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POMultiple alternatives with the same label, only the last gets anything assigned to it
 

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  1. POMultiple alternatives with the same label, only the last gets anything assigned to it
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    <p>I have some non-reserved keywords I'm matching with rules like:</p> <pre><code>kFOO = {self.input.LT(1).text.lower() == 'foo'}? ID; </code></pre> <p>Where the <code>ID</code> token is a standard alpha-numeric string. These kinds of rules work great, except when I try to do something like this:</p> <pre><code>some_rule @after { do_something_with($t.text) } : t=kWORD1 | t=kWORD2 | t=kWORD3 ; </code></pre> <p>In the generated parser, the <code>kWORD1</code> and <code>kWORD2</code> rule functions don't return anything, but the <code>kWORD3</code> function does. As well, in the <code>some_rule</code> function, only the block trying to match <code>kWORD3</code> assign the return value to <code>t</code>. The other two invocations don't reference <code>t</code> in any way.</p> <p>(Also, I expected the following to work, but it did not, I suspect for the same underlying reason.</p> <pre><code>some_rule @after { do_something_with($t.text) } : t=( kWORD1 | kWORD2 | kWORD3) ; </code></pre> <p>Nothing gets assigned to <code>t</code> under any conditions.)</p> <p>However, the following DOES work as expected:</p> <pre><code>some_rule @after { do_something_with($t1.text or $t2.text or $t3.text) } : t1=kWORD1 | t2=kWORD2 | t3=kWORD3 ; </code></pre> <p>Each of the matching functions is generated to return a value, and each of the blocks matching the keyword rules in <code>some_rule</code> assigns the return value to their label. The problem with this solution is it gets a little excessive when there are several more alternatives.</p> <p>Half of me cries "BUG!" but this is the first antlr project I've done, so more likely there's something I don't understand.</p> <p>What's the best way to do what it is I'm trying to do here?</p>
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    1. USGlenn Moss
    1. USGlenn Moss
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    1. COFWIW I see the same behavior in the C target.
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    2. COYeah, I don't think this is a target-dependent issue.
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      1. USGlenn Moss
 

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