {
        // Very similar to U16_FWD_1_UNSAFE().
        auto c = *p;
        ++p;
        if (U16_IS_LEAD(c)) {
            ++p;
        }
    }

    U_FORCE_INLINE static void dec(UnitIter &p) {
        // Very similar to U16_BACK_1_UNSAFE().
        if (U16_IS_TRAIL(*--p)) {
            --p;
        }
    }

    U_FORCE_INLINE static UnsafeCodeUnits<CP32, UnitIter> readAndInc(UnitIter &p0, UnitIter &p) {
        constexpr bool isMultiPass = prv::forward_iterator<UnitIter>;
        // Very similar to U16_NEXT_UNSAFE().
        CP32 c = static_cast<CP32>(*p);
        ++p;
        if (!U16_IS_LEAD(c)) {
            if constexpr (isMultiPass) {
                return {c, 1, p0, p};
            } else {
                return {c, 1};
            }
        } else {
            uint16_t c2 = *p;
            ++p;
            c = U16_GET_SUPPLEMENTARY(c, c2);
            if constexpr (isMultiPass) {
                return {c, 2, p0, p};
            } else {
                return {c, 2};
            }
        }
    }

    U_FORCE_INLINE static UnsafeCodeUnits<CP32, UnitIter> decAndRead(UnitIter &p) {
        // Very similar to U16_PREV_UNSAFE().
        UnitIter p0 = p;
        CP32 c = static_cast<CP32>(*--p);
        if (!U16_IS_TRAIL(c)) {
            return {c, 1, p, p0};
        } else {
            uint16_t c2 = *--p;
            c = U16_GET_SUPPLEMENTARY(c2, c);
            return {c, 2, p, p0};
        }
    }
};

// UTF-32: trivial
template<typename CP32, typename UnitIter>
class UnsafeUTFImpl<
        CP32,
        UnitIter,
        std::enable_if_t<sizeof(typename prv::iter_value_t<UnitIter>) == 4>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    U_FORCE_INLINE static void inc(UnitIter &p) {
        ++p;
    }

    U_FORCE_INLINE static void dec(UnitIter &p) {
        --p;
    }

    U_FORCE_INLINE static UnsafeCodeUnits<CP32, UnitIter> readAndInc(UnitIter &p0, UnitIter &p) {
        constexpr bool isMultiPass = prv::forward_iterator<UnitIter>;
        CP32 c = *p;
        ++p;
        if constexpr (isMultiPass) {
            return {c, 1, p0, p};
        } else {
            return {c, 1};
        }
    }

    U_FORCE_INLINE static UnsafeCodeUnits<CP32, UnitIter> decAndRead(UnitIter &p) {
        UnitIter p0 = p;
        CP32 c = *--p;
        return {c, 1, p, p0};
    }
};

#endif

// Validating iterators ---------------------------------------------------- ***

/**
 * Validating iterator over the code points in a Unicode string.
 *
 * The UnitIter can be
 * an input_iterator, a forward_iterator, or a bidirectional_iterator (including a pointer).
 * The UTFIterator will have the corresponding iterator_category.
 *
 * Call utfIterator() to have the compiler deduce the UnitIter and LimitIter types.
 *
 * For reverse iteration, either use this iterator directly as in <code>*--iter</code>
 * or wrap it using std::make_reverse_iterator(iter).
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t;
 *              should be signed if UTF_BEHAVIOR_NEGATIVE
 * @tparam behavior How to handle ill-formed Unicode strings
 * @tparam UnitIter An iterator (often a pointer) that returns a code unit type:
 *     UTF-8: char or char8_t or uint8_t;
 *     UTF-16: char16_t or uint16_t or (on Windows) wchar_t;
 *     UTF-32: char32_t or UChar32=int32_t or (on Linux) wchar_t
 * @tparam LimitIter Either the same as UnitIter, or an iterator sentinel type.
 * @draft ICU 78
 * @see utfIterator
 */
template<typename CP32, UTFIllFormedBehavior behavior,
         typename UnitIter, typename LimitIter = UnitIter, typename = void>
class UTFIterator {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
    using Impl = UTFImpl<CP32, behavior, UnitIter, LimitIter>;

    // Proxy type for operator->() (required by LegacyInputIterator)
    // so that we don't promise always returning CodeUnits.
    class Proxy {
    public:
        explicit Proxy(CodeUnits<CP32, UnitIter> &units) : units_(units) {}
        CodeUnits<CP32, UnitIter> &operator*() { return units_; }
        CodeUnits<CP32, UnitIter> *operator->() { return &units_; }
    private:
        CodeUnits<CP32, UnitIter> units_;
    };

public:
    /** C++ iterator boilerplate @internal */
    using value_type = CodeUnits<CP32, UnitIter>;
    /** C++ iterator boilerplate @internal */
    using reference = value_type;
    /** C++ iterator boilerplate @internal */
    using pointer = Proxy;
    /** C++ iterator boilerplate @internal */
    using difference_type = prv::iter_difference_t<UnitIter>;
    /** C++ iterator boilerplate @internal */
    using iterator_category = std::conditional_t<
        prv::bidirectional_iterator<UnitIter>,
        std::bidirectional_iterator_tag,
        std::forward_iterator_tag>;

    /**
     * Constructor with start <= p < limit.
     * All of these iterators/pointers should be at code point boundaries.
     * Only enabled if UnitIter is a (multi-pass) forward_iterator or better.
     *
     * When using a code unit sentinel (UnitIter≠LimitIter),
     * then that sentinel also works as a sentinel for this code point iterator.
     *
     * @param start Start of the range
     * @param p Initial position inside the range
     * @param limit Limit (exclusive end) of the range
     * @draft ICU 78
     */
    U_FORCE_INLINE UTFIterator(UnitIter start, UnitIter p, LimitIter limit) :
            p_(p), start_(start), limit_(limit), units_(0, 0, false, p, p) {}
    /**
     * Constructor with start == p < limit.
     * All of these iterators/pointers should be at code point boundaries.
     *
     * When using a code unit sentinel (UnitIter≠LimitIter),
     * then that sentinel also works as a sentinel for this code point iterator.
     *
     * @param p Start of the range, and the initial position
     * @param limit Limit (exclusive end) of the range
     * @draft ICU 78
     */
    U_FORCE_INLINE UTFIterator(UnitIter p, LimitIter limit) :
            p_(p), start_(p), limit_(limit), units_(0, 0, false, p, p) {}
    /**
     * Constructs an iterator start or limit sentinel.
     * The iterator/pointer should be at a code point boundary.
     * Requires UnitIter to be copyable.
     *
     * When using a code unit sentinel (UnitIter≠LimitIter),
     * then that sentinel also works as a sentinel for this code point iterator.
     *
     * @param p Range start or limit
     * @draft ICU 78
     */
    U_FORCE_INLINE explicit UTFIterator(UnitIter p) : p_(p), start_(p), limit_(p), units_(0, 0, false, p, p) {}
    /**
     * Default constructor. Makes a non-functional iterator.
     *
     * @draft ICU 78
     */
    U_FORCE_INLINE UTFIterator() : p_{}, start_{}, limit_{}, units_(0, 0, false, p_, p_) {}

    /** Move constructor. @draft ICU 78 */
    U_FORCE_INLINE UTFIterator(UTFIterator &&src) noexcept = default;
    /** Move assignment operator. @draft ICU 78 */
    U_FORCE_INLINE UTFIterator &operator=(UTFIterator &&src) noexcept = default;

    /** Copy constructor. @draft ICU 78 */
    U_FORCE_INLINE UTFIterator(const UTFIterator &other) = default;
    /** Copy assignment operator. @draft ICU 78 */
    U_FORCE_INLINE UTFIterator &operator=(const UTFIterator &other) = default;

    /**
     * @param other Another iterator
     * @return true if this iterator is at the same position as the other one
     * @draft ICU 78
     */
    U_FORCE_INLINE bool operator==(const UTFIterator &other) const {
        return getLogicalPosition() == other.getLogicalPosition();
    }
    /**
     * @param other Another iterator
     * @return true if this iterator is not at the same position as the other one
     * @draft ICU 78
     */
    U_FORCE_INLINE bool operator!=(const UTFIterator &other) const { return !operator==(other); }

    // Asymmetric equality & nonequality with a sentinel type.

    /**
     * @param iter A UTFIterator
     * @param s A unit iterator sentinel
     * @return true if the iterator’s position is equal to the sentinel
     * @draft ICU 78
     */
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator==(const UTFIterator &iter, const Sentinel &s) {
        return iter.getLogicalPosition() == s;
    }

#if U_CPLUSPLUS_VERSION < 20
    // C++17: Need to define all four combinations of == / != vs. parameter order.
    // Once we require C++20, we could remove all but the first == because
    // the compiler would generate the rest.

    /**
     * @param s A unit iterator sentinel
     * @param iter A UTFIterator
     * @return true if the iterator’s position is equal to the sentinel
     * @internal
     */
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator==(const Sentinel &s, const UTFIterator &iter) {
        return iter.getLogicalPosition() == s;
    }
    /**
     * @param iter A UTFIterator
     * @param s A unit iterator sentinel
     * @return true if the iterator’s position is not equal to the sentinel
     * @internal
     */
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator!=(const UTFIterator &iter, const Sentinel &s) { return !(iter == s); }
    /**
     * @param s A unit iterator sentinel
     * @param iter A UTFIterator
     * @return true if the iterator’s position is not equal to the sentinel
     * @internal
     */
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator!=(const Sentinel &s, const UTFIterator &iter) { return !(iter == s); }
#endif  // C++17

    /**
     * Decodes the code unit sequence at the current position.
     *
     * @return CodeUnits with the decoded code point etc.
     * @draft ICU 78
     */
    U_FORCE_INLINE CodeUnits<CP32, UnitIter> operator*() const {
        if (state_ == 0) {
            UnitIter p0 = p_;
            units_ = Impl::readAndInc(p0, p_, limit_);
            state_ = 1;
        }
        return units_;
    }

    /**
     * Decodes the code unit sequence at the current position.
     * Used like <code>iter->codePoint()</code> or <code>iter->stringView()</code> etc.
     *
     * @return CodeUnits with the decoded code point etc., wrapped into
     *     an opaque proxy object so that <code>iter->codePoint()</code> etc. works.
     * @draft ICU 78
     */
    U_FORCE_INLINE Proxy operator->() const {
        if (state_ == 0) {
            UnitIter p0 = p_;
            units_ = Impl::readAndInc(p0, p_, limit_);
            state_ = 1;
        }
        return Proxy(units_);
    }

    /**
     * Pre-increment operator.
     *
     * @return this iterator
     * @draft ICU 78
     */
    U_FORCE_INLINE UTFIterator &operator++() {  // pre-increment
        if (state_ > 0) {
            // operator*() called readAndInc() so p_ is already ahead.
            state_ = 0;
        } else if (state_ == 0) {
            Impl::inc(p_, limit_);
        } else /* state_ < 0 */ {
            // operator--() called decAndRead() so we know how far to skip.
            p_ = units_.end();
            state_ = 0;
        }
        return *this;
    }

    /**
     * Post-increment operator.
     *
     * @return a copy of this iterator from before the increment.
     *     If UnitIter is a single-pass input_iterator, then this function
     *     returns an opaque proxy object so that <code>*iter++</code> still works.
     * @draft ICU 78
     */
    U_FORCE_INLINE UTFIterator operator++(int) {  // post-increment
        if (state_ > 0) {
            // operator*() called readAndInc() so p_ is already ahead.
            UTFIterator result(*this);
            state_ = 0;
            return result;
        } else if (state_ == 0) {
            UnitIter p0 = p_;
            units_ = Impl::readAndInc(p0, p_, limit_);
            UTFIterator result(*this);
            result.state_ = 1;
            // keep this->state_ == 0
            return result;
        } else /* state_ < 0 */ {
            UTFIterator result(*this);
            // operator--() called decAndRead() so we know how far to skip.
            p_ = units_.end();
            state_ = 0;
            return result;
        }
    }

    /**
     * Pre-decrement operator.
     * Only enabled if UnitIter is a bidirectional_iterator (including a pointer).
     *
     * @return this iterator
     * @draft ICU 78
     */
    template<typename Iter = UnitIter>
    U_FORCE_INLINE
    std::enable_if_t<prv::bidirectional_iterator<Iter>, UTFIterator &>
    operator--() {  // pre-decrement
        if (state_ > 0) {
            // operator*() called readAndInc() so p_ is ahead of the logical position.
            p_ = units_.begin();
        }
        units_ = Impl::decAndRead(start_, p_);
        state_ = -1;
        return *this;
    }

    /**
     * Post-decrement operator.
     * Only enabled if UnitIter is a bidirectional_iterator (including a pointer).
     *
     * @return a copy of this iterator from before the decrement.
     * @draft ICU 78
     */
    template<typename Iter = UnitIter>
    U_FORCE_INLINE
    std::enable_if_t<prv::bidirectional_iterator<Iter>, UTFIterator>
    operator--(int) {  // post-decrement
        UTFIterator result(*this);
        operator--();
        return result;
    }

private:
    friend class std::reverse_iterator<UTFIterator<CP32, behavior, UnitIter>>;

    U_FORCE_INLINE UnitIter getLogicalPosition() const {
        return state_ <= 0 ? p_ : units_.begin();
    }

    // operator*() etc. are logically const.
    mutable UnitIter p_;
    // In a validating iterator, we need start_ & limit_ so that when we read a code point
    // (forward or backward) we can test if there are enough code units.
    UnitIter start_;
    LimitIter limit_;
    // Keep state so that we call readAndInc() only once for both operator*() and ++
    // to make it easy for the compiler to optimize.
    mutable CodeUnits<CP32, UnitIter> units_;
    // >0: units_ = readAndInc(), p_ = units limit
    //     which means that p_ is ahead of its logical position
    //  0: initial state
    // <0: units_ = decAndRead(), p_ = units start
    mutable int8_t state_ = 0;
};

#ifndef U_IN_DOXYGEN
// Partial template specialization for single-pass input iterator.
template<typename CP32, UTFIllFormedBehavior behavior, typename UnitIter, typename LimitIter>
class UTFIterator<
        CP32, behavior,
        UnitIter, LimitIter,
        std::enable_if_t<!prv::forward_iterator<UnitIter>>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
    using Impl = UTFImpl<CP32, behavior, UnitIter, LimitIter>;

    // Proxy type for post-increment return value, to make *iter++ work.
    // Also for operator->() (required by LegacyInputIterator)
    // so that we don't promise always returning CodeUnits.
    class Proxy {
    public:
        explicit Proxy(CodeUnits<CP32, UnitIter> &units) : units_(units) {}
        CodeUnits<CP32, UnitIter> &operator*() { return units_; }
        CodeUnits<CP32, UnitIter> *operator->() { return &units_; }
    private:
        CodeUnits<CP32, UnitIter> units_;
    };

public:
    using value_type = CodeUnits<CP32, UnitIter>;
    using reference = value_type;
    using pointer = Proxy;
    using difference_type = prv::iter_difference_t<UnitIter>;
    using iterator_category = std::input_iterator_tag;

    U_FORCE_INLINE UTFIterator(UnitIter p, LimitIter limit) : p_(std::move(p)), limit_(std::move(limit)) {}

    // Constructs an iterator start or limit sentinel.
    // Requires p to be copyable.
    U_FORCE_INLINE explicit UTFIterator(UnitIter p) : p_(std::move(p)), limit_(p_) {}

    U_FORCE_INLINE UTFIterator(UTFIterator &&src) noexcept = default;
    U_FORCE_INLINE UTFIterator &operator=(UTFIterator &&src) noexcept = default;

    U_FORCE_INLINE UTFIterator(const UTFIterator &other) = default;
    U_FORCE_INLINE UTFIterator &operator=(const UTFIterator &other) = default;

    U_FORCE_INLINE bool operator==(const UTFIterator &other) const {
        return p_ == other.p_ && ahead_ == other.ahead_;
        // Strictly speaking, we should check if the logical position is the same.
        // However, we cannot advance, or do arithmetic with, a single-pass UnitIter.
    }
    U_FORCE_INLINE bool operator!=(const UTFIterator &other) const { return !operator==(other); }

    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator==(const UTFIterator &iter, const Sentinel &s) {
        return !iter.ahead_ && iter.p_ == s;
    }

#if U_CPLUSPLUS_VERSION < 20
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator==(const Sentinel &s, const UTFIterator &iter) {
        return !iter.ahead_ && iter.p_ == s;
    }

    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator!=(const UTFIterator &iter, const Sentinel &s) { return !(iter == s); }

    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator!=(const Sentinel &s, const UTFIterator &iter) { return !(iter == s); }
#endif  // C++17

    U_FORCE_INLINE CodeUnits<CP32, UnitIter> operator*() const {
        if (!ahead_) {
            units_ = Impl::readAndInc(p_, p_, limit_);
            ahead_ = true;
        }
        return units_;
    }

    U_FORCE_INLINE Proxy operator->() const {
        if (!ahead_) {
            units_ = Impl::readAndInc(p_, p_, limit_);
            ahead_ = true;
        }
        return Proxy(units_);
    }

    U_FORCE_INLINE UTFIterator &operator++() {  // pre-increment
        if (ahead_) {
            // operator*() called readAndInc() so p_ is already ahead.
            ahead_ = false;
        } else {
            Impl::inc(p_, limit_);
        }
        return *this;
    }

    U_FORCE_INLINE Proxy operator++(int) {  // post-increment
        if (ahead_) {
            // operator*() called readAndInc() so p_ is already ahead.
            ahead_ = false;
        } else {
            units_ = Impl::readAndInc(p_, p_, limit_);
            // keep this->ahead_ == false
        }
        return Proxy(units_);
    }

private:
    // operator*() etc. are logically const.
    mutable UnitIter p_;
    // In a validating iterator, we need limit_ so that when we read a code point
    // we can test if there are enough code units.
    LimitIter limit_;
    // Keep state so that we call readAndInc() only once for both operator*() and ++
    // so that we can use a single-pass input iterator for UnitIter.
    mutable CodeUnits<CP32, UnitIter> units_ = {0, 0, false};
    // true: units_ = readAndInc(), p_ = units limit
    //     which means that p_ is ahead of its logical position
    // false: initial state
    mutable bool ahead_ = false;
};
#endif  // U_IN_DOXYGEN

}  // namespace U_HEADER_ONLY_NAMESPACE

#ifndef U_IN_DOXYGEN
// Bespoke specialization of reverse_iterator.
// The default implementation implements reverse operator*() and ++ in a way
// that does most of the same work twice for reading variable-length sequences.
template<typename CP32, UTFIllFormedBehavior behavior, typename UnitIter>
class std::reverse_iterator<U_HEADER_ONLY_NAMESPACE::UTFIterator<CP32, behavior, UnitIter>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
    using Impl = U_HEADER_ONLY_NAMESPACE::UTFImpl<CP32, behavior, UnitIter>;
    using CodeUnits_ = U_HEADER_ONLY_NAMESPACE::CodeUnits<CP32, UnitIter>;

    // Proxy type for operator->() (required by LegacyInputIterator)
    // so that we don't promise always returning CodeUnits.
    class Proxy {
    public:
        explicit Proxy(CodeUnits_ units) : units_(units) {}
        CodeUnits_ &operator*() { return units_; }
        CodeUnits_ *operator->() { return &units_; }
    private:
        CodeUnits_ units_;
    };

public:
    using value_type = CodeUnits_;
    using reference = value_type;
    using pointer = Proxy;
    using difference_type = U_HEADER_ONLY_NAMESPACE::prv::iter_difference_t<UnitIter>;
    using iterator_category = std::bidirectional_iterator_tag;

    U_FORCE_INLINE explicit reverse_iterator(U_HEADER_ONLY_NAMESPACE::UTFIterator<CP32, behavior, UnitIter> iter) :
            p_(iter.getLogicalPosition()), start_(iter.start_), limit_(iter.limit_),
            units_(0, 0, false, p_, p_) {}
    U_FORCE_INLINE reverse_iterator() : p_{}, start_{}, limit_{}, units_(0, 0, false, p_, p_) {}

    U_FORCE_INLINE reverse_iterator(reverse_iterator &&src) noexcept = default;
    U_FORCE_INLINE reverse_iterator &operator=(reverse_iterator &&src) noexcept = default;

    U_FORCE_INLINE reverse_iterator(const reverse_iterator &other) = default;
    U_FORCE_INLINE reverse_iterator &operator=(const reverse_iterator &other) = default;

    U_FORCE_INLINE bool operator==(const reverse_iterator &other) const {
        return getLogicalPosition() == other.getLogicalPosition();
    }
    U_FORCE_INLINE bool operator!=(const reverse_iterator &other) const { return !operator==(other); }

    U_FORCE_INLINE CodeUnits_ operator*() const {
        if (state_ == 0) {
            units_ = Impl::decAndRead(start_, p_);
            state_ = -1;
        }
        return units_;
    }

    U_FORCE_INLINE Proxy operator->() const {
        if (state_ == 0) {
            units_ = Impl::decAndRead(start_, p_);
            state_ = -1;
        }
        return Proxy(units_);
    }

    U_FORCE_INLINE reverse_iterator &operator++() {  // pre-increment
        if (state_ < 0) {
            // operator*() called decAndRead() so p_ is already behind.
            state_ = 0;
        } else if (state_ == 0) {
            Impl::dec(start_, p_);
        } else /* state_ > 0 */ {
            // operator--() called readAndInc() so we know how far to skip.
            p_ = units_.begin();
            state_ = 0;
        }
        return *this;
    }

    U_FORCE_INLINE reverse_iterator operator++(int) {  // post-increment
        if (state_ < 0) {
            // operator*() called decAndRead() so p_ is already behind.
            reverse_iterator result(*this);
            state_ = 0;
            return result;
        } else if (state_ == 0) {
            units_ = Impl::decAndRead(start_, p_);
            reverse_iterator result(*this);
            result.state_ = -1;
            // keep this->state_ == 0
            return result;
        } else /* state_ > 0 */ {
            reverse_iterator result(*this);
            // operator--() called readAndInc() so we know how far to skip.
            p_ = units_.begin();
            state_ = 0;
            return result;
        }
    }

    U_FORCE_INLINE reverse_iterator &operator--() {  // pre-decrement
        if (state_ < 0) {
            // operator*() called decAndRead() so p_ is behind the logical position.
            p_ = units_.end();
        }
        UnitIter p0 = p_;
        units_ = Impl::readAndInc(p0, p_, limit_);
        state_ = 1;
        return *this;
    }

    U_FORCE_INLINE reverse_iterator operator--(int) {  // post-decrement
        reverse_iterator result(*this);
        operator--();
        return result;
    }

private:
    U_FORCE_INLINE UnitIter getLogicalPosition() const {
        return state_ >= 0 ? p_ : units_.end();
    }

    // operator*() etc. are logically const.
    mutable UnitIter p_;
    // In a validating iterator, we need start_ & limit_ so that when we read a code point
    // (forward or backward) we can test if there are enough code units.
    UnitIter start_;
    UnitIter limit_;
    // Keep state so that we call decAndRead() only once for both operator*() and ++
    // to make it easy for the compiler to optimize.
    mutable CodeUnits_ units_;
    // >0: units_ = readAndInc(), p_ = units limit
    //  0: initial state
    // <0: units_ = decAndRead(), p_ = units start
    //     which means that p_ is behind its logical position
    mutable int8_t state_ = 0;
};
#endif  // U_IN_DOXYGEN

namespace U_HEADER_ONLY_NAMESPACE {

/**
 * UTFIterator factory function for start <= p < limit.
 * Deduces the UnitIter and LimitIter template parameters from the inputs.
 * Only enabled if UnitIter is a (multi-pass) forward_iterator or better.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @tparam behavior How to handle ill-formed Unicode strings
 * @tparam UnitIter Can usually be omitted/deduced:
 *     An iterator (often a pointer) that returns a code unit type:
 *     UTF-8: char or char8_t or uint8_t;
 *     UTF-16: char16_t or uint16_t or (on Windows) wchar_t;
 *     UTF-32: char32_t or UChar32=int32_t or (on Linux) wchar_t
 * @tparam LimitIter Either the same as UnitIter, or an iterator sentinel type.
 * @param start start code unit iterator
 * @param p current-position code unit iterator
 * @param limit limit (exclusive-end) code unit iterator.
 *     When using a code unit sentinel (UnitIter≠LimitIter),
 *     then that sentinel also works as a sentinel for the code point iterator.
 * @return a UTFIterator&lt;CP32, behavior, UnitIter&gt;
 *     for the given code unit iterators or character pointers
 * @draft ICU 78
 */
template<typename CP32, UTFIllFormedBehavior behavior,
         typename UnitIter, typename LimitIter = UnitIter>
auto utfIterator(UnitIter start, UnitIter p, LimitIter limit) {
    return UTFIterator<CP32, behavior, UnitIter, LimitIter>(
        std::move(start), std::move(p), std::move(limit));
}

/**
 * UTFIterator factory function for start = p < limit.
 * Deduces the UnitIter and LimitIter template parameters from the inputs.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @tparam behavior How to handle ill-formed Unicode strings
 * @tparam UnitIter Can usually be omitted/deduced:
 *     An iterator (often a pointer) that returns a code unit type:
 *     UTF-8: char or char8_t or uint8_t;
 *     UTF-16: char16_t or uint16_t or (on Windows) wchar_t;
 *     UTF-32: char32_t or UChar32=int32_t or (on Linux) wchar_t
 * @tparam LimitIter Either the same as UnitIter, or an iterator sentinel type.
 * @param p start and current-position code unit iterator
 * @param limit limit (exclusive-end) code unit iterator.
 *     When using a code unit sentinel (UnitIter≠LimitIter),
 *     then that sentinel also works as a sentinel for the code point iterator.
 * @return a UTFIterator&lt;CP32, behavior, UnitIter&gt;
 *     for the given code unit iterators or character pointers
 * @draft ICU 78
 */
template<typename CP32, UTFIllFormedBehavior behavior,
         typename UnitIter, typename LimitIter = UnitIter>
auto utfIterator(UnitIter p, LimitIter limit) {
    return UTFIterator<CP32, behavior, UnitIter, LimitIter>(
        std::move(p), std::move(limit));
}

// Note: We should only enable the following factory function for a copyable UnitIter.
// In C++17, we would have to partially specialize with enable_if_t testing for forward_iterator,
// but a function template partial specialization is not allowed.
// In C++20, we might be able to require the std::copyable concept.

/**
 * UTFIterator factory function for a start or limit sentinel.
 * Deduces the UnitIter template parameter from the input.
 * Requires UnitIter to be copyable.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @tparam behavior How to handle ill-formed Unicode strings
 * @tparam UnitIter Can usually be omitted/deduced:
 *     An iterator (often a pointer) that returns a code unit type:
 *     UTF-8: char or char8_t or uint8_t;
 *     UTF-16: char16_t or uint16_t or (on Windows) wchar_t;
 *     UTF-32: char32_t or UChar32=int32_t or (on Linux) wchar_t
 * @param p code unit iterator.
 *     When using a code unit sentinel,
 *     then that sentinel also works as a sentinel for the code point iterator.
 * @return a UTFIterator&lt;CP32, behavior, UnitIter&gt;
 *     for the given code unit iterator or character pointer
 * @draft ICU 78
 */
template<typename CP32, UTFIllFormedBehavior behavior, typename UnitIter>
auto utfIterator(UnitIter p) {
    return UTFIterator<CP32, behavior, UnitIter>(std::move(p));
}

/**
 * A C++ "range" for validating iteration over all of the code points of a code unit range.
 *
 * Call utfStringCodePoints() to have the compiler deduce the Range type.
 *
 * UTFStringCodePoints is conditionally borrowed; that is, if Range is a borrowed range
 * so is UTFStringCodePoints<CP32, behavior, Range>.
 * Note that when given a range r that is an lvalue and is not a view,  utfStringCodePoints(r) uses a
 * ref_view of r as the Range type, which is a borrowed range.
 * In practice, this means that given a container variable r, the iterators of utfStringCodePoints(r) can
 * be used as long as iterators on r are valid, without having to keep utfStringCodePoints(r) around.
 * For instance:
 * \code
 *     std::u8string s = "𒇧𒇧";
 *     // it outlives utfStringCodePoints<char32_t>(s).
 *     auto it = utfStringCodePoints<char32_t>(s).begin();
 *     ++it;
 *     char32_t second_code_point = it->codePoint();  // OK.
 * \endcode
 * 
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t;
 *              should be signed if UTF_BEHAVIOR_NEGATIVE
 * @tparam behavior How to handle ill-formed Unicode strings
 * @tparam Range A C++ "range" of Unicode UTF-8/16/32 code units
 * @draft ICU 78
 * @see utfStringCodePoints
 */
template<typename CP32, UTFIllFormedBehavior behavior, typename Range>
class UTFStringCodePoints {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    /**
     * Constructs an empty C++ "range" object.
     * @draft ICU 78
     */
    UTFStringCodePoints() = default;

    /**
     * Constructs a C++ "range" object over the code points in the string.
     * @param unitRange input range
     * @draft ICU 78
     */
    template<typename R = Range, typename = std::enable_if_t<!std::is_reference_v<R>>>
    explicit UTFStringCodePoints(Range unitRange) : unitRange(std::move(unitRange)) {}
    /**
     * Constructs a C++ "range" object over the code points in the string,
     * keeping a reference to the code unit range.  This overload is used by
     * utfStringCodePoints in C++17; in C+20, a ref_view is used instead (via
     * views::all).
     * @param unitRange input range
     * @draft ICU 78
     */
    template<typename R = Range, typename = std::enable_if_t<std::is_reference_v<R>>, typename = void>
    explicit UTFStringCodePoints(Range unitRange) : unitRange(unitRange) {}

    /** Copy constructor. @draft ICU 78 */
    UTFStringCodePoints(const UTFStringCodePoints &other) = default;

    /** Copy assignment operator. @draft ICU 78 */
    UTFStringCodePoints &operator=(const UTFStringCodePoints &other) = default;

    /**
     * @return the range start iterator
     * @draft ICU 78
     */
    auto begin() {
        return utfIterator<CP32, behavior>(unitRange.begin(), unitRange.end());
    }

    /**
     * @return the range start iterator
     * @draft ICU 78
     */
    template<typename R = Range, typename = std::enable_if_t<prv::range<const R>>>
    auto begin() const {
        return utfIterator<CP32, behavior>(unitRange.begin(), unitRange.end());
    }

    /**
     * @return the range limit (exclusive end) iterator
     * @draft ICU 78
     */
    auto end() {
        using UnitIter = decltype(unitRange.begin());
        using LimitIter = decltype(unitRange.end());
        if constexpr (!std::is_same_v<UnitIter, LimitIter>) {
            // Return the code unit sentinel.
            return unitRange.end();
        } else if constexpr (prv::bidirectional_iterator<UnitIter>) {
            return utfIterator<CP32, behavior>(unitRange.begin(), unitRange.end(), unitRange.end());
        } else {
            // The input iterator specialization has no three-argument constructor.
            return utfIterator<CP32, behavior>(unitRange.end(), unitRange.end());
        }
    }

    /**
     * @return the range limit (exclusive end) iterator
     * @draft ICU 78
     */
    template<typename R = Range, typename = std::enable_if_t<prv::range<const R>>>
    auto end() const {
        using UnitIter = decltype(unitRange.begin());
        using LimitIter = decltype(unitRange.end());
        if constexpr (!std::is_same_v<UnitIter, LimitIter>) {
            // Return the code unit sentinel.
            return unitRange.end();
        } else if constexpr (prv::bidirectional_iterator<UnitIter>) {
            return utfIterator<CP32, behavior>(unitRange.begin(), unitRange.end(), unitRange.end());
        } else {
            // The input iterator specialization has no three-argument constructor.
            return utfIterator<CP32, behavior>(unitRange.end(), unitRange.end());
        }
    }

    /**
     * @return std::reverse_iterator(end())
     * @draft ICU 78
     */
    auto rbegin() const {
        return std::make_reverse_iterator(end());
    }

    /**
     * @return std::reverse_iterator(begin())
     * @draft ICU 78
     */
    auto rend() const {
        return std::make_reverse_iterator(begin());
    }

private:
    Range unitRange;
};

/** @internal */
template<typename CP32, UTFIllFormedBehavior behavior>
struct UTFStringCodePointsAdaptor
#if U_CPLUSPLUS_VERSION >= 23 && __cpp_lib_ranges >= 2022'02 &&                                         \
    __cpp_lib_bind_back >= 2022'02 // http://wg21.link/P2387R3.
    : std::ranges::range_adaptor_closure<UTFStringCodePointsAdaptor<CP32, behavior>>
#endif
{
    /** @internal */
    template<typename Range>
    auto operator()(Range &&unitRange) const {
#if defined(__cpp_lib_ranges) && __cpp_lib_ranges >= 2021'10  // We need https://wg21.link/P2415R2.
        return UTFStringCodePoints<CP32, behavior, std::ranges::views::all_t<Range>>(
            std::forward<Range>(unitRange));
#else
        if constexpr (prv::is_basic_string_view_v<std::decay_t<Range>>) {
            // Take basic_string_view by copy, not by reference.  In C++20 this is handled by
            // all_t<Range>, which is Range if Range is a view.
            return UTFStringCodePoints<CP32, behavior, std::decay_t<Range>>(
                std::forward<Range>(unitRange));
        } else {
            return UTFStringCodePoints<CP32, behavior, Range>(std::forward<Range>(unitRange));
        }
#endif
    }
};

/**
 * Range adaptor function object returning a UTFStringCodePoints object that represents a "range" of code
 * points in a code unit range, which validates while decoding.
 * Deduces the Range template parameter from the input, taking into account the value category: the
 * code units will be referenced if possible, and moved if necessary.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t;
 *              should be signed if UTF_BEHAVIOR_NEGATIVE
 * @tparam behavior How to handle ill-formed Unicode strings
 * @tparam Range A C++ "range" of Unicode UTF-8/16/32 code units
 * @param unitRange input range
 * @return a UTFStringCodePoints&lt;CP32, behavior, Range&gt; for the given unitRange
 * @draft ICU 78
 */
template<typename CP32, UTFIllFormedBehavior behavior>
constexpr UTFStringCodePointsAdaptor<CP32, behavior> utfStringCodePoints;

// Non-validating iterators ------------------------------------------------ ***

/**
 * Non-validating iterator over the code points in a Unicode string.
 * The string must be well-formed.
 *
 * The UnitIter can be
 * an input_iterator, a forward_iterator, or a bidirectional_iterator (including a pointer).
 * The UTFIterator will have the corresponding iterator_category.
 *
 * Call unsafeUTFIterator() to have the compiler deduce the UnitIter type.
 *
 * For reverse iteration, either use this iterator directly as in <code>*--iter</code>
 * or wrap it using std::make_reverse_iterator(iter).
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @tparam UnitIter An iterator (often a pointer) that returns a code unit type:
 *     UTF-8: char or char8_t or uint8_t;
 *     UTF-16: char16_t or uint16_t or (on Windows) wchar_t;
 *     UTF-32: char32_t or UChar32=int32_t or (on Linux) wchar_t
 * @draft ICU 78
 * @see unsafeUTFIterator
 */
template<typename CP32, typename UnitIter, typename = void>
class UnsafeUTFIterator {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
    using Impl = UnsafeUTFImpl<CP32, UnitIter>;

    // Proxy type for operator->() (required by LegacyInputIterator)
    // so that we don't promise always returning UnsafeCodeUnits.
    class Proxy {
    public:
        explicit Proxy(UnsafeCodeUnits<CP32, UnitIter> &units) : units_(units) {}
        UnsafeCodeUnits<CP32, UnitIter> &operator*() { return units_; }
        UnsafeCodeUnits<CP32, UnitIter> *operator->() { return &units_; }
    private:
        UnsafeCodeUnits<CP32, UnitIter> units_;
    };

public:
    /** C++ iterator boilerplate @internal */
    using value_type = UnsafeCodeUnits<CP32, UnitIter>;
    /** C++ iterator boilerplate @internal */
    using reference = value_type;
    /** C++ iterator boilerplate @internal */
    using pointer = Proxy;
    /** C++ iterator boilerplate @internal */
    using difference_type = prv::iter_difference_t<UnitIter>;
    /** C++ iterator boilerplate @internal */
    using iterator_category = std::conditional_t<
        prv::bidirectional_iterator<UnitIter>,
        std::bidirectional_iterator_tag,
        std::forward_iterator_tag>;

    /**
     * Constructor; the iterator/pointer should be at a code point boundary.
     *
     * When using a code unit sentinel,
     * then that sentinel also works as a sentinel for this code point iterator.
     *
     * @param p Initial position inside the range, or a range sentinel
     * @draft ICU 78
     */
    U_FORCE_INLINE explicit UnsafeUTFIterator(UnitIter p) : p_(p), units_(0, 0, p, p) {}
    /**
     * Default constructor. Makes a non-functional iterator.
     *
     * @draft ICU 78
     */
    U_FORCE_INLINE UnsafeUTFIterator() : p_{}, units_(0, 0, p_, p_) {}

    /** Move constructor. @draft ICU 78 */
    U_FORCE_INLINE UnsafeUTFIterator(UnsafeUTFIterator &&src) noexcept = default;
    /** Move assignment operator. @draft ICU 78 */
    U_FORCE_INLINE UnsafeUTFIterator &operator=(UnsafeUTFIterator &&src) noexcept = default;

    /** Copy constructor. @draft ICU 78 */
    U_FORCE_INLINE UnsafeUTFIterator(const UnsafeUTFIterator &other) = default;
    /** Copy assignment operator. @draft ICU 78 */
    U_FORCE_INLINE UnsafeUTFIterator &operator=(const UnsafeUTFIterator &other) = default;

    /**
     * @param other Another iterator
     * @return true if this iterator is at the same position as the other one
     * @draft ICU 78
     */
    U_FORCE_INLINE bool operator==(const UnsafeUTFIterator &other) const {
        return getLogicalPosition() == other.getLogicalPosition();
    }
    /**
     * @param other Another iterator
     * @return true if this iterator is not at the same position as the other one
     * @draft ICU 78
     */
    U_FORCE_INLINE bool operator!=(const UnsafeUTFIterator &other) const { return !operator==(other); }

    /**
     * @param iter An UnsafeUTFIterator
     * @param s A unit iterator sentinel
     * @return true if the iterator’s position is equal to the sentinel
     * @draft ICU 78
     */
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UnsafeUTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator==(const UnsafeUTFIterator &iter, const Sentinel &s) {
        return iter.getLogicalPosition() == s;
    }

#if U_CPLUSPLUS_VERSION < 20
    /**
     * @param s A unit iterator sentinel
     * @param iter An UnsafeUTFIterator
     * @return true if the iterator’s position is equal to the sentinel
     * @internal
     */
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UnsafeUTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator==(const Sentinel &s, const UnsafeUTFIterator &iter) {
        return iter.getLogicalPosition() == s;
    }
    /**
     * @param iter An UnsafeUTFIterator
     * @param s A unit iterator sentinel
     * @return true if the iterator’s position is not equal to the sentinel
     * @internal
     */
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UnsafeUTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator!=(const UnsafeUTFIterator &iter, const Sentinel &s) { return !(iter == s); }
    /**
     * @param s A unit iterator sentinel
     * @param iter An UnsafeUTFIterator
     * @return true if the iterator’s position is not equal to the sentinel
     * @internal
     */
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UnsafeUTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator!=(const Sentinel &s, const UnsafeUTFIterator &iter) { return !(iter == s); }
#endif  // C++17

    /**
     * Decodes the code unit sequence at the current position.
     *
     * @return CodeUnits with the decoded code point etc.
     * @draft ICU 78
     */
    U_FORCE_INLINE UnsafeCodeUnits<CP32, UnitIter> operator*() const {
        if (state_ == 0) {
            UnitIter p0 = p_;
            units_ = Impl::readAndInc(p0, p_);
            state_ = 1;
        }
        return units_;
    }

    /**
     * Decodes the code unit sequence at the current position.
     * Used like <code>iter->codePoint()</code> or <code>iter->stringView()</code> etc.
     *
     * @return CodeUnits with the decoded code point etc., wrapped into
     *     an opaque proxy object so that <code>iter->codePoint()</code> etc. works.
     * @draft ICU 78
     */
    U_FORCE_INLINE Proxy operator->() const {
        if (state_ == 0) {
            UnitIter p0 = p_;
            units_ = Impl::readAndInc(p0, p_);
            state_ = 1;
        }
        return Proxy(units_);
    }

    /**
     * Pre-increment operator.
     *
     * @return this iterator
     * @draft ICU 78
     */
    U_FORCE_INLINE UnsafeUTFIterator &operator++() {  // pre-increment
        if (state_ > 0) {
            // operator*() called readAndInc() so p_ is already ahead.
            state_ = 0;
        } else if (state_ == 0) {
            Impl::inc(p_);
        } else /* state_ < 0 */ {
            // operator--() called decAndRead() so we know how far to skip.
            p_ = units_.end();
            state_ = 0;
        }
        return *this;
    }

    /**
     * Post-increment operator.
     *
     * @return a copy of this iterator from before the increment.
     *     If UnitIter is a single-pass input_iterator, then this function
     *     returns an opaque proxy object so that <code>*iter++</code> still works.
     * @draft ICU 78
     */
    U_FORCE_INLINE UnsafeUTFIterator operator++(int) {  // post-increment
        if (state_ > 0) {
            // operator*() called readAndInc() so p_ is already ahead.
            UnsafeUTFIterator result(*this);
            state_ = 0;
            return result;
        } else if (state_ == 0) {
            UnitIter p0 = p_;
            units_ = Impl::readAndInc(p0, p_);
            UnsafeUTFIterator result(*this);
            result.state_ = 1;
            // keep this->state_ == 0
            return result;
        } else /* state_ < 0 */ {
            UnsafeUTFIterator result(*this);
            // operator--() called decAndRead() so we know how far to skip.
            p_ = units_.end();
            state_ = 0;
            return result;
        }
    }

    /**
     * Pre-decrement operator.
     * Only enabled if UnitIter is a bidirectional_iterator (including a pointer).
     *
     * @return this iterator
     * @draft ICU 78
     */
    template<typename Iter = UnitIter>
    U_FORCE_INLINE
    std::enable_if_t<prv::bidirectional_iterator<Iter>, UnsafeUTFIterator &>
    operator--() {  // pre-decrement
        if (state_ > 0) {
            // operator*() called readAndInc() so p_ is ahead of the logical position.
            p_ = units_.begin();
        }
        units_ = Impl::decAndRead(p_);
        state_ = -1;
        return *this;
    }

    /**
     * Post-decrement operator.
     * Only enabled if UnitIter is a bidirectional_iterator (including a pointer).
     *
     * @return a copy of this iterator from before the decrement.
     * @draft ICU 78
     */
    template<typename Iter = UnitIter>
    U_FORCE_INLINE
    std::enable_if_t<prv::bidirectional_iterator<Iter>, UnsafeUTFIterator>
    operator--(int) {  // post-decrement
        UnsafeUTFIterator result(*this);
        operator--();
        return result;
    }

private:
    friend class std::reverse_iterator<UnsafeUTFIterator<CP32, UnitIter>>;

    U_FORCE_INLINE UnitIter getLogicalPosition() const {
        return state_ <= 0 ? p_ : units_.begin();
    }

    // operator*() etc. are logically const.
    mutable UnitIter p_;
    // Keep state so that we call readAndInc() only once for both operator*() and ++
    // to make it easy for the compiler to optimize.
    mutable UnsafeCodeUnits<CP32, UnitIter> units_;
    // >0: units_ = readAndInc(), p_ = units limit
    //     which means that p_ is ahead of its logical position
    //  0: initial state
    // <0: units_ = decAndRead(), p_ = units start
    mutable int8_t state_ = 0;
};

#ifndef U_IN_DOXYGEN
// Partial template specialization for single-pass input iterator.
template<typename CP32, typename UnitIter>
class UnsafeUTFIterator<
        CP32,
        UnitIter,
        std::enable_if_t<!prv::forward_iterator<UnitIter>>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
    using Impl = UnsafeUTFImpl<CP32, UnitIter>;

    // Proxy type for post-increment return value, to make *iter++ work.
    // Also for operator->() (required by LegacyInputIterator)
    // so that we don't promise always returning UnsafeCodeUnits.
    class Proxy {
    public:
        explicit Proxy(UnsafeCodeUnits<CP32, UnitIter> &units) : units_(units) {}
        UnsafeCodeUnits<CP32, UnitIter> &operator*() { return units_; }
        UnsafeCodeUnits<CP32, UnitIter> *operator->() { return &units_; }
    private:
        UnsafeCodeUnits<CP32, UnitIter> units_;
    };

public:
    using value_type = UnsafeCodeUnits<CP32, UnitIter>;
    using reference = value_type;
    using pointer = Proxy;
    using difference_type = prv::iter_difference_t<UnitIter>;
    using iterator_category = std::input_iterator_tag;

    U_FORCE_INLINE explicit UnsafeUTFIterator(UnitIter p) : p_(std::move(p)) {}

    U_FORCE_INLINE UnsafeUTFIterator(UnsafeUTFIterator &&src) noexcept = default;
    U_FORCE_INLINE UnsafeUTFIterator &operator=(UnsafeUTFIterator &&src) noexcept = default;

    U_FORCE_INLINE UnsafeUTFIterator(const UnsafeUTFIterator &other) = default;
    U_FORCE_INLINE UnsafeUTFIterator &operator=(const UnsafeUTFIterator &other) = default;

    U_FORCE_INLINE bool operator==(const UnsafeUTFIterator &other) const {
        return p_ == other.p_ && ahead_ == other.ahead_;
        // Strictly speaking, we should check if the logical position is the same.
        // However, we cannot advance, or do arithmetic with, a single-pass UnitIter.
    }
    U_FORCE_INLINE bool operator!=(const UnsafeUTFIterator &other) const { return !operator==(other); }

    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UnsafeUTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator==(const UnsafeUTFIterator &iter, const Sentinel &s) {
        return !iter.ahead_ && iter.p_ == s;
    }

#if U_CPLUSPLUS_VERSION < 20
    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UnsafeUTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator==(const Sentinel &s, const UnsafeUTFIterator &iter) {
        return !iter.ahead_ && iter.p_ == s;
    }

    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UnsafeUTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator!=(const UnsafeUTFIterator &iter, const Sentinel &s) { return !(iter == s); }

    template<typename Sentinel> U_FORCE_INLINE friend
    std::enable_if_t<
        !std::is_same_v<Sentinel, UnsafeUTFIterator> && !std::is_same_v<Sentinel, UnitIter>,
        bool>
    operator!=(const Sentinel &s, const UnsafeUTFIterator &iter) { return !(iter == s); }
#endif  // C++17

    U_FORCE_INLINE UnsafeCodeUnits<CP32, UnitIter> operator*() const {
        if (!ahead_) {
            units_ = Impl::readAndInc(p_, p_);
            ahead_ = true;
        }
        return units_;
    }

    U_FORCE_INLINE Proxy operator->() const {
        if (!ahead_) {
            units_ = Impl::readAndInc(p_, p_);
            ahead_ = true;
        }
        return Proxy(units_);
    }

    U_FORCE_INLINE UnsafeUTFIterator &operator++() {  // pre-increment
        if (ahead_) {
            // operator*() called readAndInc() so p_ is already ahead.
            ahead_ = false;
        } else {
            Impl::inc(p_);
        }
        return *this;
    }

    U_FORCE_INLINE Proxy operator++(int) {  // post-increment
        if (ahead_) {
            // operator*() called readAndInc() so p_ is already ahead.
            ahead_ = false;
        } else {
            units_ = Impl::readAndInc(p_, p_);
            // keep this->ahead_ == false
        }
        return Proxy(units_);
    }

private:
    // operator*() etc. are logically const.
    mutable UnitIter p_;
    // Keep state so that we call readAndInc() only once for both operator*() and ++
    // so that we can use a single-pass input iterator for UnitIter.
    mutable UnsafeCodeUnits<CP32, UnitIter> units_ = {0, 0};
    // true: units_ = readAndInc(), p_ = units limit
    //     which means that p_ is ahead of its logical position
    // false: initial state
    mutable bool ahead_ = false;
};
#endif  // U_IN_DOXYGEN

}  // namespace U_HEADER_ONLY_NAMESPACE

#ifndef U_IN_DOXYGEN
// Bespoke specialization of reverse_iterator.
// The default implementation implements reverse operator*() and ++ in a way
// that does most of the same work twice for reading variable-length sequences.
template<typename CP32, typename UnitIter>
class std::reverse_iterator<U_HEADER_ONLY_NAMESPACE::UnsafeUTFIterator<CP32, UnitIter>> {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
    using Impl = U_HEADER_ONLY_NAMESPACE::UnsafeUTFImpl<CP32, UnitIter>;
    using UnsafeCodeUnits_ = U_HEADER_ONLY_NAMESPACE::UnsafeCodeUnits<CP32, UnitIter>;

    // Proxy type for operator->() (required by LegacyInputIterator)
    // so that we don't promise always returning UnsafeCodeUnits.
    class Proxy {
    public:
        explicit Proxy(UnsafeCodeUnits_ units) : units_(units) {}
        UnsafeCodeUnits_ &operator*() { return units_; }
        UnsafeCodeUnits_ *operator->() { return &units_; }
    private:
        UnsafeCodeUnits_ units_;
    };

public:
    using value_type = UnsafeCodeUnits_;
    using reference = value_type;
    using pointer = Proxy;
    using difference_type = U_HEADER_ONLY_NAMESPACE::prv::iter_difference_t<UnitIter>;
    using iterator_category = std::bidirectional_iterator_tag;

    U_FORCE_INLINE explicit reverse_iterator(U_HEADER_ONLY_NAMESPACE::UnsafeUTFIterator<CP32, UnitIter> iter) :
            p_(iter.getLogicalPosition()), units_(0, 0, p_, p_) {}
    U_FORCE_INLINE reverse_iterator() : p_{}, units_(0, 0, p_, p_) {}

    U_FORCE_INLINE reverse_iterator(reverse_iterator &&src) noexcept = default;
    U_FORCE_INLINE reverse_iterator &operator=(reverse_iterator &&src) noexcept = default;

    U_FORCE_INLINE reverse_iterator(const reverse_iterator &other) = default;
    U_FORCE_INLINE reverse_iterator &operator=(const reverse_iterator &other) = default;

    U_FORCE_INLINE bool operator==(const reverse_iterator &other) const {
        return getLogicalPosition() == other.getLogicalPosition();
    }
    U_FORCE_INLINE bool operator!=(const reverse_iterator &other) const { return !operator==(other); }

    U_FORCE_INLINE UnsafeCodeUnits_ operator*() const {
        if (state_ == 0) {
            units_ = Impl::decAndRead(p_);
            state_ = -1;
        }
        return units_;
    }

    U_FORCE_INLINE Proxy operator->() const {
        if (state_ == 0) {
            units_ = Impl::decAndRead(p_);
            state_ = -1;
        }
        return Proxy(units_);
    }

    U_FORCE_INLINE reverse_iterator &operator++() {  // pre-increment
        if (state_ < 0) {
            // operator*() called decAndRead() so p_ is already behind.
            state_ = 0;
        } else if (state_ == 0) {
            Impl::dec(p_);
        } else /* state_ > 0 */ {
            // operator--() called readAndInc() so we know how far to skip.
            p_ = units_.begin();
            state_ = 0;
        }
        return *this;
    }

    U_FORCE_INLINE reverse_iterator operator++(int) {  // post-increment
        if (state_ < 0) {
            // operator*() called decAndRead() so p_ is already behind.
            reverse_iterator result(*this);
            state_ = 0;
            return result;
        } else if (state_ == 0) {
            units_ = Impl::decAndRead(p_);
            reverse_iterator result(*this);
            result.state_ = -1;
            // keep this->state_ == 0
            return result;
        } else /* state_ > 0 */ {
            reverse_iterator result(*this);
            // operator--() called readAndInc() so we know how far to skip.
            p_ = units_.begin();
            state_ = 0;
            return result;
        }
    }

    U_FORCE_INLINE reverse_iterator &operator--() {  // pre-decrement
        if (state_ < 0) {
            // operator*() called decAndRead() so p_ is behind the logical position.
            p_ = units_.end();
        }
        UnitIter p0 = p_;
        units_ = Impl::readAndInc(p0, p_);
        state_ = 1;
        return *this;
    }

    U_FORCE_INLINE reverse_iterator operator--(int) {  // post-decrement
        reverse_iterator result(*this);
        operator--();
        return result;
    }

private:
    U_FORCE_INLINE UnitIter getLogicalPosition() const {
        return state_ >= 0 ? p_ : units_.end();
    }

    // operator*() etc. are logically const.
    mutable UnitIter p_;
    // Keep state so that we call decAndRead() only once for both operator*() and ++
    // to make it easy for the compiler to optimize.
    mutable UnsafeCodeUnits_ units_;
    // >0: units_ = readAndInc(), p_ = units limit
    //  0: initial state
    // <0: units_ = decAndRead(), p_ = units start
    //     which means that p_ is behind its logical position
    mutable int8_t state_ = 0;
};
#endif  // U_IN_DOXYGEN

namespace U_HEADER_ONLY_NAMESPACE {

/**
 * UnsafeUTFIterator factory function.
 * Deduces the UnitIter template parameter from the input.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @tparam UnitIter Can usually be omitted/deduced:
 *     An iterator (often a pointer) that returns a code unit type:
 *     UTF-8: char or char8_t or uint8_t;
 *     UTF-16: char16_t or uint16_t or (on Windows) wchar_t;
 *     UTF-32: char32_t or UChar32=int32_t or (on Linux) wchar_t
 * @param iter code unit iterator
 * @return an UnsafeUTFIterator&lt;CP32, UnitIter&gt;
 *     for the given code unit iterator or character pointer
 * @draft ICU 78
 */
template<typename CP32, typename UnitIter>
auto unsafeUTFIterator(UnitIter iter) {
    return UnsafeUTFIterator<CP32, UnitIter>(std::move(iter));
}

/**
 * A C++ "range" for non-validating iteration over all of the code points of a code unit range.
 * The string must be well-formed.
 *
 * Call unsafeUTFStringCodePoints() to have the compiler deduce the Range type.
 *
 * UnsafeUTFStringCodePoints is conditionally borrowed; that is, if Range is a borrowed range
 * so is UnsafeUTFStringCodePoints<CP32, behavior, Range>.
 * Note that when given a range r that is an lvalue and is not a view,  unsafeUTFStringCodePoints(r) uses
 * a ref_view of r as the Range type, which is a borrowed range.
 * In practice, this means that given a container variable r, the iterators of
 * unsafeUTFStringCodePoints(r) can be used as long as iterators on r are valid, without having to keep
 * unsafeUTFStringCodePoints(r) around.
 * For instance:
 * \code
 *     std::u8string s = "𒇧𒇧";
 *     // it outlives unsafeUTFStringCodePoints<char32_t>(s).
 *     auto it = unsafeUTFStringCodePoints<char32_t>(s).begin();
 *     ++it;
 *     char32_t second_code_point = it->codePoint();  // OK.
 * \endcode
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @tparam Range A C++ "range" of Unicode UTF-8/16/32 code units
 * @draft ICU 78
 * @see unsafeUTFStringCodePoints
 */
template<typename CP32, typename Range>
class UnsafeUTFStringCodePoints {
    static_assert(sizeof(CP32) == 4, "CP32 must be a 32-bit type to hold a code point");
public:
    /**
     * Constructs an empty C++ "range" object.
     * @draft ICU 78
     */
    UnsafeUTFStringCodePoints() = default;

    /**
     * Constructs a C++ "range" object over the code points in the string.
     * @param unitRange input range
     * @draft ICU 78
     */
    template<typename R = Range, typename = std::enable_if_t<!std::is_reference_v<R>>>
    explicit UnsafeUTFStringCodePoints(Range unitRange) : unitRange(std::move(unitRange)) {}
    /**
     * Constructs a C++ "range" object over the code points in the string,
     * keeping a reference to the code unit range.  This overload is used by
     * utfStringCodePoints in C++17; in C++20, a ref_view is used instead (via
     * views::all).
     * @param unitRange input range
     * @draft ICU 78
     */
    template<typename R = Range, typename = std::enable_if_t<std::is_reference_v<R>>, typename = void>
    explicit UnsafeUTFStringCodePoints(Range unitRange) : unitRange(unitRange) {}

    /** Copy constructor. @draft ICU 78 */
    UnsafeUTFStringCodePoints(const UnsafeUTFStringCodePoints &other) = default;

    /** Copy assignment operator. @draft ICU 78 */
    UnsafeUTFStringCodePoints &operator=(const UnsafeUTFStringCodePoints &other) = default;

    /**
     * @return the range start iterator
     * @draft ICU 78
     */
    auto begin() {
        return unsafeUTFIterator<CP32>(unitRange.begin());
    }

    /**
     * @return the range start iterator
     * @draft ICU 78
     */
    template<typename R = Range, typename = std::enable_if_t<prv::range<const R>>>
    auto begin() const {
        return unsafeUTFIterator<CP32>(unitRange.begin());
    }

    /**
     * @return the range limit (exclusive end) iterator
     * @draft ICU 78
     */
    auto end() {
        using UnitIter = decltype(unitRange.begin());
        using LimitIter = decltype(unitRange.end());
        if constexpr (!std::is_same_v<UnitIter, LimitIter>) {
            // Return the code unit sentinel.
            return unitRange.end();
        } else {
            return unsafeUTFIterator<CP32>(unitRange.end());
        }
    }

    /**
     * @return the range limit (exclusive end) iterator
     * @draft ICU 78
     */
    template<typename R = Range, typename = std::enable_if_t<prv::range<const R>>>
    auto end() const {
        using UnitIter = decltype(unitRange.begin());
        using LimitIter = decltype(unitRange.end());
        if constexpr (!std::is_same_v<UnitIter, LimitIter>) {
            // Return the code unit sentinel.
            return unitRange.end();
        } else {
            return unsafeUTFIterator<CP32>(unitRange.end());
        }
    }

    /**
     * @return std::reverse_iterator(end())
     * @draft ICU 78
     */
    auto rbegin() const {
        return std::make_reverse_iterator(end());
    }

    /**
     * @return std::reverse_iterator(begin())
     * @draft ICU 78
     */
    auto rend() const {
        return std::make_reverse_iterator(begin());
    }

private:
    Range unitRange;
};

/** @internal */
template<typename CP32>
struct UnsafeUTFStringCodePointsAdaptor
#if U_CPLUSPLUS_VERSION >= 23 && __cpp_lib_ranges >= 2022'02 &&                                         \
    __cpp_lib_bind_back >= 2022'02 // http://wg21.link/P2387R3.
    : std::ranges::range_adaptor_closure<UnsafeUTFStringCodePointsAdaptor<CP32>>
#endif
{
    /** @internal */
    template<typename Range>
    auto operator()(Range &&unitRange) const {
#if defined(__cpp_lib_ranges) && __cpp_lib_ranges >= 2021'10  // We need https://wg21.link/P2415R2.
        return UnsafeUTFStringCodePoints<CP32, std::ranges::views::all_t<Range>>(std::forward<Range>(unitRange));
#else
        if constexpr (prv::is_basic_string_view_v<std::decay_t<Range>>) {
            // Take basic_string_view by copy, not by reference.  In C++20 this is handled by
            // all_t<Range>, which is Range if Range is a view.
            return UnsafeUTFStringCodePoints<CP32, std::decay_t<Range>>(std::forward<Range>(unitRange));
        } else {
            return UnsafeUTFStringCodePoints<CP32, Range>(std::forward<Range>(unitRange));
        }
#endif
    }
};


/**
 * Range adaptor function object returning an UnsafeUTFStringCodePoints object that represents a
 * "range" of code points in a code unit range. The string must be well-formed.
 * Deduces the Range template parameter from the input, taking into account the value category: the
 * code units will be referenced if possible, and moved if necessary.
 *
 * @tparam CP32 Code point type: UChar32 (=int32_t) or char32_t or uint32_t
 * @tparam Range A C++ "range" of Unicode UTF-8/16/32 code units
 * @param unitRange input range
 * @return an UnsafeUTFStringCodePoints&lt;CP32, Range&gt; for the given unitRange
 * @draft ICU 78
 */
template<typename CP32>
constexpr UnsafeUTFStringCodePointsAdaptor<CP32> unsafeUTFStringCodePoints;

}  // namespace U_HEADER_ONLY_NAMESPACE


#if defined(__cpp_lib_ranges)
template <typename CP32, UTFIllFormedBehavior behavior, typename Range>
constexpr bool std::ranges::enable_borrowed_range<
    U_HEADER_ONLY_NAMESPACE::UTFStringCodePoints<CP32, behavior, Range>> =
    std::ranges::enable_borrowed_range<Range>;

template <typename CP32, typename Range>
constexpr bool std::ranges::enable_borrowed_range<
    U_HEADER_ONLY_NAMESPACE::UnsafeUTFStringCodePoints<CP32, Range>> =
    std::ranges::enable_borrowed_range<Range>;
#endif

#endif  // U_HIDE_DRAFT_API
#endif  // U_SHOW_CPLUSPLUS_API || U_SHOW_CPLUSPLUS_HEADER_API
#endif  // __UTFITERATOR_H__

Youez - 2016 - github.com/yon3zu
LinuXploit