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<!doctype html>
<html>
<head>
<title>CodeMirror: EBNF Mode</title>
<meta charset="utf-8"/>
<link rel=stylesheet href="../../doc/docs.css">
<link rel="stylesheet" href="../../lib/codemirror.css">
<script src="../../lib/codemirror.js"></script>
<script src="../javascript/javascript.js"></script>
<script src="ebnf.js"></script>
<style>.CodeMirror {border-top: 1px solid black; border-bottom: 1px solid black;}</style>
</head>
<body>
<div id=nav>
<a href="https://codemirror.net/5"><h1>CodeMirror</h1><img id=logo src="../../doc/logo.png" alt=""></a>
<ul>
<li><a href="../../index.html">Home</a>
<li><a href="../../doc/manual.html">Manual</a>
<li><a href="https://github.com/codemirror/codemirror5">Code</a>
</ul>
<ul>
<li><a href="../index.html">Language modes</a>
<li><a class=active href="#">EBNF Mode</a>
</ul>
</div>
<article>
<h2>EBNF Mode (bracesMode setting = "javascript")</h2>
<form><textarea id="code" name="code">
/* description: Parses end executes mathematical expressions. */
/* lexical grammar */
%lex
%%
\s+ /* skip whitespace */
[0-9]+("."[0-9]+)?\b return 'NUMBER';
"*" return '*';
"/" return '/';
"-" return '-';
"+" return '+';
"^" return '^';
"(" return '(';
")" return ')';
"PI" return 'PI';
"E" return 'E';
<<EOF>> return 'EOF';
/lex
/* operator associations and precedence */
%left '+' '-'
%left '*' '/'
%left '^'
%left UMINUS
%start expressions
%% /* language grammar */
expressions
: e EOF
{print($1); return $1;}
;
e
: e '+' e
{$$ = $1+$3;}
| e '-' e
{$$ = $1-$3;}
| e '*' e
{$$ = $1*$3;}
| e '/' e
{$$ = $1/$3;}
| e '^' e
{$$ = Math.pow($1, $3);}
| '-' e %prec UMINUS
{$$ = -$2;}
| '(' e ')'
{$$ = $2;}
| NUMBER
{$$ = Number(yytext);}
| E
{$$ = Math.E;}
| PI
{$$ = Math.PI;}
;</textarea></form>
<script>
var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
mode: {name: "ebnf"},
lineNumbers: true,
bracesMode: 'javascript'
});
</script>
<h3>The EBNF Mode</h3>
<p> Created by <a href="https://github.com/robertleeplummerjr">Robert Plummer</a></p>
</article>
</body>
</html>