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POUsing different case keywords in ANTLR grammar
 

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  1. POUsing different case keywords in ANTLR grammar
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    <p>Some keywords (string constant) in my grammar contain capital letters e.g. </p> <pre><code>PREV_VALUE : 'PreviousValue'; </code></pre> <p>This causes strange parsing behavior: other tokens that contain same capital letters ('P','V') are parsed incorrectly.</p> <p>Here's a simplified version of the lexer grammar:</p> <pre><code>lexer grammar ExpressionLexer; COMMA : ','; LPAREN : '('; RPAREN : ')'; LBRACK : '['; RBRACK : ']'; PLUS : '+'; MINUS : '-'; MULT : '*'; DIV : '/'; PREV_VALUE : 'PreviousValue'; fragment DIGIT : ('0'..'9'); fragment LETTER : ('a'..'z'|'A'..'Z'|'_'); fragment TAB : ('\t') ; fragment NEWLINE : ('\r'|'\n') ; fragment SPACE : (' ') ; </code></pre> <p>When I try parsing such expression:</p> <pre><code>var expression = "P"; //Capital 'P' which included to the keyword 'PreviousValue' var stringReader = new StringReader(expression); var input = new ANTLRReaderStream(stringReader); var expressionLexer = new ExpressionLexer(input); var tokens = new CommonTokenStream(expressionLexer); </code></pre> <p><code>tokens._tokens</code> collection contains one value</p> <pre><code>[0] = {[@0,1:1='&lt;EOF&gt;',&lt;-1&gt;,1:1]} </code></pre> <p>It's incorrect.</p> <p>If I change <code>expression</code> to 'p' (lowercase letter) <code>tokens._tokens</code> collection contains two values</p> <pre><code>[0] = {[@0,0:0='p',&lt;0&gt;,1:0]} [1] = {[@1,1:1='&lt;EOF&gt;',&lt;-1&gt;,1:1]} </code></pre> <p>It's correct.</p> <p>When string <code>PREV_VALUE : 'PreviousValue';</code> is removed from grammar, both expressions are parsed correctly.</p> <p>Is it possible to use different case in keywords? Is there any example of using such keywords in ANTLR grammar?</p>
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    1. USVilla F.
    1. USVilla F.
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    1. COSorry for the confusion I've edited my initial post. Hope that clears it up.
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      1. POUsing different case keywords in ANTLR grammar
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