ÿØÿà JFIF    ÿÛ „ !.%+&8&+/1555$;@;4?.451 4,$,44444444444414444444444444444444444444444444444444ÿÀ  á á" ÿÄ     ÿÄ ?    !1AQaq"2‘¡±ÁðBRbrÑá#‚’¢²3S CñÿÄ   ÿÄ !    !1QAa‘2ÿÚ   ? 5˜Z¯V¦cø)›t/? z¨±>Õ5€¶‹Á¤·¼z¼Ü¬+ñ®v¤¨_ˆR­BFn©—˜ý®ç̝P8gýt·ÉSTŦˆìät?þé¼íìN/Þa)ì–í6ô… Ï¿øÃj´¿KÇü]ÿ ªô¹-eKànëÕHTx}ýSÜ›ÿ ”7Ø×&µ<¦  ¥ÑO¶[Ù¯ä¨ÞÃÿ PZ-¬;#õ|•oaÿ ©CìÞz3˜öː/¤­ñTûIØ}š^ mÓ%ªxˆ¥ÉŸu=Z+ISe¿45™¼u;ú&WØ÷€æßQ™®{|íx*TC“#ZŠìZ§²‹ 6pv…³¿¡äª*áZÐ%ÒOáˆo"x«OHk w±æ+¬V(kMúŸ5Vö«$ ÁrÏbàb57/luR ¸ÑÛj Òµì`Ðœq­û žICÀÊ•©4€Âcà¨Ï€O´<èÐ:›ù(Ë^L8þ‘ÍÌ#¸Ð_Ì©ÙK(Öz 4¬û+¸;ü’V’84‘¬ÃŽ:[â‡ÔÌáõp¢~§ªlæ£ö{®G>J¼"°‡7¯ÆÉèßû ‹É‹§ÁòÃýâßî ^ƾÙõ‹×óH#«LP½ïX=xÑÍ$|W?•~• îëÔ©ª‹ {ÝT…Kÿ ”hûâá)J*ö˜–ÔU;iÇ€/ ÆþjóZ\ýwØ=Ìm ºèËL9 ýèÆð/¨’¥öo=nË.%Îì ŽÕ¯È|{Oj²ƒE6e/ßdÄõ²Ìâ1O®ò×TsəԸhOMýíMˆ¿¼H˜l²,7Â¥#MF/Úf°Ö½± ¸–dr‹NýÊ íjqx{œÉ ä-È ¦ øÄër¨q°ð †nцýÑÄÆ’mä…n<0È™;ÁÝá¯ÁZƒ7FÀmì­ É&9ˆîéi¶ùN§Y• ÃZãAâ?•‡©‰ , ó¾IŸŠc1 4â&y­&pŠ­6;M À 0¹qç»p.á …ŸÅáK@%6·y6ƒ‰3?”úºŽ‰éX5ªPT §µ!=Mž«Ú½‹ÅgÂSâÉaþÓoö–¯ÁÔìR>5éÿ üs¶ÆUcÌ kÇR ]ÿ ù¬¼«VŽ;Â|‡~¢¦”ÏÅ°æ {L™Õ°Óv¹ò¸írŽ¡×¢CÃ!íVÕ {¶»sŒNPg/ "uÕbkm²“$ďå¿é¹§°½æz¯6 †s¿!s–wÚÝ“™Œ °.ûj>·+™Òa…©Œ&rÝÎtÛë긪Ît’LAVp%c Úý[ÄzJ¾ÇàXXç@˜ó<êL]·T˜¾¥1Ó©V‡g´æ½¦Ý@¹óø!_@´ÞâSÁ —S3™•& ]@JHÚý©ZŽ €×æÔr»Áf!‡yÞ4Mv*èÓã_{‘åóUuљØ«Oïé*®EvÑ Œ÷‡U \"㪒ÍK+À 4“M¡ï:0¥5í!'<@î´”>Ç»&Z–ïCCV˜Ì5Šo&îhè.žû |ÓK©h$s6KìŒëã)¹hI¦GïOåóI;ììü#É$Š0…Ææ¥TØ.5­¾gn´ “ÂÖ\:hœ89G)J@„}œ:’Ò{/Š"¦_Æ×7Æ3VÇŠÊa]ÚŒÙ€Ä–=®uÁßâACZƒ§§£ Qnâ:«,×{tyø¬iÛcœÜÄ€H½ÄÍCk´÷šß .W'b¤Íåh]÷€=,Žv×cÚEÚHXJX¶îo¨FÒtèöŸ>ªª6[J®Fµ£sGÁeqõfe\íjÒÐïÄÐGˆe1Ø‹.Ø”‘Ëuø Y­ˆÜ ŽG|zùªüMpDnQWÄ”%JŠ™)â*p@Örš«ÕT2Ð%ˆG#ª„ ·¤!°ŸOTÂT¸aÚ%4&h™LµšØüÐ.F¿²ÐÞ_Ç‚¾ÅÃaÜ÷09Æ q€öy˜v‡85õN÷]¬äѼóS{°_MŽ¬úÔ#°Ç¸0åÞè2ëôPcvÆw9®ií1Ä8F™˜à‰´+‰Ik1òÝ7“Ñ×ÒsÝ\x‚h`ÞÑ`ó"|µEcý£n˜h`}GÞ !±ù²Ápü²ß6 0ïi󜵩SÈÇ7˜-ÕURO˜¦´f$ªž-Í6(œ}<„ éc øs]ŽŽ„*—¾ ìdŽ„)méª\¿êÎIg¾ØÞ~I#C/¼¼´EÁÈŽi8“©õådô·>euä ƒ'Ê×लR1ÉJE1ÐAát`t;ÇР%Ý<‡¥„ÍÆ`×Oyó)õiI€ñQaŸ4Ûù\áàaÃÔ¹HÃu¹*k€¦<„e S‡&õÏ B!ŽhüÞ`yj}mªf×\¿ Ç~æ­9‡û\՞Ǖg²1Žû5V7 !àöšm° c`ܬøÇìµÒ'P"?…´Ö,"§^•õŽ¨sÔ)6˜sæéÍR¼ ò|Sl”‹7 nPW Gòú÷½§O¯‡„l¡kSÞŒr½PÊ@æ¢pŽ-mÿ #Ÿ˜Àº¶Áä¦;ïÔæ$1££`“Õ>„—·ž)ßð³ñ#Ï Ô$¶œ‰ÊE‹À;÷º ¯«P:Ñ”8–IÊtpÞ3ª“>ê“þës4ò2OÏÕ­±zô†Õ§‰.÷ä¸;¿˜“'œ›žª}«Œ{ª±Ì 9ÔóÞÕ‡0 $íWV3Üì¬ —@kÝ4@¿r¼±½¬™›?øØæ´'Áé®CË3-g$˜ö‡×auÚi´Žp/êÛ æF›Ú2v‹ã¿¿,nB1̨ƃqÞa5͝@&Æû“él÷ \C²½UÍc ¯k×¢U ÖéQå™—-r wô ÞÏ<Ò=&=ÿ Ôê Òêˈt,i—;LîÜ á¸*ÚÃ1$êL•LÍ <É)ýÐà’ ;F™{ƒ™˜€&'}‚ãÄK`¡ÞT@I;®žZóè‚s’7®°›+§O­Åq©é»²9<Ô J ¼9O’HL»Ùïì¸rk¼Ž_ý‘TŸu[²ßÚŒ·ü÷B%¯E ŸÔX5êO´ Ç•€’I0 ÉJX` ñ¹õ%;µŸD‘«´€àwÒ™U ûئžÖö\×®×´8 ½‡ºÐÆÓ§?Àkmœ=;d5*@-ì0F Rªýš[Ü6âö̃ڸr*KA9· u*µæ£?U¸Âêí†8@¦X4 e-ò„0s{ HâUpU?¼mñRa°®a%Ð'tÉ×’\¾ÊÉ]t›h>·(Ë@R¼¡Ãt h}’O÷au<+nT…Ö…MӐ??Óe95 q>í/;&JSû °¯ÊéÞ øƒ*Ã2½Ài&:nôUl=¾¿5eˆ3”ñc|Ú2V”>„»&eE;«ÚäC p¢Û úy 9š[ŒÌx¼擼A&DåÒ¯ˆ¤ÀÌ;"˜ ÏQä¸åhÊ}Ûq«Û0WžÒ|»€ø®öCm5•\ÇÀ§Pe3£]0ÃàLDÉ‰1øªxjgwT‚÷¿LΨK‹›ùs—xˆÜ±µ kæ¸f‰‰ÜGk/LÛØ6d9ò¶ùA{ƒA3š/¬D¬khÓk‰`˜"㯒r¿±Óã jx‡°e}<Ñø\3y:'À•/h½Í€Ç4~g ?Û(¼]v‘ªlKÎâ~?O‚W%{Ì:“'©úNq¾›úo(X’¥¯ˆ nFê{Ç€ü?º'ë ø‹ì Þ09ŒÌç9Æ —ËC`j@ÓÄ(+a‹un¸#ÂꟋ{K`‘ÑÍÍ'à´»/Û,KW;Þ4²þð ï Nm|~fGÏ(…³Ã)«1ö­Õ ¥‡¨©ƒÃ™ü-s=à=U66Ï«Ýc蓦W¹íž®›nÔ%êÇìŒ<#Ü×84ån®Ð ÒåOC` ñânÑs‡¢ç 1õ%Îhì½Ã½® e:ݼUZo™`  ÅZŸŒÊ«ê1ÏÄo$q¹Þ€©ˆhÐÉä¯ñ[!…Ú˜àJ:x2$Íß&PåT£6ç— ‡Í*4Ýšçjÿ ‰É nófÐ ó(L5C•åÆ\rMÒ@ò }y-W}™üýVù—ú¢=Ù”c®‘< M ž ´Phr ¦©TD ‘ù.$´÷O‡‘V2Æò.=IUŒ=ž‡â¬i™aþÓåÙ?òUø'ØÖ•.~* šTŒ!•-×áºTâ®ä#õü'´ eýlYÅÓeÕKÂrT"CÚ@u!Óxƒ{š3€}1¿(r}%«nËamjÑ%ÑNEò v ˜à  σöK³,*º.àzù¨™Ó ÚçâU¦*¿ 9{%Ö¹ njûdaXöb) kÛƱûÓ\°M7ˆÂ=û›ç¿Ã‚­V»Cg–8ÙêE- j)k$º`Ã-ùEýeBÆÇ]c¡°ñty&Òd0nõ'¡W+ƒ*|–øµFa\GQªEAÔp5\Ǽ·¼Ç8·õ -â§Ú[ ‡ uZeÖ 3}×d'+¹:ð+K†Û®s!Ï$úe€<Û”x)1»a­¡LC]¸µík…ÚàA»AYº{†ªS[¦5HÒ7ù --,ísòDØ€èk ÞÀîÜ ò@â( ËNˆë›4ô½•/¦o‡€Û7 ê•ÆêòðÜy'Án½µ á˜ݦ ndeo…[ì¶Ê,¥R³Ä=À±—–ß;£™´ñSâ*g§”ïaið‘Jå~™ÓÞ ß³Õ¢»8x埒²52>AÊb&-÷\7´éÄù€T˜,w;3{ï˜k…à¹ÄqÀ«œ{€\ ˆ¾[´¨јr &Úé„Ívˆ±8†¿]|¬ņ4I×pÞS1ÈÖz‰#Ìv‡G!YNògñ:màTz¢Ý1ô©^O=~ë|5Bã™ç•¼µõ•bÆ@úÕS¬ÈŒ#¬zünrŸ û” Z²•ï›èðV"ÁHÚý©wÝ €7¼Ìu1hÑa3Éä û f$o¿É ™Ú›ÝçnpÒ3äÌ3†Í§,Äï]$‰/pê †«À¼¸e9­Æê_C]žƒ·ý·frÁN«, E=›Çq -‰öŒ:aÏ¿±í&£Í:-} 84‘ÿ eƒQÑeëSsuiA ³g㟥ú£?ÿ ʼn*”“÷aühe:ÊWa@ÒÞk±eØ] F Ô—r.åä˜ @ö¥ªZoÐýYL·¥S²G/‡ñ <~*ZÆ´è>JlòàÛƽÿ 窘ìGN¢:I®KšJp/`íIÁÀõ#Ä-€ö­šµŒoF4|ÆQØÆ@Ì|£Ô…¢À{9˜è½Üó›€ôYÒÎYsið;ís¤€à²ˆ‚4qÉVŒI$ ‰"° æµ8cXGjœˏ¡Aâý•ËÜ¢ûï e·çLx']á"oÅÎê3¯Ç—¹”ó0nå‚âg{Œñ> S´˜îè°g238‚ãköÝfÚd´6Ò€;ò÷±¢™¼›º ¢Æ'¥Ðx'e¬ç ]bÈÆV¢ó‹kýBO ðÊâ$Ÿ!×T 3Mýמ žìٍàÌü‘8÷€àæØ8æ©6‰©L´«…oãpð„~Çk‰!ñ;‹”ÛžÍ àž±z Ÿôû øŸÝužÏ;ÿ #|u6™Þ¬ÚˆÐõA4¶â|ôl|Ê2ŽÇ¤ÝÅÇY.<#Aí.k§hóF‚”Y; M½Ö4hŸ4&›­¿tès´%FìL¥£Ãk‰ÇT¤haÁ¤ÚxfÉ`ÑìË›>i 3t‚:,–+^÷´–{Û–Nxi"x‘Ûg î¨>¥Õ܁ùZH,2Û“:8xÊ¢Çí9.É-Ìâã-=çjwµS˜dütžçwýGòú®®ûº_ˆýx$–¡ãøO EÚÛÏ÷R„×w+3£Á£öUMyR²¹âŒ°š›¸Ñãò9§Ó_Dl+Ùßc›úšGÅÌc†Ž!Ko=¶.‘Îÿ c²(2®V mª.ÿ ¹B›¹å ù„öŸSV>™ü¯$y:G¢Z×àøúdî¹û­·ýÇ´:•c LÍõi_‹ö+ÎæGÊè>OŠ•äž´§Þ{X}¨1ÚTc›»Qþ•êô°t¿OP?eæ~É{5]•ÙR£r5†nZ\ã@ &îJõ ¾àC°þV>fé¥/ü5ñÊIº_é5 ;e­h<@ Ä&æÃëE%;X,ÒãÆÞ`Oò¦kŸm#˜!ÀyÄ¢| óLšò¥Ä` ¶R=|ÈCâh5ò3DˆïF†ðÒ#ÅìÛœ?¸yhBãœí ZxßÎÄhºRK„`Þödvײ™ÀÈÑÒgŒuY w³%†ƒÓzõ ÖÏp‚dH®¦A´ù§»ÓÇMæ~)ˆð‡û:ù&Ä •vGD´À n ݇¼Ö8Fö óáà£~Ë¥x`oK|Ä?fxiØü%pìR>éò+Û±éÎ>núlFŤ'tq8LZÏvÃ?„¡ß±È⽆¯³íü@x|PöUäèØã¡ð‚ŒAìÏ"vÍwóŸÍ{ ý0.z È•Ö{,N¡£¡ŸKÕÙž>Ýœþ ÍÀ°<×EA!Å‚D™IúOÍ¡>ôG}Â` ÍßkÜL™Ž Þð™ {IøF²¹òQ3&!ÃÂÞz.d&Ï-sH¸,Ôõ˜ŽP€ 77ˆÝ¼ÊëÜw =cÕ Ú,ØÐ5ÎYÐ)ì´öœgŒ[¤ßv㙑8心>h]§µháYš£²ºÑ.{Ï7Sð•?´~×SÃKýJÛ˜ ™Íäiúu<µX¶1õ^kâçIÑ£sZ4h>j*ÔšD:4­¿_ ÷¸ Õxæÿ ¸?Mù _•­ÊÐ ä ÷ý ÑwL œ­ïnTkÛUÍN©ë:¦fV ¶ÜÔÜMªÅâA½–¿R×TXš-%iTÊT•‡Ù‚JôϐZxWÑè‰f‰òG º ×Õû2aZ7OU3[“×AT–ÞŒ…-‘¤”Ì ì&(ˆ¿­•ƒkï’:ðY¦W‘ Å)“†‘˜³Åtcø˜ñTÂwÚÇ4|üLÇªí–v- qˆèU qPE.†â‘˜µ Æ,ÐÅs]8¾„oúÑ i>ÜxxÈó)ƒ ´æÁâØ$À‰vžŸf$Ž |ãw;ÀÁIJ»b` {¦Ó¤Ú$©YÀ‘n@Óïž«9J¼êG m¤ ܯ¹ÌW4€ÐÒÅÛ‡#褕Ÿn-?í|с¥÷Ú¹¬'´ÞÜ9ÓK `hê£SÄSà?7—Wí_´…óB›»:=Ãïq`<8ñÓŒÑlú2d¬ê³£hÖ[l|$vÝro~'R®‰§°ñmY ͧäP |PUª¹·:3Œ[Û{Xÿ ºâ@‚W–Äé u‚ ¯´*=íή.pûÒdt @G‰¬ s¸ ëÉücr ÞæѨÊ@>¤¢Ö±. Þ'¯°ÌME[YéïĵÂCå½ Ué©Áû'Ê9%eÔðNU”ë‘ÌsD3/®+UI˜9h.WC”빓$#:pz:YÓ ¿xž* ³$Í +$kñAŠ‹†¢ Uê>¸)_š¬÷©ßAÂÔb9ÇU ¯¾á•9¯ÏÏ÷O÷¼¼Fähal1‰3Ì[Ïr•´UCksNÐ] R‘¸¥H+§Šé†c©vÖÞ0iÓ76s†î!§=ß ¼~Ô'°Ãmäoäš³ªøi1úÉ)³yV8 CLÄØÁ‘WYïi€H6ÖÑiámø^ÈY´°Ñ7¥Û*—Ñ©L«Qƒï—Ùrÿ ›£Ð*š¸ˆL©ˆ$ˆ ÷¾D§9È®«qbqC)–ˆïv´çñsÑVT­Ø, <àïºÀO«Jý·õ àfPìð .wFšir´þ’2_Y *Æ€x\« ì€9š@ Ž|F⇥ˆkZ@hÖÄ0t¿-<“‹qµ¾*ZL¤Ú)&BJpÓF5=$„at*Zš$’ÑtdûÝRI1 2Ž‰$€$I$#‰SÞ’Hë¬ï;Á$¡t$’`<(ñÇt)$‡Ð.Êf¢X’Kt=Éé$‚ˆªè¢oÝëòI%Rgcª÷ŠyI%¡‰ÿ !ñ)´õ $¤ Ô’IIGÿÙ""" Test Iterator Length Transparency Some functions or methods which accept general iterable arguments have optional, more efficient code paths if they know how many items to expect. For instance, map(func, iterable), will pre-allocate the exact amount of space required whenever the iterable can report its length. The desired invariant is: len(it)==len(list(it)). A complication is that an iterable and iterator can be the same object. To maintain the invariant, an iterator needs to dynamically update its length. For instance, an iterable such as range(10) always reports its length as ten, but it=iter(range(10)) starts at ten, and then goes to nine after next(it). Having this capability means that map() can ignore the distinction between map(func, iterable) and map(func, iter(iterable)). When the iterable is immutable, the implementation can straight-forwardly report the original length minus the cumulative number of calls to next(). This is the case for tuples, range objects, and itertools.repeat(). Some containers become temporarily immutable during iteration. This includes dicts, sets, and collections.deque. Their implementation is equally simple though they need to permanently set their length to zero whenever there is an attempt to iterate after a length mutation. The situation slightly more involved whenever an object allows length mutation during iteration. Lists and sequence iterators are dynamically updatable. So, if a list is extended during iteration, the iterator will continue through the new items. If it shrinks to a point before the most recent iteration, then no further items are available and the length is reported at zero. Reversed objects can also be wrapped around mutable objects; however, any appends after the current position are ignored. Any other approach leads to confusion and possibly returning the same item more than once. The iterators not listed above, such as enumerate and the other itertools, are not length transparent because they have no way to distinguish between iterables that report static length and iterators whose length changes with each call (i.e. the difference between enumerate('abc') and enumerate(iter('abc')). """ import unittest from itertools import repeat from collections import deque from operator import length_hint n = 10 class TestInvariantWithoutMutations: def test_invariant(self): it = self.it for i in reversed(range(1, n+1)): self.assertEqual(length_hint(it), i) next(it) self.assertEqual(length_hint(it), 0) self.assertRaises(StopIteration, next, it) self.assertEqual(length_hint(it), 0) class TestTemporarilyImmutable(TestInvariantWithoutMutations): def test_immutable_during_iteration(self): # objects such as deques, sets, and dictionaries enforce # length immutability during iteration it = self.it self.assertEqual(length_hint(it), n) next(it) self.assertEqual(length_hint(it), n-1) self.mutate() self.assertRaises(RuntimeError, next, it) self.assertEqual(length_hint(it), 0) ## ------- Concrete Type Tests ------- class TestRepeat(TestInvariantWithoutMutations, unittest.TestCase): def setUp(self): self.it = repeat(None, n) class TestXrange(TestInvariantWithoutMutations, unittest.TestCase): def setUp(self): self.it = iter(range(n)) class TestXrangeCustomReversed(TestInvariantWithoutMutations, unittest.TestCase): def setUp(self): self.it = reversed(range(n)) class TestTuple(TestInvariantWithoutMutations, unittest.TestCase): def setUp(self): self.it = iter(tuple(range(n))) ## ------- Types that should not be mutated during iteration ------- class TestDeque(TestTemporarilyImmutable, unittest.TestCase): def setUp(self): d = deque(range(n)) self.it = iter(d) self.mutate = d.pop class TestDequeReversed(TestTemporarilyImmutable, unittest.TestCase): def setUp(self): d = deque(range(n)) self.it = reversed(d) self.mutate = d.pop class TestDictKeys(TestTemporarilyImmutable, unittest.TestCase): def setUp(self): d = dict.fromkeys(range(n)) self.it = iter(d) self.mutate = d.popitem class TestDictItems(TestTemporarilyImmutable, unittest.TestCase): def setUp(self): d = dict.fromkeys(range(n)) self.it = iter(d.items()) self.mutate = d.popitem class TestDictValues(TestTemporarilyImmutable, unittest.TestCase): def setUp(self): d = dict.fromkeys(range(n)) self.it = iter(d.values()) self.mutate = d.popitem class TestSet(TestTemporarilyImmutable, unittest.TestCase): def setUp(self): d = set(range(n)) self.it = iter(d) self.mutate = d.pop ## ------- Types that can mutate during iteration ------- class TestList(TestInvariantWithoutMutations, unittest.TestCase): def setUp(self): self.it = iter(range(n)) def test_mutation(self): d = list(range(n)) it = iter(d) next(it) next(it) self.assertEqual(length_hint(it), n - 2) d.append(n) self.assertEqual(length_hint(it), n - 1) # grow with append d[1:] = [] self.assertEqual(length_hint(it), 0) self.assertEqual(list(it), []) d.extend(range(20)) self.assertEqual(length_hint(it), 0) class TestListReversed(TestInvariantWithoutMutations, unittest.TestCase): def setUp(self): self.it = reversed(range(n)) def test_mutation(self): d = list(range(n)) it = reversed(d) next(it) next(it) self.assertEqual(length_hint(it), n - 2) d.append(n) self.assertEqual(length_hint(it), n - 2) # ignore append d[1:] = [] self.assertEqual(length_hint(it), 0) self.assertEqual(list(it), []) # confirm invariant d.extend(range(20)) self.assertEqual(length_hint(it), 0) ## -- Check to make sure exceptions are not suppressed by __length_hint__() class BadLen(object): def __iter__(self): return iter(range(10)) def __len__(self): raise RuntimeError('hello') class BadLengthHint(object): def __iter__(self): return iter(range(10)) def __length_hint__(self): raise RuntimeError('hello') class NoneLengthHint(object): def __iter__(self): return iter(range(10)) def __length_hint__(self): return NotImplemented class TestLengthHintExceptions(unittest.TestCase): def test_issue1242657(self): self.assertRaises(RuntimeError, list, BadLen()) self.assertRaises(RuntimeError, list, BadLengthHint()) self.assertRaises(RuntimeError, [].extend, BadLen()) self.assertRaises(RuntimeError, [].extend, BadLengthHint()) b = bytearray(range(10)) self.assertRaises(RuntimeError, b.extend, BadLen()) self.assertRaises(RuntimeError, b.extend, BadLengthHint()) def test_invalid_hint(self): # Make sure an invalid result doesn't muck-up the works self.assertEqual(list(NoneLengthHint()), list(range(10))) if __name__ == "__main__": unittest.main()