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authorKartik K. Agaram <vc@akkartik.com>2016-08-20 20:01:25 -0700
committerKartik K. Agaram <vc@akkartik.com>2016-08-20 20:01:34 -0700
commit8e7b4429787bc2b7fe289f264d09a4b1f5f6b081 (patch)
treeda78a0432f4cc01f9083bda4b04a9cb0e5c46142 /html/101run_sandboxed.cc.html
parentc31209c6a14cebad97976b4089fe6a69f074f748 (diff)
downloadmu-8e7b4429787bc2b7fe289f264d09a4b1f5f6b081.tar.gz
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+<title>Mu - 101run_sandboxed.cc</title>
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+.cSpecial { color: #008000; }
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+<pre id='vimCodeElement'>
+<span class="Comment">//: Helper for various programming environments: run arbitrary mu code and</span>
+<span class="Comment">//: return some result in string form.</span>
+
+<span class="Delimiter">:(scenario run_interactive_code)</span>
+def main [
+  <span class="Constant">1</span>:number/<span class="Special">raw &lt;- </span>copy <span class="Constant">0</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [<span class="Constant">1</span>:number/<span class="Special">raw &lt;- </span>copy <span class="Constant">34</span>]
+  run-sandboxed <span class="Constant">2</span>:address:array:character
+  <span class="Constant">3</span>:number/<span class="Special">raw &lt;- </span>copy <span class="Constant">1</span>:number/<span class="Special">raw</span>
+]
+<span class="traceContains">+mem: storing 34 in location 3</span>
+
+<span class="Delimiter">:(scenario run_interactive_empty)</span>
+def main [
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>/unsafe
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>run-sandboxed <span class="Constant">1</span>:address:array:character
+]
+<span class="Comment"># result is null</span>
+<span class="traceContains">+mem: storing 0 in location 2</span>
+
+<span class="Comment">//: As the name suggests, 'run-sandboxed' will prevent certain operations that</span>
+<span class="Comment">//: regular Mu code can perform.</span>
+<span class="Delimiter">:(before &quot;End Globals&quot;)</span>
+<span class="Normal">bool</span> Sandbox_mode = <span class="Constant">false</span><span class="Delimiter">;</span>
+<span class="Comment">//: for starters, users can't override 'main' when the environment is running</span>
+<span class="Delimiter">:(before &quot;End Load Recipe Name&quot;)</span>
+<span class="Normal">if</span> <span class="Delimiter">(</span>Sandbox_mode &amp;&amp; result<span class="Delimiter">.</span>name == <span class="Constant">&quot;main&quot;</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  slurp_balanced_bracket<span class="Delimiter">(</span>in<span class="Delimiter">);</span>
+  <span class="Identifier">return</span> -<span class="Constant">1</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Comment">//: run code in 'interactive mode', i.e. with errors off and return:</span>
+<span class="Comment">//:   stringified output in case we want to print it to screen</span>
+<span class="Comment">//:   any errors encountered</span>
+<span class="Comment">//:   simulated screen any prints went to</span>
+<span class="Comment">//:   any 'app' layer traces generated</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+RUN_SANDBOXED<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;run-sandboxed&quot;</span><span class="Delimiter">,</span> RUN_SANDBOXED<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+<span class="Normal">case</span> RUN_SANDBOXED: <span class="Delimiter">{</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    raise &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'run-sandboxed' requires exactly one ingredient, but got '&quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>original_string &lt;&lt; <span class="Constant">&quot;'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>!is_mu_string<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    raise &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'run-sandboxed' should be a string, but got '&quot;</span> &lt;&lt; to_string<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">))</span> &lt;&lt; <span class="Constant">&quot;'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+<span class="Normal">case</span> RUN_SANDBOXED: <span class="Delimiter">{</span>
+  <span class="Normal">bool</span> new_code_pushed_to_stack = run_interactive<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>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>!new_code_pushed_to_stack<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">5</span><span class="Delimiter">);</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><span class="Constant">0</span><span class="Delimiter">);</span>
+    products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>trace_error_contents<span class="Delimiter">());</span>
+    products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">2</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+    products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">3</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>trace_app_contents<span class="Delimiter">());</span>
+    products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">4</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>  <span class="Comment">// completed</span>
+    run_code_end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>  <span class="Comment">// done with this instruction</span>
+  <span class="Delimiter">}</span>
+  <span class="Normal">else</span> <span class="Delimiter">{</span>
+    <span class="Identifier">continue</span><span class="Delimiter">;</span>  <span class="Comment">// not done with caller; don't increment current_step_index()</span>
+  <span class="Delimiter">}</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Globals&quot;)</span>
+<span class="Normal">bool</span> Track_most_recent_products = <span class="Constant">false</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Tracing&quot;)</span>
+trace_stream* Save_trace_stream = <span class="Constant">NULL</span><span class="Delimiter">;</span>
+string Save_trace_file<span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Setup&quot;)</span>
+Track_most_recent_products = <span class="Constant">false</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(code)</span>
+<span class="Comment">// reads a string, tries to call it as code (treating it as a test), saving</span>
+<span class="Comment">// all errors.</span>
+<span class="Comment">// returns true if successfully called (no errors found during load and transform)</span>
+<span class="Normal">bool</span> run_interactive<span class="Delimiter">(</span><span class="Normal">int</span> address<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  assert<span class="Delimiter">(</span>contains_key<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;interactive&quot;</span><span class="Delimiter">)</span> &amp;&amp; get<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;interactive&quot;</span><span class="Delimiter">)</span> != <span class="Constant">0</span><span class="Delimiter">);</span>
+  <span class="Comment">// try to sandbox the run as best you can</span>
+  <span class="Comment">// todo: test this</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>!Current_scenario<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">1</span><span class="Delimiter">;</span> i &lt; Reserved_for_tests<span class="Delimiter">;</span> ++i<span class="Delimiter">)</span>
+      Memory<span class="Delimiter">.</span>erase<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  string command = trim<span class="Delimiter">(</span>strip_comments<span class="Delimiter">(</span>read_mu_string<span class="Delimiter">(</span>address<span class="Delimiter">)));</span>
+  Name[get<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;interactive&quot;</span><span class="Delimiter">)</span>]<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+  run_code_begin<span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">should_stash_snapshots</span><span class="Comment">*/</span><span class="Constant">true</span><span class="Delimiter">);</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>command<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
+  <span class="Comment">// don't kill the current routine on parse errors</span>
+  routine* save_current_routine = Current_routine<span class="Delimiter">;</span>
+  Current_routine = <span class="Constant">NULL</span><span class="Delimiter">;</span>
+  <span class="Comment">// call run(string) but without the scheduling</span>
+  load<span class="Delimiter">(</span>string<span class="Delimiter">(</span><span class="Constant">&quot;recipe! interactive [</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span><span class="Delimiter">)</span> +
+          <span class="Constant">&quot;new-default-space</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +  <span class="Comment">// disable automatic abandon so tests can see changes</span>
+          <span class="Constant">&quot;screen:address:screen &lt;- next-ingredient</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+          <span class="Constant">&quot;$start-tracking-products</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+          command + <span class="Constant">&quot;</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+          <span class="Constant">&quot;$stop-tracking-products</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+          <span class="Constant">&quot;return screen</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+       <span class="Constant">&quot;]</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span><span class="Delimiter">);</span>
+  transform_all<span class="Delimiter">();</span>
+  Current_routine = save_current_routine<span class="Delimiter">;</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>trace_count<span class="Delimiter">(</span><span class="Constant">&quot;error&quot;</span><span class="Delimiter">)</span> &gt; <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
+  <span class="Comment">// now call 'sandbox' which will run 'interactive' in a separate routine,</span>
+  <span class="Comment">// and wait for it</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>Save_trace_stream<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    ++Save_trace_stream<span class="Delimiter">-&gt;</span>callstack_depth<span class="Delimiter">;</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;trace&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;run-sandboxed: incrementing callstack depth to &quot;</span> &lt;&lt; Save_trace_stream<span class="Delimiter">-&gt;</span>callstack_depth &lt;&lt; end<span class="Delimiter">();</span>
+    assert<span class="Delimiter">(</span>Save_trace_stream<span class="Delimiter">-&gt;</span>callstack_depth &lt; <span class="Constant">9000</span><span class="Delimiter">);</span>  <span class="Comment">// 9998-101 plus cushion</span>
+  <span class="Delimiter">}</span>
+  Current_routine<span class="Delimiter">-&gt;</span>calls<span class="Delimiter">.</span>push_front<span class="Delimiter">(</span>call<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;sandbox&quot;</span><span class="Delimiter">)));</span>
+  <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Comment">//: Carefully update all state to exactly how it was -- including snapshots.</span>
+
+<span class="Delimiter">:(before &quot;End Globals&quot;)</span>
+map&lt;string<span class="Delimiter">,</span> recipe_ordinal&gt; Recipe_ordinal_snapshot_stash<span class="Delimiter">;</span>
+map&lt;recipe_ordinal<span class="Delimiter">,</span> recipe&gt; Recipe_snapshot_stash<span class="Delimiter">;</span>
+map&lt;string<span class="Delimiter">,</span> type_ordinal&gt; Type_ordinal_snapshot_stash<span class="Delimiter">;</span>
+map&lt;type_ordinal<span class="Delimiter">,</span> type_info&gt; Type_snapshot_stash<span class="Delimiter">;</span>
+map&lt;recipe_ordinal<span class="Delimiter">,</span> map&lt;string<span class="Delimiter">,</span> <span class="Normal">int</span>&gt; &gt; Name_snapshot_stash<span class="Delimiter">;</span>
+map&lt;string<span class="Delimiter">,</span> vector&lt;recipe_ordinal&gt; &gt; Recipe_variants_snapshot_stash<span class="Delimiter">;</span>
+
+<span class="Delimiter">:(code)</span>
+<span class="Normal">void</span> run_code_begin<span class="Delimiter">(</span><span class="Normal">bool</span> should_stash_snapshots<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  <span class="Comment">// stuff to undo later, in run_code_end()</span>
+  Hide_errors = <span class="Constant">true</span><span class="Delimiter">;</span>
+  Disable_redefine_checks = <span class="Constant">true</span><span class="Delimiter">;</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>should_stash_snapshots<span class="Delimiter">)</span>
+    stash_snapshots<span class="Delimiter">();</span>
+  Save_trace_stream = Trace_stream<span class="Delimiter">;</span>
+  Trace_stream = <span class="Normal">new</span> trace_stream<span class="Delimiter">;</span>
+  Trace_stream<span class="Delimiter">-&gt;</span>collect_depth = App_depth<span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Normal">void</span> run_code_end<span class="Delimiter">()</span> <span class="Delimiter">{</span>
+  Hide_errors = <span class="Constant">false</span><span class="Delimiter">;</span>
+  Disable_redefine_checks = <span class="Constant">false</span><span class="Delimiter">;</span>
+  <span class="Normal">delete</span> Trace_stream<span class="Delimiter">;</span>
+  Trace_stream = Save_trace_stream<span class="Delimiter">;</span>
+  Save_trace_stream = <span class="Constant">NULL</span><span class="Delimiter">;</span>
+  Save_trace_file<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+  Recipe<span class="Delimiter">.</span>erase<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;interactive&quot;</span><span class="Delimiter">));</span>  <span class="Comment">// keep past sandboxes from inserting errors</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>!Recipe_snapshot_stash<span class="Delimiter">.</span>empty<span class="Delimiter">())</span>
+    unstash_snapshots<span class="Delimiter">();</span>
+<span class="Delimiter">}</span>
+
+<span class="Comment">// keep sync'd with save_snapshots and restore_snapshots</span>
+<span class="Normal">void</span> stash_snapshots<span class="Delimiter">()</span> <span class="Delimiter">{</span>
+  assert<span class="Delimiter">(</span>Recipe_ordinal_snapshot_stash<span class="Delimiter">.</span>empty<span class="Delimiter">());</span>
+  Recipe_ordinal_snapshot_stash = Recipe_ordinal_snapshot<span class="Delimiter">;</span>
+  assert<span class="Delimiter">(</span>Recipe_snapshot_stash<span class="Delimiter">.</span>empty<span class="Delimiter">());</span>
+  Recipe_snapshot_stash = Recipe_snapshot<span class="Delimiter">;</span>
+  assert<span class="Delimiter">(</span>Type_ordinal_snapshot_stash<span class="Delimiter">.</span>empty<span class="Delimiter">());</span>
+  Type_ordinal_snapshot_stash = Type_ordinal_snapshot<span class="Delimiter">;</span>
+  assert<span class="Delimiter">(</span>Type_snapshot_stash<span class="Delimiter">.</span>empty<span class="Delimiter">());</span>
+  Type_snapshot_stash = Type_snapshot<span class="Delimiter">;</span>
+  assert<span class="Delimiter">(</span>Name_snapshot_stash<span class="Delimiter">.</span>empty<span class="Delimiter">());</span>
+  Name_snapshot_stash = Name_snapshot<span class="Delimiter">;</span>
+  assert<span class="Delimiter">(</span>Recipe_variants_snapshot_stash<span class="Delimiter">.</span>empty<span class="Delimiter">());</span>
+  Recipe_variants_snapshot_stash = Recipe_variants_snapshot<span class="Delimiter">;</span>
+  save_snapshots<span class="Delimiter">();</span>
+<span class="Delimiter">}</span>
+<span class="Normal">void</span> unstash_snapshots<span class="Delimiter">()</span> <span class="Delimiter">{</span>
+  restore_snapshots<span class="Delimiter">();</span>
+  Recipe_ordinal_snapshot = Recipe_ordinal_snapshot_stash<span class="Delimiter">;</span>  Recipe_ordinal_snapshot_stash<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+  Recipe_snapshot = Recipe_snapshot_stash<span class="Delimiter">;</span>  Recipe_snapshot_stash<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+  Type_ordinal_snapshot = Type_ordinal_snapshot_stash<span class="Delimiter">;</span>  Type_ordinal_snapshot_stash<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+  Type_snapshot = Type_snapshot_stash<span class="Delimiter">;</span>  Type_snapshot_stash<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+  Name_snapshot = Name_snapshot_stash<span class="Delimiter">;</span>  Name_snapshot_stash<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+  Recipe_variants_snapshot = Recipe_variants_snapshot_stash<span class="Delimiter">;</span>  Recipe_variants_snapshot_stash<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Load Recipes&quot;)</span>
+load<span class="Delimiter">(</span>string<span class="Delimiter">(</span>
+<span class="Constant">&quot;recipe interactive [</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span><span class="Delimiter">)</span> +  <span class="Comment">// just a dummy version to initialize the Recipe_ordinal and so on</span>
+<span class="Constant">&quot;]</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+<span class="Constant">&quot;recipe sandbox [</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;local-scope</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;screen:address:screen &lt;- new-fake-screen 30, 5</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;routine-id:number &lt;- start-running interactive, screen</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;limit-time routine-id, 100000/instructions</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;wait-for-routine routine-id</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;instructions-run:number &lt;- number-of-instructions routine-id</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;stash instructions-run [instructions run]</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;sandbox-state:number &lt;- routine-state routine-id</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;completed?:boolean &lt;- equal sandbox-state, 1/completed</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;output:address:array:character &lt;- $most-recent-products</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;errors:address:array:character &lt;- save-errors</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;stashes:address:array:character &lt;- save-app-trace</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;$cleanup-run-sandboxed</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+  <span class="Constant">&quot;return output, errors, screen, stashes, completed?</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> +
+<span class="Constant">&quot;]</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span><span class="Delimiter">);</span>
+
+<span class="Comment">//: adjust errors in the sandbox</span>
+<span class="Delimiter">:(after &quot;string maybe(string s)&quot;)</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>s == <span class="Constant">&quot;interactive&quot;</span><span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">&quot;&quot;</span><span class="Delimiter">;</span>
+
+<span class="Delimiter">:(scenario run_interactive_comments)</span>
+def main [
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [<span class="Comment"># ab</span>
+add <span class="Constant">2</span><span class="Delimiter">,</span> <span class="Constant">2</span>]
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>run-sandboxed <span class="Constant">1</span>:address:array:character
+  <span class="Constant">3</span>:array:character<span class="Special"> &lt;- </span>copy *<span class="Constant">2</span>:address:array:character
+]
+<span class="traceContains">+mem: storing 52 in location 4</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+_START_TRACKING_PRODUCTS<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;$start-tracking-products&quot;</span><span class="Delimiter">,</span> _START_TRACKING_PRODUCTS<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+<span class="Normal">case</span> _START_TRACKING_PRODUCTS: <span class="Delimiter">{</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+<span class="Normal">case</span> _START_TRACKING_PRODUCTS: <span class="Delimiter">{</span>
+  Track_most_recent_products = <span class="Constant">true</span><span class="Delimiter">;</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+_STOP_TRACKING_PRODUCTS<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;$stop-tracking-products&quot;</span><span class="Delimiter">,</span> _STOP_TRACKING_PRODUCTS<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+<span class="Normal">case</span> _STOP_TRACKING_PRODUCTS: <span class="Delimiter">{</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+<span class="Normal">case</span> _STOP_TRACKING_PRODUCTS: <span class="Delimiter">{</span>
+  Track_most_recent_products = <span class="Constant">false</span><span class="Delimiter">;</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+_MOST_RECENT_PRODUCTS<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;$most-recent-products&quot;</span><span class="Delimiter">,</span> _MOST_RECENT_PRODUCTS<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+<span class="Normal">case</span> _MOST_RECENT_PRODUCTS: <span class="Delimiter">{</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+<span class="Normal">case</span> _MOST_RECENT_PRODUCTS: <span class="Delimiter">{</span>
+  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</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>new_mu_string<span class="Delimiter">(</span>Most_recent_products<span class="Delimiter">));</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+SAVE_ERRORS<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;save-errors&quot;</span><span class="Delimiter">,</span> SAVE_ERRORS<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+<span class="Normal">case</span> SAVE_ERRORS: <span class="Delimiter">{</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+<span class="Normal">case</span> SAVE_ERRORS: <span class="Delimiter">{</span>
+  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</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>trace_error_contents<span class="Delimiter">());</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+SAVE_APP_TRACE<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;save-app-trace&quot;</span><span class="Delimiter">,</span> SAVE_APP_TRACE<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+<span class="Normal">case</span> SAVE_APP_TRACE: <span class="Delimiter">{</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+<span class="Normal">case</span> SAVE_APP_TRACE: <span class="Delimiter">{</span>
+  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</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>trace_app_contents<span class="Delimiter">());</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+_CLEANUP_RUN_SANDBOXED<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;$cleanup-run-sandboxed&quot;</span><span class="Delimiter">,</span> _CLEANUP_RUN_SANDBOXED<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+<span class="Normal">case</span> _CLEANUP_RUN_SANDBOXED: <span class="Delimiter">{</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+<span class="Normal">case</span> _CLEANUP_RUN_SANDBOXED: <span class="Delimiter">{</span>
+  run_code_end<span class="Delimiter">();</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(scenario &quot;run_interactive_converts_result_to_text&quot;)</span>
+def main [
+  <span class="Comment"># try to interactively add 2 and 2</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [add <span class="Constant">2</span><span class="Delimiter">,</span> <span class="Constant">2</span>]
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>run-sandboxed <span class="Constant">1</span>:address:array:character
+  <span class="Constant">10</span>:array:character<span class="Special"> &lt;- </span>copy <span class="Constant">2</span>:address:array:character/lookup
+]
+<span class="Comment"># first letter in the output should be '4' in unicode</span>
+<span class="traceContains">+mem: storing 52 in location 11</span>
+
+<span class="Delimiter">:(scenario &quot;run_interactive_returns_text&quot;)</span>
+def main [
+  <span class="Comment"># try to interactively add 2 and 2</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [
+    <span class="Normal">x</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [a]
+    <span class="Normal">y</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [b]
+    <span class="Normal">z</span>:address:array:character<span class="Special"> &lt;- </span>append x:address:array:character<span class="Delimiter">,</span> y:address:array:character
+  ]
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>run-sandboxed <span class="Constant">1</span>:address:array:character
+  <span class="Constant">10</span>:array:character<span class="Special"> &lt;- </span>copy <span class="Constant">2</span>:address:array:character/lookup
+]
+<span class="Comment"># output contains &quot;ab&quot;</span>
+<span class="traceContains">+mem: storing 97 in location 11</span>
+<span class="traceContains">+mem: storing 98 in location 12</span>
+
+<span class="Delimiter">:(scenario &quot;run_interactive_returns_errors&quot;)</span>
+def main [
+  <span class="Comment"># run a command that generates an error</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [x:number<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
+get x:number<span class="Delimiter">,</span> foo:offset]
+  <span class="Constant">2</span>:address:array:character<span class="Delimiter">,</span> <span class="Constant">3</span>:address:array:character<span class="Special"> &lt;- </span>run-sandboxed <span class="Constant">1</span>:address:array:character
+  <span class="Constant">10</span>:array:character<span class="Special"> &lt;- </span>copy <span class="Constant">3</span>:address:array:character/lookup
+]
+<span class="Comment"># error should be &quot;unknown element foo in container number&quot;</span>
+<span class="traceContains">+mem: storing 117 in location 11</span>
+<span class="traceContains">+mem: storing 110 in location 12</span>
+<span class="traceContains">+mem: storing 107 in location 13</span>
+<span class="traceContains">+mem: storing 110 in location 14</span>
+<span class="Comment"># ...</span>
+
+<span class="Delimiter">:(scenario run_interactive_with_comment)</span>
+def main [
+  <span class="Comment"># 2 instructions, with a comment after the first</span>
+  <span class="Constant">1</span>:address:array:number<span class="Special"> &lt;- </span><span class="Normal">new</span> [a:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>  <span class="Comment"># abc</span>
+<span class="Normal">b</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+  <span class="Constant">2</span>:address:array:character<span class="Delimiter">,</span> <span class="Constant">3</span>:address:array:character<span class="Special"> &lt;- </span>run-sandboxed <span class="Constant">1</span>:address:array:character
+]
+<span class="Comment"># no errors</span>
+<span class="traceContains">+mem: storing 0 in location 3</span>
+
+<span class="Delimiter">:(before &quot;End Globals&quot;)</span>
+string Most_recent_products<span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Setup&quot;)</span>
+Most_recent_products = <span class="Constant">&quot;&quot;</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Running One Instruction&quot;)</span>
+<span class="Normal">if</span> <span class="Delimiter">(</span>Track_most_recent_products<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  track_most_recent_products<span class="Delimiter">(</span>current_instruction<span class="Delimiter">(),</span> products<span class="Delimiter">);</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(code)</span>
+<span class="Normal">void</span> track_most_recent_products<span class="Delimiter">(</span><span class="Normal">const</span> instruction&amp; instruction<span class="Delimiter">,</span> <span class="Normal">const</span> vector&lt;vector&lt;<span class="Normal">double</span>&gt; &gt;&amp; products<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  ostringstream out<span class="Delimiter">;</span>
+  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>products<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Comment">// string</span>
+    <span class="Normal">if</span> <span class="Delimiter">(</span>i &lt; SIZE<span class="Delimiter">(</span>instruction<span class="Delimiter">.</span>products<span class="Delimiter">))</span> <span class="Delimiter">{</span>
+      <span class="Normal">if</span> <span class="Delimiter">(</span>is_mu_string<span class="Delimiter">(</span>instruction<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+        <span class="Normal">if</span> <span class="Delimiter">(</span>!scalar<span class="Delimiter">(</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)))</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>  <span class="Comment">// error handled elsewhere</span>
+        out &lt;&lt; read_mu_string<span class="Delimiter">(</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">))</span> &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
+        <span class="Identifier">continue</span><span class="Delimiter">;</span>
+      <span class="Delimiter">}</span>
+      <span class="Comment">// End Record Product Special-cases</span>
+    <span class="Delimiter">}</span>
+    <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> j = <span class="Constant">0</span><span class="Delimiter">;</span> j &lt; SIZE<span class="Delimiter">(</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">));</span> ++j<span class="Delimiter">)</span>
+      out &lt;&lt; no_scientific<span class="Delimiter">(</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>at<span class="Delimiter">(</span>j<span class="Delimiter">))</span> &lt;&lt; <span class="Constant">' '</span><span class="Delimiter">;</span>
+    out &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  Most_recent_products = out<span class="Delimiter">.</span>str<span class="Delimiter">();</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(code)</span>
+string strip_comments<span class="Delimiter">(</span>string in<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  ostringstream result<span class="Delimiter">;</span>
+  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>in<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Normal">if</span> <span class="Delimiter">(</span>in<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)</span> != <span class="Constant">'#'</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      result &lt;&lt; in<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
+    <span class="Delimiter">}</span>
+    <span class="Normal">else</span> <span class="Delimiter">{</span>
+      <span class="Normal">while</span> <span class="Delimiter">(</span>i+<span class="Constant">1</span> &lt; SIZE<span class="Delimiter">(</span>in<span class="Delimiter">)</span> &amp;&amp; in<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i+<span class="Constant">1</span><span class="Delimiter">)</span> != <span class="cSpecial">'\n'</span><span class="Delimiter">)</span>
+        ++i<span class="Delimiter">;</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">return</span> result<span class="Delimiter">.</span>str<span class="Delimiter">();</span>
+<span class="Delimiter">}</span>
+
+<span class="Normal">int</span> stringified_value_of_location<span class="Delimiter">(</span><span class="Normal">int</span> address<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  <span class="Comment">// convert to string</span>
+  ostringstream out<span class="Delimiter">;</span>
+  out &lt;&lt; no_scientific<span class="Delimiter">(</span>get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> address<span class="Delimiter">));</span>
+  <span class="Identifier">return</span> new_mu_string<span class="Delimiter">(</span>out<span class="Delimiter">.</span>str<span class="Delimiter">());</span>
+<span class="Delimiter">}</span>
+
+<span class="Normal">int</span> trace_error_contents<span class="Delimiter">()</span> <span class="Delimiter">{</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>!Trace_stream<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
+  ostringstream out<span class="Delimiter">;</span>
+  <span class="Normal">for</span> <span class="Delimiter">(</span>vector&lt;trace_line&gt;::iterator p = Trace_stream<span class="Delimiter">-&gt;</span>past_lines<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != Trace_stream<span class="Delimiter">-&gt;</span>past_lines<span class="Delimiter">.</span>end<span class="Delimiter">();</span> ++p<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Normal">if</span> <span class="Delimiter">(</span>p<span class="Delimiter">-&gt;</span>label != <span class="Constant">&quot;error&quot;</span><span class="Delimiter">)</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
+    out &lt;&lt; p<span class="Delimiter">-&gt;</span>contents<span class="Delimiter">;</span>
+    <span class="Normal">if</span> <span class="Delimiter">(</span>*--p<span class="Delimiter">-&gt;</span>contents<span class="Delimiter">.</span>end<span class="Delimiter">()</span> != <span class="cSpecial">'\n'</span><span class="Delimiter">)</span> out &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  string result = out<span class="Delimiter">.</span>str<span class="Delimiter">();</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>result<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
+  truncate<span class="Delimiter">(</span>result<span class="Delimiter">);</span>
+  <span class="Identifier">return</span> new_mu_string<span class="Delimiter">(</span>result<span class="Delimiter">);</span>
+<span class="Delimiter">}</span>
+
+<span class="Normal">int</span> trace_app_contents<span class="Delimiter">()</span> <span class="Delimiter">{</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>!Trace_stream<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
+  ostringstream out<span class="Delimiter">;</span>
+  <span class="Normal">for</span> <span class="Delimiter">(</span>vector&lt;trace_line&gt;::iterator p = Trace_stream<span class="Delimiter">-&gt;</span>past_lines<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != Trace_stream<span class="Delimiter">-&gt;</span>past_lines<span class="Delimiter">.</span>end<span class="Delimiter">();</span> ++p<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Normal">if</span> <span class="Delimiter">(</span>p<span class="Delimiter">-&gt;</span>depth != App_depth<span class="Delimiter">)</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
+    out &lt;&lt; p<span class="Delimiter">-&gt;</span>contents<span class="Delimiter">;</span>
+    <span class="Normal">if</span> <span class="Delimiter">(</span>*--p<span class="Delimiter">-&gt;</span>contents<span class="Delimiter">.</span>end<span class="Delimiter">()</span> != <span class="cSpecial">'\n'</span><span class="Delimiter">)</span> out &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  string result = out<span class="Delimiter">.</span>str<span class="Delimiter">();</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>result<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
+  truncate<span class="Delimiter">(</span>result<span class="Delimiter">);</span>
+  <span class="Identifier">return</span> new_mu_string<span class="Delimiter">(</span>result<span class="Delimiter">);</span>
+<span class="Delimiter">}</span>
+
+<span class="Normal">void</span> truncate<span class="Delimiter">(</span>string&amp; x<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>x<span class="Delimiter">)</span> &gt; <span class="Constant">1024</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    x<span class="Delimiter">.</span>erase<span class="Delimiter">(</span><span class="Constant">1024</span><span class="Delimiter">);</span>
+    *x<span class="Delimiter">.</span>rbegin<span class="Delimiter">()</span> = <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
+    *++x<span class="Delimiter">.</span>rbegin<span class="Delimiter">()</span> = <span class="Constant">'.'</span><span class="Delimiter">;</span>
+    *++++x<span class="Delimiter">.</span>rbegin<span class="Delimiter">()</span> = <span class="Constant">'.'</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+<span class="Delimiter">}</span>
+
+<span class="Comment">//: simpler version of run-sandboxed: doesn't do any running, just loads</span>
+<span class="Comment">//: recipes and reports errors.</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+RELOAD<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;reload&quot;</span><span class="Delimiter">,</span> RELOAD<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+<span class="Normal">case</span> RELOAD: <span class="Delimiter">{</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    raise &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'reload' requires exactly one ingredient, but got '&quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>original_string &lt;&lt; <span class="Constant">&quot;'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Normal">if</span> <span class="Delimiter">(</span>!is_mu_string<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    raise &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'reload' should be a string, but got '&quot;</span> &lt;&lt; inst<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 &lt;&lt; <span class="Constant">&quot;'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+<span class="Normal">case</span> RELOAD: <span class="Delimiter">{</span>
+  <span class="Comment">// conundrum: need to support repeated reloads of the same code, but not</span>
+  <span class="Comment">// wipe out state for the current test</span>
+  <span class="Comment">// hacky solution: subset of restore_snapshots() without restoring recipes {</span>
+  <span class="Comment">// can't yet define containers in a test that runs 'reload'</span>
+  Type_ordinal = Type_ordinal_snapshot<span class="Delimiter">;</span>
+  Type = Type_snapshot<span class="Delimiter">;</span>
+  <span class="Comment">// can't yet create new specializations of shape-shifting recipes in a test</span>
+  <span class="Comment">// that runs 'reload'</span>
+  Recipe_variants = Recipe_variants_snapshot<span class="Delimiter">;</span>
+  Name = Name_snapshot<span class="Delimiter">;</span>
+  <span class="Comment">// }</span>
+  string code = read_mu_string<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>
+  run_code_begin<span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">should_stash_snapshots</span><span class="Comment">*/</span><span class="Constant">false</span><span class="Delimiter">);</span>
+  routine* save_current_routine = Current_routine<span class="Delimiter">;</span>
+  Current_routine = <span class="Constant">NULL</span><span class="Delimiter">;</span>
+  Sandbox_mode = <span class="Constant">true</span><span class="Delimiter">;</span>
+  vector&lt;recipe_ordinal&gt; recipes_reloaded = load<span class="Delimiter">(</span>code<span class="Delimiter">);</span>
+  transform_all<span class="Delimiter">();</span>
+  Trace_stream<span class="Delimiter">-&gt;</span>newline<span class="Delimiter">();</span>  <span class="Comment">// flush trace</span>
+  Sandbox_mode = <span class="Constant">false</span><span class="Delimiter">;</span>
+  Current_routine = save_current_routine<span class="Delimiter">;</span>
+  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</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>trace_error_contents<span class="Delimiter">());</span>
+  run_code_end<span class="Delimiter">();</span>  <span class="Comment">// wait until we're done with the trace contents</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(scenario reload_continues_past_error)</span>
+def main [
+  local-scope
+  <span class="Normal">x</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [recipe foo [
+  get <span class="Constant">1234</span>:number<span class="Delimiter">,</span> foo:offset
+]]
+  reload x
+  <span class="Constant">1</span>:number/<span class="Special">raw &lt;- </span>copy <span class="Constant">34</span>
+]
+<span class="traceContains">+mem: storing 34 in location 1</span>
+
+<span class="Delimiter">:(scenario reload_can_repeatedly_load_container_definitions)</span>
+<span class="Comment"># define a container and try to create it (merge requires knowing container size)</span>
+def main [
+  local-scope
+  <span class="Normal">x</span>:address:array:character<span class="Special"> &lt;- </span><span class="Normal">new</span> [
+    container foo [
+      <span class="Normal">x</span>:number
+      <span class="Normal">y</span>:number
+    ]
+    recipe bar [
+      local-scope
+      <span class="Normal">x</span>:foo<span class="Special"> &lt;- </span>merge <span class="Constant">34</span><span class="Delimiter">,</span> <span class="Constant">35</span>
+    ]
+  ]
+  <span class="Comment"># save warning addresses in locations of type 'number' to avoid spurious changes to them due to 'abandon'</span>
+  <span class="Constant">1</span>:number/<span class="Special">raw &lt;- </span>reload x
+  <span class="Constant">2</span>:number/<span class="Special">raw &lt;- </span>reload x
+]
+<span class="Comment"># no errors on either load</span>
+<span class="traceContains">+mem: storing 0 in location 1</span>
+<span class="traceContains">+mem: storing 0 in location 2</span>
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->