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POHow do I lex this input?
 

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  1. POHow do I lex this input?
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    <p>I currently have a working, simple language implemented in Java using ANTLR. What I want to do is embed it in plain text, in a similar fashion to PHP.</p> <p>For example:</p> <pre><code>Lorem ipsum dolor sit amet &lt;% print('consectetur adipiscing elit'); %&gt; Phasellus volutpat dignissim sapien. </code></pre> <p>I anticipate that the resulting token stream would look something like:</p> <pre><code>CDATA OPEN PRINT OPAREN APOS STRING APOS CPAREN SEMI CLOSE CDATA </code></pre> <p>How can I achieve this, or is there a better way?</p> <p>There is no restriction on what might be outside the <code>&lt;%</code> block. I assumed something like <code>&lt;% print('%&gt;'); %&gt;</code>, as per Michael Mrozek's answer, would be possible, but outside of a situation like that, <code>&lt;%</code> would always indicate the start of a code block.</p> <hr> <h2>Sample Implementation</h2> <p>I developed a solution based on ideas given in Michael Mrozek's answer, simulating Flex's start conditions using ANTLR's gated semantic predicates:</p> <pre><code>lexer grammar Lexer; @members { boolean codeMode = false; } OPEN : {!codeMode}?=&gt; '&lt;%' { codeMode = true; } ; CLOSE : {codeMode}?=&gt; '%&gt;' { codeMode = false;} ; LPAREN : {codeMode}?=&gt; '('; //etc. CHAR : {!codeMode}?=&gt; ~('&lt;%'); parser grammar Parser; options { tokenVocab = Lexer; output = AST; } tokens { VERBATIM; } program : (code | verbatim)+ ; code : OPEN statement+ CLOSE -&gt; statement+ ; verbatim : CHAR -&gt; ^(VERBATIM CHAR) ; </code></pre>
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    1. COSo you only want to create a grammar that tokenizes the part between `<%` and `%>` ignoring everything else?
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    2. COI don't want to ignore it completely; I'd like to echo it back verbatim.
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    3. COAre there any restrictions on what may occur outside the `<%` and `%>`'s, or can it take any form? Can comments occur outside them (that can potentially contain either `<%` or `%>`)?
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