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<span id="L1" class="LineNr"> 1 </span><span class="Comment">//: Continuations are a powerful primitive for constructing advanced kinds of</span>
<span id="L2" class="LineNr"> 2 </span><span class="Comment">//: control *policies* like back-tracking.</span>
<span id="L3" class="LineNr"> 3 </span><span class="Comment">//:</span>
<span id="L4" class="LineNr"> 4 </span><span class="Comment">//: In Mu, continuations are first-class and delimited, and are constructed</span>
<span id="L5" class="LineNr"> 5 </span><span class="Comment">//: out of two primitives:</span>
<span id="L6" class="LineNr"> 6 </span><span class="Comment">//:</span>
<span id="L7" class="LineNr"> 7 </span><span class="Comment">//: * 'call-with-continuation-mark' marks the top of the call stack and then</span>
<span id="L8" class="LineNr"> 8 </span><span class="Comment">//: calls the provided function.</span>
<span id="L9" class="LineNr"> 9 </span><span class="Comment">//: * 'return-continuation-until-mark' copies the top of the stack</span>
<span id="L10" class="LineNr"> 10 </span><span class="Comment">//: until the mark, and returns it as the result of</span>
<span id="L11" class="LineNr"> 11 </span><span class="Comment">//: call-with-continuation-mark (which might be a distant ancestor on the call</span>
<span id="L12" class="LineNr"> 12 </span><span class="Comment">//: stack; intervening calls don't return)</span>
<span id="L13" class="LineNr"> 13 </span><span class="Comment">//:</span>
<span id="L14" class="LineNr"> 14 </span><span class="Comment">//: The resulting slice of the stack can now be called just like a regular</span>
<span id="L15" class="LineNr"> 15 </span><span class="Comment">//: function.</span>
<span id="L16" class="LineNr"> 16 </span>
<span id="L17" class="LineNr"> 17 </span><span class="Delimiter">:(before "End Mu Types Initialization")</span>
<span id="L18" class="LineNr"> 18 </span><a href='010vm.cc.html#L123'>type_ordinal</a> continuation = Type_ordinal[<span class="Constant">"continuation"</span>] = Next_type_ordinal++<span class="Delimiter">;</span>
<span id="L19" class="LineNr"> 19 </span>Type[continuation]<span class="Delimiter">.</span>name = <span class="Constant">"continuation"</span><span class="Delimiter">;</span>
<span id="L20" class="LineNr"> 20 </span>
<span id="L21" class="LineNr"> 21 </span><span class="Comment">//: A continuation can be called like a recipe.</span>
<span id="L22" class="LineNr"> 22 </span><span class="Delimiter">:(before "End <a href='072recipe.cc.html#L277'>is_mu_recipe</a> Atom Cases(r)")</span>
<span id="L23" class="LineNr"> 23 </span><span class="Normal">if</span> <span class="Delimiter">(</span>r<span class="Delimiter">.</span>type<span class="Delimiter">-></span>name == <span class="Constant">"continuation"</span><span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
<span id="L24" class="LineNr"> 24 </span>
<span id="L25" class="LineNr"> 25 </span><span class="Comment">//: However, it can't be type-checked like most recipes. Pretend it's like a</span>
<span id="L26" class="LineNr"> 26 </span><span class="Comment">//: header-less recipe.</span>
<span id="L27" class="LineNr"> 27 </span><span class="Delimiter">:(after "Begin Reagent->Recipe(r, recipe_header)")</span>
<span id="L28" class="LineNr"> 28 </span><span class="Normal">if</span> <span class="Delimiter">(</span>r<span class="Delimiter">.</span>type<span class="Delimiter">-></span>atom && r<span class="Delimiter">.</span>type<span class="Delimiter">-></span>name == <span class="Constant">"continuation"</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L29" class="LineNr"> 29 </span> result_header<span class="Delimiter">.</span>has_header = <span class="Constant">false</span><span class="Delimiter">;</span>
<span id="L30" class="LineNr"> 30 </span> <span class="Identifier">return</span> result_header<span class="Delimiter">;</span>
<span id="L31" class="LineNr"> 31 </span><span class="Delimiter">}</span>
<span id="L32" class="LineNr"> 32 </span>
<span id="L33" class="LineNr"> 33 </span><span class="Delimiter">:(scenario delimited_continuation)</span>
<span id="L34" class="LineNr"> 34 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> <a href='000organization.cc.html#L113'>main</a> [
<span id="L35" class="LineNr"> 35 </span> <span class="Constant">1</span>:continuation<span class="Special"> <- </span>call-with-continuation-mark f<span class="Delimiter">,</span> <span class="Constant">77</span> <span class="Comment"># 77 is an argument to f</span>
<span id="L36" class="LineNr"> 36 </span> <span class="Constant">2</span>:number<span class="Special"> <- </span>copy <span class="Constant">5</span>
<span id="L37" class="LineNr"> 37 </span> <span class="Delimiter">{</span>
<span id="L38" class="LineNr"> 38 </span> <span class="Conceal">¦</span> <span class="Constant">2</span>:number<span class="Special"> <- </span>call <span class="Constant">1</span>:continuation<span class="Delimiter">,</span> <span class="Constant">2</span>:number <span class="Comment"># 2 is an argument to g, the 'top' of the continuation</span>
<span id="L39" class="LineNr"> 39 </span> <span class="Conceal">¦</span> <span class="Constant">3</span>:boolean<span class="Special"> <- </span>greater-<span class="Normal">or</span>-equal <span class="Constant">2</span>:number<span class="Delimiter">,</span> <span class="Constant">8</span>
<span id="L40" class="LineNr"> 40 </span> <span class="Conceal">¦</span> <span class="Identifier">break</span>-<span class="Normal">if</span> <span class="Constant">3</span>:boolean
<span id="L41" class="LineNr"> 41 </span> <span class="Conceal">¦</span> loop
<span id="L42" class="LineNr"> 42 </span> <span class="Delimiter">}</span>
<span id="L43" class="LineNr"> 43 </span>]
<span id="L44" class="LineNr"> 44 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> f [
<span id="L45" class="LineNr"> 45 </span> <span class="Constant">11</span>:number<span class="Special"> <- </span>next-ingredient
<span id="L46" class="LineNr"> 46 </span> <span class="Constant">12</span>:number<span class="Special"> <- </span>g <span class="Constant">11</span>:number
<span id="L47" class="LineNr"> 47 </span> <span class="Identifier">return</span> <span class="Constant">12</span>:number
<span id="L48" class="LineNr"> 48 </span>]
<span id="L49" class="LineNr"> 49 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> g [
<span id="L50" class="LineNr"> 50 </span> <span class="Constant">21</span>:number<span class="Special"> <- </span>next-ingredient
<span id="L51" class="LineNr"> 51 </span> rewind-ingredients
<span id="L52" class="LineNr"> 52 </span> <span class="Identifier">return</span>-continuation-until-mark
<span id="L53" class="LineNr"> 53 </span> <span class="Comment"># calls of the continuation start from here</span>
<span id="L54" class="LineNr"> 54 </span> <span class="Constant">22</span>:number<span class="Special"> <- </span>next-ingredient
<span id="L55" class="LineNr"> 55 </span> <span class="Constant">23</span>:number<span class="Special"> <- </span>add <span class="Constant">22</span>:number<span class="Delimiter">,</span> <span class="Constant">1</span>
<span id="L56" class="LineNr"> 56 </span> <span class="Identifier">return</span> <span class="Constant">23</span>:number
<span id="L57" class="LineNr"> 57 </span>]
<span id="L58" class="LineNr"> 58 </span><span class="Comment"># first call of 'g' executes the part before return-continuation-until-mark</span>
<span id="L59" class="LineNr"> 59 </span><span class="traceContains">+mem: storing 77 in location 21</span>
<span id="L60" class="LineNr"> 60 </span><span class="traceContains">+run: {2: "number"} <- copy {5: "literal"}</span>
<span id="L61" class="LineNr"> 61 </span><span class="traceContains">+mem: storing 5 in location 2</span>
<span id="L62" class="LineNr"> 62 </span><span class="Comment"># calls of the continuation execute the part after return-continuation-until-mark</span>
<span id="L63" class="LineNr"> 63 </span><span class="traceContains">+run: {2: "number"} <- call {1: "continuation"}, {2: "number"}</span>
<span id="L64" class="LineNr"> 64 </span><span class="traceContains">+mem: storing 5 in location 22</span>
<span id="L65" class="LineNr"> 65 </span><span class="traceContains">+mem: storing 6 in location 2</span>
<span id="L66" class="LineNr"> 66 </span><span class="traceContains">+run: {2: "number"} <- call {1: "continuation"}, {2: "number"}</span>
<span id="L67" class="LineNr"> 67 </span><span class="traceContains">+mem: storing 6 in location 22</span>
<span id="L68" class="LineNr"> 68 </span><span class="traceContains">+mem: storing 7 in location 2</span>
<span id="L69" class="LineNr"> 69 </span><span class="traceContains">+run: {2: "number"} <- call {1: "continuation"}, {2: "number"}</span>
<span id="L70" class="LineNr"> 70 </span><span class="traceContains">+mem: storing 7 in location 22</span>
<span id="L71" class="LineNr"> 71 </span><span class="traceContains">+mem: storing 8 in location 2</span>
<span id="L72" class="LineNr"> 72 </span><span class="Comment"># first call of 'g' does not execute the part after return-continuation-until-mark</span>
<span id="L73" class="LineNr"> 73 </span><span class="traceAbsent">-mem: storing 77 in location 22</span>
<span id="L74" class="LineNr"> 74 </span><span class="Comment"># calls of the continuation don't execute the part before return-continuation-until-mark</span>
<span id="L75" class="LineNr"> 75 </span><span class="traceAbsent">-mem: storing 5 in location 21</span>
<span id="L76" class="LineNr"> 76 </span><span class="traceAbsent">-mem: storing 6 in location 21</span>
<span id="L77" class="LineNr"> 77 </span><span class="traceAbsent">-mem: storing 7 in location 21</span>
<span id="L78" class="LineNr"> 78 </span><span class="Comment"># termination</span>
<span id="L79" class="LineNr"> 79 </span><span class="traceAbsent">-mem: storing 9 in location 2</span>
<span id="L80" class="LineNr"> 80 </span>
<span id="L81" class="LineNr"> 81 </span><span class="Delimiter">:(before "End call Fields")</span>
<span id="L82" class="LineNr"> 82 </span><span class="Normal">bool</span> is_base_of_continuation<span class="Delimiter">;</span>
<span id="L83" class="LineNr"> 83 </span><span class="Delimiter">:(before "End call Constructor")</span>
<span id="L84" class="LineNr"> 84 </span>is_base_of_continuation = <span class="Constant">false</span><span class="Delimiter">;</span>
<span id="L85" class="LineNr"> 85 </span>
<span id="L86" class="LineNr"> 86 </span><span class="Delimiter">:(before "End Primitive Recipe Declarations")</span>
<span id="L87" class="LineNr"> 87 </span>CALL_WITH_CONTINUATION_MARK<span class="Delimiter">,</span>
<span id="L88" class="LineNr"> 88 </span><span class="Delimiter">:(before "End Primitive Recipe Numbers")</span>
<span id="L89" class="LineNr"> 89 </span>Recipe_ordinal[<span class="Constant">"call-with-continuation-mark"</span>] = CALL_WITH_CONTINUATION_MARK<span class="Delimiter">;</span>
<span id="L90" class="LineNr"> 90 </span><span class="Delimiter">:(before "End Primitive Recipe Checks")</span>
<span id="L91" class="LineNr"> 91 </span><span class="Normal">case</span> CALL_WITH_CONTINUATION_MARK: <span class="Delimiter">{</span>
<span id="L92" class="LineNr"> 92 </span> <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L93" class="LineNr"> 93 </span><span class="Delimiter">}</span>
<span id="L94" class="LineNr"> 94 </span><span class="Delimiter">:(before "End Primitive Recipe Implementations")</span>
<span id="L95" class="LineNr"> 95 </span><span class="Normal">case</span> CALL_WITH_CONTINUATION_MARK: <span class="Delimiter">{</span>
<span id="L96" class="LineNr"> 96 </span> <span class="Comment">// like call, but mark the current call as a 'base of continuation' call</span>
<span id="L97" class="LineNr"> 97 </span> <span class="Comment">// before pushing the next one on it</span>
<span id="L98" class="LineNr"> 98 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>Trace_stream<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L99" class="LineNr"> 99 </span> <span class="Conceal">¦</span> ++Trace_stream<span class="Delimiter">-></span>callstack_depth<span class="Delimiter">;</span>
<span id="L100" class="LineNr">100 </span> <span class="Conceal">¦</span> <a href='003trace.cc.html#L161'>trace</a><span class="Delimiter">(</span><span class="Constant">"trace"</span><span class="Delimiter">)</span> << <span class="Constant">"delimited continuation; incrementing callstack depth to "</span> << Trace_stream<span class="Delimiter">-></span>callstack_depth << <a href='003trace.cc.html#L197'>end</a><span class="Delimiter">();</span>
<span id="L101" class="LineNr">101 </span> <span class="Conceal">¦</span> assert<span class="Delimiter">(</span>Trace_stream<span class="Delimiter">-></span>callstack_depth < <span class="Constant">9000</span><span class="Delimiter">);</span> <span class="Comment">// 9998-101 plus cushion</span>
<span id="L102" class="LineNr">102 </span> <span class="Delimiter">}</span>
<span id="L103" class="LineNr">103 </span> <span class="Normal">const</span> instruction& caller_instruction = <a href='026call.cc.html#L85'>current_instruction</a><span class="Delimiter">();</span>
<span id="L104" class="LineNr">104 </span> Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>front<span class="Delimiter">().</span>is_base_of_continuation = <span class="Constant">true</span><span class="Delimiter">;</span>
<span id="L105" class="LineNr">105 </span> Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>push_front<span class="Delimiter">(</span>call<span class="Delimiter">(</span>Recipe_ordinal[current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>name]<span class="Delimiter">));</span>
<span id="L106" class="LineNr">106 </span> ingredients<span class="Delimiter">.</span>erase<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>begin<span class="Delimiter">());</span> <span class="Comment">// drop the callee</span>
<span id="L107" class="LineNr">107 </span> finish_call_housekeeping<span class="Delimiter">(</span>caller_instruction<span class="Delimiter">,</span> ingredients<span class="Delimiter">);</span>
<span id="L108" class="LineNr">108 </span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
<span id="L109" class="LineNr">109 </span><span class="Delimiter">}</span>
<span id="L110" class="LineNr">110 </span>
<span id="L111" class="LineNr">111 </span><span class="Comment">//: save the slice of current call stack until the 'call-with-continuation-mark'</span>
<span id="L112" class="LineNr">112 </span><span class="Comment">//: call, and return it as the result.</span>
<span id="L113" class="LineNr">113 </span><span class="Comment">//: todo: implement delimited continuations in Mu's memory</span>
<span id="L114" class="LineNr">114 </span><span class="Delimiter">:(before "End Globals")</span>
<span id="L115" class="LineNr">115 </span>map<<span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span><span class="Delimiter">,</span> call_stack> Delimited_continuation<span class="Delimiter">;</span>
<span id="L116" class="LineNr">116 </span><span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> Next_delimited_continuation_id = <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L117" class="LineNr">117 </span><span class="Delimiter">:(before "End Reset")</span>
<span id="L118" class="LineNr">118 </span>Delimited_continuation<span class="Delimiter">.</span><a href='050scenario.cc.html#L60'>clear</a><span class="Delimiter">();</span>
<span id="L119" class="LineNr">119 </span>Next_delimited_continuation_id = <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L120" class="LineNr">120 </span>
<span id="L121" class="LineNr">121 </span><span class="Delimiter">:(before "End Primitive Recipe Declarations")</span>
<span id="L122" class="LineNr">122 </span>RETURN_CONTINUATION_UNTIL_MARK<span class="Delimiter">,</span>
<span id="L123" class="LineNr">123 </span><span class="Delimiter">:(before "End Primitive Recipe Numbers")</span>
<span id="L124" class="LineNr">124 </span>Recipe_ordinal[<span class="Constant">"return-continuation-until-mark"</span>] = RETURN_CONTINUATION_UNTIL_MARK<span class="Delimiter">;</span>
<span id="L125" class="LineNr">125 </span><span class="Delimiter">:(before "End Primitive Recipe Checks")</span>
<span id="L126" class="LineNr">126 </span><span class="Normal">case</span> RETURN_CONTINUATION_UNTIL_MARK: <span class="Delimiter">{</span>
<span id="L127" class="LineNr">127 </span> <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L128" class="LineNr">128 </span><span class="Delimiter">}</span>
<span id="L129" class="LineNr">129 </span><span class="Delimiter">:(before "End Primitive Recipe Implementations")</span>
<span id="L130" class="LineNr">130 </span><span class="Normal">case</span> RETURN_CONTINUATION_UNTIL_MARK: <span class="Delimiter">{</span>
<span id="L131" class="LineNr">131 </span> <span class="Comment">// first clear any existing ingredients, to isolate the creation of the</span>
<span id="L132" class="LineNr">132 </span> <span class="Comment">// continuation from its calls</span>
<span id="L133" class="LineNr">133 </span> Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>front<span class="Delimiter">().</span>ingredient_atoms<span class="Delimiter">.</span><a href='050scenario.cc.html#L60'>clear</a><span class="Delimiter">();</span>
<span id="L134" class="LineNr">134 </span> Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>front<span class="Delimiter">().</span>next_ingredient_to_process = <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L135" class="LineNr">135 </span> <span class="Comment">// copy the current call stack until the most recent marked call</span>
<span id="L136" class="LineNr">136 </span> call_stack::iterator find_base_of_continuation<span class="Delimiter">(</span>call_stack& c<span class="Delimiter">);</span> <span class="Comment">// manual prototype containing '::'</span>
<span id="L137" class="LineNr">137 </span> call_stack::iterator base = find_base_of_continuation<span class="Delimiter">(</span>Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">);</span>
<span id="L138" class="LineNr">138 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>base == Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span><a href='003trace.cc.html#L197'>end</a><span class="Delimiter">())</span> <span class="Delimiter">{</span>
<span id="L139" class="LineNr">139 </span> <span class="Conceal">¦</span> <a href='003trace.cc.html#L168'>raise</a> << <a href='013update_operation.cc.html#L25'>maybe</a><span class="Delimiter">(</span><a href='026call.cc.html#L83'>current_recipe_name</a><span class="Delimiter">())</span> << <span class="Constant">"couldn't find a 'call-with-continuation-mark' to return to</span><span class="cSpecial">\n</span><span class="Constant">"</span> << end<span class="Delimiter">();</span>
<span id="L140" class="LineNr">140 </span> <span class="Conceal">¦</span> <a href='003trace.cc.html#L168'>raise</a> << <a href='013update_operation.cc.html#L25'>maybe</a><span class="Delimiter">(</span><a href='026call.cc.html#L83'>current_recipe_name</a><span class="Delimiter">())</span> << <span class="Constant">"call stack:</span><span class="cSpecial">\n</span><span class="Constant">"</span> << <a href='003trace.cc.html#L197'>end</a><span class="Delimiter">();</span>
<span id="L141" class="LineNr">141 </span> <span class="Conceal">¦</span> <span class="Normal">for</span> <span class="Delimiter">(</span>call_stack::iterator p = Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span><a href='003trace.cc.html#L197'>end</a><span class="Delimiter">();</span> ++p<span class="Delimiter">)</span>
<span id="L142" class="LineNr">142 </span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='003trace.cc.html#L168'>raise</a> << <a href='013update_operation.cc.html#L25'>maybe</a><span class="Delimiter">(</span><a href='026call.cc.html#L83'>current_recipe_name</a><span class="Delimiter">())</span> << <span class="Constant">" "</span> << get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> p<span class="Delimiter">-></span>running_recipe<span class="Delimiter">).</span>name << <span class="cSpecial">'\n'</span> << <a href='003trace.cc.html#L197'>end</a><span class="Delimiter">();</span>
<span id="L143" class="LineNr">143 </span> <span class="Conceal">¦</span> <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L144" class="LineNr">144 </span> <span class="Delimiter">}</span>
<span id="L145" class="LineNr">145 </span> Delimited_continuation[Next_delimited_continuation_id] = call_stack<span class="Delimiter">(</span>Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>begin<span class="Delimiter">(),</span> base<span class="Delimiter">);</span>
<span id="L146" class="LineNr">146 </span> <span class="Normal">while</span> <span class="Delimiter">(</span>Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>begin<span class="Delimiter">()</span> != base<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L147" class="LineNr">147 </span> <span class="Conceal">¦</span> <span class="Normal">if</span> <span class="Delimiter">(</span>Trace_stream<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L148" class="LineNr">148 </span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> --Trace_stream<span class="Delimiter">-></span>callstack_depth<span class="Delimiter">;</span>
<span id="L149" class="LineNr">149 </span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> assert<span class="Delimiter">(</span>Trace_stream<span class="Delimiter">-></span>callstack_depth >= <span class="Constant">0</span><span class="Delimiter">);</span>
<span id="L150" class="LineNr">150 </span> <span class="Conceal">¦</span> <span class="Delimiter">}</span>
<span id="L151" class="LineNr">151 </span> <span class="Conceal">¦</span> Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>pop_front<span class="Delimiter">();</span>
<span id="L152" class="LineNr">152 </span> <span class="Delimiter">}</span>
<span id="L153" class="LineNr">153 </span> <span class="Comment">// return it as the result of the marked call</span>
<span id="L154" class="LineNr">154 </span> products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
<span id="L155" class="LineNr">155 </span> products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>Next_delimited_continuation_id<span class="Delimiter">);</span>
<span id="L156" class="LineNr">156 </span> ++Next_delimited_continuation_id<span class="Delimiter">;</span>
<span id="L157" class="LineNr">157 </span> <span class="Identifier">break</span><span class="Delimiter">;</span> <span class="Comment">// continue to process rest of marked call</span>
<span id="L158" class="LineNr">158 </span><span class="Delimiter">}</span>
<span id="L159" class="LineNr">159 </span>
<span id="L160" class="LineNr">160 </span><span class="Delimiter">:(code)</span>
<span id="L161" class="LineNr">161 </span>call_stack::iterator find_base_of_continuation<span class="Delimiter">(</span>call_stack& c<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L162" class="LineNr">162 </span> <span class="Normal">for</span> <span class="Delimiter">(</span>call_stack::iterator p = c<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != c<span class="Delimiter">.</span><a href='003trace.cc.html#L197'>end</a><span class="Delimiter">();</span> ++p<span class="Delimiter">)</span>
<span id="L163" class="LineNr">163 </span> <span class="Conceal">¦</span> <span class="Normal">if</span> <span class="Delimiter">(</span>p<span class="Delimiter">-></span>is_base_of_continuation<span class="Delimiter">)</span> <span class="Identifier">return</span> p<span class="Delimiter">;</span>
<span id="L164" class="LineNr">164 </span> <span class="Identifier">return</span> c<span class="Delimiter">.</span><a href='003trace.cc.html#L197'>end</a><span class="Delimiter">();</span>
<span id="L165" class="LineNr">165 </span><span class="Delimiter">}</span>
<span id="L166" class="LineNr">166 </span>
<span id="L167" class="LineNr">167 </span><span class="Comment">//: overload 'call' for continuations</span>
<span id="L168" class="LineNr">168 </span><span class="Delimiter">:(after "Begin Call")</span>
<span id="L169" class="LineNr">169 </span><span class="Normal">if</span> <span class="Delimiter">(</span><a href='026call.cc.html#L85'>current_instruction</a><span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>type<span class="Delimiter">-></span>atom
<span id="L170" class="LineNr">170 </span> <span class="Conceal">¦</span> && <a href='026call.cc.html#L85'>current_instruction</a><span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>type<span class="Delimiter">-></span>name == <span class="Constant">"continuation"</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L171" class="LineNr">171 </span> <span class="Comment">// copy multiple calls on to current call stack</span>
<span id="L172" class="LineNr">172 </span> assert<span class="Delimiter">(</span>scalar<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)));</span>
<span id="L173" class="LineNr">173 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>Delimited_continuation<span class="Delimiter">.</span>find<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">))</span> == Delimited_continuation<span class="Delimiter">.</span><a href='003trace.cc.html#L197'>end</a><span class="Delimiter">())</span>
<span id="L174" class="LineNr">174 </span> <span class="Conceal">¦</span> <a href='003trace.cc.html#L168'>raise</a> << <a href='013update_operation.cc.html#L25'>maybe</a><span class="Delimiter">(</span><a href='026call.cc.html#L83'>current_recipe_name</a><span class="Delimiter">())</span> << <span class="Constant">"no such delimited continuation "</span> << <a href='026call.cc.html#L85'>current_instruction</a><span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>original_string << <span class="cSpecial">'\n'</span> << <a href='003trace.cc.html#L197'>end</a><span class="Delimiter">();</span>
<span id="L175" class="LineNr">175 </span> <span class="Normal">const</span> call_stack& new_calls = Delimited_continuation[ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)</span>]<span class="Delimiter">;</span>
<span id="L176" class="LineNr">176 </span> <span class="Normal">const</span> call& caller = <span class="Delimiter">(</span><a href='001help.cc.html#L141'>SIZE</a><span class="Delimiter">(</span>new_calls<span class="Delimiter">)</span> > <span class="Constant">1</span><span class="Delimiter">)</span> ? *++new_calls<span class="Delimiter">.</span>begin<span class="Delimiter">()</span> : Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>front<span class="Delimiter">();</span>
<span id="L177" class="LineNr">177 </span> <span class="Normal">for</span> <span class="Delimiter">(</span>call_stack::const_reverse_iterator p = new_calls<span class="Delimiter">.</span>rbegin<span class="Delimiter">();</span> p != new_calls<span class="Delimiter">.</span>rend<span class="Delimiter">();</span> ++p<span class="Delimiter">)</span>
<span id="L178" class="LineNr">178 </span> <span class="Conceal">¦</span> Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>push_front<span class="Delimiter">(</span>*p<span class="Delimiter">);</span>
<span id="L179" class="LineNr">179 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>Trace_stream<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L180" class="LineNr">180 </span> <span class="Conceal">¦</span> Trace_stream<span class="Delimiter">-></span>callstack_depth += <a href='001help.cc.html#L141'>SIZE</a><span class="Delimiter">(</span>new_calls<span class="Delimiter">);</span>
<span id="L181" class="LineNr">181 </span> <span class="Conceal">¦</span> <a href='003trace.cc.html#L161'>trace</a><span class="Delimiter">(</span><span class="Constant">"trace"</span><span class="Delimiter">)</span> << <span class="Constant">"calling delimited continuation; growing callstack depth to "</span> << Trace_stream<span class="Delimiter">-></span>callstack_depth << <a href='003trace.cc.html#L197'>end</a><span class="Delimiter">();</span>
<span id="L182" class="LineNr">182 </span> <span class="Conceal">¦</span> assert<span class="Delimiter">(</span>Trace_stream<span class="Delimiter">-></span>callstack_depth < <span class="Constant">9000</span><span class="Delimiter">);</span> <span class="Comment">// 9998-101 plus cushion</span>
<span id="L183" class="LineNr">183 </span> <span class="Delimiter">}</span>
<span id="L184" class="LineNr">184 </span> ++current_step_index<span class="Delimiter">();</span> <span class="Comment">// skip past the return-continuation-until-mark</span>
<span id="L185" class="LineNr">185 </span> ingredients<span class="Delimiter">.</span>erase<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>begin<span class="Delimiter">());</span> <span class="Comment">// drop the callee</span>
<span id="L186" class="LineNr">186 </span> finish_call_housekeeping<span class="Delimiter">(</span><a href='026call.cc.html#L84'>to_instruction</a><span class="Delimiter">(</span>caller<span class="Delimiter">),</span> ingredients<span class="Delimiter">);</span>
<span id="L187" class="LineNr">187 </span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
<span id="L188" class="LineNr">188 </span><span class="Delimiter">}</span>
</pre>
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