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<!--Weave of '5/gt' generated by 7-->
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<ul class="crumbs"><li><a href="../webs.html">★</a></li><li><a href="index.html">if</a></li><li><a href="index.html#5">Chapter 5: Command Grammar</a></li><li><b>Grammar Types</b></li></ul><p class="purpose">Some grammar text specifies one or more values, and we need to keep track of their kind(s). Here we manage the data structure doing this.</p>
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<ul class="toc"><li><a href="#SP1">§1. Definitions</a></li></ul><hr class="tocbar">
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<p class="inwebparagraph"><a id="SP1"></a><b>§1. Definitions. </b></p>
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<pre class="display">
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<span class="reserved">typedef</span><span class="plain"> </span><span class="reserved">struct</span><span class="plain"> </span><span class="reserved">grammar_type</span><span class="plain"> {</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">no_resulting_values</span><span class="plain">; </span> <span class="comment">number of resulting values: 0, 1 or 2; or <code class="display"><span class="extract">-1</span></code></span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="identifier">parse_node</span><span class="plain"> *</span><span class="identifier">first_type</span><span class="plain">; </span> <span class="comment">and their types</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="identifier">parse_node</span><span class="plain"> *</span><span class="identifier">second_type</span><span class="plain">;</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">first_multiplicity</span><span class="plain">; </span> <span class="comment">lines only: allow a multiple object here?</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">second_multiplicity</span><span class="plain">; </span> <span class="comment">lines only: allow a multiple object here?</span>
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<span class="plain">} </span><span class="reserved">grammar_type</span><span class="plain">;</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The structure grammar_type is private to this section.</p>
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<p class="inwebparagraph"><a id="SP2"></a><b>§2. </b></p>
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<pre class="display">
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<span class="reserved">grammar_type</span><span class="plain"> </span><span class="functiontext">PL::Parsing::Tokens::Types::new</span><span class="plain">(</span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">supports_return_type</span><span class="plain">) {</span>
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<span class="reserved">grammar_type</span><span class="plain"> </span><span class="identifier">gty</span><span class="plain">;</span>
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<span class="identifier">gty</span><span class="element">.first_type</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="identifier">gty</span><span class="element">.second_type</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="identifier">gty</span><span class="element">.first_multiplicity</span><span class="plain"> = </span><span class="identifier">FALSE</span><span class="plain">;</span>
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<span class="identifier">gty</span><span class="element">.second_multiplicity</span><span class="plain"> = </span><span class="identifier">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">supports_return_type</span><span class="plain">)</span>
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<span class="identifier">gty</span><span class="element">.no_resulting_values</span><span class="plain"> = 0;</span>
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<span class="reserved">else</span>
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<span class="identifier">gty</span><span class="element">.no_resulting_values</span><span class="plain"> = -1;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">gty</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::new is used in 5/gv (<a href="5-gv.html#SP5">§5</a>), 5/gl (<a href="5-gl.html#SP4">§4</a>).</p>
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<p class="inwebparagraph"><a id="SP3"></a><b>§3. </b>The multiplication by 10 here is explained in the discussion of GSB
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tallying during GL sorting in "Grammar Lines". Do not amend it without
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changing that discussion.
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</p>
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<pre class="display">
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<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">PL::Parsing::Tokens::Types::add_type</span><span class="plain">(</span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty</span><span class="plain">, </span><span class="identifier">parse_node</span><span class="plain"> *</span><span class="identifier">spec</span><span class="plain">,</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">multiple_flag</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">score</span><span class="plain">) {</span>
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<span class="reserved">switch</span><span class="plain">((</span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain">)++) {</span>
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<span class="reserved">case</span><span class="plain"> 0:</span>
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<span class="identifier">gty</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain"> = </span><span class="identifier">spec</span><span class="plain">;</span>
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<span class="identifier">gty</span><span class="plain">-</span><span class="element">>first_multiplicity</span><span class="plain"> = </span><span class="identifier">multiple_flag</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> 10*</span><span class="identifier">score</span><span class="plain">;</span>
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<span class="reserved">case</span><span class="plain"> 1:</span>
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<span class="identifier">gty</span><span class="plain">-</span><span class="element">>second_type</span><span class="plain"> = </span><span class="identifier">spec</span><span class="plain">;</span>
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<span class="identifier">gty</span><span class="plain">-</span><span class="element">>second_multiplicity</span><span class="plain"> = </span><span class="identifier">multiple_flag</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">score</span><span class="plain">;</span>
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<span class="reserved">case</span><span class="plain"> 2:</span>
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<span class="identifier">Problems::Issue::sentence_problem</span><span class="plain">(</span><span class="identifier">_p_</span><span class="plain">(</span><span class="identifier">PM_ThreeValuedLine</span><span class="plain">),</span>
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<span class="string">"there can be at most two varying parts to a line of grammar"</span><span class="plain">,</span>
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<span class="string">"so 'put [something] in [a container]' is allowed but 'put "</span>
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<span class="string">"[something] in [something] beside [a door]' is not."</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="reserved">return</span><span class="plain"> 0;</span>
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<span class="plain">}</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">PL::Parsing::Tokens::Types::has_return_type</span><span class="plain">(</span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain"> == -1) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">PL::Parsing::Tokens::Types::get_no_resulting_values</span><span class="plain">(</span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty</span><span class="plain">) {</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="identifier">parse_node</span><span class="plain"> *</span><span class="functiontext">PL::Parsing::Tokens::Types::get_single_type</span><span class="plain">(</span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty</span><span class="plain">) {</span>
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<span class="reserved">switch</span><span class="plain">(</span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain">) {</span>
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<span class="reserved">case</span><span class="plain"> 0: </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="reserved">case</span><span class="plain"> 1: </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain">;</span>
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<span class="reserved">default</span><span class="plain">: </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"gty improperly typed"</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">PL::Parsing::Tokens::Types::set_single_type</span><span class="plain">(</span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty</span><span class="plain">, </span><span class="identifier">parse_node</span><span class="plain"> *</span><span class="identifier">spec</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">spec</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain"> = 0;</span>
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<span class="reserved">else</span><span class="plain"> {</span>
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<span class="identifier">gty</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain"> = 1;</span>
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<span class="identifier">gty</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain"> = </span><span class="identifier">spec</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="plain">}</span>
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">PL::Parsing::Tokens::Types::compile_to_string</span><span class="plain">(</span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty</span><span class="plain">) {</span>
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<span class="identifier">Specifications::Compiler::emit_as_val</span><span class="plain">(</span><span class="identifier">K_value</span><span class="plain">, </span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="identifier">kind</span><span class="plain"> *</span><span class="functiontext">PL::Parsing::Tokens::Types::get_data_type_as_token</span><span class="plain">(</span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain"> > 0) {</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">ParseTree::is</span><span class="plain">(</span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain">, </span><span class="identifier">CONSTANT_NT</span><span class="plain">)) ||</span>
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<span class="plain">(</span><span class="identifier">Specifications::is_description</span><span class="plain">(</span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain">)))</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">Specifications::to_kind</span><span class="plain">(</span><span class="identifier">gty</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::add_type is used in 5/gl (<a href="5-gl.html#SP15">§15</a>).</p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::has_return_type is used in 5/gv (<a href="5-gv.html#SP25">§25</a>).</p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::get_no_resulting_values is used in 5/gl (<a href="5-gl.html#SP15">§15</a>).</p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::get_single_type is used in 5/gv (<a href="5-gv.html#SP25">§25</a>), 5/gl (<a href="5-gl.html#SP15">§15</a>).</p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::set_single_type is used in 5/gv (<a href="5-gv.html#SP25">§25</a>), 5/gl (<a href="5-gl.html#SP4">§4</a>).</p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::compile_to_string is used in 5/gl (<a href="5-gl.html#SP20">§20</a>).</p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::get_data_type_as_token is used in 5/gv (<a href="5-gv.html#SP21">§21</a>).</p>
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<p class="inwebparagraph"><a id="SP4"></a><b>§4. </b>The behaviour of this sorting routine is documented in the discussion
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of GL sorting in "Grammar Lines". Do not amend it without changing that
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discussion.
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</p>
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<pre class="display">
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<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">PL::Parsing::Tokens::Types::must_precede</span><span class="plain">(</span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty1</span><span class="plain">, </span><span class="reserved">grammar_type</span><span class="plain"> *</span><span class="identifier">gty2</span><span class="plain">) {</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">cs</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain">) < (</span><span class="identifier">gty2</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain">) > (</span><span class="identifier">gty2</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain"> == 0) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">NOT_APPLICABLE</span><span class="plain">;</span>
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<span class="identifier">cs</span><span class="plain"> = </span><span class="identifier">Specifications::compare_specificity</span><span class="plain">(</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain">, </span><span class="identifier">gty2</span><span class="plain">-</span><span class="element">>first_type</span><span class="plain">, </span><span class="identifier">NULL</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">cs</span><span class="plain"> == 1) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">cs</span><span class="plain"> == -1) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>first_multiplicity</span><span class="plain">) && (</span><span class="identifier">gty2</span><span class="plain">-</span><span class="element">>first_multiplicity</span><span class="plain"> == </span><span class="identifier">FALSE</span><span class="plain">))</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>first_multiplicity</span><span class="plain"> == </span><span class="identifier">FALSE</span><span class="plain">) && (</span><span class="identifier">gty2</span><span class="plain">-</span><span class="element">>first_multiplicity</span><span class="plain">))</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>no_resulting_values</span><span class="plain"> == 1) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">NOT_APPLICABLE</span><span class="plain">;</span>
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<span class="identifier">cs</span><span class="plain"> = </span><span class="identifier">Specifications::compare_specificity</span><span class="plain">(</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>second_type</span><span class="plain">, </span><span class="identifier">gty2</span><span class="plain">-</span><span class="element">>second_type</span><span class="plain">, </span><span class="identifier">NULL</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">cs</span><span class="plain"> == 1) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">cs</span><span class="plain"> == -1) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>second_multiplicity</span><span class="plain">) && (</span><span class="identifier">gty2</span><span class="plain">-</span><span class="element">>second_multiplicity</span><span class="plain"> == </span><span class="identifier">FALSE</span><span class="plain">))</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">gty1</span><span class="plain">-</span><span class="element">>second_multiplicity</span><span class="plain"> == </span><span class="identifier">FALSE</span><span class="plain">) && (</span><span class="identifier">gty2</span><span class="plain">-</span><span class="element">>second_multiplicity</span><span class="plain">))</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">NOT_APPLICABLE</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The function PL::Parsing::Tokens::Types::must_precede is used in 5/gl (<a href="5-gl.html#SP17">§17</a>).</p>
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<hr class="tocbar">
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<ul class="toc"><li><a href="5-gl.html">Back to 'Grammar Lines'</a></li><li><a href="5-gt2.html">Continue with 'Grammar Tokens'</a></li></ul><hr class="tocbar">
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