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