mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

	Commit message (Expand)	Author	Age	Files	Lines
*	6622 - new syscalls: time and ntime	Kartik Agaram	2020-07-08	1	-0/+0
*	6618 - new docs	Kartik Agaram	2020-07-06	1	-0/+0
*	6604 - new app	Kartik Agaram	2020-07-01	1	-0/+0
*	6409 - primitives for text-mode UIs	Kartik Agaram	2020-05-27	1	-0/+0
*	5856	Kartik Agaram	2020-01-01	1	-0/+0

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Mu - 001help.cc</title> <meta name="Generator" content="Vim/7.4"> <meta name="plugin-version" content="vim7.4_v1"> <meta name="syntax" content="cpp"> <meta name="settings" content="use_css,pre_wrap,no_foldcolumn,expand_tabs,prevent_copy="> <meta name="colorscheme" content="minimal"> <style type="text/css">  </style> <script type='text/javascript'>  </script> </head> <body> <pre id='vimCodeElement'> //: Everything this project/binary supports. //: This should give you a sense for what to look forward to in later layers. :(before "End Commandline Parsing") if (argc <= 1 || is_equal(argv[1], "--help")) { // this is the functionality later layers will provide // currently no automated tests for commandline arg parsing cerr << "To load files and run 'main':\n" << " mu file1.mu file2.mu ...\n" << "To run all tests:\n" << " mu test\n" << "To load files and then run all tests:\n" << " mu test file1.mu file2.mu ...\n" ; return 0; } //:: Helper function used by the above fragment of code (and later layers too, //:: who knows?). //: The :(code) directive appends function definitions to the end of the //: project. Regardless of where functions are defined, we can call them //: anywhere we like as long as we format the function header in a specific //: way: put it all on a single line without indent, end the line with ') {' //: and no trailing whitespace. As long as functions uniformly start this //: way, our makefile contains a little command to automatically generate //: declarations for them. :(code) bool is_equal(char* s, const char* lit) { return strncmp(s, lit, strlen(lit)) == 0; } // I'll throw some style conventions here for want of a better place for them. // As a rule I hate style guides. Do what you want, that's my motto. But since // we're dealing with C/C++, the one big thing we want to avoid is undefined // behavior. If a compiler ever encounters undefined behavior it can make // your program do anything it wants. // // For reference, my checklist of undefined behaviors to watch out for: // out-of-bounds access // uninitialized variables // use after free // dereferencing invalid pointers: null, a new of size 0, others // // casting a large number to a type too small to hold it // // integer overflow // division by zero and other undefined expressions // left-shift by negative count // shifting values by more than or equal to the number of bits they contain // bitwise operations on signed numbers // // Converting pointers to types of different alignment requirements // T* -> void* -> T*: defined // T* -> U* -> T*: defined if non-function pointers and alignment requirements are same // function pointers may be cast to other function pointers // // Casting a numeric value into a value that can't be represented by the target type (either directly or via static_cast) // // To guard against these, some conventions: // // 0. Initialize all primitive variables in functions and constructors. // // 1. Minimize use of pointers and pointer arithmetic. Avoid 'new' and // 'delete' as far as possible. Rely on STL to perform memory management to // avoid use-after-free issues (and memory leaks). // // 2. Avoid naked arrays to avoid out-of-bounds access. Never use operator[] // except with map. Use at() with STL vectors and so on. // // 3. Valgrind all the things. // // 4. Avoid unsigned numbers. Not strictly an undefined-behavior issue, but // the extra range doesn't matter, and it's one less confusing category of // interaction gotchas to worry about. // // Corollary: don't use the size() method on containers, since it returns an // unsigned and that'll cause warnings about mixing signed and unsigned, // yadda-yadda. Instead use this macro below to perform an unsafe cast to // signed. We'll just give up immediately if a container's every too large. :(before "End Includes") #define SIZE(X) (assert(X.size() < (1LL<<(sizeof(long long int)*8-2))), static_cast<long long int>(X.size())) // // 5. Integer overflow is still impossible to guard against. Maybe after // reading <a href="http://www.cs.utah.edu/~regehr/papers/overflow12.pdf">http://www.cs.utah.edu/~regehr/papers/overflow12.pdf</a> :(before "End Includes") #include<assert.h> #include<iostream> using std::istream; using std::ostream; using std::iostream; using std::cin; using std::cout; using std::cerr; #include<cstring> #include<string> using std::string; </pre> </body> </html>