投稿時間:2022-05-07 22:17:51 RSSフィード2022-05-07 22:00 分まとめ(22件)

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python	Pythonタグが付けられた新着投稿 - Qiita	PCEPに出題される範囲で間違いやすいところ	https://qiita.com/nagaia/items/5ae90cacc943ddad067b	binboctodechexxpower	2022-05-07 21:48:58
js	JavaScriptタグが付けられた新着投稿 - Qiita	jQuery 遅延実行　setTimeout	https://qiita.com/tatsukikane/items/d8486cdb6674c1406e53	settimeout	2022-05-07 21:24:37
AWS	AWSタグが付けられた新着投稿 - Qiita	AWSのRDSでメンテナンスの案内が来た時におまえがすること	https://qiita.com/Usadasonoko/items/5489db356f74762e8edc	開発	2022-05-07 21:34:09
golang	Goタグが付けられた新着投稿 - Qiita	go初学者へのすゝめ	https://qiita.com/omeinu/items/dde77f859f2c43bd4b36	開発	2022-05-07 21:37:46
Azure	Azureタグが付けられた新着投稿 - Qiita	AzureのCloud ShellでSSH接続先のVMをCodeEditorで操作したかったけどうまくいかなかったのでVSCode経由でSSH	https://qiita.com/kazuya-ho2/items/e1825df869e1ec0a8948	azure	2022-05-07 21:45:38
海外TECH	Ars Technica	Why Severance is one of the best shows on TV	https://arstechnica.com/?p=1852550	apple	2022-05-07 12:00:36
海外TECH	MakeUseOf	The 25 Best Alexa Skills of All Time (Free and Paid)	https://www.makeuseof.com/best-alexa-skills-free-paid/	alexa	2022-05-07 13:00:13
海外TECH	MakeUseOf	7 Tips to Choose the Right Online Courses for Upskilling	https://www.makeuseof.com/tips-to-choose-right-online-courses/	Tips to Choose the Right Online Courses for UpskillingWith so many e learning platforms out there online courses are everywhere But how do you pick the right one Here are a few tips to help you choose	2022-05-07 12:45:13
海外TECH	MakeUseOf	3 Simple Tips for Creating an Effective Nighttime Routine	https://www.makeuseof.com/simple-tips-creating-effective-nighttime-routine/	Simple Tips for Creating an Effective Nighttime RoutineYou might have a tried and true routine for a productive start to each day but a nighttime routine is just as important for your energy and health	2022-05-07 12:30:13
海外TECH	MakeUseOf	Can Video Games Save Netflix? The Company Seems to Think So	https://www.makeuseof.com/can-video-games-save-netflix/	games	2022-05-07 12:15:14
海外TECH	MakeUseOf	How to Trace Emails Back to Their Source IP Address	https://www.makeuseof.com/tag/how-to-trace-your-emails-back-to-the-source/	addresshere	2022-05-07 12:05:14
海外TECH	DEV Community	Parsers for Dummies	https://dev.to/frolovdev/parsers-for-dummies-23d0	Parsers for DummiesHere are my notes about parsers They are not particulary academic but I hope they can help someone dig into amazing parsing concepts The high level overview of compilers can be found right here What is lexing It s a process of dividing a string into words tokens A very important part of the job of the lexer is dealing with whitespace Most of the times you want the lexer to discard whitespace Otherwise the parser would have to check for the presence of whitespace between every single token which would quickly become annoying Sometimes you also want to wipe out all the comments on lexer stage as they don t make any sense for parsing grammar What is parsing It s a process of text processing In our case it s a program which somehow understands the grammar of an actual string Parsers groupsLet s start by splitting parsers into two big groupsHand written parsers ーparsers that you write manually Examples recursive decent parsersAutomatically generated ーthere are parser generators these tools can take the grammar of your language and produce a result Examples LL LL K LR K SLR LALR GLRPEGParsing tools are traditionally designed to handle context free languages but sometimes the languages are context sensitive This might be the case to simplify the life of programmers or simply because of bad design A typical example of context sensitive elements are the so called soft keywords i e strings that can be considered keywords in certain places but otherwise can be used as identifiers Language and GrammarLet s create our brand new language Alphabet Σ x y set of characters Language L Σ x y xx xy So language is also a set of some random combinations of two characters from an alphabet set In a nutshell a grammar is a set of restrictions or constraints applied to an alphabet Formal grammarG N T P S N ーnon terminals variables T ーterminals specific character or symbol P ーproductions ーrules of the grammarS ーstarting symbolLet s take an example and try to apply our new knowledge about grammar ⭢ in other words mean is can be defined as ε epsilon means nothing or an empty stringS ⭢xZZ ⭢ySo let s start to read this as a sentence Starting symbol S is can be defined as xZwhere x is terminal and Z is non terminalAfter that let s take a look at the second production Z ⭢y Let s make a substitution or apply derivationS ⭢xZ ⭢xyDerivation ーa sequence of production rules in order to get the input string Context free grammarThese grammars are used for parsing programming languages so to come under the definition of context free grammar grammar should use these rules Only non terminals on LHS left hand side No context on LHSRHS mix of non terminals and terminals BNF notationSuch notations are treated as BNF notationsS xZZ yor they can look something like this lt postal address gt lt name part gt lt street address gt lt zip part gt lt name part gt lt personal part gt lt last name gt lt opt suffix part gt lt EOL gt lt personal part gt lt name part gt lt personal part gt lt initial gt lt first name gt lt street address gt lt house num gt lt street name gt lt opt apt num gt lt EOL gt lt zip part gt lt town name gt lt state code gt lt ZIP code gt lt EOL gt lt opt suffix part gt Sr Jr lt roman numeral gt lt opt apt num gt lt apt num gt Derivations processSubstitution sequence to retrieve an actual string Let s take a look at this kind of grammar E E E E E number ーmeans ornumber ーis any valid numberLet s start a derivation process E ⇒E E ⇒number E ⇒number E E ⇒number number E ⇒number number number ⇒ So we always replace the left most non terminal but let s try replacing the rightmost non terminal E ⇒E E ⇒E E E ⇒E E number ⇒E number number ⇒number number number ⇒ The left most derivation is used in LL parsing and recursive decent parsing On the other side right most derivation can be more powerful and cover more complex languages LR parsing Parse treesA parse tree is a representation of the code closer to the concrete syntax It shows many details of the implementation of the parser For instance each rule usually corresponds to a specific type of a node Let s build a parse tree for the above example In the case of the left most derivation we get the following result And in the case rightmost derivation we get the following result So if we try to DFS depth first search on such trees we get a kind of non determinism So these kind of grammars are called ambiguous grammars as there are have multiple ways to build a sequence of derivations Ambiguous grammarsWhy is ambiguous grammars a problem Because you can get different results from executing your expression Here are the reasons why grammar can be ambiguous Operator precedenceLet s take an example from our previous paragraph The result of this parse tree will be And if we take a look at the one on the right The result will be So it s wrong because the multiplication operator has more precedence than the plus operator AssociativityLet s take a look at this kind of grammar and build some parse trees E E E numberSo for mathematical operations we should have left associativity to avoid errors Left recursive rules to the rescueTo fix the problem with associativity we can use left recursion In the context of parsers an important feature is support for left recursive rules This means that a rule starts with a reference to itself Sometimes this reference can also be indirect that is to say it could appear in another rule referenced by the first one E E number numberThis way you always get the correct result in other words your parse tree will also grow to the left This statement is correct for left associative operators Enforcing correct precedenceTo enforce correct precedence we should find a way to tell the parser which of operators should be executed first In general we can fix this by introducing new layers of non terminals and force operator come first before operator Let s take a look at some grammar E E E E E numberLet s introduce new non terminals E E T T T T F F F number Let s take a look at the result tree Abstract syntax treesA parse tree is usually transformed into an AST by the user possibly with some help from the parser generator A common help allows us to annotate some rules in the grammar to exclude the corresponding nodes from the generated tree Another option is to collapse some kinds of nodes if they have only one child This makes sense because the parse tree is easier to produce for the parser since it is a direct representation of the parsing process However the AST is simpler and easier to process through the following steps of the program They typically include all the operations that you may want to perform on the tree code validation interpretation compilation etc So in other words root nodes are actually operators in such trees So the result tree is much smaller than the parse tree representation Feel free to ask questions express any opinions or concerns or discuss your point of view Share subscribe and make code not war ️If you ll find an error I ll be glad to fix it or learn from you ーjust let me know You can DM me on Twitter or connect on LinkedIn I m always open to new connections people and opportunities	2022-05-07 12:09:23
海外TECH	DEV Community	Getting understand "useReducer in React" from real life sample	https://dev.to/kaziusan/getting-understand-usereducer-in-react-from-real-life-sample-h02	Getting understand quot useReducer in React quot from real life sampleFor those who have learned about useReducer but still can t get when you should use intuitively I implemented toggle button by useStateconst showMenu setShowMenu useState lt boolean gt true when I want to show hide toggle buttonsetShowMenu showMenu But I realised there is better way by useReducerconst showMenu toggleShowMenu useReducer prev gt prev true when I want to show hide toggle button that s all toggleShowMenu If you had like this experience real life example of useReducer make a comment please	2022-05-07 12:07:35
海外TECH	Engadget	Federal judge dismisses Trump's lawsuit against Twitter	https://www.engadget.com/federal-judge-dismisses-trump-lawsuit-twitter-120654477.html?src=rss	Federal judge dismisses Trump x s lawsuit against TwitterSan Francisco federal district court Judge James Donato has tossed the lawsuit Donald Trump filed against Twitter last year in a bid to get his account back The social network permanently suspended the former president s account after his supporters stormed the Capitol in January In the company s announcement Twitter cited two of his tweets in particular that it believes were quot highly likely to encourage and inspire people to replicate the criminal acts that took place at the US Capitol quot on January th last year Trump filed a lawsuit in October seeking a preliminary injunction on the ban and arguing that it violates his First Amendment rights Donato disagreed and noted in his ruling that Twitter is a private company quot The First Amendment applies only to governmental abridgements of speech quot he explained quot and not to alleged abridgements by private companies quot The judge also rejected the notion that the social network had acted as a government entity after being pressured by Trump s opponents and had thereby violated the First Amendment when it banned the former President nbsp In his lawsuit Trump asked the judge to rule the federal Communications Decency Act which states that online service providers such as Twitter can t be held liable for content posted by users as unconstitutional The judge shot down that claim as well and ruled that the former President didn t have legal standing to challenge Section of CDA Trump is a known critic of Section and proposed to limit the protections social media platforms enjoy under it during his term The former President was an avid Twitter user before his suspension and formed his own social network called Truth Social after he was banned Just recently he told CNBC that he won t be going back to Twitter even if Elon Musk reverses his suspension and will stay on Truth Social instead According to a recent report by the Daily Beast Truth Social has daily active users compared to Twitter s million	2022-05-07 12:06:54
ニュース	BBC News - Home	NI election results 2022: Sinn Féin set to win most seats in historic poll	https://www.bbc.co.uk/news/uk-northern-ireland-61355419?at_medium=RSS&at_campaign=KARANGA	leader	2022-05-07 12:52:27
北海道	北海道新聞	フィギュア、本田真凜が始球式　東京ドーム、巨人対ヤクルト戦	https://www.hokkaido-np.co.jp/article/678020/	本田真凜	2022-05-07 21:26:00
北海道	北海道新聞	ヤクルト村上が２試合連続満塁弾　プロ野球タイ記録、９人目	https://www.hokkaido-np.co.jp/article/678017/	村上宗隆	2022-05-07 21:20:00
北海道	北海道新聞	上川管内３２０人感染　旭川は２４７人　新型コロナ	https://www.hokkaido-np.co.jp/article/677933/	上川管内	2022-05-07 21:18:32
北海道	北海道新聞	道南で２０６人感染　新型コロナ	https://www.hokkaido-np.co.jp/article/677942/	道南	2022-05-07 21:06:03
北海道	北海道新聞	胆振管内８２人感染　新型コロナ	https://www.hokkaido-np.co.jp/article/678014/	新型コロナウイルス	2022-05-07 21:05:00
北海道	北海道新聞	知床、強風の中１２人の捜索続く　調査作業船も現場海域へ	https://www.hokkaido-np.co.jp/article/678013/	沈没事故	2022-05-07 21:04:00
北海道	北海道新聞	韓国の俳優、姜受延さん死去　ベネチア映画祭で主演女優賞	https://www.hokkaido-np.co.jp/article/678012/	聯合ニュース	2022-05-07 21:01:00