html/044space_surround.cc.html


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<span class="Comment">//: So far you can have global variables by not setting default-space, and</span>
<span class="Comment">//: local variables by setting default-space. You can isolate variables</span>
<span class="Comment">//: between those extremes by creating 'surrounding' spaces.</span>
<span class="Comment">//:</span>
<span class="Comment">//: (Surrounding spaces are like lexical scopes in other languages.)</span>

<span class="Delimiter">:(scenario surrounding_space)</span>
<span class="Comment"># location 1 in space 1 refers to the space surrounding the default space, here 20.</span>
def main [
  <span class="Comment"># pretend shared:array:location; in practice we'll use new</span>
  <span class="Constant">10</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>  <span class="Comment"># refcount</span>
  <span class="Constant">11</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">5</span>  <span class="Comment"># length</span>
  <span class="Comment"># pretend shared:array:location; in practice we'll use new</span>
  <span class="Constant">20</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>  <span class="Comment"># refcount</span>
  <span class="Constant">21</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">5</span>  <span class="Comment"># length</span>
  <span class="Comment"># actual start of this recipe</span>
  <span class="Normal">default</span>-space:address:shared:array:location<span class="Special"> &lt;- </span>copy <span class="Constant">10</span>/unsafe
  <span class="Constant">0</span>:address:shared:array:location/names:dummy<span class="Special"> &lt;- </span>copy <span class="Constant">20</span>/unsafe  <span class="Comment"># later layers will explain the /names: property</span>
  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">32</span>
  <span class="Constant">1</span>:number/space:<span class="Constant">1</span><span class="Special"> &lt;- </span>copy <span class="Constant">33</span>
]
def dummy [  <span class="Comment"># just for the /names: property above</span>
]
<span class="Comment"># chain space: 10 + /*skip refcount*/1 + /*skip length*/1</span>
<span class="traceContains">+mem: storing 20 in location 12</span>
<span class="Comment"># store to default space: 10 + /*skip refcount*/1 + /*skip length*/1 + /*index*/1</span>
<span class="traceContains">+mem: storing 32 in location 13</span>
<span class="Comment"># store to chained space: /*contents of location 12*/20 + /*skip refcount*/1 + /*skip length*/1 + /*index*/1</span>
<span class="traceContains">+mem: storing 33 in location 23</span>

<span class="Comment">//: If you think of a space as a collection of variables with a common</span>
<span class="Comment">//: lifetime, surrounding allows managing shorter lifetimes inside a longer</span>
<span class="Comment">//: one.</span>

<span class="Delimiter">:(replace{} &quot;long long int space_base(const reagent&amp; x)&quot;)</span>
<span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> space_base<span class="Delimiter">(</span><span class="Normal">const</span> reagent&amp; x<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> base = current_call<span class="Delimiter">().</span>default_space ? <span class="Delimiter">(</span>current_call<span class="Delimiter">().</span>default_space+<span class="Comment">/*</span><span class="Comment">skip refcount</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">)</span> : <span class="Constant">0</span><span class="Delimiter">;</span>
  <span class="Identifier">return</span> space_base<span class="Delimiter">(</span>x<span class="Delimiter">,</span> space_index<span class="Delimiter">(</span>x<span class="Delimiter">),</span> base<span class="Delimiter">);</span>
<span class="Delimiter">}</span>

<span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> space_base<span class="Delimiter">(</span><span class="Normal">const</span> reagent&amp; x<span class="Delimiter">,</span> <span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> space_index<span class="Delimiter">,</span> <span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> base<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Normal">if</span> <span class="Delimiter">(</span>space_index == <span class="Constant">0</span><span class="Delimiter">)</span>
    <span class="Identifier">return</span> base<span class="Delimiter">;</span>
  <span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> result = space_base<span class="Delimiter">(</span>x<span class="Delimiter">,</span> space_index-<span class="Constant">1</span><span class="Delimiter">,</span> get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> base+<span class="Comment">/*</span><span class="Comment">skip length</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">))</span>+<span class="Comment">/*</span><span class="Comment">skip refcount</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">;</span>
  <span class="Identifier">return</span> result<span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> space_index<span class="Delimiter">(</span><span class="Normal">const</span> reagent&amp; x<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>x<span class="Delimiter">.</span>properties<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>x<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>first == <span class="Constant">&quot;space&quot;</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
      <span class="Normal">if</span> <span class="Delimiter">(</span>!x<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>second || x<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>second<span class="Delimiter">-&gt;</span>right<span class="Delimiter">)</span>
        raise &lt;&lt; maybe<span class="Delimiter">(</span>current_recipe_name<span class="Delimiter">())</span> &lt;&lt; <span class="Constant">&quot;/space metadata should take exactly one value in &quot;</span> &lt;&lt; x<span class="Delimiter">.</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
      <span class="Identifier">return</span> to_integer<span class="Delimiter">(</span>x<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>second<span class="Delimiter">-&gt;</span>value<span class="Delimiter">);</span>
    <span class="Delimiter">}</span>
  <span class="Delimiter">}</span>
  <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="Delimiter">:(scenario permit_space_as_variable_name)</span>
def main [
  space:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
]
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