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<span class="Comment">//: Exclusive containers contain exactly one of a fixed number of 'variants'</span>
<span class="Comment">//: of different types.</span>
<span class="Comment">//:</span>
<span class="Comment">//: They also implicitly contain a tag describing precisely which variant is</span>
<span class="Comment">//: currently stored in them.</span>
<span class="Delimiter">:(before "End Mu Types Initialization")</span>
<span class="Comment">//: We'll use this container as a running example, with two number elements.</span>
<span class="Delimiter">{</span>
type_ordinal tmp = put<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">"number-or-point"</span><span class="Delimiter">,</span> Next_type_ordinal++<span class="Delimiter">);</span>
get_or_insert<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> tmp<span class="Delimiter">).</span>size = <span class="Constant">2</span><span class="Delimiter">;</span>
get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> tmp<span class="Delimiter">).</span>kind = EXCLUSIVE_CONTAINER<span class="Delimiter">;</span>
get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> tmp<span class="Delimiter">).</span>name = <span class="Constant">"number-or-point"</span><span class="Delimiter">;</span>
get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> tmp<span class="Delimiter">).</span>elements<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>new type_tree<span class="Delimiter">(</span>number<span class="Delimiter">));</span>
get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> tmp<span class="Delimiter">).</span>element_names<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span><span class="Constant">"i"</span><span class="Delimiter">);</span>
get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> tmp<span class="Delimiter">).</span>elements<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>new type_tree<span class="Delimiter">(</span>point<span class="Delimiter">));</span>
get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> tmp<span class="Delimiter">).</span>element_names<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span><span class="Constant">"p"</span><span class="Delimiter">);</span>
<span class="Delimiter">}</span>
<span class="Comment">//: Tests in this layer often explicitly setup memory before reading it as an</span>
<span class="Comment">//: array. Don't do this in general. I'm tagging exceptions with /raw to</span>
<span class="Comment">//: avoid errors.</span>
<span class="Delimiter">:(scenario copy_exclusive_container)</span>
<span class="Comment"># Copying exclusive containers copies all their contents and an extra location for the tag.</span>
recipe main [
<span class="Constant">1</span>:number<span class="Special"> <- </span>copy <span class="Constant">1</span> <span class="Comment"># 'point' variant</span>
<span class="Constant">2</span>:number<span class="Special"> <- </span>copy <span class="Constant">34</span>
<span class="Constant">3</span>:number<span class="Special"> <- </span>copy <span class="Constant">35</span>
<span class="Constant">4</span>:number-or-point<span class="Special"> <- </span>copy <span class="Constant">1</span>:number-or-point/unsafe
]
<span class="traceContains">+mem: storing 1 in location 4</span>
<span class="traceContains">+mem: storing 34 in location 5</span>
<span class="traceContains">+mem: storing 35 in location 6</span>
<span class="Delimiter">:(before "End size_of(type) Cases")</span>
if <span class="Delimiter">(</span>t<span class="Delimiter">.</span>kind == EXCLUSIVE_CONTAINER<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span class="Comment">// size of an exclusive container is the size of its largest variant</span>
<span class="Comment">// (So like containers, it can't contain arrays.)</span>
long long int result = <span class="Constant">0</span><span class="Delimiter">;</span>
for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i < t<span class="Delimiter">.</span>size<span class="Delimiter">;</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
long long int tmp = size_of<span class="Delimiter">(</span>t<span class="Delimiter">.</span>elements<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">));</span>
if <span class="Delimiter">(</span>tmp > result<span class="Delimiter">)</span> result = tmp<span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Comment">// ...+1 for its tag.</span>
<span class="Identifier">return</span> result+<span class="Constant">1</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="SalientComment">//:: To access variants of an exclusive container, use 'maybe-convert'.</span>
<span class="Comment">//: It always returns an address (so that you can modify it) or null (to</span>
<span class="Comment">//: signal that the conversion failed (because the container contains a</span>
<span class="Comment">//: different variant).</span>
<span class="Comment">//: 'maybe-convert' requires a literal in ingredient 1. We'll use a synonym</span>
<span class="Comment">//: called 'variant'.</span>
<span class="Delimiter">:(before "End Mu Types Initialization")</span>
put<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">"variant"</span><span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">);</span>
<span class="Delimiter">:(scenario maybe_convert)</span>
recipe main [
<span class="Constant">12</span>:number<span class="Special"> <- </span>copy <span class="Constant">1</span>
<span class="Constant">13</span>:number<span class="Special"> <- </span>copy <span class="Constant">35</span>
<span class="Constant">14</span>:number<span class="Special"> <- </span>copy <span class="Constant">36</span>
<span class="Constant">20</span>:address:point<span class="Special"> <- </span>maybe-convert <span class="Constant">12</span>:number-or-point/unsafe<span class="Delimiter">,</span> <span class="Constant">1</span>:variant
]
<span class="traceContains">+mem: storing 13 in location 20</span>
<span class="Delimiter">:(scenario maybe_convert_fail)</span>
recipe main [
<span class="Constant">12</span>:number<span class="Special"> <- </span>copy <span class="Constant">1</span>
<span class="Constant">13</span>:number<span class="Special"> <- </span>copy <span class="Constant">35</span>
<span class="Constant">14</span>:number<span class="Special"> <- </span>copy <span class="Constant">36</span>
<span class="Constant">20</span>:address:number<span class="Special"> <- </span>maybe-convert <span class="Constant">12</span>:number-or-point/unsafe<span class="Delimiter">,</span> <span class="Constant">0</span>:variant
]
<span class="traceContains">+mem: storing 0 in location 20</span>
<span class="Delimiter">:(before "End Primitive Recipe Declarations")</span>
MAYBE_CONVERT<span class="Delimiter">,</span>
<span class="Delimiter">:(before "End Primitive Recipe Numbers")</span>
put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">"maybe-convert"</span><span class="Delimiter">,</span> MAYBE_CONVERT<span class="Delimiter">);</span>
<span class="Delimiter">:(before "End Primitive Recipe Checks")</span>
case MAYBE_CONVERT: <span class="Delimiter">{</span>
const recipe& caller = get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">);</span>
if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">2</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
raise_error << maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> << <span class="Constant">"'maybe-convert' expects exactly 2 ingredients in '"</span> << inst<span class="Delimiter">.</span>to_string<span class="Delimiter">()</span> << <span class="Constant">"'</span><span class="cSpecial">\n</span><span class="Constant">"</span> << end<span class="Delimiter">();</span>
<span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
reagent base = inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
canonize_type<span class="Delimiter">(</span>base<span class="Delimiter">);</span>
if <span class="Delimiter">(</span>!base<span class="Delimiter">.</span>type || !base<span class="Delimiter">.</span>type<span class="Delimiter">-></span>value || get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> base<span class="Delimiter">.</span>type<span class="Delimiter">-></span>value<span class="Delimiter">).</span>kind != EXCLUSIVE_CONTAINER<span class="Delimiter">)</span> <span class="Delimiter">{</span>
raise_error << maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> << <span class="Constant">"first ingredient of 'maybe-convert' should be an exclusive-container, but got "</span> << base<span class="Delimiter">.</span>original_string << <span class="cSpecial">'\n'</span> << end<span class="Delimiter">();</span>
<span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
if <span class="Delimiter">(</span>!is_literal<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
raise_error << maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> << <span class="Constant">"second ingredient of 'maybe-convert' should have type 'variant', but got "</span> << inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>original_string << <span class="cSpecial">'\n'</span> << end<span class="Delimiter">();</span>
<span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
if <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Identifier">break</span><span class="Delimiter">;</span>
reagent product = inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
if <span class="Delimiter">(</span>!canonize_type<span class="Delimiter">(</span>product<span class="Delimiter">))</span> <span class="Identifier">break</span><span class="Delimiter">;</span>
const reagent& offset = inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
long long int tag = <span class="Constant">0</span><span class="Delimiter">;</span>
if <span class="Delimiter">(</span>is_integer<span class="Delimiter">(</span>offset<span class="Delimiter">.</span>name<span class="Delimiter">))</span> <span class="Delimiter">{</span>
tag = to_integer<span class="Delimiter">(</span>offset<span class="Delimiter">.</span>name<span class="Delimiter">);</span>
<span class="Delimiter">}</span>
else <span class="Delimiter">{</span>
tag = offset<span class="Delimiter">.</span>value<span class="Delimiter">;</span>
<span class="Delimiter">}</span>
reagent variant = variant_type<span class="Delimiter">(</span>base<span class="Delimiter">,</span> tag<span class="Delimiter">);</span>
variant<span class="Delimiter">.</span>type = new type_tree<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">"address"</span><span class="Delimiter">),</span> variant<span class="Delimiter">.</span>type<span class="Delimiter">);</span>
if <span class="Delimiter">(</span>!types_coercible<span class="Delimiter">(</span>product<span class="Delimiter">,</span> variant<span class="Delimiter">))</span> <span class="Delimiter">{</span>
raise_error << maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> << <span class="Constant">"'maybe-convert "</span> << base<span class="Delimiter">.</span>original_string << <span class="Constant">", "</span> << inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>original_string << <span class="Constant">"' should write to "</span> << debug_string<span class="Delimiter">(</span>variant<span class="Delimiter">.</span>type<span class="Delimiter">)</span> << <span class="Constant">" but "</span> << product<span class="Delimiter">.</span>name << <span class="Constant">" has type "</span> << debug_string<span class="Delimiter">(</span>product<span class="Delimiter">.</span>type<span class="Delimiter">)</span> << <span class="cSpecial">'\n'</span> << 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 "End Primitive Recipe Implementations")</span>
case MAYBE_CONVERT: <span class="Delimiter">{</span>
reagent base = 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>
canonize<span class="Delimiter">(</span>base<span class="Delimiter">);</span>
long long int base_address = base<span class="Delimiter">.</span>value<span class="Delimiter">;</span>
if <span class="Delimiter">(</span>base_address == <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
raise_error << maybe<span class="Delimiter">(</span>current_recipe_name<span class="Delimiter">())</span> << <span class="Constant">"tried to access location 0 in '"</span> << current_instruction<span class="Delimiter">().</span>to_string<span class="Delimiter">()</span> << <span class="Constant">"'</span><span class="cSpecial">\n</span><span class="Constant">"</span> << end<span class="Delimiter">();</span>
<span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
long long int tag = current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>value<span class="Delimiter">;</span>
long long int result<span class="Delimiter">;</span>
if <span class="Delimiter">(</span>tag == static_cast<long long int><span class="Delimiter">(</span>get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> base_address<span class="Delimiter">)))</span> <span class="Delimiter">{</span>
result = base_address+<span class="Constant">1</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
else <span class="Delimiter">{</span>
result = <span class="Constant">0</span><span class="Delimiter">;</span>
<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>result<span class="Delimiter">);</span>
<span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Delimiter">:(code)</span>
const reagent variant_type<span class="Delimiter">(</span>const reagent& canonized_base<span class="Delimiter">,</span> long long int tag<span class="Delimiter">)</span> <span class="Delimiter">{</span>
assert<span class="Delimiter">(</span>tag >= <span class="Constant">0</span><span class="Delimiter">);</span>
assert<span class="Delimiter">(</span>contains_key<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> canonized_base<span class="Delimiter">.</span>type<span class="Delimiter">-></span>value<span class="Delimiter">));</span>
assert<span class="Delimiter">(</span>!get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> canonized_base<span class="Delimiter">.</span>type<span class="Delimiter">-></span>value<span class="Delimiter">).</span>name<span class="Delimiter">.</span>empty<span class="Delimiter">());</span>
const type_info& info = get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> canonized_base<span class="Delimiter">.</span>type<span class="Delimiter">-></span>value<span class="Delimiter">);</span>
assert<span class="Delimiter">(</span>info<span class="Delimiter">.</span>kind == EXCLUSIVE_CONTAINER<span class="Delimiter">);</span>
reagent element<span class="Delimiter">;</span>
element<span class="Delimiter">.</span>type = new type_tree<span class="Delimiter">(</span>*info<span class="Delimiter">.</span>elements<span class="Delimiter">.</span>at<span class="Delimiter">(</span>tag<span class="Delimiter">));</span>
<span class="Comment">// End variant_type Special-cases</span>
<span class="Identifier">return</span> element<span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Delimiter">:(scenario maybe_convert_product_type_mismatch)</span>
<span class="Special">% Hide_errors = true;</span>
recipe main [
<span class="Constant">12</span>:number<span class="Special"> <- </span>copy <span class="Constant">1</span>
<span class="Constant">13</span>:number<span class="Special"> <- </span>copy <span class="Constant">35</span>
<span class="Constant">14</span>:number<span class="Special"> <- </span>copy <span class="Constant">36</span>
<span class="Constant">20</span>:address:number<span class="Special"> <- </span>maybe-convert <span class="Constant">12</span>:number-or-point/unsafe<span class="Delimiter">,</span> <span class="Constant">1</span>:variant
]
<span class="traceContains">+error: main: 'maybe-convert 12:number-or-point/unsafe, 1:variant' should write to <address : <point : <>>> but 20 has type <address : <number : <>>></span>
<span class="SalientComment">//:: Allow exclusive containers to be defined in mu code.</span>
<span class="Delimiter">:(scenario exclusive_container)</span>
exclusive-container foo [
x:number
y:number
]
<span class="traceContains">+parse: --- defining exclusive-container foo</span>
<span class="traceContains">+parse: element name: x</span>
<span class="traceContains">+parse: type: 1</span>
<span class="traceContains">+parse: element name: y</span>
<span class="traceContains">+parse: type: 1</span>
<span class="Delimiter">:(before "End Command Handlers")</span>
else if <span class="Delimiter">(</span>command == <span class="Constant">"exclusive-container"</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
insert_container<span class="Delimiter">(</span>command<span class="Delimiter">,</span> EXCLUSIVE_CONTAINER<span class="Delimiter">,</span> in<span class="Delimiter">);</span>
<span class="Delimiter">}</span>
<span class="SalientComment">//:: To construct exclusive containers out of variant types, use 'merge'.</span>
<span class="Delimiter">:(scenario lift_to_exclusive_container)</span>
exclusive-container foo [
x:number
y:number
]
recipe main [
<span class="Constant">1</span>:number<span class="Special"> <- </span>copy <span class="Constant">34</span>
<span class="Constant">2</span>:foo<span class="Special"> <- </span>merge <span class="Constant">0</span>/x<span class="Delimiter">,</span> <span class="Constant">1</span>:number
<span class="Constant">4</span>:foo<span class="Special"> <- </span>merge <span class="Constant">1</span>/x<span class="Delimiter">,</span> <span class="Constant">1</span>:number
]
<span class="traceContains">+mem: storing 0 in location 2</span>
<span class="traceContains">+mem: storing 34 in location 3</span>
<span class="traceContains">+mem: storing 1 in location 4</span>
<span class="traceContains">+mem: storing 34 in location 5</span>
<span class="Comment">//: Since the different variants of an exclusive-container might have</span>
<span class="Comment">//: different sizes, relax the size mismatch check for 'merge' instructions.</span>
<span class="Delimiter">:(before "End size_mismatch(x) Cases")</span>
if <span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>operation == MERGE
&& !current_instruction<span class="Delimiter">().</span>products<span class="Delimiter">.</span>empty<span class="Delimiter">()</span>
&& current_instruction<span class="Delimiter">().</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>type<span class="Delimiter">)</span> <span class="Delimiter">{</span>
reagent x = current_instruction<span class="Delimiter">().</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
canonize<span class="Delimiter">(</span>x<span class="Delimiter">);</span>
if <span class="Delimiter">(</span>get<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> x<span class="Delimiter">.</span>type<span class="Delimiter">-></span>value<span class="Delimiter">).</span>kind == EXCLUSIVE_CONTAINER<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span class="Identifier">return</span> size_of<span class="Delimiter">(</span>x<span class="Delimiter">)</span> < SIZE<span class="Delimiter">(</span>data<span class="Delimiter">);</span>
<span class="Delimiter">}</span>
<span class="Delimiter">}</span>
<span class="Delimiter">:(scenario merge_exclusive_container_with_mismatched_sizes)</span>
container foo [
x:number
y:number
]
exclusive-container bar [
x:number
y:foo
]
recipe main [
<span class="Constant">1</span>:number<span class="Special"> <- </span>copy <span class="Constant">34</span>
<span class="Constant">2</span>:number<span class="Special"> <- </span>copy <span class="Constant">35</span>
<span class="Constant">3</span>:bar<span class="Special"> <- </span>merge <span class="Constant">0</span>/x<span class="Delimiter">,</span> <span class="Constant">1</span>:number
<span class="Constant">6</span>:bar<span class="Special"> <- </span>merge <span class="Constant">1</span>/foo<span class="Delimiter">,</span> <span class="Constant">1</span>:number<span class="Delimiter">,</span> <span class="Constant">2</span>:number
]
<span class="traceContains">+mem: storing 0 in location 3</span>
<span class="traceContains">+mem: storing 34 in location 4</span>
<span class="Comment"># bar is always 3 large so location 5 is skipped</span>
<span class="traceContains">+mem: storing 1 in location 6</span>
<span class="traceContains">+mem: storing 34 in location 7</span>
<span class="traceContains">+mem: storing 35 in location 8</span>
</pre>
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