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<span class="Comment">//: Introduce a new transform to perform various checks in instructions before</span>
<span class="Comment">//: we start running them. It'll be extensible, so that we can add checks for</span>
<span class="Comment">//: new recipes as we extend 'run' to support them.</span>
<span class="Comment">//:</span>
<span class="Comment">//: Doing checking in a separate part complicates things, because the values</span>
<span class="Comment">//: of variables in memory and the processor (current_recipe_name,</span>
<span class="Comment">//: current_instruction) aren't available at checking time. If I had a more</span>
<span class="Comment">//: sophisticated layer system I'd introduce the simpler version first and</span>
<span class="Comment">//: transform it in a separate layer or set of layers.</span>

<span class="Delimiter">:(before &quot;End Checks&quot;)</span>
Transform<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>check_instruction<span class="Delimiter">);</span>  <span class="Comment">// idempotent</span>

<span class="Delimiter">:(code)</span>
void check_instruction<span class="Delimiter">(</span>const recipe_ordinal r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  trace<span class="Delimiter">(</span><span class="Constant">9991</span><span class="Delimiter">,</span> <span class="Constant">&quot;transform&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;--- perform checks for recipe &quot;</span> &lt;&lt; get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name &lt;&lt; end<span class="Delimiter">();</span>
<span class="CommentedCode">//?   cerr &lt;&lt; &quot;--- perform checks for recipe &quot; &lt;&lt; get(Recipe, r).name &lt;&lt; '\n';</span>
  map&lt;string<span class="Delimiter">,</span> vector&lt;type_ordinal&gt; &gt; metadata<span class="Delimiter">;</span>
  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>steps<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    instruction&amp; inst = get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>steps<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
    if <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>is_label<span class="Delimiter">)</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
    switch <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>operation<span class="Delimiter">)</span> <span class="Delimiter">{</span>
      <span class="Comment">// Primitive Recipe Checks</span>
      case COPY: <span class="Delimiter">{</span>
        if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">)</span> != SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">))</span> <span class="Delimiter">{</span>
          raise_error &lt;&lt; <span class="Constant">&quot;ingredients and products should match in '&quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>to_string<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>
        for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
          if <span class="Delimiter">(</span>!types_coercible<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">),</span> inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)))</span> <span class="Delimiter">{</span>
            raise_error &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;can't copy &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>original_string &lt;&lt; <span class="Constant">&quot; to &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>original_string &lt;&lt; <span class="Constant">&quot;; types don't match</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
            <span class="Identifier">goto</span> finish_checking_instruction<span class="Delimiter">;</span>
          <span class="Delimiter">}</span>
        <span class="Delimiter">}</span>
        <span class="Identifier">break</span><span class="Delimiter">;</span>
      <span class="Delimiter">}</span>
      <span class="Comment">// End Primitive Recipe Checks</span>
      default: <span class="Delimiter">{</span>
        <span class="Comment">// Defined Recipe Checks</span>
        <span class="Comment">// End Defined Recipe Checks</span>
      <span class="Delimiter">}</span>
    <span class="Delimiter">}</span>
    finish_checking_instruction:<span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
<span class="Delimiter">}</span>

<span class="Delimiter">:(scenario copy_checks_reagent_count)</span>
<span class="Special">% Hide_errors = true;</span>
recipe main [
  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">34</span><span class="Delimiter">,</span> <span class="Constant">35</span>
]
<span class="traceContains">+error: ingredients and products should match in '1:number &lt;- copy 34, 35'</span>

<span class="Delimiter">:(scenario write_scalar_to_array_disallowed)</span>
<span class="Special">% Hide_errors = true;</span>
recipe main [
  <span class="Constant">1</span>:array:number<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
]
<span class="traceContains">+error: main: can't copy 34 to 1:array:number; types don't match</span>

<span class="Delimiter">:(scenario write_scalar_to_array_disallowed_2)</span>
<span class="Special">% Hide_errors = true;</span>
recipe main [
  <span class="Constant">1</span>:number<span class="Delimiter">,</span> <span class="Constant">2</span>:array:number<span class="Special"> &lt;- </span>copy <span class="Constant">34</span><span class="Delimiter">,</span> <span class="Constant">35</span>
]
<span class="traceContains">+error: main: can't copy 35 to 2:array:number; types don't match</span>

<span class="Delimiter">:(scenario write_scalar_to_address_disallowed)</span>
<span class="Special">% Hide_errors = true;</span>
recipe main [
  <span class="Constant">1</span>:address:number<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
]
<span class="traceContains">+error: main: can't copy 34 to 1:address:number; types don't match</span>

<span class="Delimiter">:(scenario write_address_to_number_allowed)</span>
<span class="Special">% Hide_errors = true;</span>
recipe main [
  <span class="Constant">1</span>:address:number<span class="Special"> &lt;- </span>copy <span class="Constant">12</span>/unsafe
  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>:address:number
]
<span class="traceContains">+mem: storing 12 in location 2</span>
$error: <span class="Constant">0</span>

<span class="Delimiter">:(code)</span>
<span class="Comment">// types_match with some leniency</span>
bool types_coercible<span class="Delimiter">(</span>const reagent&amp; lhs<span class="Delimiter">,</span> const reagent&amp; rhs<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>types_match<span class="Delimiter">(</span>lhs<span class="Delimiter">,</span> rhs<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>is_mu_address<span class="Delimiter">(</span>rhs<span class="Delimiter">)</span> &amp;&amp; is_mu_number<span class="Delimiter">(</span>lhs<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  <span class="Comment">// End types_coercible Special-cases</span>
  <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

bool types_match<span class="Delimiter">(</span>const reagent&amp; lhs<span class="Delimiter">,</span> const reagent&amp; rhs<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Comment">// to sidestep type-checking, use /unsafe in the source.</span>
  <span class="Comment">// this will be highlighted in red inside vim. just for setting up some tests.</span>
  if <span class="Delimiter">(</span>is_unsafe<span class="Delimiter">(</span>rhs<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>is_literal<span class="Delimiter">(</span>rhs<span class="Delimiter">))</span> <span class="Delimiter">{</span>
    if <span class="Delimiter">(</span>is_mu_array<span class="Delimiter">(</span>lhs<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
    <span class="Comment">// End Matching Types For Literal(lhs)</span>
    <span class="Comment">// allow writing 0 to any address</span>
    if <span class="Delimiter">(</span>is_mu_address<span class="Delimiter">(</span>lhs<span class="Delimiter">))</span> <span class="Identifier">return</span> rhs<span class="Delimiter">.</span>name == <span class="Constant">&quot;0&quot;</span><span class="Delimiter">;</span>
    if <span class="Delimiter">(</span>!lhs<span class="Delimiter">.</span>type<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
    if <span class="Delimiter">(</span>lhs<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value == get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;boolean&quot;</span><span class="Delimiter">))</span>
      <span class="Identifier">return</span> boolean_matches_literal<span class="Delimiter">(</span>lhs<span class="Delimiter">,</span> rhs<span class="Delimiter">);</span>
    <span class="Identifier">return</span> size_of<span class="Delimiter">(</span>lhs<span class="Delimiter">)</span> == <span class="Constant">1</span><span class="Delimiter">;</span>  <span class="Comment">// literals are always scalars</span>
  <span class="Delimiter">}</span>
  <span class="Identifier">return</span> types_strictly_match<span class="Delimiter">(</span>lhs<span class="Delimiter">,</span> rhs<span class="Delimiter">);</span>
<span class="Delimiter">}</span>

bool boolean_matches_literal<span class="Delimiter">(</span>const reagent&amp; lhs<span class="Delimiter">,</span> const reagent&amp; rhs<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>!is_literal<span class="Delimiter">(</span>rhs<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>!lhs<span class="Delimiter">.</span>type<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>lhs<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value != get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;boolean&quot;</span><span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  <span class="Identifier">return</span> rhs<span class="Delimiter">.</span>name == <span class="Constant">&quot;0&quot;</span> || rhs<span class="Delimiter">.</span>name == <span class="Constant">&quot;1&quot;</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="Comment">// copy arguments because later layers will want to make changes to them</span>
<span class="Comment">// without perturbing the caller</span>
bool types_strictly_match<span class="Delimiter">(</span>reagent lhs<span class="Delimiter">,</span> reagent rhs<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>is_literal<span class="Delimiter">(</span>rhs<span class="Delimiter">)</span> &amp;&amp; lhs<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value == get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;number&quot;</span><span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  <span class="Comment">// to sidestep type-checking, use /unsafe in the source.</span>
  <span class="Comment">// this will be highlighted in red inside vim. just for setting up some tests.</span>
  if <span class="Delimiter">(</span>is_unsafe<span class="Delimiter">(</span>rhs<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  <span class="Comment">// '_' never raises type error</span>
  if <span class="Delimiter">(</span>is_dummy<span class="Delimiter">(</span>lhs<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>!lhs<span class="Delimiter">.</span>type<span class="Delimiter">)</span> <span class="Identifier">return</span> !rhs<span class="Delimiter">.</span>type<span class="Delimiter">;</span>
  <span class="Identifier">return</span> types_strictly_match<span class="Delimiter">(</span>lhs<span class="Delimiter">.</span>type<span class="Delimiter">,</span> rhs<span class="Delimiter">.</span>type<span class="Delimiter">);</span>
<span class="Delimiter">}</span>

<span class="Comment">// two types match if the second begins like the first</span>
<span class="Comment">// (trees perform the same check recursively on each subtree)</span>
bool types_strictly_match<span class="Delimiter">(</span>type_tree* lhs<span class="Delimiter">,</span> type_tree* rhs<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>!lhs<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>!rhs<span class="Delimiter">)</span> <span class="Identifier">return</span> lhs<span class="Delimiter">-&gt;</span>value == <span class="Constant">0</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>lhs<span class="Delimiter">-&gt;</span>value != rhs<span class="Delimiter">-&gt;</span>value<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  <span class="Identifier">return</span> types_strictly_match<span class="Delimiter">(</span>lhs<span class="Delimiter">-&gt;</span>left<span class="Delimiter">,</span> rhs<span class="Delimiter">-&gt;</span>left<span class="Delimiter">)</span> &amp;&amp; types_strictly_match<span class="Delimiter">(</span>lhs<span class="Delimiter">-&gt;</span>right<span class="Delimiter">,</span> rhs<span class="Delimiter">-&gt;</span>right<span class="Delimiter">);</span>
<span class="Delimiter">}</span>

bool is_raw<span class="Delimiter">(</span>const reagent&amp; r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Identifier">return</span> has_property<span class="Delimiter">(</span>r<span class="Delimiter">,</span> <span class="Constant">&quot;raw&quot;</span><span class="Delimiter">);</span>
<span class="Delimiter">}</span>

bool is_unsafe<span class="Delimiter">(</span>const reagent&amp; r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Identifier">return</span> has_property<span class="Delimiter">(</span>r<span class="Delimiter">,</span> <span class="Constant">&quot;unsafe&quot;</span><span class="Delimiter">);</span>
<span class="Delimiter">}</span>

bool is_mu_array<span class="Delimiter">(</span>reagent r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>!r<span class="Delimiter">.</span>type<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>is_literal<span class="Delimiter">(</span>r<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  <span class="Identifier">return</span> r<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value == get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;array&quot;</span><span class="Delimiter">);</span>
<span class="Delimiter">}</span>

bool is_mu_address<span class="Delimiter">(</span>reagent r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>!r<span class="Delimiter">.</span>type<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>is_literal<span class="Delimiter">(</span>r<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  <span class="Identifier">return</span> r<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value == get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;address&quot;</span><span class="Delimiter">);</span>
<span class="Delimiter">}</span>

bool is_mu_number<span class="Delimiter">(</span>reagent r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>!r<span class="Delimiter">.</span>type<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>is_literal<span class="Delimiter">(</span>r<span class="Delimiter">))</span>
    <span class="Identifier">return</span> r<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>second<span class="Delimiter">-&gt;</span>value == <span class="Constant">&quot;literal-number&quot;</span>
        || r<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>second<span class="Delimiter">-&gt;</span>value == <span class="Constant">&quot;literal&quot;</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>r<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value == get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;character&quot;</span><span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>  <span class="Comment">// permit arithmetic on unicode code points</span>
  <span class="Identifier">return</span> r<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value == get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;number&quot;</span><span class="Delimiter">);</span>
<span class="Delimiter">}</span>

bool is_mu_scalar<span class="Delimiter">(</span>reagent r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>!r<span class="Delimiter">.</span>type<span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>is_literal<span class="Delimiter">(</span>r<span class="Delimiter">))</span>
    <span class="Identifier">return</span> !r<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>second || r<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>second<span class="Delimiter">-&gt;</span>value != <span class="Constant">&quot;literal-string&quot;</span><span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>is_mu_array<span class="Delimiter">(</span>r<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
  <span class="Identifier">return</span> size_of<span class="Delimiter">(</span>r<span class="Delimiter">)</span> == <span class="Constant">1</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
</pre>
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