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<title>Mu - subx/001help.cc</title>
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<a href='https://github.com/akkartik/mu/blob/master/subx/001help.cc'>https://github.com/akkartik/mu/blob/master/subx/001help.cc</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="Comment">//: Everything this project/binary supports.</span>
<span id="L2" class="LineNr"> 2 </span><span class="Comment">//: This should give you a sense for what to look forward to in later layers.</span>
<span id="L3" class="LineNr"> 3 </span>
<span id="L4" class="LineNr"> 4 </span><span class="Delimiter">:(before "End Commandline Parsing")</span>
<span id="L5" class="LineNr"> 5 </span><span class="Normal">if</span> <span class="Delimiter">(</span>argc <= <span class="Constant">1</span> || <a href='001help.cc.html#L97'>is_equal</a><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 id="L6" class="LineNr"> 6 </span> <span class="Comment">//: this is the functionality later layers will provide</span>
<span id="L7" class="LineNr"> 7 </span> <span class="Comment">// currently no automated tests for commandline arg parsing</span>
<span id="L8" class="LineNr"> 8 </span> cerr << get<span class="Delimiter">(</span><span class="Special"><a href='001help.cc.html#L53'>Help</a></span><span class="Delimiter">,</span> <span class="Constant">"usage"</span><span class="Delimiter">);</span>
<span id="L9" class="LineNr"> 9 </span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L10" class="LineNr"> 10 </span><span class="Delimiter">}</span>
<span id="L11" class="LineNr"> 11 </span>
<span id="L12" class="LineNr"> 12 </span><span class="Comment">//: Support for option parsing.</span>
<span id="L13" class="LineNr"> 13 </span><span class="Comment">//: Options always begin with '--' and are always the first arguments. An</span>
<span id="L14" class="LineNr"> 14 </span><span class="Comment">//: option will never follow a non-option.</span>
<span id="L15" class="LineNr"> 15 </span><span class="Normal">char</span>** <a href='001help.cc.html#L15'>arg</a> = &argv[<span class="Constant">1</span>]<span class="Delimiter">;</span>
<span id="L16" class="LineNr"> 16 </span><span class="Normal">while</span> <span class="Delimiter">(</span>argc > <span class="Constant">1</span> && <a href='001help.cc.html#L101'>starts_with</a><span class="Delimiter">(</span>*arg<span class="Delimiter">,</span> <span class="Constant">"--"</span><span class="Delimiter">))</span> <span class="Delimiter">{</span>
<span id="L17" class="LineNr"> 17 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><span class="Constant">false</span><span class="Delimiter">)</span>
<span id="L18" class="LineNr"> 18 </span> <span class="Delimiter">;</span> <span class="Comment">// no-op branch just so any further additions can consistently always start with 'else'</span>
<span id="L19" class="LineNr"> 19 </span> <span class="Comment">// End Commandline Options(*arg)</span>
<span id="L20" class="LineNr"> 20 </span> <span class="Normal">else</span>
<span id="L21" class="LineNr"> 21 </span> cerr << <span class="Constant">"skipping unknown option "</span> << *arg << <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
<span id="L22" class="LineNr"> 22 </span> --argc<span class="Delimiter">;</span> ++argv<span class="Delimiter">;</span> ++arg<span class="Delimiter">;</span>
<span id="L23" class="LineNr"> 23 </span><span class="Delimiter">}</span>
<span id="L24" class="LineNr"> 24 </span>
<span id="L25" class="LineNr"> 25 </span><span class="Normal">if</span> <span class="Delimiter">(</span><a href='001help.cc.html#L97'>is_equal</a><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 id="L26" class="LineNr"> 26 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>argc == <span class="Constant">2</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L27" class="LineNr"> 27 </span> cerr << <span class="Constant">"help on what?\n"</span><span class="Delimiter">;</span>
<span id="L28" class="LineNr"> 28 </span> <a href='001help.cc.html#L46'>help_contents</a><span class="Delimiter">();</span>
<span id="L29" class="LineNr"> 29 </span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L30" class="LineNr"> 30 </span> <span class="Delimiter">}</span>
<span id="L31" class="LineNr"> 31 </span> string key<span class="Delimiter">(</span>argv[<span class="Constant">2</span>]<span class="Delimiter">);</span>
<span id="L32" class="LineNr"> 32 </span> <span class="Comment">// End Help Special-cases(key)</span>
<span id="L33" class="LineNr"> 33 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='001help.cc.html#L255'>contains_key</a><span class="Delimiter">(</span><span class="Special"><a href='001help.cc.html#L53'>Help</a></span><span class="Delimiter">,</span> key<span class="Delimiter">))</span> <span class="Delimiter">{</span>
<span id="L34" class="LineNr"> 34 </span> cerr << get<span class="Delimiter">(</span><span class="Special"><a href='001help.cc.html#L53'>Help</a></span><span class="Delimiter">,</span> key<span class="Delimiter">);</span>
<span id="L35" class="LineNr"> 35 </span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L36" class="LineNr"> 36 </span> <span class="Delimiter">}</span>
<span id="L37" class="LineNr"> 37 </span> <span class="Normal">else</span> <span class="Delimiter">{</span>
<span id="L38" class="LineNr"> 38 </span> cerr << <span class="Constant">"No help found for '"</span> << key << <span class="Constant">"'\n"</span><span class="Delimiter">;</span>
<span id="L39" class="LineNr"> 39 </span> <a href='001help.cc.html#L46'>help_contents</a><span class="Delimiter">();</span>
<span id="L40" class="LineNr"> 40 </span> cerr << <span class="Constant">"Please check your command for typos.\n"</span><span class="Delimiter">;</span>
<span id="L41" class="LineNr"> 41 </span> <span class="Identifier">return</span> <span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L42" class="LineNr"> 42 </span> <span class="Delimiter">}</span>
<span id="L43" class="LineNr"> 43 </span><span class="Delimiter">}</span>
<span id="L44" class="LineNr"> 44 </span>
<span id="L45" class="LineNr"> 45 </span><span class="Delimiter">:(code)</span>
<span id="L46" class="LineNr"> 46 </span><span class="Normal">void</span> <a href='001help.cc.html#L46'>help_contents</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L47" class="LineNr"> 47 </span> cerr << <span class="Constant">"Available top-level topics:\n"</span><span class="Delimiter">;</span>
<span id="L48" class="LineNr"> 48 </span> cerr << <span class="Constant">" usage\n"</span><span class="Delimiter">;</span>
<span id="L49" class="LineNr"> 49 </span> <span class="Comment">// End Help Contents</span>
<span id="L50" class="LineNr"> 50 </span><span class="Delimiter">}</span>
<span id="L51" class="LineNr"> 51 </span>
<span id="L52" class="LineNr"> 52 </span><span class="Delimiter">:(before "End Globals")</span>
<span id="L53" class="LineNr"> 53 </span>map<string<span class="Delimiter">,</span> string> <span class="Special"><a href='001help.cc.html#L53'>Help</a></span><span class="Delimiter">;</span>
<span id="L54" class="LineNr"> 54 </span><span class="Delimiter">:(before "End Includes")</span>
<span id="L55" class="LineNr"> 55 </span><span class="PreProc">#include </span><span class="Constant"><map></span>
<span id="L56" class="LineNr"> 56 </span><span class="Normal">using</span> std::map<span class="Delimiter">;</span>
<span id="L57" class="LineNr"> 57 </span><span class="Delimiter">:(before "End One-time Setup")</span>
<span id="L58" class="LineNr"> 58 </span><a href='001help.cc.html#L60'>init_help</a><span class="Delimiter">();</span>
<span id="L59" class="LineNr"> 59 </span><span class="Delimiter">:(code)</span>
<span id="L60" class="LineNr"> 60 </span><span class="Normal">void</span> <a href='001help.cc.html#L60'>init_help</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L61" class="LineNr"> 61 </span> <a href='001help.cc.html#L251'>put</a><span class="Delimiter">(</span><span class="Special"><a href='001help.cc.html#L53'>Help</a></span><span class="Delimiter">,</span> <span class="Constant">"usage"</span><span class="Delimiter">,</span>
<span id="L62" class="LineNr"> 62 </span> <span class="Constant">"Welcome to SubX, a better way to <a href='011run.cc.html#L101'>program</a> in machine code.\n"</span>
<span id="L63" class="LineNr"> 63 </span> <span class="Constant">"SubX uses a subset of the x86 instruction set. SubX programs will run\n"</span>
<span id="L64" class="LineNr"> 64 </span> <span class="Constant">"without modification on Linux computers.\n"</span>
<span id="L65" class="LineNr"> 65 </span> <span class="Constant">"It provides a better experience and better error messages than\n"</span>
<span id="L66" class="LineNr"> 66 </span> <span class="Constant">"programming directly in machine code, but you have to stick to the\n"</span>
<span id="L67" class="LineNr"> 67 </span> <span class="Constant">"instructions it supports.\n"</span>
<span id="L68" class="LineNr"> 68 </span> <span class="Constant">"\n"</span>
<span id="L69" class="LineNr"> 69 </span> <span class="Constant">"== Ways to invoke subx\n"</span>
<span id="L70" class="LineNr"> 70 </span> <span class="Constant">"- Run tests:\n"</span>
<span id="L71" class="LineNr"> 71 </span> <span class="Constant">" subx test\n"</span>
<span id="L72" class="LineNr"> 72 </span> <span class="Constant">"- See this message:\n"</span>
<span id="L73" class="LineNr"> 73 </span> <span class="Constant">" subx --help\n"</span>
<span id="L74" class="LineNr"> 74 </span> <span class="Constant">"- Convert a textual SubX <a href='011run.cc.html#L101'>program</a> into a standard ELF binary that you can\n"</span>
<span id="L75" class="LineNr"> 75 </span> <span class="Constant">" <a href='011run.cc.html#L85'>run</a> on your computer:\n"</span>
<span id="L76" class="LineNr"> 76 </span> <span class="Constant">" subx translate input1.subx intput2.subx ... -o <output ELF binary>\n"</span>
<span id="L77" class="LineNr"> 77 </span> <span class="Constant">"- Run a SubX binary using SubX itself (for better error messages):\n"</span>
<span id="L78" class="LineNr"> 78 </span> <span class="Constant">" subx <a href='011run.cc.html#L85'>run</a> <ELF binary>\n"</span>
<span id="L79" class="LineNr"> 79 </span> <span class="Constant">"\n"</span>
<span id="L80" class="LineNr"> 80 </span> <span class="Constant">"== Debugging aids\n"</span>
<span id="L81" class="LineNr"> 81 </span> <span class="Constant">"- Add '--trace' to any of these commands to print a <a href='003trace.cc.html#L96'>trace</a> to stderr\n"</span>
<span id="L82" class="LineNr"> 82 </span> <span class="Constant">" for debugging purposes.\n"</span>
<span id="L83" class="LineNr"> 83 </span> <span class="Constant">"- Add '--debug' to add information to traces. 'subx --debug translate' will\n"</span>
<span id="L84" class="LineNr"> 84 </span> <span class="Constant">" save various mappings to files that 'subx --debug --trace run'\n"</span>
<span id="L85" class="LineNr"> 85 </span> <span class="Constant">" can use to make traces more informative.\n"</span>
<span id="L86" class="LineNr"> 86 </span> <span class="Constant">"\n"</span>
<span id="L87" class="LineNr"> 87 </span> <span class="Constant">"Options starting with '--' must always come before any other arguments.\n"</span>
<span id="L88" class="LineNr"> 88 </span> <span class="Constant">"\n"</span>
<span id="L89" class="LineNr"> 89 </span> <span class="Constant">"To start learning how to write SubX programs, see Readme.md (particularly\n"</span>
<span id="L90" class="LineNr"> 90 </span> <span class="Constant">"the section on the x86 instruction set) and then <a href='011run.cc.html#L85'>run</a>:\n"</span>
<span id="L91" class="LineNr"> 91 </span> <span class="Constant">" subx help\n"</span>
<span id="L92" class="LineNr"> 92 </span> <span class="Delimiter">);</span>
<span id="L93" class="LineNr"> 93 </span> <span class="Comment">// End Help Texts</span>
<span id="L94" class="LineNr"> 94 </span><span class="Delimiter">}</span>
<span id="L95" class="LineNr"> 95 </span>
<span id="L96" class="LineNr"> 96 </span><span class="Delimiter">:(code)</span>
<span id="L97" class="LineNr"> 97 </span><span class="Normal">bool</span> <a href='001help.cc.html#L97'>is_equal</a><span class="Delimiter">(</span><span class="Normal">char</span>* s<span class="Delimiter">,</span> <span class="Normal">const</span> <span class="Normal">char</span>* lit<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L98" class="LineNr"> 98 </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 id="L99" class="LineNr"> 99 </span><span class="Delimiter">}</span>
<span id="L100" class="LineNr">100 </span>
<span id="L101" class="LineNr">101 </span><span class="Normal">bool</span> <a href='001help.cc.html#L101'>starts_with</a><span class="Delimiter">(</span><span class="Normal">const</span> string& s<span class="Delimiter">,</span> <span class="Normal">const</span> string& pat<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L102" class="LineNr">102 </span> string::const_iterator a=s<span class="Delimiter">.</span>begin<span class="Delimiter">(),</span> b=pat<span class="Delimiter">.</span>begin<span class="Delimiter">();</span>
<span id="L103" class="LineNr">103 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">nada</span><span class="Comment">*/</span><span class="Delimiter">;</span> a!=s<span class="Delimiter">.</span>end<span class="Delimiter">()</span> && b!=pat<span class="Delimiter">.</span>end<span class="Delimiter">();</span> ++a<span class="Delimiter">,</span> ++b<span class="Delimiter">)</span>
<span id="L104" class="LineNr">104 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>*a != *b<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
<span id="L105" class="LineNr">105 </span> <span class="Identifier">return</span> b == pat<span class="Delimiter">.</span>end<span class="Delimiter">();</span>
<span id="L106" class="LineNr">106 </span><span class="Delimiter">}</span>
<span id="L107" class="LineNr">107 </span>
<span id="L108" class="LineNr">108 </span><span class="Comment">//: I'll throw some style conventions here for want of a better place for them.</span>
<span id="L109" class="LineNr">109 </span><span class="Comment">//: As a rule I hate style guides. Do what you want, that's my motto. But since</span>
<span id="L110" class="LineNr">110 </span><span class="Comment">//: we're dealing with C/C++, the one big thing we want to avoid is undefined</span>
<span id="L111" class="LineNr">111 </span><span class="Comment">//: behavior. If a compiler ever encounters undefined behavior it can make</span>
<span id="L112" class="LineNr">112 </span><span class="Comment">//: your program do anything it wants.</span>
<span id="L113" class="LineNr">113 </span><span class="Comment">//:</span>
<span id="L114" class="LineNr">114 </span><span class="Comment">//: For reference, my checklist of undefined behaviors to watch out for:</span>
<span id="L115" class="LineNr">115 </span><span class="Comment">//: out-of-bounds access</span>
<span id="L116" class="LineNr">116 </span><span class="Comment">//: uninitialized variables</span>
<span id="L117" class="LineNr">117 </span><span class="Comment">//: use after free</span>
<span id="L118" class="LineNr">118 </span><span class="Comment">//: dereferencing invalid pointers: null, a new of size 0, others</span>
<span id="L119" class="LineNr">119 </span><span class="Comment">//:</span>
<span id="L120" class="LineNr">120 </span><span class="Comment">//: casting a large number to a type too small to hold it</span>
<span id="L121" class="LineNr">121 </span><span class="Comment">//:</span>
<span id="L122" class="LineNr">122 </span><span class="Comment">//: integer overflow</span>
<span id="L123" class="LineNr">123 </span><span class="Comment">//: division by zero and other undefined expressions</span>
<span id="L124" class="LineNr">124 </span><span class="Comment">//: left-shift by negative count</span>
<span id="L125" class="LineNr">125 </span><span class="Comment">//: shifting values by more than or equal to the number of bits they contain</span>
<span id="L126" class="LineNr">126 </span><span class="Comment">//: bitwise operations on signed numbers</span>
<span id="L127" class="LineNr">127 </span><span class="Comment">//:</span>
<span id="L128" class="LineNr">128 </span><span class="Comment">//: Converting pointers to types of different alignment requirements</span>
<span id="L129" class="LineNr">129 </span><span class="Comment">//: T* -> void* -> T*: defined</span>
<span id="L130" class="LineNr">130 </span><span class="Comment">//: T* -> U* -> T*: defined if non-function pointers and alignment requirements are same</span>
<span id="L131" class="LineNr">131 </span><span class="Comment">//: function pointers may be cast to other function pointers</span>
<span id="L132" class="LineNr">132 </span><span class="Comment">//:</span>
<span id="L133" class="LineNr">133 </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 id="L134" class="LineNr">134 </span><span class="Comment">//:</span>
<span id="L135" class="LineNr">135 </span><span class="Comment">//: To guard against these, some conventions:</span>
<span id="L136" class="LineNr">136 </span><span class="Comment">//:</span>
<span id="L137" class="LineNr">137 </span><span class="Comment">//: 0. Initialize all primitive variables in functions and constructors.</span>
<span id="L138" class="LineNr">138 </span><span class="Comment">//:</span>
<span id="L139" class="LineNr">139 </span><span class="Comment">//: 1. Minimize use of pointers and pointer arithmetic. Avoid 'new' and</span>
<span id="L140" class="LineNr">140 </span><span class="Comment">//: 'delete' as far as possible. Rely on STL to perform memory management to</span>
<span id="L141" class="LineNr">141 </span><span class="Comment">//: avoid use-after-free issues (and memory leaks).</span>
<span id="L142" class="LineNr">142 </span><span class="Comment">//:</span>
<span id="L143" class="LineNr">143 </span><span class="Comment">//: 2. Avoid naked arrays to avoid out-of-bounds access. Never use operator[]</span>
<span id="L144" class="LineNr">144 </span><span class="Comment">//: except with map. Use at() with STL vectors and so on.</span>
<span id="L145" class="LineNr">145 </span><span class="Comment">//:</span>
<span id="L146" class="LineNr">146 </span><span class="Comment">//: 3. Valgrind all the things.</span>
<span id="L147" class="LineNr">147 </span><span class="Comment">//:</span>
<span id="L148" class="LineNr">148 </span><span class="Comment">//: 4. Avoid unsigned numbers. Not strictly an undefined-behavior issue, but</span>
<span id="L149" class="LineNr">149 </span><span class="Comment">//: the extra range doesn't matter, and it's one less confusing category of</span>
<span id="L150" class="LineNr">150 </span><span class="Comment">//: interaction gotchas to worry about.</span>
<span id="L151" class="LineNr">151 </span><span class="Comment">//:</span>
<span id="L152" class="LineNr">152 </span><span class="Comment">//: Corollary: don't use the size() method on containers, since it returns an</span>
<span id="L153" class="LineNr">153 </span><span class="Comment">//: unsigned and that'll cause warnings about mixing signed and unsigned,</span>
<span id="L154" class="LineNr">154 </span><span class="Comment">//: yadda-yadda. Instead use this macro below to perform an unsafe cast to</span>
<span id="L155" class="LineNr">155 </span><span class="Comment">//: signed. We'll just give up immediately if a container's ever too large.</span>
<span id="L156" class="LineNr">156 </span><span class="Comment">//: Basically, Mu is not concerned about this being a little slower than it</span>
<span id="L157" class="LineNr">157 </span><span class="Comment">//: could be. (<a href="https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7">https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7</a>)</span>
<span id="L158" class="LineNr">158 </span><span class="Comment">//:</span>
<span id="L159" class="LineNr">159 </span><span class="Comment">//: Addendum to corollary: We're going to uniformly use int everywhere, to</span>
<span id="L160" class="LineNr">160 </span><span class="Comment">//: indicate that we're oblivious to number size, and since Clang on 32-bit</span>
<span id="L161" class="LineNr">161 </span><span class="Comment">//: platforms doesn't yet support multiplication over 64-bit integers, and</span>
<span id="L162" class="LineNr">162 </span><span class="Comment">//: since multiplying two integers seems like a more common situation to end</span>
<span id="L163" class="LineNr">163 </span><span class="Comment">//: up in than integer overflow.</span>
<span id="L164" class="LineNr">164 </span><span class="Delimiter">:(before "End Includes")</span>
<span id="L165" class="LineNr">165 </span><span class="PreProc">#define SIZE(</span><span class="Special">X</span><span class="PreProc">) (assert((</span><span class="Special">X</span><span class="PreProc">)</span><span class="Delimiter">.</span><span class="PreProc">size() < (</span><span class="Constant">1LL</span><span class="PreProc"><<(</span><span class="Normal">sizeof</span><span class="PreProc">(</span><span class="Normal">int</span><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><span class="Normal">static_cast</span><span class="PreProc"><</span><span class="Normal">int</span><span class="PreProc">>((</span><span class="Special">X</span><span class="PreProc">)</span><span class="Delimiter">.</span><span class="PreProc">size()))</span>
<span id="L166" class="LineNr">166 </span>
<span id="L167" class="LineNr">167 </span><span class="Comment">//: 5. Integer overflow is guarded against at runtime using the -ftrapv flag</span>
<span id="L168" class="LineNr">168 </span><span class="Comment">//: to the compiler, supported by Clang (GCC version only works sometimes:</span>
<span id="L169" class="LineNr">169 </span><span class="Comment">//: <a href="http://stackoverflow.com/questions/20851061/how-to-make-gcc-ftrapv-work">http://stackoverflow.com/questions/20851061/how-to-make-gcc-ftrapv-work</a>).</span>
<span id="L170" class="LineNr">170 </span><span class="Delimiter">:(before "atexit(reset)")</span>
<span id="L171" class="LineNr">171 </span><a href='001help.cc.html#L176'>initialize_signal_handlers</a><span class="Delimiter">();</span> <span class="Comment">// not always necessary, but doesn't hurt</span>
<span id="L172" class="LineNr">172 </span><span class="CommentedCode">//? cerr << INT_MAX+1 << '\n'; // test overflow</span>
<span id="L173" class="LineNr">173 </span><span class="CommentedCode">//? assert(false); // test SIGABRT</span>
<span id="L174" class="LineNr">174 </span><span class="Delimiter">:(code)</span>
<span id="L175" class="LineNr">175 </span><span class="Comment">// based on <a href="https://spin.atomicobject.com/2013/01/13/exceptions-stack-traces-c">https://spin.atomicobject.com/2013/01/13/exceptions-stack-traces-c</a></span>
<span id="L176" class="LineNr">176 </span><span class="Normal">void</span> <a href='001help.cc.html#L176'>initialize_signal_handlers</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L177" class="LineNr">177 </span> <span class="Normal">struct</span> sigaction action<span class="Delimiter">;</span>
<span id="L178" class="LineNr">178 </span> bzero<span class="Delimiter">(</span>&action<span class="Delimiter">,</span> <span class="Normal">sizeof</span><span class="Delimiter">(</span>action<span class="Delimiter">));</span>
<span id="L179" class="LineNr">179 </span> action<span class="Delimiter">.</span>sa_sigaction = <a href='001help.cc.html#L184'>dump_and_exit</a><span class="Delimiter">;</span>
<span id="L180" class="LineNr">180 </span> sigemptyset<span class="Delimiter">(</span>&action<span class="Delimiter">.</span>sa_mask<span class="Delimiter">);</span>
<span id="L181" class="LineNr">181 </span> sigaction<span class="Delimiter">(</span><span class="Constant">SIGABRT</span><span class="Delimiter">,</span> &action<span class="Delimiter">,</span> <span class="Constant">NULL</span><span class="Delimiter">);</span> <span class="Comment">// assert() failure or integer overflow on linux (with -ftrapv)</span>
<span id="L182" class="LineNr">182 </span> sigaction<span class="Delimiter">(</span><span class="Constant">SIGILL</span><span class="Delimiter">,</span> &action<span class="Delimiter">,</span> <span class="Constant">NULL</span><span class="Delimiter">);</span> <span class="Comment">// integer overflow on OS X (with -ftrapv)</span>
<span id="L183" class="LineNr">183 </span><span class="Delimiter">}</span>
<span id="L184" class="LineNr">184 </span><span class="Normal">void</span> <a href='001help.cc.html#L184'>dump_and_exit</a><span class="Delimiter">(</span><span class="Normal">int</span> sig<span class="Delimiter">,</span> siginfo_t* <span class="Comment">/*</span><span class="Comment">unused</span><span class="Comment">*/</span><span class="Delimiter">,</span> <span class="Normal">void</span>* <span class="Comment">/*</span><span class="Comment">unused</span><span class="Comment">*/</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L185" class="LineNr">185 </span> <span class="Normal">switch</span> <span class="Delimiter">(</span>sig<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L186" class="LineNr">186 </span> <span class="Normal">case</span> <span class="Constant">SIGABRT</span>:
<span id="L187" class="LineNr">187 </span> <span class="PreProc">#ifndef __APPLE__</span>
<span id="L188" class="LineNr">188 </span> cerr << <span class="Constant">"SIGABRT: might be an integer overflow if it wasn't an assert() failure\n"</span><span class="Delimiter">;</span>
<span id="L189" class="LineNr">189 </span> _Exit<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
<span id="L190" class="LineNr">190 </span> <span class="PreProc">#endif</span>
<span id="L191" class="LineNr">191 </span> <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L192" class="LineNr">192 </span> <span class="Normal">case</span> <span class="Constant">SIGILL</span>:
<span id="L193" class="LineNr">193 </span> <span class="PreProc">#ifdef __APPLE__</span>
<span id="L194" class="LineNr">194 </span> cerr << <span class="Constant">"SIGILL: most likely caused by integer overflow\n"</span><span class="Delimiter">;</span>
<span id="L195" class="LineNr">195 </span> _Exit<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
<span id="L196" class="LineNr">196 </span> <span class="PreProc">#endif</span>
<span id="L197" class="LineNr">197 </span> <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L198" class="LineNr">198 </span> <span class="Normal">default</span>:
<span id="L199" class="LineNr">199 </span> <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L200" class="LineNr">200 </span> <span class="Delimiter">}</span>
<span id="L201" class="LineNr">201 </span><span class="Delimiter">}</span>
<span id="L202" class="LineNr">202 </span><span class="Delimiter">:(before "End Includes")</span>
<span id="L203" class="LineNr">203 </span><span class="PreProc">#include </span><span class="Constant"><signal.h></span>
<span id="L204" class="LineNr">204 </span>
<span id="L205" class="LineNr">205 </span><span class="Comment">//: For good measure we'll also enable SIGFPE.</span>
<span id="L206" class="LineNr">206 </span><span class="Delimiter">:(before "atexit(reset)")</span>
<span id="L207" class="LineNr">207 </span><a href='001help.cc.html#L220'>feenableexcept</a><span class="Delimiter">(</span>FE_OVERFLOW | FE_UNDERFLOW<span class="Delimiter">);</span>
<span id="L208" class="LineNr">208 </span><span class="CommentedCode">//? assert(sizeof(int) == 4 && sizeof(float) == 4);</span>
<span id="L209" class="LineNr">209 </span><span class="CommentedCode">//? // | exp | mantissa</span>
<span id="L210" class="LineNr">210 </span><span class="CommentedCode">//? int smallest_subnormal = 0b00000000000000000000000000000001;</span>
<span id="L211" class="LineNr">211 </span><span class="CommentedCode">//? float smallest_subnormal_f = *reinterpret_cast<float*>(&smallest_subnormal);</span>
<span id="L212" class="LineNr">212 </span><span class="CommentedCode">//? cerr << "ε: " << smallest_subnormal_f << '\n';</span>
<span id="L213" class="LineNr">213 </span><span class="CommentedCode">//? cerr << "ε/2: " << smallest_subnormal_f/2 << " (underflow)\n"; // test SIGFPE</span>
<span id="L214" class="LineNr">214 </span><span class="Delimiter">:(before "End Includes")</span>
<span id="L215" class="LineNr">215 </span><span class="PreProc">#include </span><span class="Constant"><fenv.h></span>
<span id="L216" class="LineNr">216 </span><span class="Delimiter">:(code)</span>
<span id="L217" class="LineNr">217 </span><span class="PreProc">#ifdef __APPLE__</span>
<span id="L218" class="LineNr">218 </span><span class="Comment">// Public domain polyfill for feenableexcept on OS X</span>
<span id="L219" class="LineNr">219 </span><span class="Comment">// <a href="http://www-personal.umich.edu/~williams/archive/computation/fe-handling-example.c">http://www-personal.umich.edu/~williams/archive/computation/fe-handling-example.c</a></span>
<span id="L220" class="LineNr">220 </span><span class="Normal">int</span> <a href='001help.cc.html#L220'>feenableexcept</a><span class="Delimiter">(</span><span class="Normal">unsigned</span> <span class="Normal">int</span> excepts<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L221" class="LineNr">221 </span> <span class="Normal">static</span> fenv_t fenv<span class="Delimiter">;</span>
<span id="L222" class="LineNr">222 </span> <span class="Normal">unsigned</span> <span class="Normal">int</span> new_excepts = excepts & FE_ALL_EXCEPT<span class="Delimiter">;</span>
<span id="L223" class="LineNr">223 </span> <span class="Normal">unsigned</span> <span class="Normal">int</span> old_excepts<span class="Delimiter">;</span>
<span id="L224" class="LineNr">224 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>fegetenv<span class="Delimiter">(</span>&fenv<span class="Delimiter">))</span> <span class="Identifier">return</span> -<span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L225" class="LineNr">225 </span> old_excepts = fenv<span class="Delimiter">.</span>__control & FE_ALL_EXCEPT<span class="Delimiter">;</span>
<span id="L226" class="LineNr">226 </span> fenv<span class="Delimiter">.</span>__control &= ~new_excepts<span class="Delimiter">;</span>
<span id="L227" class="LineNr">227 </span> fenv<span class="Delimiter">.</span>__mxcsr &= ~<span class="Delimiter">(</span>new_excepts << <span class="Constant">7</span><span class="Delimiter">);</span>
<span id="L228" class="LineNr">228 </span> <span class="Identifier">return</span> fesetenv<span class="Delimiter">(</span>&fenv<span class="Delimiter">)</span> ? -<span class="Constant">1</span> : old_excepts<span class="Delimiter">;</span>
<span id="L229" class="LineNr">229 </span><span class="Delimiter">}</span>
<span id="L230" class="LineNr">230 </span><span class="PreProc">#endif</span>
<span id="L231" class="LineNr">231 </span>
<span id="L232" class="LineNr">232 </span><span class="Comment">//: 6. Map's operator[] being non-const is fucking evil.</span>
<span id="L233" class="LineNr">233 </span><span class="Delimiter">:(before "Globals")</span> <span class="Comment">// can't generate prototypes for these</span>
<span id="L234" class="LineNr">234 </span><span class="Comment">// from <a href="http://stackoverflow.com/questions/152643/idiomatic-c-for-reading-from-a-const-map">http://stackoverflow.com/questions/152643/idiomatic-c-for-reading-from-a-const-map</a></span>
<span id="L235" class="LineNr">235 </span><span class="Normal">template</span><<span class="Normal">typename</span> <span class="Special">T</span>> <span class="Normal">typename</span> <span class="Special">T</span>::mapped_type& get<span class="Delimiter">(</span><span class="Special">T</span>& map<span class="Delimiter">,</span> <span class="Normal">typename</span> <span class="Special">T</span>::key_type <span class="Normal">const</span>& key<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L236" class="LineNr">236 </span> <span class="Normal">typename</span> <span class="Special">T</span>::iterator iter<span class="Delimiter">(</span>map<span class="Delimiter">.</span>find<span class="Delimiter">(</span>key<span class="Delimiter">));</span>
<span id="L237" class="LineNr">237 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>iter == map<span class="Delimiter">.</span>end<span class="Delimiter">())</span> <span class="Delimiter">{</span>
<span id="L238" class="LineNr">238 </span> cerr << <span class="Constant">"get couldn't find key '"</span> << key << <span class="Constant">"'\n"</span><span class="Delimiter">;</span>
<span id="L239" class="LineNr">239 </span> assert<span class="Delimiter">(</span>iter != map<span class="Delimiter">.</span>end<span class="Delimiter">());</span>
<span id="L240" class="LineNr">240 </span> <span class="Delimiter">}</span>
<span id="L241" class="LineNr">241 </span> <span class="Identifier">return</span> iter<span class="Delimiter">-></span>second<span class="Delimiter">;</span>
<span id="L242" class="LineNr">242 </span><span class="Delimiter">}</span>
<span id="L243" class="LineNr">243 </span><span class="Normal">template</span><<span class="Normal">typename</span> <span class="Special">T</span>> <span class="Normal">typename</span> <span class="Special">T</span>::mapped_type <span class="Normal">const</span>& get<span class="Delimiter">(</span><span class="Normal">const</span> <span class="Special">T</span>& map<span class="Delimiter">,</span> <span class="Normal">typename</span> <span class="Special">T</span>::key_type <span class="Normal">const</span>& key<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L244" class="LineNr">244 </span> <span class="Normal">typename</span> <span class="Special">T</span>::const_iterator iter<span class="Delimiter">(</span>map<span class="Delimiter">.</span>find<span class="Delimiter">(</span>key<span class="Delimiter">));</span>
<span id="L245" class="LineNr">245 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>iter == map<span class="Delimiter">.</span>end<span class="Delimiter">())</span> <span class="Delimiter">{</span>
<span id="L246" class="LineNr">246 </span> cerr << <span class="Constant">"get couldn't find key '"</span> << key << <span class="Constant">"'\n"</span><span class="Delimiter">;</span>
<span id="L247" class="LineNr">247 </span> assert<span class="Delimiter">(</span>iter != map<span class="Delimiter">.</span>end<span class="Delimiter">());</span>
<span id="L248" class="LineNr">248 </span> <span class="Delimiter">}</span>
<span id="L249" class="LineNr">249 </span> <span class="Identifier">return</span> iter<span class="Delimiter">-></span>second<span class="Delimiter">;</span>
<span id="L250" class="LineNr">250 </span><span class="Delimiter">}</span>
<span id="L251" class="LineNr">251 </span><span class="Normal">template</span><<span class="Normal">typename</span> <span class="Special">T</span>> <span class="Normal">typename</span> <span class="Special">T</span>::mapped_type <span class="Normal">const</span>& <a href='001help.cc.html#L251'>put</a><span class="Delimiter">(</span><span class="Special">T</span>& map<span class="Delimiter">,</span> <span class="Normal">typename</span> <span class="Special">T</span>::key_type <span class="Normal">const</span>& key<span class="Delimiter">,</span> <span class="Normal">typename</span> <span class="Special">T</span>::mapped_type <span class="Normal">const</span>& value<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L252" class="LineNr">252 </span> map[key] = value<span class="Delimiter">;</span>
<span id="L253" class="LineNr">253 </span> <span class="Identifier">return</span> map[key]<span class="Delimiter">;</span>
<span id="L254" class="LineNr">254 </span><span class="Delimiter">}</span>
<span id="L255" class="LineNr">255 </span><span class="Normal">template</span><<span class="Normal">typename</span> <span class="Special">T</span>> <span class="Normal">bool</span> <a href='001help.cc.html#L255'>contains_key</a><span class="Delimiter">(</span><span class="Special">T</span>& map<span class="Delimiter">,</span> <span class="Normal">typename</span> <span class="Special">T</span>::key_type <span class="Normal">const</span>& key<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L256" class="LineNr">256 </span> <span class="Identifier">return</span> map<span class="Delimiter">.</span>find<span class="Delimiter">(</span>key<span class="Delimiter">)</span> != map<span class="Delimiter">.</span>end<span class="Delimiter">();</span>
<span id="L257" class="LineNr">257 </span><span class="Delimiter">}</span>
<span id="L258" class="LineNr">258 </span><span class="Normal">template</span><<span class="Normal">typename</span> <span class="Special">T</span>> <span class="Normal">typename</span> <span class="Special">T</span>::mapped_type& <a href='001help.cc.html#L258'>get_or_insert</a><span class="Delimiter">(</span><span class="Special">T</span>& map<span class="Delimiter">,</span> <span class="Normal">typename</span> <span class="Special">T</span>::key_type <span class="Normal">const</span>& key<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L259" class="LineNr">259 </span> <span class="Identifier">return</span> map[key]<span class="Delimiter">;</span>
<span id="L260" class="LineNr">260 </span><span class="Delimiter">}</span>
<span id="L261" class="LineNr">261 </span><span class="Normal">template</span><<span class="Normal">typename</span> <span class="Special">T</span>> <span class="Normal">typename</span> <span class="Special">T</span>::mapped_type <span class="Normal">const</span>& <a href='001help.cc.html#L261'>put_new</a><span class="Delimiter">(</span><span class="Special">T</span>& map<span class="Delimiter">,</span> <span class="Normal">typename</span> <span class="Special">T</span>::key_type <span class="Normal">const</span>& key<span class="Delimiter">,</span> <span class="Normal">typename</span> <span class="Special">T</span>::mapped_type <span class="Normal">const</span>& value<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L262" class="LineNr">262 </span> assert<span class="Delimiter">(</span>map<span class="Delimiter">.</span>find<span class="Delimiter">(</span>key<span class="Delimiter">)</span> == map<span class="Delimiter">.</span>end<span class="Delimiter">());</span>
<span id="L263" class="LineNr">263 </span> map[key] = value<span class="Delimiter">;</span>
<span id="L264" class="LineNr">264 </span> <span class="Identifier">return</span> map[key]<span class="Delimiter">;</span>
<span id="L265" class="LineNr">265 </span><span class="Delimiter">}</span>
<span id="L266" class="LineNr">266 </span><span class="Comment">//: The contract: any container that relies on get_or_insert should never call</span>
<span id="L267" class="LineNr">267 </span><span class="Comment">//: contains_key.</span>
<span id="L268" class="LineNr">268 </span>
<span id="L269" class="LineNr">269 </span><span class="Comment">//: 7. istreams are a royal pain in the arse. You have to be careful about</span>
<span id="L270" class="LineNr">270 </span><span class="Comment">//: what subclass you try to putback into. You have to watch out for the pesky</span>
<span id="L271" class="LineNr">271 </span><span class="Comment">//: failbit and badbit. Just avoid eof() and use this helper instead.</span>
<span id="L272" class="LineNr">272 </span><span class="Delimiter">:(code)</span>
<span id="L273" class="LineNr">273 </span><span class="Normal">bool</span> <a href='001help.cc.html#L273'>has_data</a><span class="Delimiter">(</span>istream& in<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L274" class="LineNr">274 </span> <span class="Identifier">return</span> in && !in<span class="Delimiter">.</span>eof<span class="Delimiter">();</span>
<span id="L275" class="LineNr">275 </span><span class="Delimiter">}</span>
<span id="L276" class="LineNr">276 </span>
<span id="L277" class="LineNr">277 </span><span class="Delimiter">:(before "End Includes")</span>
<span id="L278" class="LineNr">278 </span><span class="PreProc">#include </span><span class="Constant"><assert.h></span>
<span id="L279" class="LineNr">279 </span>
<span id="L280" class="LineNr">280 </span><span class="PreProc">#include </span><span class="Constant"><iostream></span>
<span id="L281" class="LineNr">281 </span><span class="Normal">using</span> std::istream<span class="Delimiter">;</span>
<span id="L282" class="LineNr">282 </span><span class="Normal">using</span> std::ostream<span class="Delimiter">;</span>
<span id="L283" class="LineNr">283 </span><span class="Normal">using</span> std::iostream<span class="Delimiter">;</span>
<span id="L284" class="LineNr">284 </span><span class="Normal">using</span> std::cin<span class="Delimiter">;</span>
<span id="L285" class="LineNr">285 </span><span class="Normal">using</span> std::cout<span class="Delimiter">;</span>
<span id="L286" class="LineNr">286 </span><span class="Normal">using</span> std::cerr<span class="Delimiter">;</span>
<span id="L287" class="LineNr">287 </span><span class="PreProc">#include </span><span class="Constant"><iomanip></span>
<span id="L288" class="LineNr">288 </span>
<span id="L289" class="LineNr">289 </span><span class="PreProc">#include </span><span class="Constant"><string.h></span>
<span id="L290" class="LineNr">290 </span><span class="PreProc">#include </span><span class="Constant"><string></span>
<span id="L291" class="LineNr">291 </span><span class="Normal">using</span> std::string<span class="Delimiter">;</span>
<span id="L292" class="LineNr">292 </span>
<span id="L293" class="LineNr">293 </span><span class="PreProc">#include </span><span class="Constant"><algorithm></span>
<span id="L294" class="LineNr">294 </span><span class="Normal">using</span> std::min<span class="Delimiter">;</span>
<span id="L295" class="LineNr">295 </span><span class="Normal">using</span> std::max<span class="Delimiter">;</span>
</pre>
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